Quasar outflows at z ≥ 6: the impact on the host galaxies

BARAI, ParamitaParamitaBARAIGALLERANI, SimonaSimonaGALLERANIPallottini, AndreaAndreaPallottiniFerrara, AndreaAndreaFerraraMarconi, AlessandroAlessandroMarconiCICONE, CLAUDIACLAUDIACICONEMaiolino, RobertoRobertoMaiolinoCarniani, StefanoStefanoCarniani2021-03-152021-03-1520180035-8711http://hdl.handle.net/20.500.12386/30701We investigate quasar outflows at z ≥ 6 by performing zoom-in cosmological hydrodynamical simulations. By employing the smoothed particle hydrodynamics code GADGET-3, we zoom in the 2R200 region around a 2 × 1012 M☉ halo at z = 6, inside a (500 Mpc)3 comoving volume. We compare the results of our active galactic nuclei (AGN) runs with a control simulation in which only stellar/SN feedback is considered. Seeding 105 M☉ black holes (BHs) at the centres of 109 M☉ haloes, we find the following results. BHs accrete gas at the Eddington rate over z = 9-6. At z = 6, our most-massive BH has grown to MBH = 4 × 109 M☉. Fast (vr > 1000 km s-1), powerful (\dot{M}_out ∼ 2000 M_{☉} yr-1) outflows of shock-heated low-density gas form at z ∼ 7, and propagate up to hundreds kpc. Star formation is quenched over z = 8-6, and the total star formation rate (SFR surface density near the galaxy centre) is reduced by a factor of 5 (1000). We analyse the relative contribution of multiple physical process: (i) disrupting cosmic filamentary cold gas inflows, (ii) reducing central gas density, (iii) ejecting gas outside the galaxy; and find that AGN feedback has the following effects at z = 6. The inflowing gas mass fraction is reduced by ∼ 12 per cent, the high-density gas fraction is lowered by ∼ 13 per cent, and ∼ 20 per cent of the gas outflows at a speed larger than the escape velocity (500 km s-1). We conclude that quasar-host galaxies at z ≥ 6 are accreting non-negligible amount of cosmic gas, nevertheless AGN feedback quenches their star formation dominantly by powerful outflows ejecting gas out of the host galaxy halo.STAMPAenQuasar outflows at z ≥ 6: the impact on the host galaxiesArticle10.1093/mnras/stx25632-s2.0-85042731396000423809400086https://academic.oup.com/mnras/article-abstract/473/3/4003/4349752?redirectedFrom=fulltext2018MNRAS.473.4003BFIS/05 - ASTRONOMIA E ASTROFISICAERC sectors::Physical Sciences and Engineering::PE9 Universe sciences: astro-physics/chemistry/biology; solar systems; stellar, galactic and extragalactic astronomy, planetary systems, cosmology, space science, instrumentation::PE9_8 Formation and evolution of galaxies