17-P

Gaspari, Justine L.; Hess, Jean; Kumer, Lorie H.; Malec, Lori A.; Habig, Dennis F.; Fisher, Carolyn U.; Casey, Heather; Goss, Kimberly J.; Frenchek, Scott; Domen, Ronald E.; Shike, Hiroko

doi:10.1016/j.humimm.2013.08.092

Cited by 4 publications

(4 citation statements)

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“…However, recent simulations that include realistic prescriptions for cooling, heating and turbulence, provide evidence that much of the hot gas in the nuclear regions on a scale of ∼0.1 -1 kpc can condense into filaments of cool gas that fall near-radially towards the nucleus, with cloud-cloud collisions helping to dissipate any angular momentum in the gas (e.g. Gaspari, Peng & Oh, 2013;Gaspari, Brighenti & Temi, 2015). As a result, the accretion rates associated with such chaotic cold accretion (CCA) can be orders of magnitude higher than the Bondi rate -sufficient to trigger a quasar-like AGN.…”

Section: Accretion Rates and Modesmentioning

confidence: 99%

Radio AGN in the local universe: unification, triggering and evolution

Tadhunter

2016

Astron Astrophys Rev

146

150

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Associated with one of the most important forms of active galactic nucleus (AGN) feedback, and showing a strong preference for giant elliptical host galaxies, radio AGN (L_1.4GHz > 10^24 W Hz^-1) are a key sub-class of the overall AGN population. Here I review our current state of understanding of the population of radio AGN at low and intermediate redshifts (z < 0.7), concentrating on their AGN and host galaxy properties, and covering three interlocking themes: the classification of radio AGN and its interpretation; the triggering and fuelling of the jet and AGN activity; and the evolution of the host galaxies. I show that much of the observed diversity in the AGN properties of radio AGN can be explained in terms of a combination of orientation/anisotropy, mass accretion rate, and variability effects. The detailed morphologies of the host galaxies are consistent with the triggering of strong-line radio galaxies (SLRG) in galaxy mergers. However, the star formation properties and cool ISM contents suggest that the triggering mergers are relatively minor in terms of their gas masses in most cases, and would not lead to major growth of the supermassive black holes and stellar bulges; therefore, apart from a minority (<20%) that show evidence for higher star formation rates and more massive cool ISM reservoirs, the SLRG represent late-time re-triggering of activity in mature giant elliptical galaxies. In contrast, the host and environmental properties of weak-line radio galaxies (WLRG) with Fanaroff-Riley class I (FRI) radio morphologies are consistent with more gradual fuelling of the activity via gas accretion at low rates onto the supermassive black holes.Comment: Accepted for publication in Astronomy & Astrophysics Review, 67 pages, 17 figure

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Section: Accretion Rates and Modesmentioning

confidence: 99%

Radio AGN in the local universe: unification, triggering and evolution

Tadhunter

2016

Astron Astrophys Rev

146

150

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“…In the future, with calorimeters on the XRISM, Athena, and Lynx missions, we will be able to look for correlations between the level of turbulence and condensation. The Phoenix cluster would provide an excellent test-bed for theories which posit that turbulence plays a critical role in the feedback/cooling cycle (e.g., Gaspari et al 2017;Voit 2018).…”

Section: Positive Feedback (Cooling): Uplift and Turbulencementioning

confidence: 99%

Anatomy of a Cooling Flow: The Feedback Response to Pure Cooling in the Core of the Phoenix Cluster

