2016/03/08 by M J Disney, M. J. Disney, R. H. Lang +6 · 1 citation
Physics and Astronomy · #Astronomy and Astrophysical Research #Astrophysics of Galaxies (astro-ph.GA) #FOS: Physical sciences #Galaxies: Formation, Evolution, Phenomena #Scientific Research and Discoveries #astro-ph.GA
paper · pdf · doi:10.48550/arxiv.1603.02590
12 pages, 1 figure replaced because half a dozen more recent refs added, esp to sect 1. Also minor change to caption fig 1 since new SDSS optical data has become available since original version. No change in conclusions
openalex publication_date 2016/03/08 · arxiv created 2017/02/13 · arxiv updated 2017/02/14 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
We re-investigate the question of whether there is a significant population of Dim (Low Surface Brightness) and/or Dark Galaxies (DDGs). We argue that if they are clustered with bright ones then a physical resolution of ~10 kpc. will be needed to to distinguish their 21-cm. and QSO Absorption Line(QSOAL) counterparts from their brighter neighbours, leading to a real possibility of confusion. But until now such a resolution has not been available in this context. New Very Large Array (VLA) observations reveal that the identifications with bright optical objects claimed in previous single-dish blind HI surveys are often unreliable. For instance 14/36 of our high-resolution (5 arc sec, 13kpc.) sample have no optical counterparts in the Digital Sky Survey. This suggests that DDGs might be commonplace after all, and we go on to re-examine the main arguments that have been used against them.. We find that the QSOAL argument founders on the aforementioned clustering while deep CCD surveys have so far covered too small an area to set set strong constraints on Low Surface Brightness Galaxies (LSBGs). A cosmos filled with low surface brightness galaxies, dark galaxies and intergalactic gas clouds is therefore possible.