AR-2020-21

21 RESEARCH HIGHLIGHTS 2020-2021 33 rd ANNUAL REPORT 2020-21 TheMeerKATAbsorptionLine Survey (MALS) gets real! Deep galaxy surveys have revealed that the global star formation rate (SFR) density in the universe peaks at 1 ≤ z ≤ 2 and sharply declines towards z = 0. But a clear picture of the underlying processes, in particular, the evolution of cold atomic ( ∼ 100 K) and molecular gas phases, that drive such a strong evolution is yet to emerge. In 2010, the MeerKAT Absorption Line Survey (MALS), led by IUCAAresearchers Neeraj Gupta and Raghunathan Srianand , was identified as one of the ten large surveys to be carried out withMeerKAT radio telescope to better constrain the evolution of cold atomic andmolecular gas in galaxies. After a rigorous and successful telescope commissioning and science verification phase involving engineers and astronomers from the South African Radio Astronomy Observatory (SARAO), and the MALS team members, the MALS observations, finally started in June 2020. The 1,655 hrs of MALS with the MeerKAT radio telescope, which is currently the most sensitive telescope at cmwavelengths, will produce 1.5 PB of raw data! These data cannot be processed using traditional data processing approaches. IUCAAhas set up a dedicated data processing facility to overcome this big data challenge. MALS is currently producing the most sensitive spectra of radio sources ever taken by astronomers. Details of new exciting results from these early science data are described in the section “Research at IUCAA” later in this report. The large sample of HI and OH absorbers obtained from the survey will (i) lead to tightest constraints on the fundamental constants of physics, and (ii) be ideally suited to probe the evolution of magnetic fields in disks of galaxies via Zeeman Splitting or Rotation Measure synthesis. Through the excellent sensitivity of MeerKAT over a wide range of spatial resolutions and wideband spectro-polarimetry, MALS will simultaneously deliver a highly competitive blind HI/OH emission line and radio continuum survey, andwill address a wide range of science issues relevant to Square KilometerArray (SKA).