Radio and millimeter properties of $z\sim 5.7$ Ly$\alpha$ emitters in the COSMOS field: limits on radio AGN, submm galaxies, and dust obscuration

Abstract

We present observations at 1.4 and 250 GHz of the $z\sim 5.7$ Ly$\alpha$ emitters (LAE) in the COSMOS field found by Murayama et al.. At 1.4 GHz there are 99 LAEs in the lower noise regions of the radio field. We do not detect any individual source down to 3$\sigma$ limits of $\sim 30\mu$Jy beam${}^{-1}$ at 1.4 GHz, nor do we detect a source in a stacking analysis, to a 2$\sigma$ limit of $2.5\mu$Jy beam${}^{-1}$. At 250 GHz we do not detect any of the 10 LAEs that are located within the central regions of the COSMOS field covered by MAMBO ($20^{\prime }\times 20^{\prime }$) to a typical 2$\sigma$ limit of $S_{250}<2$mJy. The radio data imply that there are no low luminosity radio AGN with $L_{1.4}>6\times 10^{24}$ W Hz${}^{-1}$ in the LAE sample. The radio and millimeter observations also rule out any highly obscured, extreme starbursts in the sample, ie. any galaxies with massive star formation rates $>1500$ M${}_{\odot }$ year${}^{-1}$ in the full sample (based on the radio data), or 500 M${}_{\odot }$ year${}^{-1}$ for the 10% of the LAE sample that fall in the central MAMBO field. The stacking analysis implies an upper limit to the mean massive star formation rate of $\sim 100$ M${}_{\odot }$ year${}^{-1}$.

11 pages AAStex format 3 figures. ApJ COSMOS Special Issue. Changes: Added 'Note added in proof' to reflect nine new sources in the LAE sample

References in corpus (6)

• Observational constraints on Cosmic Reionization
• The VLA-COSMOS Survey: II. Source Catalog of the Large Project
• The XMM-Newton wide-field survey in the COSMOS field: VI. Statistical properties of clusters of galaxies
• A galaxy at a redshift z = 6.96
• Lyman Alpha Emitters at Redshift 5.7 in the COSMOS Field
• The Radio/Optical Catalog of the SSA13 Field

Cited by in corpus (6)

• The Subaru/XMM-Newton Deep Survey (SXDS). IV. Evolution of Lya Emitters from z=3.1 to 5.7 in the 1 deg^2 Field: Luminosity Functions and AGN
• The spatial clustering of X-ray selected AGN in the XMM-COSMOS field
• Lyman Alpha Emitters at Redshift 5.7 in the COSMOS Field
• Star formation rates in Lyman break galaxies: radio stacking of LBGs in the COSMOS field and the sub-$\mu$Jy radio source population
• Mid-Infrared Spectroscopic Properties of Ultra-Luminous Infrared Quasars
• Millimeter observations of HCM6A, a gravitationally lensed Lyman alpha emitting galaxy at z=6.56