Probable detection of HI at z ≃ 1:3 from DEEP2 galaxies using the GMRT

Shiv K. Sethi, K. S. Dwarakanath and Chandrashekar Murugesan
Raman Research Institute, Bangalore 560 080, India

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We analyse the redshifted HI emission from a DEEP2 field using the Giant Meterwave Radio Telescope in the frequency band of 610 MHz. There are ≃ 400 galaxies in the redshift range 1:24 < z < 1:36 and within the field of view ≃ 44'. We coadd the HI 21 cm-line emission at the locations of the DEEP2 galaxies. We apply stacking on three di erent data cubes: primary beam uncorrected, primary beam corrected (uniform weighing) and primary beam corrected (optimal weighing). We report a probable detection of the HI signal between 2–3σ level. For optimallyweighted cube, we obtain an average flux per halo: 17+8-11 μJy and velocity 270+360-180 km sec-1 (both 90% confidence limits). The average HI mass of a halo is MHI ≃ 2 X 1010Mʘ and it lies in the range 0.35– 8.3 X 1010Mʘ (90% confidence limit). We compare our results with existing N-body simulations and find reasonable agreement.

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Keywords : galaxies: high-redshift—radio lines: galaxies—cosmology: observations