Discovery of an isolated RELHIC Candidate: J1351+0039
Abstract
We report the discovery of J1351+0039, a new isolated dark galaxy candidate identified through a blind HI survey with the Five-hundred-meter Aperture Spherical radio Telescope (FAST), combined with deep optical imaging from the DESI Legacy Survey. The object displays a compact HI structure with a systemic velocity of V_{LSR} = 429.0 \kms and an inferred HI mass of 4.5*10^5 Msun at a distance of 3.6 Mpc. No optical counterpart is detected in the DESI images, with a g-band surface brightness limit of 28.1 mag arcsec^{-2}, corresponding to a stellar mass limit of M_{star} of 1.2*10^{5} Msun. The dynamical mass is estimated to be M_{dyn} of 1.3*10^{8} Msun, yielding a dark-to-baryonic mass ratio of 200, implying that J1351+0039 is overwhelmingly dominated by dark matter. While weak rotation is detected in J1351+0039, the kinematics are dominated by internal velocity dispersion, confirming pressure support and reminiscent of Reionization-Limited HI Clouds (RELHICs). J1351+0039 stands out as one of the most promising isolated RELHIC candidates, offering a unique laboratory for studying baryonic physics and dark matter in the absence of star formation.
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BibTeX
@misc{xu2026discovery,
title = {{Discovery of an isolated RELHIC Candidate: J1351+0039}},
author = {Jin-Long Xu and Alejandro Benitez-Llambay and Ming Zhu and Chuan-Peng Zhang and Nai-Ping Yu and Xiao-Lan Liu and Mei Ai and Ruilei Zhou and Bin Liu},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2609.29852},
eprint = {2609.29852},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.29852},
note = {CC BY-NC-SA 4.0},
}
RIS
TY - UNPB
TI - Discovery of an isolated RELHIC Candidate: J1351+0039
AU - Jin-Long Xu
AU - Alejandro Benitez-Llambay
AU - Ming Zhu
AU - Chuan-Peng Zhang
AU - Nai-Ping Yu
AU - Xiao-Lan Liu
AU - Mei Ai
AU - Ruilei Zhou
AU - Bin Liu
PY - 2026
DA - 2026/10/21
PB - arXiv
DO - 10.48550/arxiv.2609.29852
UR - https://arxiv.org/abs/2609.29852
AB - We report the discovery of J1351+0039, a new isolated dark galaxy candidate identified through a blind HI survey with the Five-hundred-meter Aperture Spherical radio Telescope (FAST), combined with deep optical imaging from the DESI Legacy Survey. The object displays a compact HI structure with a systemic velocity of V_{LSR} = 429.0 \kms and an inferred HI mass of 4.5*10^5 Msun at a distance of 3.6 Mpc. No optical counterpart is detected in the DESI images, with a g-band surface brightness limit of 28.1 mag arcsec^{-2}, corresponding to a stellar mass limit of M_{star} of 1.2*10^{5} Msun. The dynamical mass is estimated to be M_{dyn} of 1.3*10^{8} Msun, yielding a dark-to-baryonic mass ratio of 200, implying that J1351+0039 is overwhelmingly dominated by dark matter. While weak rotation is detected in J1351+0039, the kinematics are dominated by internal velocity dispersion, confirming pressure support and reminiscent of Reionization-Limited HI Clouds (RELHICs). J1351+0039 stands out as one of the most promising isolated RELHIC candidates, offering a unique laboratory for studying baryonic physics and dark matter in the absence of star formation.
ER -