Shutting Down AGN Nick Cowan University of Washington October 20, 2006 Nick Cowan University of Washington October 20, 2006

AGN: A Primer Active Galactic Nuclei are super-massive black-holes accreting gas from a disk in the center of a galaxy. Astronomers have come up with a dozen different names for AGN depending on how we see them. I’ll call them AGN, quasars and QSOs interchangeably.

Why AGNs? Apparently (according to Rich) they can ionize gas all the way to the outer edges of a galaxy. That sounds dangerous.

Outline Background Info MORGANA Feedbacks and Accretion Results (lots of plots) Conclusions

Some Background The M-  relation (BH- bulge relation) is an empirical observation that bulges with larger velocity dispersions (masses, luminosities, whatever) tend to host more massive black holes. AGN exhibit an “anti hierarchical” behavior.

Solutions to the M-  Relation : SN Feedback vs AGN Feedback

MORGANA … is a truly stupid acronym: MOdel for the Rise of GAlaxies aNd Active nuclei. Seriously, though, it’s a Semi- Analytical Model

Semi Analytic Models (SAMs) …as opposed to SPH, or N- body simulations. Don’t need to understand the underlying physics as well. Need to know which empirical effects are relevant. Computationally easier. Easier to analyze the results. Output and input are closely related (incestuous?).

More on MORGANA Each DM halo forms from the merger of progenitor halos, each of which has one galaxy in it. Baryons have three components: –Halo –Bulge –Disk Each component has three phases: –Cold Gas –Hot Gas –Stars Each DM halo forms from the merger of progenitor halos, each of which has one galaxy in it. Baryons have three components: –Halo –Bulge –Disk Each component has three phases: –Cold Gas –Hot Gas –Stars

Yet More About MORGANA! The DM halos are treated using merger trees. After merging DM halos, dynamical friction, tidal stripping and tidal shocks on smaller halos (and their galaxy) leads to either tidal destruction or merger with the central galaxy. Infalling IGM is shock-heated. The hot halo gas is treated using a polytropic EoS with  =1.2 Cooling of the hot halo phase is treated as a series of concentric shells which cool radiatively and are heated from AGN or SN feedback from the central galaxy. Also consider hot gas injected in by central galaxy. The DM halos are treated using merger trees. After merging DM halos, dynamical friction, tidal stripping and tidal shocks on smaller halos (and their galaxy) leads to either tidal destruction or merger with the central galaxy. Infalling IGM is shock-heated. The hot halo gas is treated using a polytropic EoS with  =1.2 Cooling of the hot halo phase is treated as a series of concentric shells which cool radiatively and are heated from AGN or SN feedback from the central galaxy. Also consider hot gas injected in by central galaxy.

MORGANA keeps on goin’ The cool gas falls into central galaxy and is divvied up between the bulge and the disk. Gas falling onto disk keeps its angular momentum. Disk instabilities and major mergers lead to bulges. In minor mergers the small galaxy’s mass is given to the larger’s bulge. Star formation treated using something like the Schmidt Law. Hot gas ejected to halo at a rate equal to the SFR (except for bulges with v>300 km/s, which can hold on to hot gas). The cool gas falls into central galaxy and is divvied up between the bulge and the disk. Gas falling onto disk keeps its angular momentum. Disk instabilities and major mergers lead to bulges. In minor mergers the small galaxy’s mass is given to the larger’s bulge. Star formation treated using something like the Schmidt Law. Hot gas ejected to halo at a rate equal to the SFR (except for bulges with v>300 km/s, which can hold on to hot gas).

MORGANA: thank God! Star-forming bulges eject cold gas by kinetic feedback. If the hot gas is heated above the DM halo’s virial temperature, it is blown out in a galactic super-wind. Metal enrichment is treated self- consistently assuming instantaneous recycling. Star-forming bulges eject cold gas by kinetic feedback. If the hot gas is heated above the DM halo’s virial temperature, it is blown out in a galactic super-wind. Metal enrichment is treated self- consistently assuming instantaneous recycling.

