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arXiv · 2408.06626

The First Large Absorption Survey in HI (FLASH): II. Pilot Survey data release and first results

Hyein Yoon·Elaine M. Sadler·Elizabeth K. Mahony·J. N. H. S. Aditya·James R. Allison·Marcin Glowacki·Emily F. Kerrison·Vanessa A. Moss·Renzhi Su·Simon Weng·Matthew Whiting·O. Ivy Wong·Joseph R. Callingham·Stephen J. Curran·Jeremy Darling·Alastair C. Edge·Sara L. Ellison·Kimberly L. Emig·Lilian Garratt-Smithson·Gordon German·Kathryn Grasha·Baerbel S. Koribalski·Raffaella Morganti·Tom Oosterloo·Céline Péroux·Max Pettini·Kevin A. Pimbblet·Zheng Zheng·Martin Zwaan·Lewis Ball·Douglas C. -J. Bock·David Brodrick·John D. Bunton·F. R. Cooray·Philip G. Edwards·Douglas B. Hayman·Aidan W. Hotan·K. Lee-Waddell·N. M. McClure-Griffiths·A. Ng·Chris J. Phillips·Wasim Raja·Maxim A. Voronkov·Tobias Westmeier
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Abstract

The First Large Absorption Survey in HI (FLASH) is a large-area radio survey for neutral hydrogen in the redshift range 0.4 1$, and appear to be a mixture of intervening and associated systems. Interestingly, around two-thirds of the lines found in this untargeted sample are detected against sources with a peaked-spectrum radio continuum, which are only a minor (5-20%) fraction of the overall radio-source population. The overall detection rate for HI absorption lines in the Pilot Surveys (0.3 to 0.5 lines per ASKAP field) is a factor of two below the expected value. One possible reason for this is the presence of a range of spectral-line artefacts in the Pilot Survey data that have now been mitigated and are not expected to recur in the full FLASH survey. A future paper will discuss the host galaxies of the HI absorption systems identified here.

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Hyein Yoon, Elaine M. Sadler, Elizabeth K. Mahony, J. N. H. S. Aditya, James R. Allison, Marcin Glowacki, Emily F. Kerrison, Vanessa A. Moss, Renzhi Su, Simon Weng, Matthew Whiting, O. Ivy Wong, Joseph R. Callingham, Stephen J. Curran, Jeremy Darling, Alastair C. Edge, Sara L. Ellison, Kimberly L. Emig, Lilian Garratt-Smithson, Gordon German, Kathryn Grasha, Baerbel S. Koribalski, Raffaella Morganti, Tom Oosterloo, Céline Péroux, Max Pettini, Kevin A. Pimbblet, Zheng Zheng, Martin Zwaan, Lewis Ball, Douglas C. -J. Bock, David Brodrick, John D. Bunton, F. R. Cooray, Philip G. Edwards, Douglas B. Hayman, Aidan W. Hotan, K. Lee-Waddell, N. M. McClure-Griffiths, A. Ng, Chris J. Phillips, Wasim Raja, Maxim A. Voronkov, Tobias Westmeier. 2024-08-13. The First Large Absorption Survey in HI (FLASH): II. Pilot Survey data release and first results. https://arxiv.org/abs/2408.06626

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