| 28th of April 2020 |
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| ASKAP FLASH detection of neutral hydrogen absorption |
| by Allison et al. |
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Allison et al. have presented early science results from the First Large
Absorption Survey in H I (FLASH), a survey for 21-cm absorption lines in
cold neutral hydrogen (HI) gas at cosmological distances using the Australian
Square Kilometre Array Pathfinder (ASKAP).
FLASH is probing how the neutral interstellar medium in galaxies has
evolved over the history of the Universe.
The team detected 21-cm neutral hydrogen absorption at
a redshift of z=0.356 towards
the galaxy NVSS J224500−343030.
The absorber is associated with GAMA
J22450.05−343031.7, a massive early-type galaxy.
The image above shows ASKAP spectra towards the radio source NVSS J224500−343030 at the redshift (z = 0.356) of the galaxy GAMA J224500.05−343031.7. The detection of HI absorption evident in the ASKAP-12 spectrum was later confirmed using the full ASKAP-36 array. The continuum-subtracted data (solid lines) are given as a fraction of the continuum flux density. The shaded regions denote 5 times the RMS noise measured from the channel images. For clarity the ASKAP-36 spectrum has been offset by 10 per cent. More details are given in the paper, to be published in Monthly Notices of the Royal Astronomical Society. |