AGN-stimulated cooling of hot gas in elliptical galaxies

Valentini, Milena; Brighenti, Fabrizio

doi:10.1093/mnras/stv090

Cited by 45 publications

(46 citation statements)

References 107 publications

(245 reference statements)

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“…Dust can then grow in cold gas by accretion of condensable elements on to pre-existing grains, but this process usually takes place on ≈Gyr time-scales (e.g. Valentini & Brighenti 2015). Dust-poor molecular gas structures originated from hot gas cooling has been observed in massive radio-loud ETGs at the centre of nearby cluster of galaxies (e.g.…”

Section: Dust and Molecular Gas Co-spatialitymentioning

confidence: 99%

The AGN fuelling/feedback cycle in nearby radio galaxies – II. Kinematics of the molecular gas

Ruffa

Davis

Prandoni

et al. 2019

Monthly Notices of the Royal Astronomical Society

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This is the second paper of a series exploring the multi-component (stars, warm and cold gas and radio jets) properties of a sample of eleven nearby low excitation radio galaxies (LERGs), with the aim of better understanding the AGN fuelling/feedback cycle in these objects. Here we present a study of the molecular gas kinematics of six sample galaxies detected in 12 CO(2-1) with ALMA. In all cases, our modelling suggests that the bulk of the gas in the observed (sub-)kpc CO discs is in ordered rotation. Nevertheless, low-level distortions are ubiquitous, indicating that the molecular gas is not fully relaxed into the host galaxy potential. The majority of the discs, however, are only marginally resolved, preventing us from drawing strong conclusions. NGC 3557 and NGC 3100 are special cases. The features observed in the CO velocity curve of NGC 3557 allow us to estimate a super-massive black hole (SMBH) mass of (7.10 ± 0.02) × 10 8 M , in agreement with expectations from the M SMBH − σ * relation. The rotation pattern of NGC 3100 shows distortions that appear to be consistent with the presence of both a position angle and inclination warp. Non-negligible radial motions are also found in the plane of the CO disc, likely consistent with streaming motions associated with the spiral pattern found in the inner regions of the disc. The dominant radial motions are likely to be inflows, supporting a scenario in which the cold gas is contributing to the fuelling of the AGN.M SMBH is the mass of the central super-massive black hole, m p is the mass of the proton, ε is the accretion efficiency, c is the speed of light and σ T is the cross-section for Thomson scattering.

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Section: Dust and Molecular Gas Co-spatialitymentioning

confidence: 99%

The AGN fuelling/feedback cycle in nearby radio galaxies – II. Kinematics of the molecular gas

Ruffa

Davis

Prandoni

et al. 2019

Monthly Notices of the Royal Astronomical Society

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“…We found that radio jets were closely correlated with declining central temperature profiles and, where it could be calculated, low minimum values of the ratio of the cooling time to the free fall time in the IGM, min(t c /t f f ) 15. This link with jet activity suggests that at low values of this instability criterion, cooling from the IGM produces sufficient cold material to fuel the AGN (see also Valentini & Brighenti 2015;Prasad et al 2015Prasad et al , 2017Prasad et al , 2018. The jet systems also had low central cooling times and entropies, but so did a number of systems without evidence of recent AGN outbursts.…”

