UV-to-FIR analysis of Spitzer/IRAC sources in the Extended Groth Strip II: Photometric redshifts, Stellar masses and Star formation rates

TL;DR

This study provides a comprehensive analysis of nearly 80,000 galaxies in the Extended Groth Strip, estimating their photometric redshifts, stellar masses, and star formation rates using UV-to-FIR data, with detailed assessments of uncertainties and systematics.

Contribution

It offers a large, detailed catalog of galaxy properties with improved accuracy and systematic error analysis, enhancing understanding of galaxy evolution in the EGS.

Findings

Photometric redshift accuracy of Delta z/(1+z)=0.034 with 2% outliers.

Systematic offsets in stellar mass estimates range from 0.1 to 0.4 dex.

IR-based SFR uncertainties are typically a factor of two.

Abstract

Based on the ultraviolet to far-infrared photometry already compiled and presented in a companion paper (Barro et al. 2011a, Paper I), we present a detailed SED analysis of nearly 80,000 IRAC 3.6+4.5 micron selected galaxies in the Extended Groth Strip. We estimate photometric redshifts, stellar masses, and star formation rates separately for each galaxy in this large sample. The catalog includes 76,936 sources with [3.6] < 23.75 (85% completeness level of the IRAC survey) over 0.48 square degrees. The typical photometric redshift accuracy is Delta z/(1+z)=0.034, with a catastrophic outlier fraction of just 2%. We quantify the systematics introduced by the use of different stellar population synthesis libraries and IMFs in the calculation of stellar masses. We find systematic offsets ranging from 0.1 to 0.4 dex, with a typical scatter of 0.3 dex. We also provide UV- and IR-based SFRs for all sample galaxies, based on several sets of dust emission templates and SFR indicators. We evaluate the systematic differences and goodness of the different SFR estimations using the deep FIDEL 70 micron data available in the EGS. Typical random uncertainties of the IR-bases SFRs are a factor of two, with non-negligible systematic effects at z$\gtrsim$1.5 observed when only MIPS 24 micron data is available. All data products (SEDs, postage stamps from imaging data, and different estimations of the photometric redshifts, stellar masses, and SFRs of each galaxy) described in this and the companion paper are publicly available, and they can be accessed through our the web-interface utility Rainbow-navigator