MALS-NOT: Identifying Radio-Bright Quasars for the MeerKAT Absorption Line Survey

TL;DR

This study identifies 72 high-redshift, radio-bright quasars suitable for the MeerKAT Absorption Line Survey by combining radio flux and infrared color criteria, providing a valuable target list for future SKA observations.

Contribution

The paper introduces a new method for selecting radio-bright quasars using combined radio and infrared data, and provides a spectroscopic catalog of high-redshift quasars for SKA follow-up.

Findings

72 quasars identified out of 99 candidates.

64 quasars at z>0.6 suitable for L-band follow-up.

48 quasars at z>1.4 suitable for UHF-band follow-up.

Abstract

We present a preparatory spectroscopic survey to identify radio-bright, high-redshift quasars for the MeerKAT Absorption Line Survey (MALS). The candidates have been selected on the basis of a single flux density limit at 1.4 GHz (>200 mJy) together with mid-infrared color criteria from the Wide-field Infrared Survey Explorer (WISE). Through spectroscopic observations using the Nordic Optical Telescope, we identify 72 quasars out of 99 candidates targeted. We measure the spectroscopic redshifts based on characteristic, broad emission lines present in the spectra. Of these 72 quasars, 64 and 48 objects are at sufficiently high redshift (z>0.6 and z>1.4) to be used for the L-band and UHF-band spectroscopic follow-up with the Square Kilometre Array (SKA) precursor in South Africa: the MeerKAT.