Radio selection of the most distant galaxy clusters

Abstract

We show that the most distant X-ray detected cluster known to date, ClJ1001 at z=2.506, hosts a strong overdensity of radio sources. Six of them are individually detected (within 10") in deep 0.75" resolution VLA 3GHz imaging, with S(3GHz)>8uJy. Of the six, AGN likely affects the radio emission in two galaxies while star formation is the dominant source powering the remaining four. We searched for cluster candidates over the full COSMOS 2-square degree field using radio-detected 3GHz sources and looking for peaks in Sigma5 density maps. ClJ1001 is the strongest overdensity by far with >10sigma, with a simple z_phot>1.5 preselection. A cruder photometric rejection of z<1 radio foregrounds leaves ClJ1001 as the second strongest overdensity, while even using all radio sources ClJ1001 remains among the four strongest projected overdensities. We conclude that there are great prospects for future, deep and wide-area radio surveys to discover large samples of the first generation of forming galaxy clusters. In these remarkable structures widespread star formation and AGN activity of massive galaxy cluster members, residing within the inner cluster core, will ultimately lead to radio continuum as one of the most effective means for their identification, with detection rates expected in the ballpark of 0.1-1 per square degree at z>2.5. Samples of hundreds such high-redshift clusters could potentially constrain cosmological parameters and test cluster and galaxy formation models.

ApJ Letters in press

References in corpus (11)

• Cold streams in early massive hot haloes as the main mode of galaxy formation
• The Herschel view of the dominant mode of galaxy growth from z=4 to the present day
• Distant Radio Galaxies and their Environments
• The faint radio sky: radio astronomy becomes mainstream
• The Spiderweb galaxy: a forming massive cluster galaxy at z~2
• KECK/MOSFIRE spectroscopic confirmation of a Virgo-like cluster ancestor at z=2.095
• Metal deficiency in cluster star-forming galaxies at z=2
• A proto-cluster at z=2.45
• The red sequence at birth in the galaxy cluster ClJ1449+0856 at z=2
• On the statistics of proto-cluster candidates detected in the Planck all-sky survey
• Passive galaxies as tracers of cluster environments at z~2

Cited by in corpus (8)

• Confirming Herschel candidate protoclusters from ALMA/VLA CO observations
• Evidence for Cold-stream to Hot-accretion Transition as Traced by Lyα Emission from Groups and Clusters at 2 < z < 3.3
• Probing the existence of a rich galaxy overdensity at z=5.2
• The brightest UV-selected galaxies in protoclusters at $z\sim 4$: Ancestors of Brightest Cluster Galaxies?
• A galaxy group candidate at z~3.7 in the COSMOS field
• NOEMA formIng Cluster survEy (NICE): Characterizing eight massive galaxy groups at $1.5<z<4$ in the COSMOS field
• Revealing Dust Obscured Star Formation in CLJ1449+0856, a Cluster at z=2
• Revealing the differences in the SMBH accretion rate distributions of starburst and non-starburst galaxies