Feedback & Large SurveysHarry Ferguson (STScI)

Feedback

Behroozi+ 2011

Halo quenching

Quasar mode AGN

Radio Mode AGN

(SNe)

SNe

Satellites: Ram

pressure, tides,

shocks…

UV back-

ground

AGN feedback in SAMs

Somerville+ 2008

AGN quenching successfully reduces the stellar masses at the bright end.

Somewhat degenerate with simple “halo quenching”

Mergers & QSOs

Hopkins+ 2006 used numerical simulations to determine the relation between merger lifetimes & luminosities and QSO lifetimes & luminosities.

Inferred contribution of mergers to the SFRD at z~2 is 30-50%.

Quenching high-mass galaxies

Successful models of feedback affect star-formation differentially along the mass sequence.

Therefore statistical constraints on SFR(t,M) have the potential to distinguish between mechanisms.

Gabor+ 2010

Successes of Feedback models Qualitative understanding of:

For galaxies: Mass-metallicity relation Star-formation efficiency as a function of halo mass Red-sequence/blue-sequence Clustering of SMGs, Early type galaxies, QSOs

For AGN: QSO lifetimes AGN column-density distributions QSO clustering

Cluster entropy floor

Example: Clustering

Hickox+ 2012Correlation length of sub-millimeter galaxies, QSOs & bright ellipticals are comparable

Evolutionary scenario for high-mass galaxies:

Key Observational tests? Measurements of feedback

Wind momenta Galaxy ICM temperatures

BH-mass stellar-mass relations with redshift

Improved clustering measurements

Red-sequence Evolution

AGN Host morphologies

Metallicity-dependent SFRs

Linking morphology to merger-driven feedback

Challenges Observational

Disk galaxy properties Simultaneously matching disk galaxy mass function,

mass-metallicity, Tully Fisher relation & bulge fraction

Spheroidal galaxy sizes & evolution SMGs are disks? (not mergers – Targett+ 2011,12) Morphologies of AGN hosts (Kocevski 2012) Moderate-luminosity AGN

Merger or instability driven? Is feedback from these AGN inportant?

Theoretical Dynamic range Microphysics of feedback

SMGs are disks?

Targett+ 2011,12

The mass-dominant components of SMGs appear to be disk-like

CANDELS AGN Hosts at z~2 • Undisturbed disks are the

most common morphology• AGN hosts do not show

irregular morphologies any more often than a mass-matched sample of non-active control galaxies.

• Merger fraction is unexpectedly low.

• Implication for AGN fueling theory: If disks have not experienced major merger in recent past, then stochastic internal accretion may play a greater role in fueling AGN activity at z~2 than expected.

Kocevski+ 2012

Challenges: Disk galaxy properties

Scannapieco+ 2012

With the same initial conditions, different models built very different galaxies.None particularly successful.

Models already diverge at z=5

Questions

What is the relative importance of ejective vs. preventative feedback?

What is the relative importance of environmental quenching vs. mass quenching?

What is the relative importance of mergers vs. smooth star formation?

How can we tell?