| Abstract : | The MeerKAT Absorption Line Survey (MALS; https://mals.iucaa.in/) has observed 391 telescope pointings using MeerKAT’s L- (900-1670 MHz) and UHF- (580-1015 MHz) bands at declination < +20 degrees. Through narrowband imaging at 15 different frequencies spanning the entire L-band, we have cataloged nearly a million radio sources and constrained their cm-wavelength radio SEDs. In this talk, I will discuss the technical aspects and usability of the catalog and present the immediate scientific results. MeerKAT's unprecedented surface brightness sensitivity transcends the sensitivity constraints limiting previous large-area surveys, opening a new window for characterizing the abundant sub-mJy radio source population. Moreover, the wide instantaneous bandwidth allows detection and kinematical study of cold gas (T~100 K), fuel for both star formation and AGN activity, associated with such faint systems in the catalog up-to z<2 through redshifted HI 21-cm and OH 18-cm absorption lines. The catalog is highly complete down-to 0.5 mJy and the reliability is >99% for sources brighter than 0.4 mJy, measured at 1.4 GHz. Through comparison with the NRAO VLA Sky Survey (NVSS) at 1.4 GHz we establish the astrometric and flux density accuracy of the catalog to be better than 1 arcsec and 6%, respectively. We have identified 1455 long-term (26 years) variable and transient radio sources, the majority of which are AGNs, but some may be stars, supernovae, and GRBs. We estimate spectral indices of a subset of 125,621 sources, confirm the flattening of spectral indices with decreasing flux density and identify 182 ultra-steep spectrum (USS) sources as prospective high-z radio galaxies. I will also present the very first serendipitous detection of a new 21-cm associated absorber at z=1.354, where joint radio-optical analysis allows us to discuss the origin and distribution of the absorbing gas. |
