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AGNThermal2018.bib
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@book{meece_jr_agn_2016,
title = {{{AGN}} Feedback and Delivery Methods for Simulations of Cool-Core Galaxy Clusters},
publisher = {{Michigan State University}},
author = {Meece Jr, Gregory Robert},
year = {2016},
file = {/home/forrest/MSU/research/zotfiles/AGN/Meece Jr_2016_AGN feedback and delivery methods for simulations of cool-core galaxy clusters.pdf}
}
@article{meece_triggering_2017,
title = {Triggering and {{Delivery Algorithms}} for {{AGN Feedback}}},
volume = {841},
number = {133},
journal = {The Astrophysical Journal},
author = {Meece, Gregory R. and Voit, G. Mark and O'Shea, Brian W.},
year = {2017},
pages = {17pp},
file = {/home/forrest/MSU/research/zotfiles/AGN/Meece et al_2017_Triggering and Delivery Algorithms for AGN Feedback.pdf}
}
@article{gaspari_unifying_2017,
title = {Unifying the {{Micro}} and {{Macro Properties}} of {{AGN Feeding}} and {{Feedback}}},
volume = {837},
issn = {0004-637X},
doi = {10.3847/1538-4357/aa61a3},
abstract = {We unify the feeding and feedback of supermassive black holes with the global properties of galaxies, groups, and clusters by linking for the first time the physical mechanical efficiency at the horizon and megaparsec scale. The macro hot halo is tightly constrained by the absence of overheating and overcooling as probed by X-ray data and hydrodynamic simulations ( \#\#IMG\#\# [http://ej.iop.org/images/0004-637X/837/2/149/apjaa61a3ieqn1.gif] \$$\backslash$varepsilon \_$\backslash$mathrmBH$\backslash$simeq 10\^-3$\backslash$,T\_$\backslash$rmx,7.4\$ ). The micro flow is shaped by general-relativistic effects tracked by state-of-the-art GR-RMHD simulations ( \#\#IMG\#\# [http://ej.iop.org/images/0004-637X/837/2/149/apjaa61a3ieqn2.gif] \$$\backslash$varepsilon \_$\backslash$bullet $\backslash$simeq 0.03\$ ). The supermassive black hole properties are tied to the X-ray halo temperature \#\#IMG\#\# [http://ej.iop.org/images/0004-637X/837/2/149/apjaa61a3ieqn3.gif] \$T\_$\backslash$rmx\$ , or related cosmic scaling relation (as \#\#IMG\#\# [http://ej.iop.org/images/0004-637X/837/2/149/apjaa61a3ieqn4.gif] \$L\_$\backslash$rmx\$ ). The model is minimally based on first principles, such as conservation of energy and mass recycling. The inflow occurs via chaotic cold accretion (CCA), the rain of cold clouds condensing out of the quenched cooling flow and then recurrently funneled via inelastic collisions. Within 100s gravitational radii, the accretion energy is transformed into ultrafast 10 4 km s -1 outflows (UFOs) ejecting most of the inflowing mass. At larger radii, the energy-driven outflow entrains progressively more mass: at roughly kiloparsec scale, the velocities of the hot/warm/cold outflows are a few 10 3 , 1000, and 500 km s -1 , with median mass rates $\sim$ 10, 100, and several 100 \#\#IMG\#\# [http://ej.iop.org/images/0004-637X/837/2/149/apjaa61a3ieqn5.gif] \$M\_\o{}dot \$ yr -1 , respectively. The unified CCA model is consistent with the observations of nuclear UFOs and ionized, neutral, and molecular macro outflows. We provide step-by-step implementation for subgrid simulations, (semi)analytic works, or observational interpretations that require self-regulated AGN feedback at coarse scales, avoiding the a-posteriori fine-tuning of efficiencies.},
language = {en},
number = {2},
journal = {The Astrophysical Journal},
author = {Gaspari, Massimo and S\k{a}dowski, Aleksander},
year = {2017},
pages = {149},
file = {/home/forrest/MSU/research/zotfiles/AGN/Gaspari_Sądowski_2017_Unifying the Micro and Macro Properties of AGN Feeding and Feedback.pdf}
}
@article{voit_regulation_2015-1,
title = {Regulation of Star Formation in Giant Galaxies by Precipitation, Feedback and Conduction},
volume = {519},
copyright = {2015 Nature Publishing Group},
issn = {1476-4687},
doi = {10.1038/nature14167},
abstract = {Mark Voit \emph{et al}. present simulations of galaxy cooling that confirm models in which cold clouds precipitate out of hot gas via thermal instability. The precipitation threshold extends over a large range in cluster radius, cluster mass, and cosmic time. The authors compare their simulations to observations to explain the thermodynamic state of hot gas in galaxy clusters and how star formation rates in the largest galaxies in the Universe are regulated.$<$/p$>$},
language = {En},
number = {7542},
journal = {Nature},
author = {Voit, G. M. and Donahue, M. and Bryan, G. L. and McDonald, M.},
month = mar,
year = {2015},
keywords = {Entropy,Environmental Studies,Sciences: Comprehensive Works,Star \& galaxy formation,Stars \& galaxies},
pages = {203},
file = {/home/forrest/MSU/research/zotfiles/MyPapers/AGNThermal2018/Voit et al_2015_Regulation of star formation in giant galaxies by precipitation, feedback and.pdf;/home/forrest/Zotero/storage/ECL9ZUXI/nature14167.html}
}
@article{kirkpatrick_chandra_2009,
title = {A {{Chandra X}}-{{Ray Analysis}} of {{Abell}} 1664: {{Cooling}}, {{Feedback}}, and {{Star Formation}} in the {{Central Cluster Galaxy}}},
volume = {697},
issn = {0004-637X},
shorttitle = {A {{Chandra X}}-{{Ray Analysis}} of {{Abell}} 1664},
doi = {10.1088/0004-637X/697/1/867},
abstract = {The brightest cluster galaxy (BCG) in the Abell 1664 cluster is
unusually blue and is forming stars at a rate of \textasciitilde{} 23 M sun
yr-1. The BCG is located within 5 kpc of the X-ray peak,
where the cooling time of 3.5 \texttimes{} 108 yr and entropy of
10.4 keV cm2 are consistent with other star-forming BCGs in
cooling flow clusters. The center of A1664 has an elongated, "barlike"
X-ray structure whose mass is comparable to the mass of molecular
hydrogen, \textasciitilde{}1010 M sun in the BCG. We show that
this gas is unlikely to have been stripped from interloping galaxies.
The cooling rate in this region is roughly consistent with the star
formation rate, suggesting that the hot gas is condensing onto the BCG.
We use the scaling relations of B\^irzan et al. to show that the
active galactic nucleus (AGN) is underpowered compared to the central
X-ray cooling luminosity by roughly a factor of three. We suggest that
A1664 is experiencing rapid cooling and star formation during a low
state of an AGN feedback cycle that regulates the rates of cooling and
star formation. Modeling the emission as a single-temperature plasma, we
find that the metallicity peaks 100 kpc from the X-ray center, resulting
in a central metallicity dip. However, a multi-temperature cooling flow
model improves the fit to the X-ray emission and is able to recover the
expected, centrally peaked metallicity profile.},
journal = {The Astrophysical Journal},
author = {Kirkpatrick, C. C. and McNamara, B. R. and Rafferty, D. A. and Nulsen, P. E. J. and B\^irzan, L. and Kazemzadeh, F. and Wise, M. W. and Gitti, M. and Cavagnolo, K. W.},
month = may,
year = {2009},
keywords = {cooling flows,galaxies: clusters: individual: A1664,galaxies: starburst,X-rays: galaxies: clusters},
pages = {867-879},
file = {/home/forrest/MSU/research/zotfiles/ChandraX-ray/Kirkpatrick et al_2009_A Chandra X-Ray Analysis of Abell 1664.pdf}
}
@article{cavagnolo_intracluster_2009,
title = {Intracluster {{Medium Entropy Profiles}} for a {{Chandra Archival Sample}} of {{Galaxy Clusters}}},
volume = {182},
issn = {0067-0049},
doi = {10.1088/0067-0049/182/1/12},
abstract = {We present radial entropy profiles of the intracluster medium (ICM) for
a collection of 239 clusters taken from the Chandra X-ray Observatory's
Data Archive. Entropy is of great interest because it controls ICM
global properties and records the thermal history of a cluster. Entropy
is therefore a useful quantity for studying the effects of feedback on
the cluster environment and investigating any breakdown of cluster
self-similarity. We find that most ICM entropy profiles are well fitted
by a model which is a power law at large radii and approaches a constant
value at small radii: K(r) = K 0 + K 100(r/100
kpc)$\alpha$, where K 0 quantifies the typical
excess of core entropy above the best-fitting power law found at larger
radii. We also show that the K 0 distributions of both the
full archival sample and the primary Highest X-Ray Flux Galaxy Cluster
Sample of Reiprich (2001) are bimodal with a distinct gap between K
0 $\approx$ 30-50 keV cm2 and population peaks at K
0 \textasciitilde{} 15 keV cm2 and K 0 \textasciitilde{} 150 keV
cm2. The effects of point-spread function smearing and
angular resolution on best-fit K 0 values are investigated
using mock Chandra observations and degraded entropy profiles,
respectively. We find that neither of these effects is sufficient to
explain the entropy-profile flattening we measure at small radii. The
influence of profile curvature and number of radial bins on best-fit K
0 is also considered, and we find no indication that K
0 is significantly impacted by either. For completeness, we
include previously unpublished optical spectroscopy of H$\alpha$ and [N
II] emission lines discussed in Cavagnolo et al. (2008a). All data and
results associated with this work are publicly available via the project
Web site.},
journal = {The Astrophysical Journal Supplement Series},
author = {Cavagnolo, Kenneth W. and Donahue, Megan and Voit, G. Mark and Sun, Ming},
month = may,
year = {2009},
keywords = {cooling flows,X-rays: galaxies: clusters,astronomical data bases: miscellaneous,X-rays: general},
pages = {12-32},
file = {/home/forrest/MSU/research/zotfiles/ChandraX-ray/Cavagnolo et al_2009_Intracluster Medium Entropy Profiles for a Chandra Archival Sample of Galaxy.pdf},
annote = {shows entropy profiles from a collection of\\
cluster observed using Chandra data showing a broken power law and entropy\\
flattening towards the center of the cluster (consider plotting on top of\\
these.)}
}
@article{bryan_enzo_2014-1,
title = {{{ENZO}}: {{An Adaptive Mesh Refinement Code}} for {{Astrophysics}}},
volume = {211},
issn = {0067-0049},
shorttitle = {{{ENZO}}},
doi = {10.1088/0067-0049/211/2/19},
abstract = {This paper describes the open-source code Enzo, which uses block-structured adaptive mesh refinement to provide high spatial and temporal resolution for modeling astrophysical fluid flows. The code is Cartesian, can be run in one, two, and three dimensions, and supports a wide variety of physics including hydrodynamics, ideal and non-ideal magnetohydrodynamics, N-body dynamics (and, more broadly, self-gravity of fluids and particles), primordial gas chemistry, optically thin radiative cooling of primordial and metal-enriched plasmas (as well as some optically-thick cooling models), radiation transport, cosmological expansion, and models for star formation and feedback in a cosmological context. In addition to explaining the algorithms implemented, we present solutions for a wide range of test problems, demonstrate the code's parallel performance, and discuss the Enzo collaboration's code development methodology.},
journal = {The Astrophysical Journal Supplement Series},
author = {Bryan, Greg L. and Norman, Michael L. and O'Shea, Brian W. and Abel, Tom and Wise, John H. and Turk, Matthew J. and Reynolds, Daniel R. and Collins, David C. and Wang, Peng and Skillman, Samuel W. and Smith, Britton and Harkness, Robert P. and Bordner, James and Kim, Ji-hoon and Kuhlen, Michael and Xu, Hao and Goldbaum, Nathan and Hummels, Cameron and Kritsuk, Alexei G. and Tasker, Elizabeth and Skory, Stephen and Simpson, Christine M. and Hahn, Oliver and Oishi, Jeffrey S. and So, Geoffrey C. and Zhao, Fen and Cen, Renyue and Li, Yuan and {Enzo Collaboration}},
month = apr,
year = {2014},
keywords = {hydrodynamics,methods: numerical},
pages = {19},
file = {/home/forrest/Zotero/storage/VHZNYTAE/Bryan et al. - 2014 - ENZO An Adaptive Mesh Refinement Code for Astroph.pdf}
}
@article{li_cooling_2015,
title = {Cooling, {{AGN Feedback}}, and {{Star Formation}} in {{Simulated Cool}}-Core {{Galaxy Clusters}}},
volume = {811},
issn = {0004-637X},
doi = {10.1088/0004-637X/811/2/73},
abstract = {Numerical simulations of active galactic nuclei (AGNs) feedback in
cool-core galaxy clusters have successfully avoided classical cooling
flows, but often produce too much cold gas. We perform adaptive mesh
simulations that include momentum-driven AGN feedback, self-gravity,
star formation, and stellar feedback, focusing on the interplay between
cooling, AGN heating, and star formation in an isolated cool-core
cluster. Cold clumps triggered by AGN jets and turbulence form
filamentary structures tens of kpc long. This cold gas feeds both star
formation and the supermassive black hole (SMBH), triggering an AGN
outburst that increases the entropy of the intracluster medium (ICM) and
reduces its cooling rate. Within 1-2 Gyr, star formation
completely consumes the cold gas, leading to a brief shutoff of the AGN.
