First Detection of CO in a Low Surface Brightness Galaxy

Authors: K. O'Neil, P. Hofner, E. Shinnerer

Published: Astrophysical Journal Letters, Vol 545, pg L99 (2000)

Abstract:
We report on the first attempts at searching for CO in red low surface brightness galaxies, and the first detection of molecular gas in a low surface brightness (µ_B(0)obs > 23 mag arcsec^-2) galaxy. Using the IRAM 30m telescope, CO(1-0) and CO(2-1) lines were searched for in four galaxies - P06-1, P05-5, C05-3, & C04-2. In three of the galaxies no CO was detected, to T_{MB} ~ 1.8mK (at the 3 sigma level). In the fourth galaxy, P06-1, both lines were detected. Comparing our findings with previous studies shows P06-1 to have a molecular-to-atomic mass ratio considerably lower than is predicted using theoretical models based on high surface brightness galaxy studies. This indicates the N(H₂)/(int{T(CO)dv}) conversion factor for low surface brightness galaxies may currently be consistently underestimated by a factor of 3 - 20.

Paper (postscript, with figures - 167 kb)