McDonald¹,

McNamara

Voit

et al. 2019

ApJ

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We present new, deep observations of the Phoenix cluster from the Chandra X-ray Observatory, the Hubble Space Telescope, and the Karl Jansky Very Large Array. These data provide an order of magnitude improvement in depth and/or angular resolution at X-ray, optical, and radio wavelengths, yielding an unprecedented view of the core of the Phoenix cluster. We find that the one-dimensional temperature and entropy profiles are consistent with expectations for pure-cooling hydrodynamic simulations and analytic descriptions of homogeneous, steady-state cooling flow models. In particular, the entropy profile is well-fit by a single power law at all radii, with no evidence for excess entropy in the core. In the inner ∼10 kpc, the cooling time is shorter by an order of magnitude than any other known cluster, while the ratio of the cooling time to freefall time (t cool /t f f ) approaches unity, signaling that the ICM is unable to resist multiphase condensation on kpc scales. When we consider the thermodynamic profiles in two dimensions, we find that the cooling is highly asymmetric. The bulk of the cooling in the inner ∼20 kpc is confined to a low-entropy filament extending northward from the central galaxy, with t cool /t f f ∼ 1 over the length of the filament. This northern filament is significantly absorbed, suggesting the presence of ∼10 10 M in cool gas that is absorbing soft X-rays. We detect a substantial reservoir of cool (∼10 4 K) gas (as traced by the [O ii]λλ3726,3729 doublet), which is coincident with the low-entropy filament. The bulk of this cool gas is draped around and behind a pair of X-ray cavities, presumably bubbles that have been inflated by radio jets, which are detected for the first time on kpc scales. These data support a picture in which AGN feedback is promoting the formation of a multiphase medium via a combination of ordered buoyant uplift and locally enhanced turbulence. These processes ought to counteract the tendency for buoyancy to suppress condensation, leading to rapid cooling along the jet axis. The recent mechanical outburst has sufficient energy to offset cooling, and appears to be coupling to the ICM via a cocoon shock, raising the entropy in the direction orthogonal to the radio jets.

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“…However, many estimates of η (e.g. Churazov et al 2005;Merloni & Heinz 2008;Gaspari et al 2012) suggest a small η, with η = 0.1 near the upper limit of reasonable values for the jet efficiency. If the average efficiency is lower, the nuclear black holes need to grow even more to power these radio sources.…”

Section: Supermassive Black Hole Growthmentioning

confidence: 99%

Radio Active Galaxy Nuclei in Galaxy Clusters: Heating Hot Atmospheres and Driving Supermassive Black Hole Growth Over Cosmic Time

McNamara

Nulsen

2013

ApJ

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We estimate the average radio-AGN (mechanical) power deposited into the hot atmospheres of galaxy clusters over more than three quarters of the age of the Universe. Our sample was drawn from eight major X-ray cluster surveys, and includes 685 clusters in the redshift range 0.1 < z < 0.6 that overlap the area covered by the NVSS. The radio-AGN mechanical power was estimated from the radio luminosity of central NVSS sources, using the relation of Cavagnolo et al. (2010) that is based on mechanical powers determined from the enthalpies of X-ray cavities. We find only a weak correlation between radio luminosity and cluster X-ray luminosity, although the most powerful radio sources resides in luminous clusters. The average AGN mechanical power of 3 × 10 44 erg s −1 exceeds the X-ray luminosity of 44% of the clusters, indicating that the accumulation of radio-AGN energy is significant in these clusters. Integrating the AGN mechanical power to redshift z = 2.0, using simple models for its evolution and disregarding the hierarchical growth of clusters, we find that the AGN energy accumulated per particle in low luminosity X-ray clusters exceeds 1 keV per particle. This result represents a conservative lower limit to the accumulated thermal energy. The estimate is comparable to the level of energy needed to "preheat" clusters, indicating that continual outbursts from radio-AGN are a significant source of gas energy in hot atmospheres. Assuming an average mass conversion efficiency of η = 0.1, our result implies that the supermassive black holes that released this energy did so by accreting an average of ∼ 10 9 M ⊙ over time, which is comparable to the level of growth expected during the quasar era.

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17-P

Cited by 4 publications

References 0 publications

Radio AGN in the local universe: unification, triggering and evolution

Radio AGN in the local universe: unification, triggering and evolution

Anatomy of a Cooling Flow: The Feedback Response to Pure Cooling in the Core of the Phoenix Cluster

Radio Active Galaxy Nuclei in Galaxy Clusters: Heating Hot Atmospheres and Driving Supermassive Black Hole Growth Over Cosmic Time

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