%0 Generic %1 costa2014feedback %A Costa, Tiago %A Sijacki, Debora %A Haehnelt, Martin G. %D 2014 %K agn energy feedback momentum %T Feedback from Active Galactic Nuclei: Energy- versus momentum-driving %U http://arxiv.org/abs/1406.2691 %X We employ hydrodynamical simulations using the moving-mesh code AREPO to investigate the role of energy and momentum input from Active Galactic Nuclei (AGN) in driving large-scale galactic outflows. We start by reproducing analytic solutions for both energy- and momentum-driven outflowing shells in simulations of a spherical isolated dark matter potential with gas in hydrostatic equilibrium and with no radiative cooling. We confirm that for this simplified setup, galactic outflows driven by a momentum input rate of order L_Edd/c can establish an M_BH - sigma relation with slope and normalisation similar to that observed. We show that momentum input at a rate of L_Edd/c is however insufficient to drive efficient outflows once cooling and gas inflows as predicted by cosmological simulations at resolved scales are taken into account. We argue that observed large-scale AGN-driven outflows are instead likely to be energy-driven and show that such outflows can reach momentum fluxes exceeding 10 L_Edd/c within the innermost 10 kpc of the galaxy. The outflows are highly anisotropic, with outflow rates and a velocity structure found to be inadequately described by spherical outflow models. We verify that the hot energy-driven outflowing gas is expected to be strongly affected by metal-line cooling, leading to significant amounts (>10^9 M_sun) of entrained cold gas.

@misc{costa2014feedback, abstract = {We employ hydrodynamical simulations using the moving-mesh code AREPO to investigate the role of energy and momentum input from Active Galactic Nuclei (AGN) in driving large-scale galactic outflows. We start by reproducing analytic solutions for both energy- and momentum-driven outflowing shells in simulations of a spherical isolated dark matter potential with gas in hydrostatic equilibrium and with no radiative cooling. We confirm that for this simplified setup, galactic outflows driven by a momentum input rate of order L_Edd/c can establish an M_BH - sigma relation with slope and normalisation similar to that observed. We show that momentum input at a rate of L_Edd/c is however insufficient to drive efficient outflows once cooling and gas inflows as predicted by cosmological simulations at resolved scales are taken into account. We argue that observed large-scale AGN-driven outflows are instead likely to be energy-driven and show that such outflows can reach momentum fluxes exceeding 10 L_Edd/c within the innermost 10 kpc of the galaxy. The outflows are highly anisotropic, with outflow rates and a velocity structure found to be inadequately described by spherical outflow models. We verify that the hot energy-driven outflowing gas is expected to be strongly affected by metal-line cooling, leading to significant amounts (>10^9 M_sun) of entrained cold gas.}, added-at = {2014-06-12T09:42:54.000+0200}, author = {Costa, Tiago and Sijacki, Debora and Haehnelt, Martin G.}, biburl = {https://www.bibsonomy.org/bibtex/2b5e1b42d5808e90547b39bd79e0b8d88/miki}, description = {[1406.2691] Feedback from Active Galactic Nuclei: Energy- versus momentum-driving}, interhash = {2cfc9b84cbf089737f2b47d62e79700c}, intrahash = {b5e1b42d5808e90547b39bd79e0b8d88}, keywords = {agn energy feedback momentum}, note = {cite arxiv:1406.2691Comment: 24 pages, 17 figures, 1 table, MNRAS submitted}, timestamp = {2014-06-12T09:42:54.000+0200}, title = {Feedback from Active Galactic Nuclei: Energy- versus momentum-driving}, url = {http://arxiv.org/abs/1406.2691}, year = 2014 }