HIPASS study of southern ultradiffuse galaxies and low surface brightness galaxies

TL;DR

This study used the HIPASS survey to search for HI in low surface brightness and ultradiffuse galaxies from DES, finding mostly non-detections that suggest these galaxies are HI deficient or distant, with implications for their size and gas content.

Contribution

First HI survey of DES-identified LSBGs and UDGs, providing insights into their gas content and environment, despite non-detections due to survey limitations.

Findings

Most galaxies are HI deficient or distant beyond HIPASS detection.

Sample likely dominated by dwarf-sized galaxies with low HI mass.

Future more sensitive observations could clarify the nature of these galaxies.

Abstract

We present results from an HI counterpart search using the HI Parkes All Sky Survey (HIPASS) for a sample of low surface brightness galaxies (LSBGs) and ultradiffuse galaxies (UDGs) identified from the Dark Energy Survey (DES). We aimed to establish the redshifts of the DES LSBGs to determine the UDG fraction and understand their properties. Out of 409 galaxies investigated, none were unambiguously detected in HI. Our study was significantly hampered by the high spectral rms of HIPASS and thus in this paper we do not make any strong conclusive claims but discuss the main trends and possible scenarios our results reflect. The overwhelming number of non-detections suggest that: (A) Either all the LSBGs in the groups, blue or red, have undergone environment aided pre-processing and are HI deficient or the majority of them are distant galaxies, beyond the HIPASS detection threshold. (B) The sample investigated is most likely dominated by galaxies with HI masses typical of dwarf galaxies. Had there been Milky Way (MW) size (R_e) galaxies in our sample, with proportionate HI content, they would have been detected, even with the limitations imposed by the HIPASS spectral quality. This leads us to infer that if some of the LSBGs have MW size optical diameters, their HI content is possibly in the dwarf range. More sensitive observations using the SKA precursors in future may resolve these questions.