The LABOCA survey of the Extended Chandra Deep Field South - radio and mid-infrared counterparts to submillimetre galaxies

TL;DR

This study identifies and analyzes radio and infrared counterparts to submillimetre galaxies in the Extended Chandra Deep Field South, providing insights into their redshift distribution and properties using multi-wavelength data.

Contribution

It presents a new method for identifying SMG counterparts using combined radio and infrared data, and estimates their redshifts with flux boosting corrections.

Findings

79 out of 126 SMGs have secure counterparts

Median redshift of SMGs is approximately 2.2

Flux boosting correction increases median redshift by 0.2

Abstract

We present radio and infrared (3.6-24um) counterparts to submillimetre galaxies (SMGs) detected in the Extended Chandra Deep Field South with the LABOCA 870-um bolometer camera on the 12-m Atacama Pathfinder Experiment. Using the Very Large Array at 1.4GHz and Spitzer we have identified secure counterparts to 79 of the 126 SMGs (SNR>3.7, S_870>4.4mJy) in the field, 62 via their radio and/or 24-um emission, the remainder using a colour-flux cut on IRAC 3.6- and 5.8-um sources chosen to maximise the number of secure, coincident radio and 24-um counterparts. In constructing our radio catalogue, we have corrected for the effects of `flux boosting', then used the corrected flux densities to estimate the redshifts of the SMGs based on the radio/submm spectral indices. The effect of the boosting correction is to increase the median redshift by 0.2 resulting in a value of z=2.2 (+0.7-0.8) (1-sigma errors) for the secure radio counterparts, in agreement with other studies, both spectroscopic and photometric.