The Giant Metrewave Radio Telescope Cold-HI AT z1 Survey

Aditya Chowdhury, Nissim Kanekar, Jayaram N. Chengalur

Submitted on 30 June 2022


We describe the design, data analysis, and basic results of the Giant Metrewave Radio Telescope Cold-HI AT z1 (GMRT-CATz1) survey, a 510-hour upgraded GMRT HI 21 cm emission survey of galaxies at z=0.741.45 in the DEEP2 survey fields. The GMRT-CATz1 survey is aimed at characterising HI in galaxies during and just after the epoch of peak star-formation activity in the Universe, a key epoch in galaxy evolution. We obtained high-quality HI 21 cm spectra for 11,419 blue star-forming galaxies at z=0.741.45, in seven pointings on the DEEP2 subfields. We detect the stacked HI 21 cm emission signal of the 11,419 star-forming galaxies, which have an average stellar mass of M1010M, at 7.1σ statistical significance, obtaining an average HI mass of MHI=(13.7±1.9)×109M. This is significantly higher than the average HI mass of MHI=(3.96±0.17)×109M in star-forming galaxies at z0 with an identical stellar-mass distribution. We stack the rest-frame 1.4 GHz continuum emission of our 11,419 galaxies to infer an average star-formation rate (SFR) of 8.07±0.82Myr1. Combining our average HI mass and average SFR estimates yields an HI depletion timescale of 1.70±0.29 Gyr, for star-forming galaxies at z1, 3 times lower than that of local galaxies. We thus find that, although main-sequence galaxies at z1 have a high HI mass, their short HI depletion timescale is likely to cause quenching of their star-formation activity in the absence of rapid gas accretion from the circumgalactic medium.


Comment: 27 pages, 15 figures; accepted for publication in The Astrophysical Journal

Subjects: Astrophysics - Astrophysics of Galaxies; Astrophysics - Cosmology and Nongalactic Astrophysics