Extremely Large Telescope

Abstract:

We present near-infrared spectroscopic observations of star-forming galaxies at z ∼ 1.4 with FMOS on the Subaru Telescope. We observed K-band selected galaxies in the SXDS/UDS fields with K ≤ 23.9mag, 1.2 ≤ zph ≤ 1.6,M ≥ 109.5M, and expected F(Hα) ≥ 10-16 erg s-1cm-2; 71 objects in the sample have significant detections of H?. For these objects, excluding possible AGNs, identified from the BPT diagram, gas-phase metallicities were obtained from the [N II] /Hα line ratio. The sample is split into three stellar-mass bins, and the spectra are stacked in each stellar-mass bin. The mass-metallicity relation obtained at z ∼ 1.4 is located between those at z ∼ 0.8 and z ∼ 2.2. We constrain the intrinsic scatter to be ∼0.1 dex, or larger in the mass-metallicity relation at z ∼ 1.4; the scatter may be larger at higher redshifts. We found trends that the deviation from the mass-metallicity relation depends on the SFR (Star-formation rate) and the half light radius: Galaxies with higher SFR and larger half light radii show lower metallicities at a given stellar mass. One possible scenario for the trends is the infall of pristine gas accreted from IGM, or through merger events. Our data points show larger scatter than the fundamental metallicity relation (FMR) at z ∼ 0.1, and the averagemetallicities slightly deviate fromthe FMR. The compilation of themass- metallicity relations at z ∼ 3 to z ∼ 0.1 shows that they evolve smoothly from z ∼ 3 to z ∼ 0 without changing the shape so much, except for the massive part at z ∼ 0. © 2012 Astronomical Society of Japan.

Abstract:

We present the Spitzer Extragalactic Representative Volume Survey (SERVS), an 18 square degrees medium-deep survey at 3.6 and 4.5 microns with the post-cryogenic Spitzer Space Telescope to ~2 microJy (AB=23.1) depth of five highly observed astronomical fields (ELAIS-N1, ELAIS-S1, Lockman Hole, Chandra Deep Field South and XMM-LSS). SERVS is designed to enable the study of galaxy evolution as a function of environment from z~5 to the present day, and is the first extragalactic survey both large enough and deep enough to put rare objects such as luminous quasars and galaxy clusters at z>1 into their cosmological context. SERVS is designed to overlap with several key surveys at optical, near- through far-infrared, submillimeter and radio wavelengths to provide an unprecedented view of the formation and evolution of massive galaxies. In this paper, we discuss the SERVS survey design, the data processing flow from image reduction and mosaicing to catalogs, as well as coverage of ancillary data from other surveys in the SERVS fields. We also highlight a variety of early science results from the survey.