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PreprintCC BY 4.0arXiv

CHORD HI-Galaxy Survey Forecasts: Searching for nearby dark galaxies and high redshift giants

  • Akanksha Bij
  • Kristine Spekkens
  • Hans S. Hopkins
  • Michael G. Jones
  • Arnab Chakraborty
  • Simon Foreman
  • Alex S. Hill
  • Dustin Lang
  • Adrian Liu
Open at sourcePDFDOICite

Abstract

Population studies of gas-rich galaxies across the full range of Neutral Hydrogen (HI) masses that galaxies are known to exhibit (105 ≲ MHI ≲ 1011 M⊙) remain limited by the need to conduct high-sensitivity, wide-band surveys across significant sky areas. The Canadian Hydrogen Observatory and Radio-transient Detector (CHORD) is a next-generation radio telescope that will significantly expand the census of HI-galaxies to date from untargeted drift-scan surveys at declinations +20∘ < δ< +80∘. We draw survey realizations from a known HI mass function (HIMF) to forecast HI detections in fiducial 1-year and 5-year CHORD surveys. The 5-year survey source counts is expected exceed currently available catalogs by roughly an order of magnitude, notwithstanding the potential impacts of radio frequency interference (RFI) and spectroscopic source confusion that we also estimate. We predict that CHORD will push the low-mass HI galaxy census to MHI ∼ 105.5 M⊙, over an order of magnitude lower than has been previously achieved. At the high mass end of the HIMF, CHORD is expected to detect ∼103 massive gas-rich giants (MHI ≳ 1010.5 M⊙) at 0.3 ≲ z ≲ 0.5, which will explore the evolution of this population relative to local universe estimates. CHORD HI surveys will therefore improve our understanding of the neutral gas reservoirs at the low-mass and high-mass extremes of the galaxy population.

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Cite

BibTeXRIS
BibTeX
@misc{bij2026chord,
  title = {{CHORD HI-Galaxy Survey Forecasts: Searching for nearby dark galaxies and high redshift giants}},
  author = {Akanksha Bij and Kristine Spekkens and Hans S. Hopkins and Michael G. Jones and Arnab Chakraborty and Simon Foreman and Alex S. Hill and Dustin Lang and Adrian Liu},
  howpublished = {arXiv},
  year = {2026},
  month = sep,
  doi = {10.48550/arxiv.2607.24903},
  eprint = {2607.24903},
  archivePrefix = {arXiv},
  url = {https://arxiv.org/abs/2607.24903},
  note = {CC BY 4.0},
}
RIS
TY  - UNPB
TI  - CHORD HI-Galaxy Survey Forecasts: Searching for nearby dark galaxies and high redshift giants
AU  - Akanksha Bij
AU  - Kristine Spekkens
AU  - Hans S. Hopkins
AU  - Michael G. Jones
AU  - Arnab Chakraborty
AU  - Simon Foreman
AU  - Alex S. Hill
AU  - Dustin Lang
AU  - Adrian Liu
PY  - 2026
DA  - 2026/09/16
PB  - arXiv
DO  - 10.48550/arxiv.2607.24903
UR  - https://arxiv.org/abs/2607.24903
AB  - Population studies of gas-rich galaxies across the full range of Neutral Hydrogen (HI) masses that galaxies are known to exhibit (10^5 ≲ M_HI ≲ 10^11 M_⊙) remain limited by the need to conduct high-sensitivity, wide-band surveys across significant sky areas. The Canadian Hydrogen Observatory and Radio-transient Detector (CHORD) is a next-generation radio telescope that will significantly expand the census of HI-galaxies to date from untargeted drift-scan surveys at declinations +20^∘ < δ< +80^∘. We draw survey realizations from a known HI mass function (HIMF) to forecast HI detections in fiducial 1-year and 5-year CHORD surveys. The 5-year survey source counts is expected exceed currently available catalogs by roughly an order of magnitude, notwithstanding the potential impacts of radio frequency interference (RFI) and spectroscopic source confusion that we also estimate. We predict that CHORD will push the low-mass HI galaxy census to M_HI ∼ 10^5.5 M_⊙, over an order of magnitude lower than has been previously achieved. At the high mass end of the HIMF, CHORD is expected to detect ∼10^3 massive gas-rich giants (M_HI ≳ 10^10.5 M_⊙) at 0.3 ≲ z ≲ 0.5, which will explore the evolution of this population relative to local universe estimates. CHORD HI surveys will therefore improve our understanding of the neutral gas reservoirs at the low-mass and high-mass extremes of the galaxy population.
ER  -