Dense gas formation and destruction in a simulated Perseus-like galaxy cluster with spin-driven black hole feedback

R S Beckmann,G Pineau Des Forets,Y Dubois,F Combes,F Polles,S Hamer,P Salome,M D Lehnert,C Cadiou,V Olivares,P Guillard

doi:10.1051/0004-6361/201936188

Abstract

Context. Extended filamentary Hα emission nebulae are a striking feature of nearby galaxy clusters but the formation mechanism of the filaments, and the processes which shape their morphology remain unclear. Aims. We conduct an investigation into the formation, evolution and destruction of dense gas in the centre of a simulated, Perseus-like, cluster under the influence of a spin-driven jet. The jet is powered by the supermassive black hole (SMBH) located in the cluster’s brightest cluster galaxy. We particularly study the role played by condensation of dense gas from the diffuse intracluster medium, and the impact of direct uplifting of existing dense gas by the jets, in determining the spatial distribution and kinematics of the dense gas. Methods. We present a hydrodynamical simulation of an idealised Perseus-like cluster using the adaptive mesh refinement code RAMSES. Our simulation includes a SMBH that self-consistently tracks its spin evolution via its local accretion, and in turn drives a large-scale jet whose direction is based on the black hole’s spin evolution. The simulation also includes a live dark matter (DM) halo, a SMBH free to move in the DM potential, star formation and stellar feedback. Results. We show that the formation and destruction of dense gas is closely linked to the SMBH’s feedback cycle, and that its morphology is highly variable throughout the simulation. While extended filamentary structures readily condense from the hot intra-cluster medium, they are easily shattered into an overly clumpy distribution of gas during their interaction with the jet driven outflows. Condensation occurs predominantly onto infalling gas located 5−15 kpc from the centre during quiescent phases of the central AGN, when the local ratio of the cooling time to free fall time falls below 20, i.e. when tcool/tff < 20. Conclusions. We find evidence for both condensation and uplifting of dense gas, but caution that purely hydrodynamical simulations struggle to effectively regulate the cluster cooling cycle and produce overly clumpy distributions of dense gas morphologies, compared to observation.

Highlights

Via the self-regulation cycle, which consists of cold gas feeding the active galactic nuclei (AGN), which in turn powers a jet, which inflates cavities that heat the intra-cluster medium (ICM), AGN are expected to play a decisive role in determining the cooling and star formation properties of the cluster
The hot gas in the intra-cluster medium, which has temperatures in the range 0.09−1131 keV (106−1.3 × 1010 K), cools down and condensates into dense clumps and filaments within the central 50 kpc of the cluster, with an average temperature of the dense gas of 4.0 × 10−4 keV (4.6 × 103 K). This dense gas falls towards the centre where it feeds the central supermassive black hole (SMBH) and thereby triggers the AGN jet, which, in return, interacts with existing dense gas and stirs turbulence into the hot gas, generating hot outflows with outflow velocities up to 3.5 × 104 km s−1
As the radio jet is oriented along the SMBH spin axis, which in turn is updated according to the chaotic cold accretion onto the central SMBH (Gaspari et al 2013; Voit et al 2017), the jet continuously re-orients throughout the simulation

Summary

Introduction

One of the most striking features of the nearby Perseus cluster, NGC 1275, is the extended filamentary Hα emission nebula in its centre (Lynds 1970; Heckman et al 1989; Crawford & Fabian 1992; Conselice et al 2001; Hatch et al 2007; Fabian et al 2008). Via the self-regulation cycle, which consists of cold gas feeding the AGN, which in turn powers a jet, which inflates cavities that heat the ICM, AGN are expected to play a decisive role in determining the cooling and star formation properties of the cluster (see McNamara & Nulsen 2007; Fabian 2012, for a review). This picture of selfregulation cycles from AGN jets is getting increasing support from hydrodynamical simulations both in an idealised (Cattaneo & Teyssier 2007; Gaspari et al 2011; Li & Bryan 2014a) and in a cosmological context (Dubois et al 2010)

Results

Discussion

Conclusion