The ICM quickly cools and redevelops multiphase gas, followed by another
cycle of star formation/AGN outburst. Within 6.5 Gyr, we observe three
such cycles. There is good agreement between our simulated cluster and
the observations of cool-core clusters. ICM cooling is dynamically
balanced by AGN heating, and a cool-core appearance is preserved. The
minimum cooling time to free-fall time ratio typically varies between a
few and $\greaterequivlnt$ 20. The star formation rate (SFR) covers a wide range,
from 0 to a few hundred \{M\}$\odot$ \{\{yr\}\}-1, with
an average of \texttildelow{} 40 \{M\}$\odot$ \{\{yr\}\}-1. The
instantaneous SMBH accretion rate shows large variations on short
timescales, but the average value correlates well with the SFR.
Simulations without stellar feedback or self-gravity produce
qualitatively similar results, but a lower SMBH feedback efficiency
(0.1\% compared to 1\%) results in too many stars.},
journal = {The Astrophysical Journal},
author = {Li, Yuan and Bryan, Greg L. and Ruszkowski, Mateusz and Voit, G. Mark and O'Shea, Brian W. and Donahue, Megan},
month = oct,
year = {2015},
keywords = {hydrodynamics,galaxies: clusters: general,galaxies: clusters: intracluster medium},
pages = {73},
file = {/home/forrest/MSU/research/zotfiles/AGN/Li et al_2015_Cooling, AGN Feedback, and Star Formation in Simulated Cool-core Galaxy Clusters.pdf},
annote = {Adaptive mesh simulations with momentum-driven AGN feedback goes through AGN\\
cycles with shutoff periods.}
}
@article{voit_global_2017,
title = {A {{Global Model}} for {{Circumgalactic}} and {{Cluster}}-Core {{Precipitation}}},
volume = {845},
issn = {0004-637X},
doi = {10.3847/1538-4357/aa7d04},
abstract = {We provide an analytic framework for interpreting observations of multiphase circumgalactic gas that is heavily informed by recent numerical simulations of thermal instability and precipitation in cool-core galaxy clusters. We start by considering the local conditions required for the formation of multiphase gas via two different modes: (1) uplift of ambient gas by galactic outflows, and (2) condensation in a stratified stationary medium in which thermal balance is explicitly maintained. Analytic exploration of these two modes provides insights into the relationships between the local ratio of the cooling and freefall timescales (I.e., \{t\}\{cool\}/\{t\}\{ff\}), the large-scale gradient of specific entropy, and the development of precipitation and multiphase media in circumgalactic gas. We then use these analytic findings to interpret recent simulations of
circumgalactic gas in which global thermal balance is maintained. We show that long-lasting configurations of gas with 5$\lessequivlnt$ $\backslash$min
(\{t\}\{cool\}/\{t\}\{ff\})$\lessequivlnt$ 20 and radial entropy profiles similar to observations of cool cores in galaxy clusters are a natural outcome of precipitation-regulated feedback. We conclude with some observational predictions that follow from these models. This work focuses primarily on precipitation and AGN feedback in galaxy-cluster cores, because that is where the observations of multiphase gas around galaxies are most complete. However, many of the physical principles that govern condensation in those environments apply to circumgalactic gas around galaxies of all masses.},
journal = {The Astrophysical Journal},
author = {Voit, G. Mark and Meece, Greg and Li, Yuan and O'Shea, Brian W. and Bryan, Greg L. and Donahue, Megan},
month = aug,
year = {2017},
keywords = {galaxies: active,galaxies: clusters: intracluster medium,cD,galaxies: elliptical and lenticular,galaxies: evolution,galaxies: halos},
pages = {80},
file = {/home/forrest/MSU/research/zotfiles/AGN/Voit et al_2016_A Global Model For Circumgalactic and Cluster-Core Precipitation.pdf;/home/forrest/MSU/research/zotfiles/AGN/Voit et al_2016_A Global Model For Circumgalactic and Cluster-Core Precipitation.pdf;/home/forrest/Zotero/storage/HTAUFP6Q/1607.html},
annote = {Heating to counteract cooling via accretion of cold gas onto AGN. Preciptation\\
at a large radius}
}
@article{fabian_subsonic_1977,
title = {Subsonic Accretion of Cooling Gas in Clusters of Galaxies},
volume = {180},
issn = {0035-8711},
doi = {10.1093/mnras/180.3.479},
abstract = {Slow-moving galaxies in the cores of X-ray emitting clusters can accrete large quantities of cooling gas. The accretion flow is most likely to occur in a subsonic fashion, stagnating at some finite radius. These ideas are applied to NGC 1275 in the Perseus cluster, and it is
suggested that they explain the soft X-ray enhancement in that region as well as the stationary optical filaments.},
journal = {Monthly Notices of the Royal Astronomical Society},
author = {Fabian, A. C. and Nulsen, P. E. J.},
month = aug,
year = {1977},
keywords = {Galactic Clusters,Astronomical Models,Galactic Evolution,Gas Temperature,Interstellar Gas,X Ray Sources,Intergalactic Media,Angular Momentum,Stellar Mass Accretion},
pages = {479-484},
file = {/home/forrest/MSU/research/zotfiles/Cool-Core/Fabian_Nulsen_1977_Subsonic accretion of cooling gas in clusters of galaxies.pdf}
}
@article{cowie_radiative_1977,
title = {Radiative Regulation of Gas Flow within Clusters of Galaxies - {{A}} Model for Cluster {{X}}-Ray Sources},
volume = {215},
issn = {0004-637X},
doi = {10.1086/155406},
abstract = {Abstract image available at:
http://adsabs.harvard.edu/abs/1977ApJ...215..723C},
journal = {The Astrophysical Journal},
author = {Cowie, L. L. and Binney, J.},
month = aug,
year = {1977},
keywords = {Galactic Clusters,Astronomical Models,Galactic Evolution,Gas Flow,X Ray Sources,Intergalactic Media,Conductive Heat Transfer,Emission Spectra,Spectral Line Width},
pages = {723-732},
file = {/home/forrest/MSU/research/zotfiles/Cool-Core/Cowie_Binney_1977_Radiative regulation of gas flow within clusters of galaxies - A model for.pdf}
}
@article{henning_origin_2009,
title = {On the {{Origin}} of {{Cool Core Galaxy Clusters}}: {{Comparing X}}-Ray {{Observations}} with {{Numerical Simulations}}},
volume = {697},
issn = {0004-637X},
shorttitle = {On the {{Origin}} of {{Cool Core Galaxy Clusters}}},
doi = {10.1088/0004-637X/697/2/1597},
abstract = {To better constrain models of cool core galaxy cluster formation, we
have used X-ray observations taken from the Chandra and ROSAT archives
to examine the properties of cool core and noncool core clusters,
especially beyond the cluster cores. Using an optimized reduction
process, we produced X-ray images, surface brightness profiles, and
hardness ratio maps of 30 nearby rich Abell clusters (17 cool cores and
13 noncool cores). We show that the use of double $\beta$ models with
cool core surface brightness profiles and single $\beta$ models for
noncool core profiles yield statistically significant differences in the
slopes (i.e., $\beta$ values) of the outer surface brightness profiles,
but similar cluster core radii, for the two types of clusters. Hardness
ratio profiles as well as spectroscopically fit temperatures suggest
that noncool core clusters are warmer than cool core clusters of
comparable mass beyond the cluster cores. We compared the properties of
these clusters with the results from analogously reduced simulations of
88 numerical clusters created by the adaptive mesh refinement Enzo code.
