The first data release from the MeerKAT Absorption Line Survey (MALS)

: Mumbai/Pune, August 25, 2023

The vast expanse of the observable universe is home to countless galaxies. Many of these galaxies have supermassive black holes (SMBHs), which become active when gas infalling towards the black hole results in release of large amounts of energy. The energy output from these Active Galactic Nuclei (AGN), often outshines the light from the entire galaxy. Additionally, they eject “jets”: collimated streams of highly-energetic ionized gas particles, piercing through the interstellar medium (ISM) amid the stars.

The interplay between energetic output from AGN and cold gas in host galaxies is central to understanding the fueling of massive black holes and the evolution of galaxies hosting these. MeerKAT Absorption Line Survey (MALS) is carrying out a sensitive search of absorption lines to characterize the properties of cold atomic and molecular gas associated with AGN. The MALS team is an international collaboration of researchers from around the world. The project is led by Prof. N. Gupta from the Inter-University Centre for Astronomy and Astrophysics (IUCAA), India. IUCAA is an autonomous institution set up by the University Grants Commission (UGC) of India to promote the nucleation and growth of active groups in astronomy and astrophysics at Indian universities.

Figure 1: The background image shows the survey footprint (391 telescope pointings) and inset images showcase the diversity of radio emission detected through the superb imaging capabilities of MeerKAT

The MALS team has released radio continuum images and a catalog of 495,325 radio sources detected over an area of 2289 deg² from 391 telescope pointings at 1 – 1.4 GHz. “Majority of these radio sources are AGNs and many are detected for the first time, thanks to excellent capabilities of MeerKAT. These radio sources will subsequently be used as background targets to detect signatures of cold gas in and around galaxies, addressing the main theme of the survey.” – explains Partha Pratim Deka, currently a Ph.D. student at IUCAA, Pune and the lead-author of the Astrophysical Journal article describing the data release.

The MALS catalogs and images are publicly available at https://mals.iucaa.in/. These may be used for a diverse range of scientific objectives by the astronomy community.

Figure 2:South Africa‚s MeerKAT telescope
Image credit: SARAO

This is the first of several radio continuum and spectral line data releases to come from MALS. Making this data release has been a team effort. The MeerKAT telescope is a facility of the National Research Foundation (NRF) in South Africa and is operated by the South African Radio Astronomy Observatory (SARAO). The huge volume of raw survey data (1.6 petabytes) received from SARAO are hosted and processed at IUCAA using an automated pipeline built at IUCAA in collaboration with Thoughtworks Technologies India Pvt. Ltd. It extensively utilizes tools and tasks from the Common Astronomy Software Applications (CASA) software built by the National Radio Astronomy Observatory (NRAO) of the USA.

Article:

“The MeerKAT Absorption Line Survey (MALS) data release I: Stokes I image catalogs at 1-1.4 GHz”
DOI: https://arxiv.org/abs/2308.12347

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SC/PK Source: IUCAA