Evolution of Massive Galaxy Structural Properties and Sizes via Star Formation

TL;DR

This study examines how star formation influences the size and structure of massive galaxies from high redshift to today, finding that star formation alone cannot explain their observed evolution, implying other processes like merging are involved.

Contribution

It provides a detailed analysis of star formation's role in galaxy structural evolution, combining stellar mass profiles and modeling to assess size growth mechanisms.

Findings

Star formation contributes minimally to size growth of massive galaxies.

Merging likely plays a significant role in structural evolution.

Star formation alone cannot account for observed size and Sersic profile changes.

Abstract

We investigate the resolved star formation properties of a sample of 45 massive galaxies (M_*>10^11M_solar) within a redshift range of 1.5 < z < 3 detected in the GOODS NICMOS Survey (Conselice et al. 2011), a HST H-band imaging program. We derive the star formation rate as a function of radius using rest frame UV data from deep z_{850} ACS imaging. The star formation present at high redshift is then extrapolated to z=0, and we examine the stellar mass produced in individual regions within each galaxy. We also construct new stellar mass profiles of the in-situ stellar mass at high redshift from Sersic fits to rest-frame optical, H_{160}-band, data. We combine the two stellar mass profiles to produce a modelled evolved stellar mass profile. We then fit a new Sersic profile to the evolved profile, from which we examine what effect the resulting stellar mass distribution added via star formation has on the structure and size of each individual galaxy. We conclude that due to the lack of sufficient size growth and Sersic evolution by star formation other mechanisms such as merging must contribute a large proportion to account for the observed structural evolution from z>1 to the present day.