The simulated surface brightness profiles have steeper $\beta$-model fits
in the outer cluster regions for both cool cores and noncool cores,
suggesting additional intracluster medium (ICM) heating is required
compared to observed cluster ICMs. Temperature and surface brightness
profiles reveal that the simulated clusters are overcooled in their
cores. As in the observations, however, simulated hardness ratio and
temperature profiles indicate that noncool core clusters are warmer than
cool core clusters of comparable mass far beyond the cluster cores. The
general similarities between observations and simulations support a
model described in Paper I suggesting that noncool core clusters
suffered early major mergers destroying nascent cool cores. Differences
between simulations and observations will be used to motivate new
approaches to feedback in subsequent numerical models.},
journal = {The Astrophysical Journal},
author = {Henning, Jason W. and Gantner, Brennan and Burns, Jack O. and Hallman, Eric J.},
month = jun,
year = {2009},
keywords = {cooling flows,X-rays: galaxies: clusters,cosmology: observations,telescopes},
pages = {1597-1620},
file = {/home/forrest/MSU/research/zotfiles/Cool-Core/W. Henning et al_2009_On the Origin of Cool Core Galaxy Clusters.pdf;/home/forrest/MSU/research/zotfiles/MyPapers/AGNThermal/Henning et al_2009_On the Origin of Cool Core Galaxy Clusters.pdf},
annote = {X-ray data from Chandra gives surface brightness profiles of 30 clusters. Enzo\\
simulations of these clusters indicate internal heating is needed. Differences\\
between simulations and data include steeper profiles in outer regions and\\
overcooling in the center of clusters}
}
@article{yang_how_2016,
title = {How {{AGN Jets Heat}} the {{Intracluster Medium}}\textemdash{{Insights}} from {{Hydrodynamic Simulations}}},
volume = {829},
issn = {0004-637X},
doi = {10.3847/0004-637X/829/2/90},
abstract = {Feedback from active galactic nuclei (AGNs) is believed to prevent catastrophic cooling in galaxy clusters. However, how the feedback energy is transformed into heat, and how the AGN jets heat the intracluster medium (ICM) isotropically, still remain elusive. In this work, we gain insights into the relative importance of different heating mechanisms using three-dimensional hydrodynamic simulations including cold gas accretion and momentum-driven jet feedback, which are the most successful models to date in terms of reproducing the properties of cool cores. We find that there is net heating within two ``jet cones'' (within $\sim$30$^\circ$ from the axis of jet precession) where the ICM gains entropy by shock heating and mixing with the hot thermal gas within bubbles. Outside the jet cones, the ambient gas is heated by weak shocks, but not enough to overcome radiative cooling, therefore, forming a ``reduced'' cooling flow. Consequently, the cluster core is in a process of ``gentle circulation'' over billions of years. Within the jet cones, there is significant adiabatic cooling as the gas is uplifted by buoyantly rising bubbles; outside the cones, energy is supplied by the inflow of already-heated gas from the jet cones as well as adiabatic compression as the gas moves toward the center. In other words, the fluid dynamics self-adjusts such that it compensates and transports the heat provided by the AGN, and hence no fine-tuning of the heating profile of any process is necessary. Throughout the cluster evolution, turbulent energy is only at the percent level compared to gas thermal energy, and thus turbulent heating is not the main source of heating in our simulation.},
language = {en},
number = {2},
journal = {The Astrophysical Journal},
author = {Yang, H.-Y. Karen and Reynolds, Christopher S.},
year = {2016},
pages = {90},
file = {/home/forrest/MSU/research/zotfiles/AGN/Yang_Reynolds_2016_How AGN Jets Heat the Intracluster Medium—Insights from Hydrodynamic Simulations.pdf},
annote = {Hydordynamic simulations with momentum driven AGN feedback, with heat dumped\\
into cones 30\$\{\}\^$\backslash$circ\$ off jet axis}
}
@article{gaspari_self-regulated_2016,
title = {The Self-Regulated {{AGN}} Feedback Loop: The Role of Chaotic Cold Accretion},
volume = {319},
shorttitle = {The Self-Regulated {{AGN}} Feedback Loop},
doi = {10.1017/S1743921315010455},
abstract = {Supermassive black hole accretion and feedback play central role in the evolution of galaxies, groups, and clusters. I review how AGN feedback is tightly coupled with the formation of multiphase gas and the newly probed chaotic cold accretion (CCA). In a turbulent and heated atmosphere, cold clouds and kpc-scale filaments condense out of the plasma via thermal instability and rain toward the black hole. In the nucleus, the recurrent chaotic collisions between the cold clouds, filaments, and central torus promote angular momentum cancellation or mixing, boosting the accretion rate up to 100 times the Bondi rate. The rapid variability triggers powerful AGN outflows, which quench the cooling flow and star formation without destroying the cool core. The AGN heating stifles the formation of multiphase gas and accretion, the feedback subsides and the hot halo is allowed to cool again, restarting a new cycle. Ultimately, CCA creates a symbiotic link between the black hole and the whole host via a tight self-regulated feedback which preserves the gaseous halo in global thermal equilibrium throughout cosmic time.},
language = {en},
journal = {Galaxies at High Redshift and Their Evolution Over Cosmic Time},
author = {Gaspari, M.},
year = {2016-00-00},
pages = {17},
file = {/home/forrest/MSU/research/zotfiles/AGN/Gaspari_2016_The self-regulated AGN feedback loop.pdf;/home/forrest/Zotero/storage/3XWA4LGE/ui.adsabs.harvard.edu.html}
}
@article{gaspari_raining_2017,
title = {Raining on Black Holes and Massive Galaxies: The Top-down Multiphase Condensation Model},
volume = {466},
shorttitle = {Raining on Black Holes and Massive Galaxies},
doi = {10.1093/mnras/stw3108},
abstract = {The plasma haloes filling massive galaxies, groups and clusters are shaped by active galactic nucleus (AGN) heating and subsonic turbulence ($\sigma$\textsubscript{v$<$/SUB$>$ \~ 150 km s\textsuperscript{-1$<$/SUP$>$), as probed by Hitomi. Novel 3D high-resolution simulations show the soft X-ray, keV hot plasma cools rapidly via radiative emission at the high-density interface of the turbulent eddies, stimulating a top-down condensation cascade of warm 10\textsuperscript{4$<$/SUP$>$ K filaments. The kpc-scale ionized (optical/ultraviolet) filaments form a skin enveloping the neutral filaments (optical/infrared/21 cm). The peaks of the warm filaments further condense into cold molecular clouds (\<50 K; radio) with total mass of several 10\textsuperscript{7$<$/SUP$>$ M\textsubscript{$\Sun$$<$/SUB$>$ and inheriting the turbulent kinematics. In the core, the clouds collide inelastically, mixing angular momentum and leading to Chaotic Cold Accretion (CCA). The black hole accretion rate (BHAR) can be modelled via quasi-spherical viscous accretion, dot\{M\}\_bullet $\propto$ $\nu$ \_c, with clump collisional viscosity $\nu$\textsubscript{c$<$/SUB$>$ $\equiv$ $\lambda$\textsubscript{c$<$/SUB$>$ $\sigma$\textsubscript{v$<$/SUB$>$ and $\lambda$\textsubscript{c$<$/SUB$>$ \~ 100 pc. Beyond the core, pressure torques shape the angular momentum transport. In CCA, the BHAR is recurrently boosted up to 2 dex compared with the disc evolution, which arises as turbulence becomes subdominant. With negligible rotation too, compressional heating inhibits the molecular phase. The CCA BHAR distribution is lognormal with pink noise, f\textsuperscript{-1$<$/SUP$>$ power spectrum characteristic of fractal phenomena. Such chaotic fluctuations can explain the rapid luminosity variability of AGN and high-mass X-ray binaries. An improved criterium to trace non-linear condensation is proposed: $\sigma$\textsubscript{v$<$/SUB$>$/v\textsubscript{cool$<$/SUB$>$ $\lessequivlnt$ 1. The three-phase CCA reproduces key observations of cospatial multiphase gas in massive galaxies, including Chandra X-ray images, SOAR H$\alpha$ filaments and kinematics, Herschel [C\textsuperscript{+$<$/SUP$>$] emission and ALMA molecular associations. CCA plays important role in AGN feedback and unification, the evolution of BHs, galaxies and clusters.}}}}}}}}}}}}}},
language = {en},
number = {1},
journal = {Monthly Notices of the Royal Astronomical Society},
author = {Gaspari, M. and Temi, P. and Brighenti, F.},
month = apr,
year = {2017},
pages = {677},
file = {/home/forrest/MSU/research/zotfiles/AGN/Gaspari et al_2017_Raining on black holes and massive galaxies.pdf;/home/forrest/Zotero/storage/JLQ7UNR3/ui.adsabs.harvard.edu.html}
}
@article{rajpurohit_deep_2018,
title = {Deep {{VLA Observations}} of the {{Cluster 1RXS J0603}}.3+4214 in the {{Frequency Range}} of 1\textendash{}2 {{GHz}}},
volume = {852},
issn = {1538-4357},
doi = {10.3847/1538-4357/aa9f13},
number = {2},
journal = {The Astrophysical Journal},
author = {Rajpurohit, K. and Hoeft, M. and {van Weeren}, R. J. and Rudnick, L. and R\"ottgering, H. J. A. and Forman, W. R. and Br\"uggen, M. and Croston, J. H. and {Andrade-Santos}, F. and Dawson, W. A. and Intema, H. T. and Kraft, R. P. and Jones, C. and Jee, M. James},
month = jan,
year = {2018},
pages = {65},
file = {/home/forrest/MSU/research/zotfiles/MyPapers/AGNThermal2018/Rajpurohit et al_2018_Deep VLA Observations of the Cluster 1RXS J0603.pdf}
}
@article{gaspari_shaken_2018,
title = {Shaken {{Snow Globes}}: {{Kinematic Tracers}} of the {{Multiphase Condensation Cascade}} in {{Massive Galaxies}}, {{Groups}}, and {{Clusters}}},
volume = {854},
issn = {0004-637X},
shorttitle = {Shaken {{Snow Globes}}},
doi = {10.3847/1538-4357/aaaa1b},
abstract = {We propose a novel method to constrain turbulence and bulk motions in massive galaxies, galaxy groups, and clusters, exploring both simulations and observations. As emerged in the recent picture of top-down multiphase condensation, hot gaseous halos are tightly linked to all other phases in terms of cospatiality and thermodynamics. While hot halos ($\sim$10 7 K) are perturbed by subsonic turbulence, warm ($\sim$10 4 K) ionized and neutral filaments condense out of the turbulent eddies. The peaks condense into cold molecular clouds ($<$100 K) raining in the core via chaotic cold accretion (CCA). We show that all phases are tightly linked in terms of the ensemble (wide-aperture) velocity dispersion along the line of sight. The correlation arises in complementary long-term AGN feedback simulations and high-resolution CCA runs, and is corroborated by the combined Hitomi and new Integral Field Unit measurements in the Perseus cluster. The ensemble multiphase gas distributions (from the UV to the radio band) are characterized by substantial spectral line broadening ( $\sigma$ v ,los $\approx$ 100\textendash{}200 \#\#IMG\#\# [http://ej.iop.org/images/0004-637X/854/2/167/apjaaaa1bieqn1.gif] \$$\backslash$mathrmkm$\backslash$,$\backslash$rms\^-1\$ ) with a mild line shift. On the other hand, pencil-beam detections (as H i absorption against the AGN backlight) sample the small-scale clouds displaying smaller broadening and significant line shifts of up to several 100 \#\#IMG\#\# [http://ej.iop.org/images/0004-637X/854/2/167/apjaaaa1bieqn2.gif] \$$\backslash$mathrmkm$\backslash$,$\backslash$rms\^-1\$ (for those falling toward the AGN), with increased scatter due to the turbulence intermittency. We present new ensemble $\sigma$ v ,los of the warm H $\alpha$ +[N ii ] gas in 72 observed cluster/group cores: the constraints are consistent with the simulations and can be used as robust proxies for the turbulent velocities, in particular for the challenging hot plasma (otherwise requiring extremely long X-ray exposures). Finally, we show that the physically motivated criterion C $\equiv$ t cool / t eddy $\approx$ 1 best traces the condensation extent region and the presence of multiphase gas in observed clusters and groups. The ensemble method can be applied to many available spectroscopic data sets and can substantially advance our understanding of multiphase halos in light of the next-generation multiwavelength missions.},
language = {en},
number = {2},
journal = {The Astrophysical Journal},
author = {Gaspari, M. and McDonald, M. and Hamer, S. L. and Brighenti, F. and Temi, P. and {Gendron-Marsolais}, M. and {Hlavacek-Larrondo}, J. and Edge, A. C. and Werner, N. and Tozzi, P. and Sun, M. and Stone, J. M. and Tremblay, G. R. and Hogan, M. T. and Eckert, D. and Ettori, S. and {H. Yu} and Biffi, V. and Planelles, S.},
year = {2018},
pages = {167},
file = {/home/forrest/MSU/research/zotfiles/MyPapers/AGNThermal2018/Gaspari et al_2018_Shaken Snow Globes.pdf}
}
@article{gaspari_shaping_2015,
title = {Shaping the {{X}}-Ray Spectrum of Galaxy Clusters with {{AGN}} Feedback and Turbulence.},
volume = {451},
doi = {10.1093/mnrasl/slv067},
