Department of Physics
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Astronomy Colloquium
Cosmic Accretion and Star formation in Dwarf Galaxies
Date: Thursday, September 17th
Time: 3:45 pm - 5:00 am
Place: 4421 Sterling Hall
Speaker: Bruce Elmegreen, IBM T.J. Watson Research Center
Abstract: Star formation in dwarf galaxies is anomalous for many reasons: Blue Compact Dwarfs have enormous bursts relative to their size but no evident mergers, dwarf Irregulars have rates per unit area that get as low as 0.1% of that in the solar neighborhood while preserving nearly perfect exponential profiles, and most galaxies with less than 10% solar metallicity have cometary shapes suggesting ram pressure or other lopsided disturbances. Dwarf irregulars also have hardly any CO emission yet can have specific star formation rates higher than the Milky Way. Here I discuss these anomalies and our recent observations to help understand
them. These observations include the relationship between star formation rate and gas surface density in 20 local dwarf Irregulars, which are gas dominated, thick, and very stable according to the Toomre condition, evidence for cosmic accretion in the form of locally low metallicities in the starburst regions of extremely metal poor galaxies, and two-sided accretion at a rate sufficient to sustain star formation in the local dwarf starburst IC 10. I also discuss CO observations with ALMA of the lowest metallicity molecular clouds in the local dwarf irregular WLM.
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