# Searching in HI for Massive Low Surface Brightness Galaxies: Samples from HyperLeda and the UGC

**Authors:** K. O'Neil, Stephan E. Schneider, W. van Driel, G. Liu, T. Joseph, A. C. Schwortz, Z. Butcher  
**arXiv:** [2307.11202](https://arxiv.org/abs/2307.11202)  
**Date:** 2023-07-18  
**Summary page:** https://www.summarizepaper.com/en/paper/2307.11202v1/

## Key points

- A search was conducted for 21 cm HI line emission in 350 unique galaxies from two samples
- First sample: 241 low surface brightness (LSB) galaxies of morphological type Sb from HyperLeda database
- Second sample: 119 LSB galaxies from UGC with morphological types Sd-m and later
- Observations made at Nancay Radio Telescope, Green Bank Telescope, and Arecibo telescope
- 84.3% (295) of the observed galaxies were detected
- Estimated that 72.3% (253) are uncontaminated by other galaxies within the telescope beam
- At least 31 detected uncontaminated galaxies appear to be massive LSB galaxies with HI mass >=10^10 M_sol assuming H_0 = 70 km/s/Mpc
- Expanding definition to include significant total mass, number of massive LSB galaxies increases to 41
- No obvious trends found between measured global galaxy properties and galaxy mass
- Study provides valuable insights into presence and characteristics of massive low surface brightness galaxies through HI line emission observations in a large sample size

## Summary

A search was conducted for 21 cm HI line emission in 350 unique galaxies from two samples with optical properties suggesting they may be massive. The first sample consisted of 241 low surface brightness (LSB) galaxies of morphological type Sb selected from the HyperLeda database and the second sample included 119 LSB galaxies from the UGC with morphological types Sd-m and later. Observations were made for 239 at the Nancay Radio Telescope, 161 at the Green Bank Telescope, and 66 at the Arecibo telescope. Of these observations, 295 (84.3%) galaxies were detected and it is estimated that 253 (72.3%) are uncontaminated by any other galaxies within the telescope beam. Analysis revealed that at least 31 of these detected uncontaminated galaxies appear to be massive LSB galaxies with a total HI mass greater than or equal to 10^10 M_sol assuming H_0 = 70 km/s/Mpc. If we expand our definition to include galaxies with significant total mass (not just gas), specifically those with inclination-corrected HI line width W_50,cor > 500 km/s, then the number of massive LSB galaxies increases to 41. No obvious trends were found between various measured global galaxy properties such as mean surface brightness and galaxy mass. This study provides valuable insights into the presence and characteristics of massive low surface brightness galaxies through HI line emission observations in a large sample size which contributes to our understanding of galaxy formation and evolution processes.