abstract = {The hot plasma filling galaxy clusters emits copious X-ray radiation. The classic unheated and unperturbed cooling flow model predicts dramatic cooling rates and an isobaric X-ray spectrum with constant differential luminosity distribution. The observed cores of clusters (and groups) show instead a strong deficit of soft X-ray emission: dL\textsubscript{x$<$/SUB$>$/dT $\propto$ (T/T\textsubscript{hot$<$/SUB$>$)\textsuperscript{$\alpha$ = 2 $\pm$ 1$<$/SUP$>$. Using 3D hydrodynamic simulations, we show that such deficit arises from the tight self-regulation between thermal instability condensation and AGN outflow injection: condensing clouds boost the AGN outflows, which quench cooling as they thermalize through the core. The resultant average distribution slope is $\alpha$ $\simeq$ 2, oscillating within the observed 1 \< $\alpha$ \< 3. In the absence of thermal instability, the X-ray spectrum remains isothermal ($\alpha$ $\greaterequivlnt$ 8), while unopposed cooling drives a too shallow slope, $\alpha$ \< 1. AGN outflows deposit their energy inside-out, releasing more heat in the inner cooler phase; radially distributed heating alone induces a declining spectrum, 1 \< $\alpha$ \< 2. Turbulence further steepens the spectrum and increases the scatter: the turbulent Mach number in the hot phase is subsonic, while it becomes transonic in the cooler phase, making perturbations to depart from the isobaric mode. Such increase in dln P/dln T leads to $\alpha$ $\approx$ 3. Self-regulated AGN outflow feedback can address the soft X-ray problem through the interplay of heating and turbulence.}}}},
language = {en},
journal = {Monthly Notices of the Royal Astronomical Society},
author = {Gaspari, M.},
month = jul,
year = {2015},
pages = {L60},
file = {/home/forrest/MSU/research/zotfiles/MyPapers/AGNThermal2018/Gaspari_2015_Shaping the X-ray spectrum of galaxy clusters with AGN feedback and turbulence.pdf;/home/forrest/Zotero/storage/AALDIV36/ui.adsabs.harvard.edu.html;/home/forrest/Zotero/storage/Y9D4WM6W/955719.html}
}
@article{gaspari_chaotic_2015,
title = {Chaotic Cold Accretion on to Black Holes in Rotating Atmospheres},
volume = {579},
copyright = {\textcopyright{} ESO, 2015},
issn = {0004-6361, 1432-0746},
doi = {10.1051/0004-6361/201526151},
abstract = {The fueling of black holes is one key problem in the evolution of baryons in the universe. Chaotic cold accretion (CCA) profoundly differs from classic accretion models, as Bondi and thin disc theories. Using 3D high-resolution hydrodynamic simulations, we now probe the impact of \emph{rotation \emph{on the hot and cold accretion flow in a typical massive galaxy. In the hot mode, with or without turbulence, the pressure-dominated flow forms a geometrically thick rotational barrier, suppressing the black hole accretion rate to \textasciitilde{}1/3 of the spherical case value. When radiative cooling is dominant, the gas loses pressure support and quickly circularizes in a cold thin disk; the accretion rate is decoupled from the cooling rate, although it is higher than that of the hot mode. In the more common state of a turbulent and heated atmosphere, CCA drives the dynamics if the gas velocity dispersion exceeds the rotational velocity, i.e., turbulent Taylor number Ta\textsubscript{t\textsubscript{$<$ 1. Extended multiphase filaments condense out of the hot phase via thermal instability (TI) and rain toward the black hole, boosting the accretion rate up to 100 times the Bondi rate (\emph{\.{M}\emph{\textsubscript{\textbullet\textsubscript{ \textasciitilde{} \emph{\.{M}\emph{\textsubscript{cool\textsubscript{). Initially, turbulence broadens the angular momentum distribution of the hot gas, allowing the cold phase to condense with prograde or retrograde motion. Subsequent chaotic collisions between the cold filaments, clouds, and a clumpy variable torus promote the cancellation of angular momentum, leading to high accretion rates. As turbulence weakens (Ta\textsubscript{t\textsubscript{ $>$ 1), the broadening of the distribution and the efficiency of collisions diminish, damping the accretion rate $\propto$ Ta\textsubscript{t\textsubscript{\textsuperscript{-1\textsuperscript{, until the cold disk drives the dynamics. This is exacerbated by the increased difficulty to grow TI in a rotating halo. The simulated sub-Eddington accretion rates cover the range inferred from AGN cavity observations. CCA predicts inner flat X-ray temperature and \emph{r\emph{\textsuperscript{-1\textsuperscript{ density profiles, as recently discovered in M 87 and NGC 3115. The synthetic H\emph{$\alpha$\emph{ images reproduce the main features of cold gas observations in massive ellipticals, as the line fluxes and the filaments versus disk morphology. Such dichotomy is key for the long-term AGN feedback cycle. As gas cools, filamentary CCA develops and boosts AGN heating; the cold mode is thus reduced and the rotating disk remains the sole cold structure. Its consumption leaves the atmosphere in hot mode with suppressed accretion and feedback, reloading the cycle.}}}}}}}}}}}}}}}}}}}}}}}}},
language = {en},
journal = {Astronomy \& Astrophysics},
author = {Gaspari, M. and Brighenti, F. and Temi, P.},
month = jul,
year = {2015},
pages = {A62},
file = {/home/forrest/MSU/research/zotfiles/MyPapers/AGNThermal2018/Gaspari et al_2015_Chaotic cold accretion on to black holes in rotating atmospheres.pdf;/home/forrest/Zotero/storage/SVWILVD8/aa26151-15.html}
}
@article{gaspari_can_2014,
title = {Can {{AGN Feedback Break}} the {{Self}}-Similarity of {{Galaxies}}, {{Groups}}, and {{Clusters}}?},
volume = {783},
doi = {10.1088/2041-8205/783/1/L10},
abstract = {It is commonly thought that active galactic nucleus (AGN) feedback can break the self-similar scaling relations of galaxies, groups, and clusters. Using high-resolution three-dimensional hydrodynamic simulations, we isolate the impact of AGN feedback on the L \textsubscript{x$<$/SUB$>$-T \textsubscript{x$<$/SUB$>$ relation, testing the two archetypal and common regimes, self-regulated mechanical feedback and a quasar thermal blast. We find that AGN feedback has severe difficulty in breaking the relation in a consistent way. The similarity breaking is directly linked to the gas evacuation within R \textsubscript{500$<$/SUB$>$, while the central cooling times are inversely proportional to the core density. Breaking self-similarity thus implies breaking the cool core, morphing all systems to non-cool-core objects, which is in clear contradiction with the observed data populated by several cool-core systems. Self-regulated feedback, which quenches cooling flows and preserves cool cores, prevents dramatic evacuation and similarity breaking at any scale; the relation scatter is also limited. The impulsive thermal blast can break the core-included L \textsubscript{x$<$/SUB$>$-T \textsubscript{x$<$/SUB$>$ at T \textsubscript{500$<$/SUB$>$ \<\textasciitilde{} 1 keV, but substantially empties and overheats the halo, generating a perennial non-cool-core group, as experienced by cosmological simulations. Even with partial evacuation, massive systems remain overheated. We show that the action of purely AGN feedback is to lower the luminosity and heat the gas, perpendicular to the fit.}}}}}}},
language = {en},
number = {1},
journal = {The Astrophysical Journal},
author = {Gaspari, M. and Brighenti, F. and Temi, P. and Ettori, S.},
month = mar,
year = {2014},
pages = {L10},
file = {/home/forrest/MSU/research/zotfiles/MyPapers/AGNThermal2018/Gaspari et al_2014_Can AGN Feedback Break the Self-similarity of Galaxies, Groups, and Clusters.pdf;/home/forrest/Zotero/storage/3V8EPVQ5/ui.adsabs.harvard.edu.html}
}
@article{gaspari_mechanical_2012,
title = {Mechanical {{AGN}} Feedback: Controlling the Thermodynamical Evolution of Elliptical Galaxies},
volume = {424},
issn = {0035-8711},
shorttitle = {Mechanical {{AGN}} Feedback},
doi = {10.1111/j.1365-2966.2012.21183.x},
abstract = {Abstract. A fundamental gap in the current understanding of galaxies concerns the thermodynamical evolution of ordinary, baryonic matter. On the one hand, radi},
language = {en},
number = {1},
journal = {Monthly Notices of the Royal Astronomical Society},
author = {Gaspari, M. and Brighenti, F. and Temi, P.},
month = jul,
year = {2012},
pages = {190-209},
file = {/home/forrest/MSU/research/zotfiles/MyPapers/AGNThermal2018/Gaspari et al_2012_Mechanical AGN feedback.pdf;/home/forrest/Zotero/storage/U8HJYNSW/1007807.html}
}
@article{gaspari_solving_2013,
title = {Solving the Cooling Flow Problem through Mechanical {{AGN}} Feedback},
volume = {334},
copyright = {Copyright \textcopyright{} 2013 WILEY-VCH Verlag GmbH \& Co. KGaA, Weinheim},
issn = {1521-3994},
doi = {10.1002/asna.201211865},
abstract = {Unopposed radiative cooling of plasma would lead to the cooling catastro-phe, a massive inflow of condensing gas, manifest in the core of galaxies, groups and clusters. The last generation X-ray telescopes, Chandra and XMM, have radically changed our view on baryons, indicating AGN heating as the balancing counterpart of cooling. This work reviews our extensive investigation on self-regulated heating. We argue that the mechanical feedback, based on massive subrelativistic outflows, is the key to solving the cooling flow problem, i.e. dramatically quenching the cooling rates for several Gyr without destroying the cool-core structure. Using a modified version of the 3D hydrocode FLASH, we show that bipolar AGN outflows can further reproduce fundamental observed features, such as buoyant bubbles, weak shocks, metals dredgeup, and turbulence. The latter is an essential ingredient to drive nonlinear thermal instabilities, which cause the formation of extended cold gas, a residual of the quenched cooling flow and, later, fuel for the feedback engine. Compared to clusters, groups and galaxies require a gentler mechanical feedback, in order to avoid catastro-phic overheating. We highlight the essential characteristics for a realistic AGN feedback, with emphasis on observational consistency. (\textcopyright{} 2013 WILEY-VCH Verlag GmbH \& Co. KGaA, Weinheim)},
language = {en},
number = {4-5},
journal = {Astronomische Nachrichten},
author = {Gaspari, M. and Brighenti, F. and Ruszkowski, M.},
month = feb,
year = {2013},
keywords = {intergalactic medium,galaxies: active,cooling flows,ISM: jets and outflows,X-rays: galaxies},
pages = {394-397},
file = {/home/forrest/MSU/research/zotfiles/MyPapers/AGNThermal2018/Gaspari et al_Solving the cooling flow problem through mechanical AGN feedback.pdf;/home/forrest/Zotero/storage/MP2APHN6/asna.html}
}
@article{gaspari_cause_2012,
title = {Cause and {{Effect}} of {{Feedback}}: {{Multiphase Gas}} in {{Cluster Cores Heated}} by {{AGN Jets}}},
volume = {746},
issn = {0004-637X},
shorttitle = {Cause and {{Effect}} of {{Feedback}}},
doi = {10.1088/0004-637X/746/1/94},
abstract = {Multiwavelength data indicate that the X-ray-emitting plasma in the cores of galaxy clusters is not cooling catastrophically. To a large extent, cooling is offset by heating due to active galactic nuclei (AGNs) via jets. The cool-core clusters, with cooler/denser plasmas, show multiphase gas and signs of some cooling in their cores. These observations suggest that the cool core is locally thermally unstable while maintaining global thermal equilibrium. Using high-resolution, three-dimensional simulations we study the formation of multiphase gas in cluster cores heated by collimated bipolar AGN jets. Our key conclusion is that spatially extended multiphase filaments form only when the instantaneous ratio of the thermal instability and free-fall timescales ( t TI / t ff ) falls below a critical threshold of \#\#IMG\#\# [http://ej.iop.org/icons/Entities/ap.gif] $\approx$ 10. When this happens, dense cold gas decouples from the hot intracluster medium (ICM) phase and generates inhomogeneous and spatially extended H$\alpha$ filaments. These cold gas clumps and filaments "rain" down onto the central regions of the core, forming a cold rotating torus and in part feeding the supermassive black hole. Consequently, the self-regulated feedback enhances AGN heating and the core returns to a higher entropy level with t TI / t ff $>$ 10. Eventually, the core reaches quasi-stable global thermal equilibrium, and cold filaments condense out of the hot ICM whenever t TI / t ff \#\#IMG\#\# [http://ej.iop.org/icons/Entities/lsim.gif] lsim 10. This occurs despite the fact that the energy from AGN jets is supplied to the core in a highly anisotropic fashion. The effective spatial redistribution of heat is enabled in part by the turbulent motions in the wake of freely falling cold filaments. Increased AGN activity can locally reverse the cold gas flow, launching cold filamentary gas away from the cluster center. Our criterion for the condensation of spatially extended cold gas is in agreement with observations and previous idealized simulations.},
language = {en},
number = {1},
journal = {The Astrophysical Journal},
author = {Gaspari, M. and Ruszkowski, M. and Sharma, P.},
year = {2012},
pages = {94},
file = {/home/forrest/MSU/research/zotfiles/MyPapers/AGNThermal2018/Gaspari et al_2012_Cause and Effect of Feedback.pdf}
}
@article{gaspari_agn_2011,
title = {{{AGN}} Feedback in Galaxy Groups: The Delicate Touch of Self-Regulated Outflows},
volume = {415},
issn = {0035-8711},
shorttitle = {{{AGN}} Feedback in Galaxy Groups},
doi = {10.1111/j.1365-2966.2011.18806.x},
