2025/06/10 by Doppel, Jessica E., Jauzac, Mathilde, Lagattuta, David J. +2
#Astrophysics of Galaxies (astro-ph.GA) #Cosmology and Nongalactic Astrophysics (astro-ph.CO) #FOS: Physical sciences
paper · doi:10.48550/arxiv.2506.09122
Dark matter haloes and subhaloes that host no luminous counterpart are predicted within our current understanding of galaxy formation within a ΛCDM paradigm. Observational tests, such as gravitational lensing, have made potential detections of such objects around individual galaxies as well as in galaxy groups and clusters. The question of whether or not a dim counterpart might reside in these objects remains an open question. We investigate this point using the TNG50-1 simulation of the IllustrisTNG project. Under the assumption of TNG50's galaxy formation model, we do not find haloes or subhaloes above a total mass of \rm 109.7 M\odot that are entirely dark. However, under realistic effective surface brightness cuts of \rm ≤ 29 mag arcsec-2, the inference of the most massive dark subhalo in galaxy groups and clusters becomes \rm MDM \gtrsim 2 × 1010 M\odot. Concentrating on galaxy groups and clusters, we find that dark subhaloes are ubiquitous with more massive dark subhaloes tending to preferentially reside further from the centers of clusters. We find that subhaloes in the mass range of \rm 4.5 × 107 ≤ MDM/M\odot ≤ 2.1× 108 tend to be the most likely to reside in the strong lensing regions of galaxy groups and clusters, and argue that future dark subhalo searches should investigate this mass range.