Decomposing Profiles of SDSS Galaxies

Decomposing Profiles of SDSSGalaxies: Systematics in the

local L-R relation and Luminosity function

M. Bernardi, A. Meert, et al.

SDSS z~0.1

Cimatti et al. 2008

Z ~ 1.8

5 kpc @ z~0 → 0.9 kpc @ z~2.3 van Dokkum et al. 2008

Z ~ 2.3

Recent work in sizes …..At fixed stellar mass, high-z sizes are smaller by (1+z)-1 or more (e.g. Trujillo et al. 2007; Cimatti et al. 2008; van Dokkum et al.

2008; Saglia et al. 2011; Bruce et al. 2012; Fan et al. 2013)

Different ways …..

Major merger Minor merger Disk instability

Duc et al. 2011

Major mergers (mass roughly equal) increase size and mass proportionally

Minor mergers tend to increase size more then mass and decrease velocity dispersion

Minor mergers is the preferred scenario, but problems still exist

Some growth scenarios ….

The densities < 1kpc are higher by a factor of 2–3!

The densities < Re are higher by a factor > 100!

Bezanson et al. 2009

Inside-out growth scenario (minor mergers) is plausible, in which the compact high z galaxies make up the centers of normal nearby Es.

More on mergers …..

Impact of Major Dry Mergers at M* > 2 x 1011

Bernardi et al. 2011b

Evidence of Major dry mergers

Wet mergers

Two scales: 3x1010 and 2x1011 MSun

Less curvature with s

+

van der Wel et al. 2011

65%±15% of the population of massive, quiescent z ~ 2 galaxies are disk-dominated

“The much-discussed ultra-dense high-redshift galaxies should generally be thought of as disk-like stellar systems with the majority of stars formed from gas that had time to settle into a disk”

Red Fraction or Early-type Fraction?

Bernardi et al. 2010

Bernardi et al. 2010

E

Red g–r

Red g–r

E

~ 30-40% diskcontamination

Model where a galaxy has doubled its luminositythrough 1:1 mergers between z ~ 0.8 and z ~ 0.1

Using 1:1 mergersMerger rates > 25% are ruled out with 50% confidence

Using 1:3 mergers Merger rates up to 40% are allowed at 50% confidence

The total stellar mass in massive red galaxies from z~0.9 must not have grown by more than 50%

(Brown et al. 2007 -> 80%of M* in 4L* galaxies was already in place at z~0.7

Wake et al. 2006 -> 50% of M* in LRGs already assembled by z~0.6)

In contrast L* galaxies have increased their stellar mass by a factor of ~2

Little evolution in the Luminosity Function (e.g. Wake et al. 2006; Brown et al. 2007; Cool et al. 2008)

Z ~ 0.8

Cool et al. 2008

Z~0.8

Bernardi et al. 2010

Uncertainties in the local M*F

Dependence on how L is computed

Bernardi et al. 2013b

Luminosity FunctionBernardi et al. 2013b

M* FunctionBernardi et al. 2013b

Dependence on Morphology

Some conclusions ….

• higher stellar mass density at z ~ 0 resolves the tension with respect to the total mass density inferred from the integrated SFR

• allows for a higher incidence of major (in addition to minor) mergers in driving the M* growth of the most massive central galaxies at late times

• Constraints on halo models• Limits effects due to AGN feedback• Constraints on IMF