abstract = {Abstract. Active galactic nucleus (AGN) heating, through massive subrelativistic outflows, might be the key to solve the long-lasting `cooling flow problem' in},
language = {en},
number = {2},
journal = {Monthly Notices of the Royal Astronomical Society},
author = {Gaspari, M. and Brighenti, F. and D'Ercole, A. and Melioli, C.},
month = aug,
year = {2011},
pages = {1549-1568},
file = {/home/forrest/MSU/research/zotfiles/MyPapers/AGNThermal2018/Gaspari et al_2011_AGN feedback in galaxy groups.pdf;/home/forrest/Zotero/storage/2X34YUKI/1041380.html},
annote = {3D Flash simulations of AGN applied to galaxies
~
50\%$>$ thermal feedback gives too hot cores.}
}
@misc{noauthor_dance_nodate,
title = {Dance of Heating and Cooling in Galaxy Clusters: Three-Dimensional Simulations of Self-Regulated Active Galactic Nuclei Outflows | {{Monthly Notices}} of the {{Royal Astronomical Society}} | {{Oxford Academic}}},
howpublished = {https://academic-oup-com.proxy2.cl.msu.edu/mnras/article/411/1/349/1040881},
file = {/home/forrest/Zotero/storage/K35NXTNH/1040881.html}
}
@article{ruszkowski_cosmic-ray_2017,
title = {Cosmic-{{Ray Feedback Heating}} of the {{Intracluster Medium}}},
volume = {844},
doi = {10.3847/1538-4357/aa79f8},
abstract = {Active galactic nuclei (AGNs) play a central role in solving the decades-old cooling-flow problem. Although there is consensus that AGNs provide the energy to prevent catastrophically large star formation, one major problem remains: How is the AGN energy thermalized in the intracluster medium (ICM)? We perform a suite of three-dimensional magnetohydrodynamical adaptive mesh refinement simulations of AGN feedback in a cool core cluster including cosmic rays (CRs). CRs are supplied to the ICM via collimated AGN jets and subsequently disperse in the magnetized ICM via streaming, and interact with the ICM via hadronic, Coulomb, and streaming instability heating. We find that CR transport is an essential model ingredient at least within the context of the physical model considered here. When streaming is included, (I) CRs come into contact with the ambient ICM and efficiently heat it, (II) streaming instability heating dominates over Coulomb and hadronic heating, (III) the AGN is variable and the atmosphere goes through low-/high-velocity dispersion cycles, and, importantly, (IV) CR pressure support in the cool core is very low and does not demonstrably violate observational constraints. However, when streaming is ignored, CR energy is not efficiently spent on the ICM heating and CR pressure builds up to a significant level, creating tension with the observations. Overall, we demonstrate that CR heating is a viable channel for the AGN energy thermalization in clusters and likely also in ellipticals, and that CRs play an important role in determining AGN intermittency and the dynamical state of cool cores.},
language = {en},
number = {1},
journal = {The Astrophysical Journal},
author = {Ruszkowski, Mateusz and Yang, H.-Y. Karen and Reynolds, Christopher S.},
month = jul,
year = {2017},
pages = {13},
file = {/home/forrest/MSU/research/zotfiles/MyPapers/AGNThermal2018/Ruszkowski et al_2017_Cosmic-Ray Feedback Heating of the Intracluster Medium.pdf;/home/forrest/Zotero/storage/BP7QR7VS/ui.adsabs.harvard.edu.html},
annote = {3D MHD simulations demonstating heating of ICM by AGN through cosmic ray streaming (heating in:stability)
CR injection through collimated AGN jets, diperse through streaming, and interact with ICM through hadronic, Coulomb, streaming instability.}
}
@article{ruszkowski_global_2017,
title = {Global {{Simulations}} of {{Galactic Winds Including Cosmic}}-Ray {{Streaming}}},
volume = {834},
doi = {10.3847/1538-4357/834/2/208},
abstract = {Galactic outflows play an important role in galactic evolution. Despite their importance, a detailed understanding of the physical mechanisms responsible for the driving of these winds is lacking. In an effort to gain more insight into the nature of these flows, we perform global three-dimensional magnetohydrodynamical simulations of an isolated Milky Way-size starburst galaxy. We focus on the dynamical role of cosmic rays (CRs) injected by supernovae, and specifically on the impact of the streaming and anisotropic diffusion of CRs along the magnetic fields. We find that these microphysical effects can have a significant effect on the wind launching and mass loading factors, depending on the details of the plasma physics. Due to the CR streaming instability, CRs propagating in the interstellar medium scatter on self-excited Alfv\'en waves and couple to the gas. When the wave growth due to the streaming instability is inhibited by some damping process, such as turbulent damping, the coupling of CRs to the gas is weaker and their effective propagation speed faster than the Alfv\'en speed. Alternatively, CRs could scatter from ``extrinsic turbulence'' that is driven by another mechanism. We demonstrate that the presence of moderately super-Alfv\'enic CR streaming enhances the efficiency of galactic wind driving. Cosmic rays stream away from denser regions near the galactic disk along partially ordered magnetic fields and in the process accelerate more tenuous gas away from the galaxy. For CR acceleration efficiencies broadly consistent with the observational constraints, CRs reduce the galactic star formation rates and significantly aid in launching galactic winds.},
language = {en},
number = {2},
journal = {The Astrophysical Journal},
author = {Ruszkowski, Mateusz and Yang, H.-Y. Karen and Zweibel, Ellen},
month = jan,
year = {2017},
keywords = {galaxies: evolution,galaxies: star formation,cosmic rays},
pages = {208},
file = {/home/forrest/MSU/research/zotfiles/MyPapers/AGNThermal2018/Ruszkowski et al_2017_Global Simulations of Galactic Winds Including Cosmic-ray Streaming.pdf;/home/forrest/Zotero/storage/7YZH6WBP/ui.adsabs.harvard.edu.html}
}
@article{ruszkowski_fermi_2014,
title = {Fermi Bubble Simulations: Black Hole Feedback in the {{Milky Way}}},
volume = {303},
shorttitle = {Fermi Bubble Simulations},
doi = {10.1017/S1743921314000994},
abstract = {The Fermi $\gamma$-ray telescope discovered a pair of bubbles at the Galactic center. These structures are spatially-correlated with the microwave emission detected by the WMAP and Planck satellites. These bubbles were likely inflated by a jet launched from the vicinity of a supermassive black hole in the Galactic center. Using MHD simulations, which self-consistently include interactions between cosmic rays and magnetic fields, we build models of the supersonic jet propagation, cosmic ray transport, and the magnetic field amplification within the Fermi bubbles. Our key findings are that: (1) the synthetic Fermi $\gamma$-ray and WMAP microwave spectra based on our simulations are consistent with the observations, suggesting that a single population of cosmic ray leptons may simultaneously explain the emission across a range of photon energies; (2) the model fits the observed centrally-peaked microwave emission if a second, more recent, pair of jets embedded in the Fermi bubbles is included in the model. This is consistent with the observationally-based suggestion made by Su \& Finkbeiner (2012); (3) the radio emission from the bubbles is expected to be strongly polarized due to the relatively high level of field ordering caused by elongated turbulent vortices. This effect is caused by the interaction of the shocks driven by the jets with the preexisting interstellar medium turbulence; (4) a layer of enhanced rotation measure in the shock-compressed region could exist in the bubble vicinity but the level of this enhancement depends on the details of the magnetic topology.},
language = {en},
journal = {The Galactic Center: Feeding and Feedback in a Normal Galactic Nucleus},
author = {Ruszkowski, M. and Yang, H.-Y. K. and Zweibel, E.},
month = may,
year = {2014},
pages = {390},
file = {/home/forrest/MSU/research/zotfiles/MyPapers/AGNThermal2018/Ruszkowski et al_2014_Fermi bubble simulations.pdf;/home/forrest/Zotero/storage/UM928IIN/ui.adsabs.harvard.edu.html}
}
@article{gaspari_dance_2011,
title = {The Dance of Heating and Cooling in Galaxy Clusters: Three-Dimensional Simulations of Self-Regulated Active Galactic Nuclei Outflows},
volume = {411},
shorttitle = {The Dance of Heating and Cooling in Galaxy Clusters},
doi = {10.1111/j.1365-2966.2010.17688.x},
abstract = {It is now widely accepted that heating processes play a fundamental role in galaxy clusters, struggling in an intricate but fascinating `dance' with its antagonist, radiative cooling. Last-generation observations, especially X-ray, are giving us tiny hints about the notes of this endless ballet. Cavities, shocks, turbulence and wide absorption lines indicate that the central active nucleus is injecting a huge amount of energy in the intracluster medium. However, which is the real dominant engine of self-regulated heating? One of the models we propose is massive subrelativistic outflows, probably generated by a wind disc or just the result of the entrainment on kpc scale by the fast radio jet. Using a modified version of the adaptive mesh refinement code FLASH 3.2, we have explored several feedback mechanisms that self-regulate the mechanical power. Two are the best schemes that answer our primary question, that is, quenching cooling flow and at the same time preserving a cool core appearance for a long-term evolution (7 Gyr): one is more explosive (with efficiencies \~ 5 \texttimes{} 10\textsuperscript{-3$<$/SUP$>$-10\textsuperscript{-2$<$/SUP$>$), triggered by central cooled gas, and the other is gentler, ignited by hot gas Bondi accretion (with $\smallin$= 0.1). These three-dimensional simulations show that the total energy injected is not the key aspect, but the results strongly depend on how energy is given to the intracluster medium. We follow the dynamics of the best models (temperature, density, surface brightness maps and profiles) and produce many observable predictions: buoyant bubbles, ripples, turbulence, iron abundance maps and hydrostatic equilibrium deviation. We present an in-depth discussion of the merits and flaws of all our models, with a critical eye towards observational concordance.}}},
language = {en},
number = {1},
journal = {Monthly Notices of the Royal Astronomical Society},
author = {Gaspari, M. and Melioli, C. and Brighenti, F. and D'Ercole, A.},
month = feb,
year = {2011},
pages = {349},
file = {/home/forrest/MSU/research/zotfiles/MyPapers/AGNThermal2018/Gaspari et al_2011_The dance of heating and cooling in galaxy clusters.pdf;/home/forrest/Zotero/storage/WZKPQ8YZ/ui.adsabs.harvard.edu.html}
}
@article{ruszkowski_heating_2002,
title = {Heating, {{Conduction}}, and {{Minimum Temperatures}} in {{Cooling Flows}}},
volume = {581},
issn = {0004-637X},
doi = {10.1086/344170},
abstract = {There is mounting observational evidence from Chandra for strong interaction between keV gas and active galactic nuclei (AGNs) in cooling flows. It is now widely accepted that the temperatures of cluster cores are maintained at a level of \textasciitilde{}1 keV and that the mass deposition rates are lower than earlier ROSAT/Einstein values. Recent theoretical results suggest that thermal conduction can be very efficient even in magnetized plasmas. Motivated by these discoveries, we consider a ‘‘double heating model'' that incorporates the effects of simultaneous heating by both the central AGN and thermal conduction from the hot outer layers of clusters. Using hydrodynamic simulations, we demonstrate that there exists a family of solutions that does not suffer from the cooling catastrophe. In these cases, clusters relax to a stable final state, which is characterized by minimum temperatures of order 1 keV and density and temperature profiles consistent with observations. Moreover, the accretion rates are much reduced, thereby reducing the need for the excessive mass deposition rates required by the standard cooling flow models.},
journal = {The Astrophysical Journal},
author = {Ruszkowski, Mateusz and Begelman, Mitchell C.},
month = dec,
year = {2002},
keywords = {Galaxies: Intergalactic Medium,Galaxies: Clusters: General,X-Rays: Galaxies: Clusters,Conduction,Galaxies: Cooling Flows},
pages = {223-228},
file = {/home/forrest/MSU/research/zotfiles/MyPapers/AGNThermal2018/Ruszkowski_Begelman_2002_Heating, Conduction, and Minimum Temperatures in Cooling Flows.pdf}
}
@article{ruszkowski_cluster_2004,
title = {Cluster {{Heating}} by {{Viscous Dissipation}} of {{Sound Waves}}},
volume = {611},
issn = {0004-637X},
doi = {10.1086/422158},
