Probable detection of HI at z≃ 1.3 from DEEP2 galaxies using the GMRT

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We have observed the DEEP2 galaxies 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', of the GMRT dishes. We have coadded the HI 21 cm-line emissions at the locations of these DEEP2 galaxies. We apply stacking on three different data cubes: primary beam uncorrected, primary beam corrected (uniform weighing) and primary beam corrected (optimal weighing). We obtain a peak signal strength in the range 8--25 μJy/beam for a velocity width in the range 270-- 810 km sec⁻¹. The error on the signal, computed by bootstrapping, lies in the range 2.5--6 μJy/beam, implying a 2.5--4.7-σ detection of the signal at z ≃ 1.3. We compare our results with N-body simulations of the signal at z≃ 1 and find reasonable agreement. We also discuss the impact of residual continuum and systematics.