Katherine E. Whitaker

THE GROWTH OF MASSIVE GALAXIES SINCE z = 2

We study the growth of massive galaxies from z = 2 to the present using data from the NOAO/Yale NEWFIRM Medium Band Survey. The sample is selected at a constant number density of n = 2 ? 10?4?Mpc?3, so that galaxies at different epochs can be compared in a meaningful way. We show that the stellar mass of galaxies at this number density has increased by a factor of 2 since z = 2, following the relation log Mn (z) = 11.45 ? 0.15z. In order to determine at what physical radii this mass growth occurred, we construct very deep stacked rest-frame R-band images of galaxies with masses near Mn (z), at redshifts z = 0.6, 1.1, 1.6, and 2.0. These image stacks of typically 70-80 galaxies enable us to characterize the stellar distribution to surface brightness limits of ~28.5 mag?arcsec?2. We find that massive galaxies gradually built up their outer regions over the past 10 Gyr. The mass within a radius of r = 5?kpc is nearly constant with redshift, whereas the mass at 5 kpc < r < 75?kpc has increased by a factor of ~4 since z = 2. Parameterizing the surface brightness profiles, we find that the effective radius and Sersic n parameter evolve as re (1 + z)?1.3 and n (1 + z)?1.0, respectively. The data demonstrate that massive galaxies have grown mostly inside-out, assembling their extended stellar halos around compact, dense cores with possibly exponential radial density distributions. Comparing the observed mass evolution to the average star formation rates of the galaxies we find that the growth is likely dominated by mergers, as in situ star formation can only account for ~20% of the mass buildup from z = 2 to z = 0. A direct consequence of these results is that massive galaxies do not evolve in a self-similar way: their structural profiles change as a function of redshift, complicating analyses which (often implicitly) assume self-similarity. The main uncertainties in this study are possible redshift-dependent systematic errors in the total stellar masses and the conversion from light-weighted to mass-weighted radial profiles.

CONSTRAINING THE LOW-MASS SLOPE OF THE STAR FORMATION SEQUENCE AT 0.5 < Z < 2.5

We constrain the slope of the star formation rate (

3D-HST WFC3-selected Photometric Catalogs in the Five CANDELS/3D-HST Fields: Photometry, Photometric Redshifts and Stellar Masses

\log\Psi

The NEWFIRM Medium-band Survey: Photometric Catalogs, Redshifts and the Bimodal Color Distribution of Galaxies out to z~3

) to stellar mass (

Galaxy clustering in the NEWFIRM Medium Band Survey: the relationship between stellar mass and dark matter halo mass at 1 <z< 2

\log\mathrm{M_{\star}}

A Large Population of Massive Compact Post-starburst Galaxies at z > 1: Implications for the Size Evolution and Quenching Mechanism of Quiescent Galaxies

) relation down to

Bulge Growth and Quenching Since Z=2.5 in Candels/3D-HST

\log(\mathrm{M_{\star}/M_{\odot}})=8.4

THE 3D-HST SURVEY: HUBBLE SPACE TELESCOPE WFC3/G141 GRISM SPECTRA, REDSHIFTS, AND EMISSION LINE MEASUREMENTS FOR ∼100,000 GALAXIES

(

THE STELLAR VELOCITY DISPERSION OF A COMPACT MASSIVE GALAXY AT z = 1.80 USING X-SHOOTER: CONFIRMATION OF THE EVOLUTION IN THE MASS-SIZE AND MASS-DISPERSION RELATIONS* , **

\log(\mathrm{M_{\star}/M_{\odot}})=9.2

FORMING COMPACT MASSIVE GALAXIES

) at