abstract = {We simulate the effects of viscous dissipation of waves that are generated by active galactic nucleus (AGN) activity in clusters of galaxies. We demonstrate that the amount of viscous heating associated with the dissipation of these waves can offset radiative cooling rates in cooling flow clusters of galaxies. This heating mechanism leads to spatially distributed and approximately symmetrical dissipation. The heating waves reach a given distance from the cluster center on a timescale shorter than the cooling time. This means that this heating mechanism has the potential to quench cooling flows in a quasi-stable fashion. Moreover, the heating is gentle, as no strong shocks are present in the simulations. We first investigated whether a single continuous episode of AGN activity can lead to adequate dissipation to balance cooling rates. These simulations demonstrated that whereas secondary waves generated by the interaction of the rising bubble with the intracluster medium are clearly present, viscous heating associated with the dissipation of these waves is insufficient to balance radiative cooling. It is only when the central source is intermittent that the viscous dissipation of waves associated with subsequent episodes of activity can offset cooling. This suggests that the ripples observed in the Perseus Cluster can be interpreted as being due to the AGN duty cycle; i.e., they trace AGN activity history. The simulations were performed using the adaptive mesh refinement code FLASH in two
dimensions.},
journal = {The Astrophysical Journal},
author = {Ruszkowski, Mateusz and Br\"uggen, Marcus and Begelman, Mitchell C.},
month = aug,
year = {2004},
keywords = {Galaxies: Active,Galaxies: Cooling Flows,Waves},
pages = {158-163},
file = {/home/forrest/MSU/research/zotfiles/MyPapers/AGNThermal2018/Ruszkowski et al_2004_Cluster Heating by Viscous Dissipation of Sound Waves.pdf}
}
@article{ruszkowski_cosmic_2008,
title = {Cosmic Ray Confinement in Fossil Cluster Bubbles},
volume = {383},
issn = {0035-8711},
doi = {10.1111/j.1365-2966.2007.12659.x},
abstract = {Most cool core clusters of galaxies possess active galactic nuclei (AGN) in their centres. These AGN inflate buoyant bubbles containing
non-thermal radio-emitting particles. If such bubbles efficiently confine cosmic rays (CRs) then this could explain ‘radio relics' seen far from cluster centres. We simulate the diffusion of CRs from buoyant bubbles inflated by AGN. Our simulations include the effects of the anisotropic particle diffusion introduced by magnetic fields. Our models are consistent with the X-ray morphology of AGN bubbles, with disruption being suppressed by the magnetic draping effect. We conclude that for such magnetic field topologies, a substantial fraction of CRs can be confined inside the bubbles on buoyant rise time-scales even when the parallel diffusivity coefficient is very large. For isotropic diffusion at a comparable level, CRs would leak out of the bubbles too rapidly to be consistent with radio observations. Thus, the long confinement times associated with the magnetic suppression of CRs diffusion can explain the presence of radio relics. We show that the partial escape of CRs is mostly confined to the wake of the rising bubbles and speculate that this effect could: (i) account for the excitation of the H$\alpha$
filaments trailing behind the bubbles in the Perseus cluster, (ii) inject entropy into the metal-enriched material being lifted by the bubbles and, thus, help to displace it permanently from the cluster centre and (iii) produce observable $\gamma$-rays via the interaction of the diffusing CRs with the thermal intracluster medium.},
journal = {Monthly Notices of the Royal Astronomical Society},
author = {Ruszkowski, M. and En\ss{}lin, T. A. and Br\"uggen, M. and Begelman, M. C. and Churazov, E.},
month = feb,
year = {2008},
keywords = {MHD,magnetic fields,cosmic rays},
pages = {1359-1365},
file = {/home/forrest/MSU/research/zotfiles/MyPapers/AGNThermal2018/Ruszkowski et al_2008_Cosmic ray confinement in fossil cluster bubbles.pdf}
}
@article{ruszkowski_impact_2007,
title = {Impact of Tangled Magnetic Fields on Fossil Radio Bubbles},
volume = {378},
issn = {0035-8711},
doi = {10.1111/j.1365-2966.2007.11801.x},
abstract = {There is growing consensus that feedback from active galactic nuclei (AGN) is the main mechanism responsible for stopping cooling flows in clusters of galaxies. AGN are known to inflate buoyant bubbles that supply mechanical power to the intracluster gas [intracluster medium (ICM)]. High Reynolds number hydrodynamical simulations show that such bubbles get entirely disrupted within 100 Myr, as they rise in cluster atmospheres, which is contrary to observations. This artificial mixing has consequences for models trying to quantify the amount of heating and star formation in cool core clusters of galaxies. It has been suggested that magnetic fields can stabilize bubbles against disruption. We perform magnetohydrodynamical simulations of fossil bubbles in the presence of tangled magnetic fields using the high-order PENCIL code. We focus on the physically motivated case where thermal pressure dominates over magnetic pressure and consider randomly oriented fields with and without maximum helicity and a case where large-scale external fields drape the bubble. We find that helicity has some stabilizing effect. However, unless the coherence length of magnetic fields exceeds the bubble size, the bubbles are quickly shredded. As observations of Hydra A suggest that length-scale of magnetic fields may be smaller than typical bubble size, this may suggest that other mechanisms, such as viscosity, may be responsible for stabilizing the bubbles. However, since Faraday rotation observations of radio lobes do not constrain large-scale ICM fields well if they are aligned with the bubble surface, the draping case may be a viable alternative solution to the problem. A generic feature found in our simulations is the formation of magnetic wakes where fields are ordered and amplified. We suggest that this effect could prevent evaporation by thermal conduction of cold H$\alpha$ filaments observed in the Perseus cluster.},
journal = {Monthly Notices of the Royal Astronomical Society},
author = {Ruszkowski, M. and En\ss{}lin, T. A. and Br\"uggen, M. and Heinz, S. and Pfrommer, C.},
month = jun,
year = {2007},
keywords = {MHD,magnetic fields},
pages = {662-672},
file = {/home/forrest/MSU/research/zotfiles/MyPapers/AGNThermal2018/Ruszkowski et al_2007_Impact of tangled magnetic fields on fossil radio bubbles.pdf}
}
@article{ruszkowski_cosmological_2011,
title = {Cosmological {{Magnetohydrodynamic Simulations}} of {{Cluster Formation}} with {{Anisotropic Thermal Conduction}}},
volume = {740},
issn = {0004-637X},
doi = {10.1088/0004-637X/740/2/81},
abstract = {The intracluster medium (ICM) has been suggested to be buoyantly
unstable in the presence of magnetic field and anisotropic thermal
conduction. We perform first cosmological simulations of galaxy cluster
formation that simultaneously include magnetic fields, radiative
cooling, and anisotropic thermal conduction. In isolated and idealized
cluster models, the magnetothermal instability (MTI) tends to reorient
the magnetic fields radially whenever the temperature gradient points in
the direction opposite to gravitational acceleration. Using cosmological
simulations of cluster formation we detect radial bias in the velocity
and magnetic fields. Such radial bias is consistent with either the
inhomogeneous radial gas flows due to substructures or residual
MTI-driven field rearrangements that are expected even in the presence
of turbulence. Although disentangling the two scenarios is challenging,
we do not detect excess bias in the runs that include anisotropic
thermal conduction. The anisotropy effect is potentially detectable via
radio polarization measurements with LOFAR and the Square Kilometer
Array and future X-ray spectroscopic studies with the International
X-ray Observatory. We demonstrate that radiative cooling boosts the
amplification of the magnetic field by about two orders of magnitude
beyond what is expected in the non-radiative cases. This effect is
caused by the compression of the gas and frozen-in magnetic field as it
accumulates in the cluster center. At z = 0 the field is amplified by a
factor of about 106 compared to the uniform magnetic field
that evolved due to the universal expansion alone. Interestingly, the
runs that include both radiative cooling and thermal conduction exhibit
stronger magnetic field amplification than purely radiative runs. In
these cases, buoyant restoring forces depend on the temperature
gradients rather than the steeper entropy gradients. Thus, the ICM is
more easily mixed and the winding up of the frozen-in magnetic field is
more efficient, resulting in stronger magnetic field amplification. We
also demonstrate that thermal conduction partially reduces the gas
accretion driven by overcooling despite the fact that the effective
conductivity is suppressed below the Spitzer-Braginskii value.},
journal = {The Astrophysical Journal},
author = {Ruszkowski, M. and Lee, D. and Br\"uggen, M. and Parrish, I. and Oh, S. Peng},
month = oct,
year = {2011},
keywords = {galaxies: active,galaxies: clusters: general,X-rays: galaxies: clusters,instabilities,conduction},
pages = {81},
file = {/home/forrest/MSU/research/zotfiles/MyPapers/AGNThermal2018/Ruszkowski et al_2011_Cosmological Magnetohydrodynamic Simulations of Cluster Formation with.pdf}
}
@article{ruszkowski_shaken_2010,
title = {Shaken and {{Stirred}}: {{Conduction}} and {{Turbulence}} in {{Clusters}} of {{Galaxies}}},
volume = {713},
issn = {0004-637X},
shorttitle = {Shaken and {{Stirred}}},
doi = {10.1088/0004-637X/713/2/1332},
abstract = {Uninhibited radiative cooling in clusters of galaxies would lead to excessive mass accretion rates contrary to observations. One of the key proposals to offset radiative energy losses is thermal conduction from outer, hotter layers of cool core (CC) clusters to their centers. However, thermal conduction is sensitive to magnetic field topology. In CC clusters where temperature decreases inwards, the heat buoyancy instability (HBI) leads to magnetic fields ordered preferentially in the direction perpendicular to that of gravity, which significantly reduces the level of conduction below the classical Spitzer-Braginskii value. However, the CC clusters are rarely in perfect hydrostatic equilibrium. Sloshing motions due to minor mergers and stirring motions induced by cluster galaxies or active galactic nuclei can significantly perturb the gas. The turbulent cascade can then affect the topology of the magnetic field and the effective level of thermal conduction. We perform
three-dimensional adaptive mesh refinement magnetohydrodynamical simulations of the effect of turbulence on the properties of the anisotropic thermal conduction in CC clusters. We show that very weak subsonic motions, well within observational constraints, can randomize the magnetic field and significantly boost effective thermal conduction beyond the saturated values expected in the pure unperturbed HBI case. We find that the turbulent motions can essentially restore the
conductive heat flow to the CC to level comparable to the theoretical maximum of \textasciitilde{}1/3 Spitzer for a highly tangled field. Runs with radiative cooling show that the cooling catastrophe can be averted and the cluster core stabilized; however, this conclusion may depend on the central gas density. Above a critical Froude number, these same turbulent motions also eliminate the tangential bias in the velocity and magnetic field that is otherwise induced by the trapped g-modes, and possibly allow significant turbulent heat diffusion. Our results can be tested with future radio polarization measurements and have implications for efficient metal dispersal in clusters.},
journal = {The Astrophysical Journal},
author = {Ruszkowski, M. and Oh, S. Peng},
month = apr,
year = {2010},
keywords = {galaxies: clusters: general,plasmas,instabilities,magnetohydrodynamics: MHD,conduction},
pages = {1332-1342},
file = {/home/forrest/MSU/research/zotfiles/MyPapers/AGNThermal2018/Ruszkowski_Oh_2010_Shaken and Stirred.pdf}
}
@article{ruszkowski_galaxy_2011,
title = {Galaxy Motions, Turbulence and Conduction in Clusters of Galaxies},
volume = {414},
issn = {0035-8711},
doi = {10.1111/j.1365-2966.2011.18482.x},
abstract = {Unopposed radiative cooling in clusters of galaxies results in excessive mass deposition rates on to the central brightest cluster galaxy. However, the cool cores of galaxy clusters are continuously heated by thermal conduction and turbulent heat diffusion due to minor mergers or the galaxies orbiting the cluster centre. These processes can either reduce the energy requirements for active galactic nucleus heating of cool cores, or they can prevent overcooling altogether. We perform three-dimensional magnetohydrodynamics simulations including
