Luke Leisman (Cornell)

Luke Leisman colloquium: Needles in a Haystack: "Almost Dark" Galaxies in the ALFALFA Survey

Abstract

Scaling relations between atomic hydrogen and stars in galaxies suggest strong ties
between their atomic gas content and star formation laws. The Arecibo Legacy Fast
ALFA (ALFALFA) blind extragalactic HI survey is well positioned to locate very low
surface brightness sources that lie off these relations, the most extreme of which
may fall below optical detection limits. Thus, the ALFALFA (Almost) Darks Project has
been investigating extreme outliers from these relations, searching for sources with
highly suppressed star formation laws. This talk will present results from this project,
including an isolated population of gas-rich galaxies with stellar masses of dwarfs,
but optical radii similar to the Milky Way, and will explore what these sources teach
us about the suppression of star formation in galaxies.