The MeerKAT Absorption Line Survey (MALS) Data Release. I. Stokes I Image Catalogs at 1-1.4 GHz
Artikel i vetenskaplig tidskrift, 2024

The MeerKAT Absorption Line Survey (MALS) has observed 391 telescope pointings at the L band (900-1670 MHz) at delta less than or similar to +20 degrees. We present radio continuum images and a catalog of 495,325 (240,321) radio sources detected at a signal-to-noise ratio (S/N) > 5 over an area of 2289 deg(2) (1132 deg(2)) at 1006 MHz (1381 MHz). Every MALS pointing contains a central bright radio source (S 1 GHz greater than or similar to 0.2 Jy). The median spatial resolution is 12 ''(8 ''). The median rms noise away from the pointing center is 25 mu Jy beam(-1) (22 mu Jy beam-1) and is within similar to 15% of the achievable theoretical sensitivity. The flux density scale ratio and astrometric accuracy deduced from multiply observed sources in MALS are <1% (8% scatter) and 1 '', respectively. Through comparisons with NVSS and FIRST at 1.4 GHz, we establish the catalog's accuracy in the flux density scale and astrometry to be better than 6% (15% scatter) and 0.'' 8, respectively. The median flux density offset is higher (9%) for an alternate beam model based on holographic measurements. The MALS radio source counts at 1.4 GHz are in agreement with literature. We estimate spectral indices (alpha) of a subset of 125,621 sources (S/N > 8), confirm the flattening of spectral indices with decreasing flux density, and identify 140 ultra-steep-spectrum (alpha < -1.3) sources as prospective high-z radio galaxies (z > 2). We have identified 1308 variable and 122 transient radio sources comprising primarily active galactic nuclei that demonstrate long-term (26 yr) variability in their observed flux densities. The MALS catalogs and images are publicly available at https://mals.iucaa.in.

Författare

P. P. Deka

Inter-University Centre for Astronomy and Astrophysics

N. Gupta

Inter-University Centre for Astronomy and Astrophysics

P. Jagannathan

National Radio Astronomy Observatory

S. Sekhar

National Radio Astronomy Observatory

South African Radio Astronomy Observatory (SARAO)

E. Momjian

National Radio Astronomy Observatory

S. Bhatnagar

National Radio Astronomy Observatory

J. Wagenveld

Max-Planck-Gesellschaft

H. -R. Kloeckner

Max-Planck-Gesellschaft

J. Jose

Thought Works Technol India Pvt Ltd

S. A. Balashev

Russian Academy of Sciences

HSE Univ

F. Combes

Université de recherche Paris Sciences et Lettres

M. Hilton

University of KwaZulu-Natal

University of Witwatersrand

D. Borgaonkar

Inter-University Centre for Astronomy and Astrophysics

A. Chatterjee

Thought Works Technol India Pvt Ltd

K. L. Emig

National Radio Astronomy Observatory

A. N. Gaunekar

Thought Works Technol India Pvt Ltd

G. I. G. Jozsa

Max-Planck-Gesellschaft

Rhodes University

D. Y. Klutse

University of KwaZulu-Natal

K. Knowles

Rhodes University

J. -k. Krogager

Université de Lyon

A. Mohapatra

Inter-University Centre for Astronomy and Astrophysics

K. Moodley

University of KwaZulu-Natal

Sebastien Muller

Chalmers, Rymd-, geo- och miljövetenskap, Onsala rymdobservatorium

P. Noterdaeme

CNRS SU

P. Petitjean

CNRS SU

P. Salas

Green Bank Observ, 155 Observ Rd

S. Sikhosana

University of KwaZulu-Natal

Astrophysical Journal, Supplement Series

0067-0049 (ISSN) 1538-4365 (eISSN)

Vol. 270 2 33

Ämneskategorier

Astronomi, astrofysik och kosmologi

DOI

10.3847/1538-4365/acf7b9

Mer information

Senast uppdaterat

2024-02-16