Accretion onto Black Holes Each DM halo starts with a 10 3 M sun BH. BHs merge when halos merge. Gas accretes onto BH only when it has lost nearly all its angular momentum. Only bulge cold gas can accrete due to additional J- loss connected to B-fields, turbulence, radiation drag, which are all caused by star formation.

Two Kinds of Winds Drying Wind (DW): moves all ISM from bulge to halo. (results from kinetic energy being injected directly by BH) Accreting Winds (AW): triggers further accretion onto BH (results from SN- winds throughout the galaxy) In either case, SF as a result of winds is neglected in MORGANA.

Quasar-Triggered Winds Preconditions: AGN evaporation of ISM matches SFR 1.Can’t remove too much cold gas from the bulge. 2.Accretion is efficient (>1% Eddington rate)

Stellar (SN) Feedback: Two Flavors Super-bubbles easily blow out of thin/diffuse disks: most energy injected into halo. In thicker/denser systems, energy injected into ISM, then dissipated through turbulence. This “kinetic feedback” leads to cold gas with large velocity dispersion. Inflow of cold IGM can switch you from one limit to the other.

Forced Quenching AGN in the radiatively inefficient (<1% Eddington) regime heat hot halo gas, quenching cooling flows in large DM halos at low z. Implemented in all their models.

The Goals of this Paper Self-consistent modeling of accreting BHs and their feedback on host galaxies. Reproduce the properties of the AGN population (their luminosity and mass functions). Reproduce the soft and hard x-ray background (not in this talk).

Soft X-ray Luminosity Function Solid Black: STD Model Red Dashed: DW Model Blue Dot-Dashed: AW Model

Hard X-ray Luminosity Function Solid Black: STD Model Red Dashed: DW Model Blue Dot-Dashed: AW Model

B-band Luminosity Function Solid Black: STD Model Red Dashed: DW Model Blue Dot-Dashed: AW Model

QSO Number Density with z Solid Black: STD Model Red Dashed: DW Model Blue Dot-Dashed: AW Model

QSO Density for DW Model Velocity Dispersion of Cold gas: Solid Black:  0 =0 km/s Magenta Dotted:  0 =30 km/s Blue Dashed:  0 =60 km/s Red Dot- Dashed:  0 =90 km/s

Cumulative Source Number Counts Solid Black: STD Model Red Dashed: DW Model Blue Dot-Dashed: AW Model

BH-Bulge Relation Models look good for large masses (slight over-estimate with the wind models). Not enough scatter in STD model. BHs in small bulges are too small.

Black Hole Mass Function Solid Black: STD Model Red Dashed: DW Model Blue Dot-Dashed: AW Model

BH Mass Accretion Black: STD Model Red: DW Model Blue: AW Model

Evolution of the BH-Bulge Relation Only the massive bulges are plotted here. Solid Black: STD Model Red Dashed: DW Model Blue Dot-Dashed: AW Model

Accretion Rates Solid Black: STD Model Red Dashed: DW Model Blue Dot-Dashed: AW Model

Eddington Ratios Solid Black: STD Model Red Dashed: DW Model Blue Dot-Dashed: AW Model

Conclusions Quasar triggered winds (Dry Winds) are needed to reproduce the number density of bright quasars. Kinetic feedbacks in star-forming bulges is a very good candidate for downsizing the AGN population.

Some Bold Predictions The BH-bulge relation is in place at high-redshift. Low-redshift faint AGN are responsible for the bulk of the hard x-ray background. BH mass is acquired through accretion rather than mergers.

Some Big Problems The BH-bulge relation is steeper than observed for M bulge <10 11 M sun or M BH <10 8 M Sun The BH mass function in this low-mass range is lower than observed. There must be some additional downsizing mechanism for elliptical galaxies.

References F. Fontanot, astro-ph/ C. Megan Urry, ASPC…311…49U