The Imacs Cluster Building Survey. I. Description of the Survey and Analysis Methods

Abstract

The IMACS Cluster Building Survey uses the wide field spectroscopic capabilities of the IMACS spectrograph on the 6.5m Baade Telescope to survey the large-scale environment surrounding rich intermediate-redshift clusters of galaxies. The goal is to understand the processes which may be transforming star-forming field galaxies into quiescent cluster members as groups and individual galaxies fall into the cluster from the surrounding supercluster. This first paper describes the survey: the data taking and reduction methods. We provide new calibrations of star formation rates derived from optical and infrared spectroscopy and photometry. We demonstrate that there is a tight relation between the observed star formation rate per unit B luminosity, and the ratio of the extinctions of the stellar continuum and the optical emission lines. With this, we can obtain accurate extinctioncorrected colors of galaxies. Using these colors as well as other spectral measures, we determine new criteria for the existence of ongoing and recent starbursts in galaxies.

Hidden starbursts and active galactic nuclei at 0 < z < 4 from theHerschel-VVDS-CFHTLS-D1 field: Inferences on coevolution and feedback

“…The second assumption is a bit more complex. In a recent study of galaxy clusters at z ∼ 0.3−0.5, Oemler et al (2013) found little difference between the strength of the EW(Hδ) and EW([OII]) for galaxies in their sample when slit apertures of two different sizes were used. The covering fraction of these two slit sizes was disparate enough for them to conclude that a spectrum observed with a 1 slit is sufficiently representative of the galaxy as a whole for a large fraction of their sample.…”

“…The covering fraction of these two slit sizes was disparate enough for them to conclude that a spectrum observed with a 1 slit is sufficiently representative of the galaxy as a whole for a large fraction of their sample. The sample we consider here is bounded on the low-redshift end by the high-redshift galaxies in the sample of Oemler et al (2013). As such, the covering fraction for the galaxies in our sample, given that the VVDS galaxies were observed with a 1 , is equivalent or higher than that of Oemler et al (2013) and approaches unity at z > ∼ 1.…”

“…The sample we consider here is bounded on the low-redshift end by the high-redshift galaxies in the sample of Oemler et al (2013). As such, the covering fraction for the galaxies in our sample, given that the VVDS galaxies were observed with a 1 , is equivalent or higher than that of Oemler et al (2013) and approaches unity at z > ∼ 1. Thus, we ignore all considerations of slit effects for the remainder of this discussion and equate the properties observed in each coadded spectrum with the properties of the galaxies as a whole.…”

Log-normal Star Formation Histories in Simulated and Observed Galaxies

“…The underlying galaxy observations were taken from a number of galaxy surveys. In particular, the stellar masses and SFRs for galaxies with * >´ M M 4 10 10 were drawn from the Sloan Digital Sky Survey (see Oemler et al 2013b, and references therein), whereas the PG2MC survey (Calvi et al 2011) was used for galaxies with * <´ M M 4 10 10 . Due to the smaller volume of the latter survey, the samples were re-normalized to create equal weights.…”

Low X-Ray Luminosity Galaxy Clusters: Main Goals, Sample Selection, Photometric and Spectroscopic Observations

“…We can mention: the ESO Distant Cluster Survey (EDisCS, White et al 2005) in a wide range of mass, with redshifts from 0.4 to almost 1.0; the X-ray-luminous clusters from the MACS survey at z ≈ 0.5 within a 1.2 Mpc diameter (Stott et al 2007); the Observations of Redshift Evolution in Large-Scale Environments (ORELSE) Survey (Lubin et al 2009), a systematic search for structure around well-known clusters at redshifts of 0.6 < z < 1.3; the galaxy populations in the core of a massive, X-ray luminous cluster (Strazzullo et al 2010) at z=1.39; and the IMACS Cluster Building Survey (Oemler et al 2013) to understand the large-scale environment surrounding rich intermediate redshift clusters of galaxies.…”