UV-TO-FIR ANALYSIS OF SPITZER /IRAC SOURCES IN THE EXTENDED GROTH STRIP. II. PHOTOMETRIC REDSHIFTS, STELLAR MASSES, AND STAR FORMATION RATES

Abstract

Based on the ultraviolet to far-infrared photometry already compiled and presented in a companion paper (Paper I), we present a detailed spectral energy distribution (SED) analysis of nearly 80,000 IRAC 3.6 + 4.5 μm selected galaxies in the Extended Groth Strip. We estimate photometric redshifts, stellar masses, and star formation rates (SFRs) 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 deg 2 . The typical photometric redshift accuracy is Δz/(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 initial mass functions 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 μm data available in the Extended Groth Strip. Typical random uncertainties of the IR-bases SFRs are a factor of two, with non-negligible systematic effects at z 1.5 observed when only MIPS 24 μm data are 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.

The evolution of the X-ray luminosity functions of unabsorbed and absorbed AGNs out to z∼ 5

“…We obtained consistent photometry by applying a single aperture across all optical and near-IR bands. We also extracted IRAC photometry, applying the procedure described in Pérez-González et al (2008) and Barro et al (2011a) to deblend the IRAC photometry when a single IRAC source is associated with multiple optical/near-IR counterparts.…”

“…We have also identified stars with fainter magnitudes that are detected at X-ray wavelengths and removed them from our samples. In the fields with Rainbow coverage (CDFS, CDFN, EGS) stars were identified by a range of colour and morphology criteria, as described in Barro et al (2011a). In the COSMOS and Bootes fields we applied a single colour criterion based on the region of colour-colour space occupied by stars in Ilbert et al (2009)…”

Seds: The Spitzer Extended Deep Survey. Survey Design, Photometry, and Deep Irac Source Counts

“…Sorba & Sawicki (2010) and Barro et al (2011) showed that the [3.6]−[4.5] color is a useful photometric redshift indicator, especially for separating galaxies at z 1.3 from those at z 1.5. Figure 30 shows a color-magnitude diagram of the SEDS sources.…”

Galaxy And Mass Assembly (GAMA): the effect of close interactions on star formation in galaxies

“…Bell et al 2005;Papovich et al 2007;Barro et al 2011) of and 3000 Å, L UV , is estimated as 1.5νf ν, 2800 , where f ν, 2800 is the rest-frame luminosity at 2800 Å. For further details of this process, see Taylor et al (in preparation).…”