AGN jet feedback on a moving mesh: cocoon inflation, gas flows and turbulence

Abstract

In many observed galaxy clusters, jets launched by the accretion process on to supermassive black holes, inflate large-scale cavities filled with energetic, relativistic plasma. This process is thought to be responsible for regulating cooling losses, thus moderating the inflow of gas on to the central galaxy, quenching further star formation and maintaining the galaxy in a red and dead state. In this paper, we implement a new jet feedback scheme into the moving mesh-code arepo, contrast different jet injection techniques and demonstrate the validity of our implementation by comparing against simple analytical models. We find that jets can significantly affect the intracluster medium (ICM), offset the overcooling through a number of heating mechanisms, as well as drive turbulence, albeit within the jet lobes only. Jet-driven turbulence is, however, a largely ineffective heating source and is unlikely to dominate the ICM heating budget even if the jet lobes efficiently fill the cooling region, as it contains at most only a few percent of the total injected energy. We instead show that the ICM gas motions, generated by orbiting substructures, while inefficient at heating the ICM, drive large-scale turbulence and when combined with jet feedback, result in line-ofsight velocities and velocity dispersions consistent with the Hitomi observations of the Perseus cluster.

AGN jet feedback on a moving mesh: lobe energetics and X-ray properties in a realistic cluster environment

“…The value of f thresh jet is similar to previous works (e.g. Hardcastle & Krause 2013;Weinberger et al 2017;Bourne & Sijacki 2017;Yang & Reynolds 2016a) that employ typical values of 0.01 − 0.001. In our work this represents the point at which the gas density/temperature start to decrease/increase respectively, transitioning from ICM like values to lobe like values.…”

“…The jet is injected into a cylinder whose volume is minimised for the conditions n t/b cell ≥ 10 and M cyl ≥ 10 4 h −1 M , where n t/b cell is the number of cells within the top/bottom half of the cylinder and M cyl is the total gas mass within the whole cylinder. Assuming the kinetic energy injection scheme of Bourne & Sijacki (2017) ‡, jet mass, energy and momentum are injected into the cells within each half cylinder , with the momentum directed along the z-axis. These quantities are weighted by the kernel function…”

“…Dubois et al 2010;McCarthy et al 2017;Barnes et al 2018;Henden et al 2018;Tremmel et al 2019) or the detailed AGN jet injection in isolated setups that lack realistic thermodynamical properties (e.g. Hardcastle & Krause 2013;Yang & Reynolds 2016b;Bourne & Sijacki 2017;Weinberger et al 2017). To date only a few, restricted studies that follow in detail the jet-inflation of cavities in a full cosmological environment exist in the literature (e.g.…”

Accelerating AGN jets to parsec scales using general relativistic MHD simulations

“…Through the exchange of energy with the ambient medium, jets heat up gas in the interstellar medium (ISM) creating a feedback loop between the AGN and its environment (e.g., Bower et al 2006;Fabian 2012). AGN feedback plays a key role in regulating the growth of galaxies and star formation (e.g., Silk & Rees 1998;Magorrian et al 1998; for a recent review, see Harrison et al 2018) and therefore, its implementation in cosmological simulations (e.g., Springel et al 2005;Anglés-Alcázar et al 2017;Weinberger et al 2018) warrants an accurate understanding of jet energetics (e.g., Sijacki et al 2007;Bourne & Sijacki 2017). Addressing how jets build up the magnetic and kinetic energy required to explain the E-mail: k.chatterjee@uva.nl radiative emission seen from jet observations is still an open problem.…”

Non-steady heating of cool cores of galaxy clusters by ubiquitous turbulence and AGN

“…We focus on the global stability of the core and consider a wide range of parameters. Lau et al (2017) and Bourne & Sijacki (2017) studied the simultaneous heating and indicated that largescale bulk and shear motions associated with cluster growth can enhance the mixing and advection of AGN feedback energy. However, they investigated only limited cases.…”