field-aligned thermal conduction and self-gravitating particles to model this in detail. Turbulence is not confined to the wakes of galaxies but is instead volume filling, due to the excitation of large-scale g-modes. We systematically probe the parameter space of galaxy masses and numbers to assess when the cooling catastrophe is prevented. For a wide range of observationally motivated galaxy parameters, we find that the magnetic field is randomized by stirring motions, restoring the conductive heat flow to the core. The cooling catastrophe either does not occur or it is sufficiently delayed to allow the cluster to experience a major merger that could reset the conditions in the intracluster medium. Whilst dissipation of turbulent motions (and hence dynamical friction heating) is negligible as a heat source, turbulent heat diffusion is extremely important; it predominates in the cluster centre. However, thermal conduction becomes important at larger radii, and simulations without thermal conduction suffer a cooling catastrophe. Conduction is important both as a heat source and to reduce stabilizing buoyancy forces, enabling more efficient diffusion. Turbulence enables conduction, and conduction enables turbulence. In these simulations, the gas vorticity - which is a good indicator of trapped g-modes - increases with time. The vorticity growth is approximately mirrored by the growth of the magnetic field, which is amplified by turbulence.},
journal = {Monthly Notices of the Royal Astronomical Society},
author = {Ruszkowski, M. and Oh, S. Peng},
month = jun,
year = {2011},
keywords = {galaxies: active,galaxies: clusters: general,X-rays: galaxies: clusters,galaxies: clusters: intracluster medium,instabilities,conduction},
pages = {1493-1507},
file = {/home/forrest/MSU/research/zotfiles/MyPapers/AGNThermal2018/Ruszkowski_Oh_2011_Galaxy motions, turbulence and conduction in clusters of galaxies.pdf}
}
@article{fabian_cooling_1994,
title = {Cooling {{Flows}} in {{Clusters}} of {{Galaxies}}},
volume = {32},
issn = {0066-4146},
doi = {10.1146/annurev.aa.32.090194.001425},
abstract = {Not Available},
journal = {Annual Review of Astronomy and Astrophysics},
author = {Fabian, A. C.},
year = {1994},
pages = {277-318},
file = {/home/forrest/MSU/research/zotfiles/MyPapers/AGNThermal2018/Fabian_1994_Cooling Flows in Clusters of Galaxies.pdf}
}
@article{fabian_deep_2003,
title = {A Deep {{Chandra}} Observation of the {{Perseus}} Cluster: Shocks and Ripples},
volume = {344},
issn = {0035-8711},
shorttitle = {A Deep {{Chandra}} Observation of the {{Perseus}} Cluster},
doi = {10.1046/j.1365-8711.2003.06902.x},
abstract = {We present preliminary results from a deep observation lasting almost 200 ks of the centre of the Perseus cluster of galaxies around NGC 1275. The X-ray surface brightness of the intracluster gas beyond the inner 20 kpc, which contains the inner radio bubbles, is very smooth apart from some low-amplitude quasi-periodic ripples. A clear density jump at a radius of 24 kpc to the north-east, about 10 kpc out from the bubble rim, appears to be due to a weak shock driven by the northern radio bubble. A similar front may exist around both inner bubbles but is masked elsewhere by rim emission from bright cooler gas. The continuous blowing of bubbles by the central radio source, leading to the
propagation of weak shocks and viscously dissipating sound waves seen as the observed fronts and ripples, gives a rate of working which balances the radiative cooling within the inner 50 kpc of the cluster core.},
journal = {Monthly Notices of the Royal Astronomical Society},
author = {Fabian, A. C. and Sanders, J. S. and Allen, S. W. and Crawford, C. S. and Iwasawa, K. and Johnstone, R. M. and Schmidt, R. W. and Taylor, G. B.},
month = sep,
year = {2003},
keywords = {intergalactic medium,shock waves,cooling flows,X-rays: galaxies: clusters,galaxies: clusters: individual: Perseus},
pages = {L43-L47},
file = {/home/forrest/MSU/research/zotfiles/MyPapers/AGNThermal2018/Fabian et al_2003_A deep Chandra observation of the Perseus cluster.pdf}
}
@article{guo_feedback_2008,
title = {Feedback Heating by Cosmic Rays in Clusters of Galaxies},
volume = {384},
issn = {0035-8711},
doi = {10.1111/j.1365-2966.2007.12692.x},
abstract = {Recent observations show that the cooling flows in the central regions of galaxy clusters are highly suppressed. Observed active galactic nuclei (AGN)-induced cavities/bubbles are a leading candidate for suppressing cooling, usually via some form of mechanical heating. At the same time, observed X-ray cavities and synchrotron emission point towards a significant non-thermal particle population. Previous studies have focused on the dynamical effects of cosmic ray pressure support, but none has built successful models in which cosmic ray heating is significant. Here, we investigate a new model of AGN heating, in which the intracluster medium is efficiently heated by cosmic rays, which are injected into the intra-cluster medium (ICM) through diffusion or the shredding of the bubbles by Rayleigh-Taylor or Kelvin-Helmholtz
instabilities. We include thermal conduction as well. Using numerical simulations, we show that the cooling catastrophe is efficiently suppressed. The cluster quickly relaxes to a quasi-equilibrium state with a highly reduced accretion rate and temperature and density profiles which match observations. Unlike the conduction-only case, no fine-tuning of the Spitzer conduction suppression factor f is needed. The cosmic ray pressure, Pc/Pg $<$\textasciitilde{} 0.1 and
$\nabla$Pc $<$\textasciitilde{} 0.1$\rho$g, is well within observational
bounds. Cosmic ray heating is a very attractive alternative to
mechanical heating, and may become particularly compelling if Gamma-ray Large Array Space Telescope (GLAST) detects the $\gamma$-ray signature of cosmic rays in clusters.},
journal = {Monthly Notices of the Royal Astronomical Society},
author = {Guo, Fulai and Oh, S. Peng},
month = feb,
year = {2008},
keywords = {galaxies: clusters: general,cooling flows,X-rays: galaxies: clusters,instabilities,cosmic rays},
pages = {251-266},
file = {/home/forrest/MSU/research/zotfiles/MyPapers/AGNThermal2018/Guo_Oh_2008_Feedback heating by cosmic rays in clusters of galaxies.pdf}
}
@article{churazov_evolution_2001-2,
title = {Evolution of {{Buoyant Bubbles}} in {{M87}}},
volume = {554},
issn = {0004-637X},
doi = {10.1086/321357},
abstract = {The morphology of the X-ray- and radio-emitting features in the central \textasciitilde{}50 kpc region around the galaxy M87 strongly suggests that buoyant bubbles of cosmic rays (inflated by an earlier nuclear active phase of the galaxy) rise through the cooling gas at roughly half the sound speed. In the absence of strong surface tension, initially spherical bubbles will transform into tori as they rise through an external medium. Such structures can be identified in the radio images of the halo of M87. During their rise, bubbles will uplift relatively cool X-ray-emitting gas from the central regions of the cooling flow to larger distances. This gas is colder than the ambient gas and has a higher volume emissivity. As a result, rising ‘‘radio'' bubbles may be trailed by elongated X-ray features, as indeed is observed in M87. We performed simple hydrodynamic simulations to illustrate qualitatively the evolution of buoyant bubbles in the M87 environment.},
journal = {The Astrophysical Journal},
author = {Churazov, E. and Br\"uggen, M. and Kaiser, C. R. and B\"ohringer, H. and Forman, W.},
month = jun,
year = {2001},
keywords = {Galaxies: Active,Galaxies: Cooling Flows,galaxies: clusters: individual (Virgo),galaxies: individual (M87),X-Rays: Galaxies},
pages = {261-273},
file = {/home/forrest/MSU/research/zotfiles/MyPapers/AGNThermal2018/Churazov et al_2001_Evolution of Buoyant Bubbles in M87.pdf}
}
@article{turk_yt_2011,
title = {Yt: {{A Multi}}-Code {{Analysis Toolkit}} for {{Astrophysical Simulation Data}}},
volume = {192},
issn = {0067-0049},
shorttitle = {Yt},
doi = {10.1088/0067-0049/192/1/9},
abstract = {The analysis of complex multiphysics astrophysical simulations presents a unique and rapidly growing set of challenges: reproducibility, parallelization, and vast increases in data size and complexity chief among them. In order to meet these challenges, and in order to open up new avenues for collaboration between users of multiple simulation platforms, we present yt (available at http://yt.enzotools.org/) an open source, community-developed astrophysical analysis and visualization toolkit. Analysis and visualization with yt are oriented around
physically relevant quantities rather than quantities native to
astrophysical simulation codes. While originally designed for handling Enzo's structure adaptive mesh refinement data, yt has been extended to work with several different simulation methods and simulation codes including Orion, RAMSES, and FLASH. We report on its methods for reading, handling, and visualizing data, including projections,
multivariate volume rendering, multi-dimensional histograms, halo finding, light cone generation, and topologically connected isocontour identification. Furthermore, we discuss the underlying algorithms yt uses for processing and visualizing data, and its mechanisms for parallelization of analysis tasks.},
journal = {The Astrophysical Journal Supplement Series},
author = {Turk, Matthew J. and Smith, Britton D. and Oishi, Jeffrey S. and Skory, Stephen and Skillman, Samuel W. and Abel, Tom and Norman, Michael L.},
month = jan,
year = {2011},
keywords = {cosmology: theory,methods: numerical,methods: data analysis},
pages = {9},
file = {/home/forrest/MSU/research/zotfiles/Codes/Turk et al_2011_yt.pdf}
}
@article{schure_new_2009-2,
title = {A New Radiative Cooling Curve Based on an Up-to-Date Plasma Emission Code},
volume = {508},
copyright = {\textcopyright{} ESO, 2009},
issn = {0004-6361, 1432-0746},
doi = {10.1051/0004-6361/200912495},
abstract = {This work presents a new plasma cooling curve that is calculated using the SPEX package. We compare our cooling rates to those in previous works, and implement the new cooling function in the grid-adaptive framework ``AMRVAC''. Contributions to the cooling rate by the individual elements are given, to allow for the creation of cooling curves tailored to specific abundance requirements. In some situations, it is important to be able to include radiative losses in the hydrodynamics. The enhanced compression ratio can trigger instabilities (such as the Vishniac thin-shell instability) that would otherwise be absent. For gas with temperatures below 10\textsuperscript{4\textsuperscript{ K, the cooling time becomes very long and does not affect the gas on the timescales that are generally of interest for hydrodynamical simulations of circumstellar plasmas. However, above this temperature, a significant fraction of the elements is ionised, and the cooling rate increases by a factor 1000 relative to lower temperature plasmas.}}},
language = {en},
number = {2},
journal = {Astronomy \& Astrophysics},
author = {Schure, K. M. and Kosenko, D. and Kaastra, J. S. and Keppens, R. and Vink, J.},
month = dec,
year = {2009},
pages = {751-757},
file = {/home/forrest/MSU/research/zotfiles/MyPapers/AGNThermal2018/Schure et al_2009_A new radiative cooling curve based on an up-to-date plasma emission code.pdf;/home/forrest/Zotero/storage/ZUYYSSKM/aa12495-09.html}
}
@article{li_simulating_2012,
title = {Simulating the {{Cooling Flow}} of {{Cool}}-Core {{Clusters}}},
volume = {747},
issn = {0004-637X},
doi = {10.1088/0004-637X/747/1/26},
abstract = {We carry out high-resolution adaptive mesh refinement simulations of a cool core cluster, resolving the flow from Mpc scales down to pc scales. We do not (yet) include any active galactic nucleus (AGN) heating, focusing instead on cooling in order to understand how gas reaches the supermassive black hole at the center of the cluster. We find that, as the gas cools, the cluster develops a very flat temperature profile, undergoing a cooling catastrophe only in the central 10-100 pc of the cluster. Outside of this region, the flow is smooth, with no local cooling instabilities, and naturally produces very little low-temperature gas (below a few keV), in agreement with observations. The gas cooling in the center of the cluster rapidly forms a thin accretion disk. The amount of cold gas produced at the very center grows rapidly until a reasonable estimate of the resulting AGN heating rate (assuming even a moderate accretion efficiency) would overwhelm cooling. We argue that this naturally produces a thermostat which links the cooling of gas out to 100 kpc with the cold gas accretion in the central 100 pc, potentially closing the loop between cooling and heating. Isotropic heat conduction does not affect the result significantly, but we show that including the potential well of the brightest cluster galaxy is necessary to obtain the correct result. Also, we found that the outcome is sensitive to resolution, requiring very high mass resolution to correctly reproduce the small transition radius.},
language = {en},
number = {1},
journal = {The Astrophysical Journal},
author = {Li, Yuan and Bryan, Greg L.},
year = {2012},
pages = {26},
file = {/home/forrest/MSU/research/zotfiles/MyPapers/AGNThermal2018/Li_Bryan_2012_Simulating the Cooling Flow of Cool-core Clusters.pdf}
}
@article{stone_zeus-2d_1992,
title = {{{ZEUS}}-{{2D}}: {{A}} Radiation Magnetohydrodynamics Code for Astrophysical Flows in Two Space Dimensions. {{I}} - {{The}} Hydrodynamic Algorithms and Tests.},
volume = {80},
issn = {0067-0049},
shorttitle = {{{ZEUS}}-{{2D}}},
doi = {10.1086/191680},
abstract = {A detailed description of ZEUS-2D, a numerical code for the simulation
of fluid dynamical flows including a self-consistent treatment of the
effects of magnetic fields and radiation transfer is presented.