Section: Thermal Instabilitymentioning

confidence: 99%

Cold gas in a complete sample of group-dominant early-type galaxies

O’Sullivan

Combes

Salomé

et al. 2018

A&A

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We present IRAM 30m and APEX telescope observations of CO(1-0) and CO(2-1) lines in 36 group-dominant early-type galaxies, completing our molecular gas survey of dominant galaxies in the Complete Local-volume Groups Sample. We detect CO emission in 12 of the galaxies at >4σ significance, with molecular gas masses in the range ∼0.01-6×10 8 M , as well as CO in absorption in the non-dominant group member galaxy NGC 5354. In total 21 of the 53 CLoGS dominant galaxies are detected in CO and we confirm our previous findings that they have low star formation rates (0.01-1M yr −1 ) but short depletion times (<1 Gyr) implying rapid replenishment of their gas reservoirs. Comparing molecular gas mass with radio luminosity, we find that a much higher fraction of our group-dominant galaxies (60±16%) are AGN-dominated than is the case for the general population of ellipticals, but that there is no clear connection between radio luminosity and the molecular gas mass. Using data from the literature, we find that at least 27 of the 53 CLoGS dominant galaxies contain H , comparable to the fraction of nearby non-cluster early type galaxies detected in H and significantly higher that the fraction in the Virgo cluster. We see no correlation between the presence of an X-ray detected intra-group medium and molecular gas in the dominant galaxy, but find that the H -richest galaxies are located in X-ray faint groups. Morphological data from the literature suggests the cold gas component most commonly takes the form of a disk, but many systems show evidence of galaxy-galaxy interactions, indicating that they may have acquired their gas through stripping or mergers. We provide improved molecular gas mass estimates for two galaxies previously identified as being in the centres of cooling flows, NGC 4636 and NGC 5846, and find that they are relatively molecular gas poor compared to our other detected systems.

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“…Over the past decade, extensive investigations have been carried out in order to understand the mechanism through which AGN inject energy into the surrounding medium and how the condensed filaments/clouds form out of the hot halos (Gaspari et al 2009(Gaspari et al , 2011a(Gaspari et al ,b, 2017Pizzolato & Soker 2010;McCourt et al 2012;Sharma et al 2012;Li & Bryan 2014;Prasad et al 2015Prasad et al , 2017Voit et al 2015aVoit et al , 2017Valentini & Brighenti 2015;Soker 2016;Yang et al 2019). A novel paradigm has emerged in which the AGN feedback cycle operates through chaotic cold accretion (CCA; Gaspari et al 2013Gaspari et al , 2015, where turbulent eddies induced by AGN outflows (and cosmic flows; Lau et al 2017) are responsible for the condensation of multiphase gas out of the hot halos via nonlinear thermal instability.…”

Section: Introductionmentioning

confidence: 99%

The X-Ray Halo Scaling Relations of Supermassive Black Holes

Gaspari

Eckert

Ettori

et al. 2019

ApJ

140

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We carry out a comprehensive Bayesian correlation analysis between hot halos and direct masses of supermassive black holes (SMBHs), by retrieving the X-ray plasma properties (temperature, luminosity, density, pressure, masses) over galactic to cluster scales for 85 diverse systems. We find new key scalings, with the tightest relation being the M • − T x , followed by M • − L x . The tighter scatter (down to 0.2 dex) and stronger correlation coefficient of all the X-ray halo scalings compared with the optical counterparts (as the M • − σ e ) suggest that plasma halos play a more central role than stars in tracing and growing SMBHs (especially those that are ultramassive). Moreover, M • correlates better with the gas mass than dark matter mass. We show the important role of the environment, morphology, and relic galaxies/coronae, as well as the main departures from virialization/self-similarity via the optical/X-ray fundamental planes. We test the three major channels for SMBH growth: hot/Bondilike models have inconsistent anti-correlation with X-ray halos and too low feeding; cosmological simulations find SMBH mergers as sub-dominant over most of the cosmic time and too rare to induce a central-limit-theorem effect; the scalings are consistent with chaotic cold accretion (CCA), the rain of matter condensing out of the turbulent X-ray halos that sustains a long-term self-regulated feedback loop. The new correlations are major observational constraints for models of SMBH feeding/feedback in galaxies, groups, and clusters (e.g., to test cosmological hydrodynamical simulations), and enable the study of SMBHs not only through X-rays, but also via the Sunyaev-Zel'dovich effect (Compton parameter), lensing (total masses), and cosmology (gas fractions).

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AGN-stimulated cooling of hot gas in elliptical galaxies

Cited by 45 publications

References 107 publications

The AGN fuelling/feedback cycle in nearby radio galaxies – II. Kinematics of the molecular gas

The AGN fuelling/feedback cycle in nearby radio galaxies – II. Kinematics of the molecular gas

Cold gas in a complete sample of group-dominant early-type galaxies

The X-Ray Halo Scaling Relations of Supermassive Black Holes

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