%0 Generic %1 hopkins2021black %A Hopkins, Philip F. %A Wellons, Sarah %A Angles-Alcazar, Daniel %A Faucher-Giguere, Claude-Andre %A Grudic, Michael Y. %D 2021 %K library %T Why do Black Holes Trace Bulges (& Central Surface Densities), Instead of Galaxies as a Whole? %U http://arxiv.org/abs/2103.10444 %X Previous studies of fueling black holes (BHs) in galactic nuclei have argued (on scales ~0.01-1000pc) accretion is dynamical with inflow rates $M\sim\eta\,M_gas/t_dyn$ in terms of gas mass $M_gas$, dynamical time $t_dyn$, and some $\eta$. But these models generally neglected expulsion of gas by stellar feedback, or considered extremely high densities where expulsion is inefficient. Studies of star formation, however, have shown on sub-kpc scales the expulsion efficiency $f_wind=M_\rm ejected/M_total$ scales with the gravitational acceleration as $(1-f_wind)/f_wind\sima_\rm grav/łanglep/m_\ast\rangle\Sigma_eff/\Sigma_crit$ where $a_gravG\,M_tot(<r)/r^2$ and $łanglep/m_\ast\rangle$ is the momentum injection rate from young stars. Adopting this as the simplest correction for stellar feedback, $\eta \eta\,(1-f_wind)$, we show this provides a more accurate description of simulations with stellar feedback at low densities. This has immediate consequences, predicting e.g. the slope and normalization of the $M-\sigma$ and $M-M_bulge$ relation, $L_AGN-$SFR relations, and explanations for outliers in compact Es. Most strikingly, because star formation simulations show expulsion is efficient ($f_wind\sim1$) below total-mass surface density $M_tot/\pi\,r^2<\Sigma_\rm crit\sim3\times10^9\,M_ødot\,kpc^-2$ (where $\Sigma_\rm crit=łanglep/m_\ast\rangle/(\pi\,G)$), BH mass is predicted to specifically trace host galaxy properties above a critical surface brightness $\Sigma_crit$ (B-band $\mu_B^crit19\,\rm mag\,arcsec^-2$). This naturally explains why BH masses preferentially reflect bulge properties or central surface-densities ($\Sigma_1\,\rm kpc$), not 'total' galaxy properties.

@misc{hopkins2021black, abstract = {Previous studies of fueling black holes (BHs) in galactic nuclei have argued (on scales ~0.01-1000pc) accretion is dynamical with inflow rates $\dot{M}\sim\eta\,M_{\rm gas}/t_{\rm dyn}$ in terms of gas mass $M_{\rm gas}$, dynamical time $t_{\rm dyn}$, and some $\eta$. But these models generally neglected expulsion of gas by stellar feedback, or considered extremely high densities where expulsion is inefficient. Studies of star formation, however, have shown on sub-kpc scales the expulsion efficiency $f_{\rm wind}=M_{\rm ejected}/M_{\rm total}$ scales with the gravitational acceleration as $(1-f_{\rm wind})/f_{\rm wind}\sim\bar{a}_{\rm grav}/\langle\dot{p}/m_{\ast}\rangle\sim \Sigma_{\rm eff}/\Sigma_{\rm crit}$ where $\bar{a}_{\rm grav}\equiv G\,M_{\rm tot}(<r)/r^{2}$ and $\langle\dot{p}/m_{\ast}\rangle$ is the momentum injection rate from young stars. Adopting this as the simplest correction for stellar feedback, $\eta \rightarrow \eta\,(1-f_{\rm wind})$, we show this provides a more accurate description of simulations with stellar feedback at low densities. This has immediate consequences, predicting e.g. the slope and normalization of the $M-\sigma$ and $M-M_{\rm bulge}$ relation, $L_{\rm AGN}-$SFR relations, and explanations for outliers in compact Es. Most strikingly, because star formation simulations show expulsion is efficient ($f_{\rm wind}\sim1$) below total-mass surface density $M_{\rm tot}/\pi\,r^{2}<\Sigma_{\rm crit}\sim3\times10^{9}\,M_{\odot}\,{\rm kpc^{-2}}$ (where $\Sigma_{\rm crit}=\langle\dot{p}/m_{\ast}\rangle/(\pi\,G)$), BH mass is predicted to specifically trace host galaxy properties above a critical surface brightness $\Sigma_{\rm crit}$ (B-band $\mu_{\rm B}^{\rm crit}\sim 19\,{\rm mag\,arcsec^{-2}}$). This naturally explains why BH masses preferentially reflect bulge properties or central surface-densities ($\Sigma_{1\,{\rm kpc}}$), not 'total' galaxy properties.}, added-at = {2021-03-22T07:37:26.000+0100}, author = {Hopkins, Philip F. and Wellons, Sarah and Angles-Alcazar, Daniel and Faucher-Giguere, Claude-Andre and Grudic, Michael Y.}, biburl = {https://www.bibsonomy.org/bibtex/20c4e599d82198a3dd07cbcb1ce6d389d/gpkulkarni}, description = {Why do Black Holes Trace Bulges (}, interhash = {6cc1b912d20c7a6e204cf8016fc12acd}, intrahash = {0c4e599d82198a3dd07cbcb1ce6d389d}, keywords = {library}, note = {cite arxiv:2103.10444Comment: 8 pages, 3 figures, submitted to MNRAS. Comments welcome}, timestamp = {2021-03-22T07:37:26.000+0100}, title = {Why do Black Holes Trace Bulges (& Central Surface Densities), Instead of Galaxies as a Whole?}, url = {http://arxiv.org/abs/2103.10444}, year = 2021 }