Attention is given to the hydrodynamic (HD) algorithms which form the
foundation for the more complex MHD and radiation HD algorithms. The
effect of self-gravity on the flow dynamics is accounted for by an
iterative solution of the sparse-banded matrix resulting from
discretizing the Poisson equation in multidimensions. The results of an
extensive series of HD test problems are presented. A detailed
description of the MHD algorithms in ZEUS-2D is presented. A new method
of computing the electromotive force is developed using the method of
characteristics (MOC). It is demonstrated through the results of an
extensive series of MHD test problems that the resulting hybrid
MOC-constrained transport method provides for the accurate evolution of
all modes of MHD wave families.},
journal = {The Astrophysical Journal Supplement Series},
author = {Stone, James M. and Norman, Michael L.},
month = jun,
year = {1992},
keywords = {Computational Astrophysics,Computational Grids,Cosmic Plasma,Finite Difference Theory,Hydrodynamic Equations,Magnetohydrodynamic Flow,Plasma Radiation,Poisson Equation,Radiative Transfer,Self Consistent Fields},
pages = {753-790},
file = {/home/forrest/MSU/research/zotfiles/Codes/Stone_Norman_1992_ZEUS-2D.pdf}
}
@article{churazov_xmm-newton_2004,
title = {{{XMM}}-{{Newton}} Observations of the {{Perseus}} Cluster - {{II}}. {{Evidence}} for Gas Motions in the Core},
volume = {347},
issn = {0035-8711},
doi = {10.1111/j.1365-2966.2004.07201.x},
abstract = {The 5-9 keV spectrum of the inner \textasciitilde{}100 kpc of the Perseus cluster
measured by XMM-Newton can be well described by an optically thin plasma
emission model as predicted by the APEC code, without any need for
invoking a strong Ni overabundance or the effects of resonant
scattering. For the strongest 6.7-keV line of He-like iron, the optical
depth of the cluster, calculated using observed density, temperature and
abundance profiles, is of the order of 3. The lack of evidence for
resonant scattering effects implies gas motion in the core with a range
in velocities of at least half of the sound velocity. If this motion has
the character of small-scale turbulence, then its dissipation would
provide enough energy to compensate for radiative cooling of the gas.
The activity of the supermassive black hole at the centre of the cluster
may be the driving force of the gas motion.},
journal = {Monthly Notices of the Royal Astronomical Society},
author = {Churazov, E. and Forman, W. and Jones, C. and Sunyaev, R. and B\"ohringer, H.},
month = jan,
year = {2004},
keywords = {cooling flows,galaxies: clusters: individual: Perseus,X-rays: galaxies: clusters},
pages = {29-35},
file = {/home/forrest/MSU/research/zotfiles/MyPapers/AGNThermal2018/Churazov et al_2004_XMM-Newton observations of the Perseus cluster - II.pdf}
}
@article{vikhlinin_chandra_2006,
title = {Chandra {{Sample}} of {{Nearby Relaxed Galaxy Clusters}}: {{Mass}}, {{Gas Fraction}}, and {{Mass}}-{{Temperature Relation}}},
volume = {640},
issn = {0004-637X},
shorttitle = {Chandra {{Sample}} of {{Nearby Relaxed Galaxy Clusters}}},
doi = {10.1086/500288},
abstract = {We present gas and total mass profiles for 13 low-redshift, relaxed
clusters spanning a temperature range 0.7-9 keV, derived from all
available Chandra data of sufficient quality. In all clusters,
gas-temperature profiles are measured to large radii (Vikhlinin et al.)
so that direct hydrostatic mass estimates are possible to nearly
r500 or beyond. The gas density was accurately traced to
larger radii; its profile is not described well by a beta model, showing
continuous steepening with radius. The derived $\rho$tot
profiles and their scaling with mass generally follow the
Navarro-Frenk-White model with concentration expected for dark matter
halos in $\Lambda$CDM cosmology. However, in three cool clusters, we
detect a central mass component in excess of the Navarro-Frenk-White
profile, apparently associated with their cD galaxies. In the inner
region (r$<$0.1r500), the gas density and temperature
profiles exhibit significant scatter and trends with mass, but they
become nearly self-similar at larger radii. Correspondingly, we find
that the slope of the mass-temperature relation for these relaxed
clusters is in good agreement with the simple self-similar behavior,
M500\textasciitilde{}T$\alpha$, where $\alpha$=(1.5-1.6)+/-0.1, if
the gas temperatures are measured excluding the central cool cores. The
normalization of this M-T relation is significantly, by \textasciitilde{}30\%, higher
than most previous X-ray determinations. We derive accurate gas mass
fraction profiles, which show an increase with both radius and cluster
mass. The enclosed fgas profiles within
r2500\textasciitilde{}=0.4r500 have not yet reached any asymptotic
value and are still far (by a factor of 1.5-2) from the universal baryon
fraction according to the cosmic microwave background (CMB)
observations. The fgas trends become weaker and its values
closer to universal at larger radii, in particular, in spherical shells
r2500500.},
journal = {The Astrophysical Journal},
author = {Vikhlinin, A. and Kravtsov, A. and Forman, W. and Jones, C. and Markevitch, M. and Murray, S. S. and Van Speybroeck, L.},
month = apr,
year = {2006},
keywords = {Cosmology: Dark Matter,Cosmology: Observations,Galaxies: Clusters: General,X-Rays: Galaxies: Clusters},
pages = {691-709},
file = {/home/forrest/MSU/research/zotfiles/MyPapers/AGNThermal2018/Vikhlinin et al_2006_Chandra Sample of Nearby Relaxed Galaxy Clusters.pdf}
}
@article{mathews_heating_2006,
title = {Heating {{Cooling Flows}} with {{Weak Shock Waves}}},
volume = {638},
issn = {0004-637X},
doi = {10.1086/499119},
abstract = {The discovery of extended, approximately spherical weak shock waves in the hot intercluster gas in Perseus and Virgo has precipitated the notion that these waves may be the primary heating process that explains why so little gas cools to low temperatures. This type of heating has received additional support from recent gasdynamical models. We show here that outwardly propagating, dissipating waves deposit most of their energy near the center of the cluster atmosphere. Consequently, if the gas is heated by (intermittent) weak shocks for several Gyr, the gas within 30-50 kpc is heated to temperatures that far exceed observed values. This heating can be avoided if dissipating shocks are sufficiently infrequent or weak so as not to be the primary source of global heating. Local PV and viscous heating associated with newly formed X-ray cavities are likely to be small, which is consistent with the low gas temperatures generally observed near the centers of groups and clusters where the cavities are located.},
language = {en},
number = {2},
journal = {The Astrophysical Journal},
author = {Mathews, William G. and Faltenbacher, Andreas and Brighenti, Fabrizio},
year = {2006},
pages = {659},
file = {/home/forrest/MSU/research/zotfiles/MyPapers/AGNThermal2018/Mathews et al_2006_Heating Cooling Flows with Weak Shock Waves.pdf}
}
@article{li_modeling_2014,
title = {Modeling {{Active Galactic Nucleus Feedback}} in {{Cool}}-Core {{Clusters}}: {{The Balance}} between {{Heating}} and {{Cooling}}},
volume = {789},
issn = {0004-637X},
shorttitle = {Modeling {{Active Galactic Nucleus Feedback}} in {{Cool}}-Core {{Clusters}}},
doi = {10.1088/0004-637X/789/1/54},
abstract = {We study the long-term evolution of an idealized cool-core galaxy cluster under the influence of momentum-driven active galactic nucleus (AGN) feedback using three-dimensional high-resolution (60 pc) adaptive mesh refinement simulations. The feedback is modeled with a pair of precessing jets whose power is calculated based on the accretion rate of the cold gas surrounding the supermassive black hole (SMBH). The intracluster medium first cools into clumps along the propagation direction of the jets. As the jet power increases, gas condensation occurs isotropically, forming spatially extended structures that resemble the observed H$\alpha$ filaments in Perseus and many other cool-core clusters. Jet heating elevates the gas entropy, halting clump formation. The cold gas that is not accreted onto the SMBH settles into a rotating disk of 10 11 M $\Sun$ . The hot gas cools directly onto the disk while the SMBH accretes from its innermost region, powering the AGN that maintains a thermally balanced state for a few Gyr. The mass cooling rate averaged over 7 Gyr is 30 M $\Sun$ yr \textendash{}1 , an order of magnitude lower than the classic cooling flow value. Medium resolution simulations produce similar results, while in low resolution runs, the cluster experiences cycles of gas condensation and AGN outbursts. Owing to its self-regulating mechanism, AGN feedback can successfully balance cooling with a wide range of model parameters. Our model also produces cold structures in early stages that are in good agreement with the observations. However, the long-lived massive cold disk is unrealistic, suggesting that additional physical processes are still needed.},
language = {en},
number = {1},
journal = {The Astrophysical Journal},
author = {Li, Yuan and Bryan, Greg L.},
year = {2014},
pages = {54},
file = {/home/forrest/MSU/research/zotfiles/MyPapers/AGNThermal2018/Li_Bryan_2014_Modeling Active Galactic Nucleus Feedback in Cool-core Clusters.pdf}
}
@article{li_modeling_2014-1,
title = {Modeling {{Active Galactic Nucleus Feedback}} in {{Cool}}-Core {{Clusters}}: {{The Formation}} of {{Cold Clumps}}},
volume = {789},
issn = {0004-637X},
shorttitle = {Modeling {{Active Galactic Nucleus Feedback}} in {{Cool}}-Core {{Clusters}}},
doi = {10.1088/0004-637X/789/2/153},
abstract = {We perform high-resolution (15-30 pc) adaptive mesh simulations to study
the impact of momentum-driven active galactic nucleus (AGN) feedback in
cool-core clusters, focusing in this paper on the formation of cold
clumps. The feedback is jet-driven with an energy determined by the
amount of cold gas within 500 pc of the super-massive black hole. When
the intracluster medium in the core of the cluster becomes marginally
stable to radiative cooling, with the thermal instability to the
free-fall timescale ratio t TI/t ff $<$ 3-10,
cold clumps of gas start to form along the propagation direction of the
AGN jets. By tracing the particles in the simulations, we find that
these cold clumps originate from low entropy (but still hot) gas that is
accelerated by the jet to outward radial velocities of a few hundred km
s-1. This gas is out of hydrostatic equilibrium and so
can cool. The clumps then grow larger as they decelerate and fall toward
the center of the cluster, eventually being accreted onto the
super-massive black hole. The general morphology, spatial distribution,
and estimated H$\alpha$ morphology of the clumps are in reasonable
agreement with observations, although we do not fully replicate the
filamentary morphology of the clumps seen in the observations, probably
due to missing physics.},
journal = {The Astrophysical Journal},
author = {Li, Yuan and Bryan, Greg L.},
month = jul,
year = {2014},
keywords = {galaxies: clusters: general,galaxies: clusters: intracluster medium,hydrodynamics},
pages = {153},
file = {/home/forrest/MSU/research/zotfiles/MyPapers/AGNThermal2018/Li_Bryan_2014_Modeling Active Galactic Nucleus Feedback in Cool-core Clusters3.pdf}
}