Properties and Distribution of the Darkest Dwarf Galaxies in the ALFALFA Survey
Amélie Saintonge (Cornell) and the ALFALFA
We present results from the Arecibo Legacy Fast ALFA Survey (ALFALFA).
Using early data from this large blind extragalactic HI survey, we have
identified a population of gas-rich, low-mass dwarf galaxies. These HI
detections are matched with very low optical surface brightness
counterparts, and as such represent a previously poorly studied population
of objects. We have obtained high quality long-slit optical spectra to
determine their chemical abundances and assess their star formation
histories. With large mass-to-light ratios, these are among the
"darkest" galaxies detected by ALFALFA. We compare the properties of
these galaxies found in groups and on the outskirts of clusters to those
found in very low density cosmic environments.