AGC 322753: A dark galaxy candidate detected by ALFALFA and FASHI
- 1Centre for Astrophysics and Supercomputing, Swinburne University of Technology , John Street, Hawthorn VIC 3122 ,
Abstract
We report the possible detection of a dark galaxy candidate (AGC 322753), via the cross-matching of the Arecibo Legacy Fast ALFA (ALFALFA) and the FAST All Sky H i (FASHI) H i blind surveys. It is detected by both surveys at the same recessional velocity, with a comparable H i mass of 2 × 109 M⊙, and with similar H i spectral features. The ALFALFA and FASHI spectra show a double-peaked profile, compatible with a disc-like ordered rotation, and an H i linewidth at 50 per cent of the peak (W50) of ∼ 85 km s−1. The common intersection of the two beams allows the source position to be constrained with much greater precision than in either survey individually. Being detected by both radio telescopes, a radio frequency interference origin is excluded. No evidence of an optical counterpart was found down to ∼ 27.5 mag arcsec−2 in the DESI Legacy Imaging Surveys, which leads to a stellar mass limit of Mbigstar ≲ 5 × 107 M⊙. Given this stellar mass limit, AGC 322753 has MH small I/Mbigstar ≳ 40. The H i mass is higher than expected for totally starless haloes; this could imply that AGC 322753 is not completely ‘dark’ but could host a luminous counterpart below the current optical detection limit.
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BibTeX
@article{monaci2026322753,
title = {{AGC 322753: A dark galaxy candidate detected by ALFALFA and FASHI}},
author = {Marco Monaci and Duncan A Forbes and Warrick J Couch and Jean P Brodie},
journal = {Monthly Notices of the Royal Astronomical Society},
year = {2026},
month = oct,
doi = {10.1093/mnras/stag1874},
url = {https://academic.oup.com/mnras/article/doi/10.1093/mnras/stag1874/8859321},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - AGC 322753: A dark galaxy candidate detected by ALFALFA and FASHI
AU - Marco Monaci
AU - Duncan A Forbes
AU - Warrick J Couch
AU - Jean P Brodie
PY - 2026
DA - 2026/10/01
JO - Monthly Notices of the Royal Astronomical Society
DO - 10.1093/mnras/stag1874
UR - https://academic.oup.com/mnras/article/doi/10.1093/mnras/stag1874/8859321
AB - We report the possible detection of a dark galaxy candidate (AGC 322753), via the cross-matching of the Arecibo Legacy Fast ALFA (ALFALFA) and the FAST All Sky H i (FASHI) H i blind surveys. It is detected by both surveys at the same recessional velocity, with a comparable H i mass of 2 × 10^9 M_⊙, and with similar H i spectral features. The ALFALFA and FASHI spectra show a double-peaked profile, compatible with a disc-like ordered rotation, and an H i linewidth at 50 per cent of the peak (W_50) of ∼ 85 km s^−1. The common intersection of the two beams allows the source position to be constrained with much greater precision than in either survey individually. Being detected by both radio telescopes, a radio frequency interference origin is excluded. No evidence of an optical counterpart was found down to ∼ 27.5 mag arcsec^−2 in the DESI Legacy Imaging Surveys, which leads to a stellar mass limit of M_bigstar ≲ 5 × 10^7 M_⊙. Given this stellar mass limit, AGC 322753 has M_H small I/M_bigstar ≳ 40. The H i mass is higher than expected for totally starless haloes; this could imply that AGC 322753 is not completely ‘dark’ but could host a luminous counterpart below the current optical detection limit.
SN - 0035-8711
SN - 1365-2966
ER -