Gregory R. Zeimann

The Era of Star Formation in Galaxy Clusters

We analyze the star formation properties of 16 infrared-selected, spectroscopically confirmed galaxy clusters at 1 1.35. Using infrared luminosities measured with deep Spitzer/Multiband Imaging Photometer for Spitzer observations at 24 μm, along with robust optical + IRAC photometric redshifts and spectral-energy-distribution-fitted stellar masses, we present the dust-obscured star-forming fractions, star formation rates, and specific star formation rates in these clusters as functions of redshift and projected clustercentric radius. We find that z ~ 1.4 represents a transition redshift for the ISCS sample, with clear evidence of an unquenched era of cluster star formation at earlier times. Beyond this redshift, the fraction of star-forming cluster members increases monotonically toward the cluster centers. Indeed, the specific star formation rate in the cores of these distant clusters is consistent with field values at similar redshifts, indicating that at z > 1.4 environment-dependent quenching had not yet been established in ISCS clusters. By combining these observations with complementary studies showing a rapid increase in the active galactic nucleus (AGN) fraction, a stochastic star formation history, and a major merging episode at the same epoch in this cluster sample, we suggest that the starburst activity is likely merger-driven and that the subsequent quenching is due to feedback from merger-fueled AGNs. The totality of the evidence suggests we are witnessing the final quenching period that brings an end to the era of star formation in galaxy clusters and initiates the era of passive evolution.

IDCS J1433.2+3306: AN INFRARED-SELECTED GALAXY CLUSTER AT z = 1.89

We report the discovery of an IR-selected galaxy cluster in the IRAC Distant Cluster Survey (IDCS). New data from the Hubble Space Telescope spectroscopically confirm IDCS J1433.2+3306 at z = 1.89 with robust spectroscopic redshifts for seven members, two of which are based on the 4000 A break. Detected emission lines such as [O II] and H{beta} indicate star formation rates of {approx}>20 M{sub Sun} yr{sup -1} for three galaxies within a 500 kpc projected radius of the cluster center. The cluster exhibits a red sequence with a scatter and color indicative of a formation redshift z{sub f} {approx}> 3.5. The stellar age of the early-type galaxy population is approximately consistent with those of clusters at lower redshift (1

X-RAY EMISSION FROM TWO INFRARED-SELECTED GALAXY CLUSTERS AT z > 1.4 IN THE IRAC SHALLOW CLUSTER SURVEY

We report the X-ray detection of two z > 1.4 infrared-selected galaxy clusters from the IRAC Shallow Cluster Survey (ISCS). We present new data from the Hubble Space Telescope and the W. M. Keck Observatory that spectroscopically confirm cluster ISCS J1432.4+3250 at z = 1.49, the most distant of 18 confirmed z > 1 clusters in the ISCS to date. We also present new spectroscopy for ISCS J1438.1+3414, previously reported at z = 1.41, and measure its dynamical mass. Clusters ISCS J1432.4+3250 and ISCS J1438.1+3414 are detected in 36 ks and 143 ks Chandra exposures at significances of 5.2{sigma} and 9.7{sigma}, from which we measure total masses of log (M{sub 200,L{sub X}}/M{sub sun}) = 14.4 {+-} 0.2 and 14.35 {sup +0.14}{sub -0.11}, respectively. The consistency of the X-ray and dynamical properties of these high-redshift clusters further demonstrates that the ISCS is robustly detecting massive clusters to at least z = 1.5.

The Spitzer Extragalactic Representative Volume Survey (SERVS): Survey Definition and Goals

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.

Discovery of a Multiply Lensed Submillimeter Galaxy in Early HerMES Herschel/SPIRE Data

We report the discovery of a bright (

HIGH-RESOLUTION VERY LARGE ARRAY IMAGING OF SLOAN DIGITAL SKY SURVEY STRIPE 82 AT 1.4 GHz

f(250\mum) > 400

The evolution of dust-obscured star formation activity in galaxy clusters relative to the field over the last 9 billion years

mJy), multiply-lensed submillimeter galaxy \obj\ in {\it Herschel}/SPIRE Science Demonstration Phase data from the HerMES project. Interferometric 880\mum\ Submillimeter Array observations resolve at least four images with a large separation of

Assembly of the Red Sequence in Infrared-selected Galaxy Clusters from the IRAC Shallow Cluster Survey

\sim 9\arcsec

SPECTRAL ENERGY DISTRIBUTION FITTING OF HETDEX PILOT SURVEY Lyα EMITTERS IN COSMOS AND GOODS-N

. A high-resolution adaptive optics

THE MASSIVE DISTANT CLUSTERS OF WISE SURVEY: THE FIRST DISTANT GALAXY CLUSTER DISCOVERED BY WISE

K_p