Feedback heating by cosmic rays in clusters of galaxies

By Fulai Guo, OH S.Peng. 2007

203 citations recorded by the source corpus.

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 nonthermal 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 quasiequilibrium 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 � 0.1 and ∇Pc � 0.1ρg, 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 γ -ray signature of cosmic rays in clusters.

Subfields: Astronomy and Astrophysics, Nuclear and High Energy Physics

View Paper: https://www.semanticscholar.org/paper/e69159cdf86d2f33f31987d0fdaa9ed8248ae8a1

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Citations in the corpus

What is a cool-core cluster? a detailed analysis of the cores of the X-ray flux-limited HIFLUGCS cluster sample (2009, background): “Among those mechanisms proposed are: conduction (e.g. Zakamska & Narayan 2003), central AGN heating via direct cosmic ray-ICM interaction+conduction (Guo & Oh 2008), AGN heating by bubble induced weak shocks (e.g. Mathews et al. 2006), soundwaves+conduction (e.g. Ruszkowski et al. 2004) and…”
CAUSE AND EFFECT OF FEEDBACK: MULTIPHASE GAS IN CLUSTER CORES HEATED BY AGN JETS (2011, background): “The coupling may occur, for example, via turbulent mixing of AGN bubbles with the ICM (Scannapieco & Brüggen 2008), viscous dissipation of weak shocks (Ruszkowski et al. 2004a,b), and cosmic ray heating (Guo & Oh 2008; Ruszkowski et al. 2008; Sharma et al. 2009).”
Cosmic ray transport in galaxy clusters: implications for radio halos, gamma-ray signatures, and cool core heating (2010, methodology): “The additional heating via streaming of the same CRs is considered in Guo & Oh (2008). diverging path of this initially neighboring line.”
SEARCH FOR COSMIC-RAY-INDUCED GAMMA-RAY EMISSION IN GALAXY CLUSTERS (2013, background): “…but could also be a signpost of the physical heating processes underlying feedback by active galactic nuclei (AGN) that has been proposed to solve the “cluster cooling flow problem” (Loewenstein et al. 1991; Guo & Oh 2008; Enßlin et al. 2011; Fujita & Ohira 2012; Wiener et al. 2013; Pfrommer 2013).”
Turbulent Motions and Shocks Waves in Galaxy Clusters simulated with AMR (2009, background): “Remarkably, the interplay between Cosmic Rays (CR) and turbulent magnetic fields may drive still poorly explored plasma processes that may potentially affect our simplified view of the IGM (Subramanian et al. 2006, Schekochihin et al.2007, Brunetti & Lazarian 2007, Guo & Oh 2008).”
Galaxy formation theory (2010, background): “This distribution may be modified, particularly on small scales, by other contributors to supporting the halo against gravity, such as turbulence (Frenk et al. 1999), cosmic ray pressure (Guo and Oh 2008) and magnetic pressure (Gonçalves and Friaça 1999).”
AGN heating and ICM cooling in the HIFLUGCS sample of galaxy clusters (2008, background): “In addition to direct AGN mechanical heating via radio bubbles, there are also alternative proposed mechanisms such as AGN cosmic-ray heating combined with convection (e.g. Chandran & Rasera 2007) or conduction (e.g. Guo & Oh 2008; Voit et al. 2008).”
SIMULATIONS OF DISK GALAXIES WITH COSMIC RAY DRIVEN GALACTIC WINDS (2013, background): “Some fraction of the energy lost by the CR population heats the thermal gas (e.g. Mannheim & Schlickeiser 1994) at a rate given by (Guo & Oh 2008b) ΓCRHeat = 2.63× 10−16 neeCR erg s−1cm−3.”
THE FERMI BUBBLES. I. POSSIBLE EVIDENCE FOR RECENT AGN JET ACTIVITY IN THE GALAXY (2011, background): “We neglect other more complicated (probably secondary) interactions, e.g., Coulomb interactions, hadronic collisions, and hydromagnetic-wavemediated CR heating, that all depend on the CR energy spectrum (e.g., Guo & Oh 2008).”
Formation of Galaxy Clusters (2012, background): “The presence of a population of relativistic particles in AGN–driven high–entropy bubbles has been suggested as a possible solution to this problem (Guo & Oh 2008, Sijacki et al. 2008).”
FIRE-2 simulations: physics versus numerics in galaxy formation (2017, methodology): “(x) Cosmic Ray Heating: from Guo & Oh (2008): ΛCR =−1.0×10−16 (0.98 + 1.65 ñe XH)eCR n−1H (B25) where we assume an approximately uniform MW-like cosmic ray background, eCR ≈ 9.0× 10−12 fCR.”