Deep investigation of neutral gas origins (DINGO): H <scp>i</scp> stacking experiments with early science data

Abstract

ABSTRACT We present early science results from Deep Investigation of Neutral Gas Origins (DINGO), an $\rm H$i survey using the Australian Square Kilometre Array Pathfinder (ASKAP). Using ASKAP subarrays available during its commissioning phase, DINGO early science data were taken over ∼60 deg2 of the Galaxy And Mass Assembly (GAMA) 23 h region with 35.5 h integration time. We make direct detections of six known and one new sources at z &amp;lt; 0.01. Using $\rm H$ i spectral stacking, we investigate the $\rm H$ i gas content of galaxies at 0.04 &amp;lt; z &amp;lt; 0.09 for different galaxy colours. The results show that galaxy morphology based on optical colour is strongly linked to $\rm H$ i gas properties. To examine environmental impacts on the $\rm H$i gas content of galaxies, three subsamples are made based on the GAMA group catalogue. The average $\rm H$i mass of group central galaxies is larger than those of satellite and isolated galaxies, but with a lower $\rm H$i gas fraction. We derive a variety of $\rm H$i scaling relations for physical properties of our sample, including stellar mass, stellar mass surface density, NUV − r colour, specific star formation rate, and halo mass. We find that the derived $\rm H$i scaling relations are comparable to other published results, with consistent trends also observed to ∼0.5 dex lower limits in stellar mass and stellar surface density. The cosmic $\rm H$i densities derived from our data are consistent with other published values at similar redshifts. DINGO early science highlights the power of $\rm H$i spectral stacking techniques with ASKAP.

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