A 610 MHz Survey of the 1H XMM-Newton/Chandra Survey Field

TL;DR

This paper reports a deep 610 MHz radio survey of the 1H XMM-Newton/Chandra field, detecting 223 sources, analyzing source counts, and comparing them with other frequencies to understand galaxy populations and their evolution.

Contribution

It provides the first detailed 610 MHz source counts in this field and models the populations explaining the counts, extending understanding of radio source evolution.

Findings

Detected 223 sources above 300 microJy at 610 MHz.

Observed flattening of source counts below 2 mJy consistent with starburst and AGN populations.

Found similar luminosity evolution for starburst galaxies at 610 MHz as at 1.4 GHz.

Abstract

We present the results of a deep 610 MHz survey of the 1^H XMM/Chandra survey area with the GMRT. The resulting maps have a resolution of ~7 arcsec and an rms noise limit of 60 microJy. To a 5 sigma detection limit of 300 microJy we detect 223 sources within a survey area of diameter 64 arcmin. We compute the 610 MHz source counts and compare them to those measured at other radio wavelengths. The well know flattening of the Euclidean-normalised 1.4 GHz source counts below ~2 mJy, usually explained by a population of starburst galaxies undergoing luminosity evolution, is seen at 610 MHz. The 610 MHz source counts can be modelled by the same populations that explain the 1.4 GHz source counts, assuming a spectral index of -0.7 for the starburst galaxies and the steep spectrum AGN population. We find a similar dependence of luminosity evolution on redshift for the starburst galaxies at 610 MHz as is found at 1.4 GHz (i.e. 'Q'= 2.45 (+0.3,-0.4)).