Unbiased Differential Size Evolution and the Inside-out Growth of Galaxies in the Deep CANDELS GOODS Fields at 1 ≤ z ≤ 7
Abstract
We present a size analysis of a sample of ∼49,000 galaxies from the Cosmic Assembly Near-infrared Deep Extragalactic Survey GOODS North and South fields, using redshift-independent relative surface-brightness metrics to determine an unbiased measure of the differential size evolution of galaxies at 1 ≤ z ≤ 7. We introduce a novel method of removing foreground objects from distant galaxy (z > 3) images that makes use of the Lyman break at 912 Å, in what we call “2D Lyman-break imaging.” The images used are in the rest-frame optical at z < 3 and progressively bluer bands at z > 3. They are therefore subject to K-correction and cosmological dimming effects, which are tested and corrected for. We separately consider a mass-selected sample (with masses in the range 109 M ⊙ ≤ M * ≤ 1010.5 M ⊙) and a number-density-selected sample (using a constant number density of n = 1 × 10-4Mpc-3). Instead of utilizing the commonly used, but potentially biased, effective radii for size measurements, we measure the redshift-independent Petrosian radius, defined by the parameter η, for each galaxy for three values of η, and use this as a proxy for size. The evolution of the measured radii can be described by a power law of the form R Petr = α(1+z) β kpc where β < 0. We find that the outer radius increases more rapidly, suggesting that as a galaxy grows, mass is added to its outer regions via an inside-out growth. This growth is stronger for the number-density-selected sample, with a growth rate of nearly three in the outer radii compared to the inner. We test and confirm these results using a series of image simulations.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- December 2019
- DOI:
- 10.3847/1538-4357/ab53d4
- arXiv:
- arXiv:1911.02589
- Bibcode:
- 2019ApJ...887..113W
- Keywords:
-
- Galaxy evolution;
- High-redshift galaxies;
- Galaxy formation;
- Galaxies;
- 594;
- 734;
- 595;
- 573;
- Astrophysics - Astrophysics of Galaxies
- E-Print:
- 16 pages, 11 figures