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Astronomy Colloquium

Wednesday, May 16, 2018
4:00pm to 5:00pm
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Cahill, Hameetman Auditorium
What Super Spirals tell us about Massive Galaxy Evolution
Patrick Ogle, STScI,

We discovered a rare class of giant spiral galaxies at redshift z=0.1-0.6 that rival giant elliptical galaxies in mass and luminosity. These  super spirals have diameters of 50-135 kpc and stellar masses of up to 1E12 solar masses. With star formation rates of 2-100 solar masses per year, they fall on the star-forming main sequence. In most respects, they appear to be scaled-up versions of normal spiral galaxies.  However, a large percentage (36%) are undergoing interactions or mergers. The AGN percentage is also large (9%). We conjecture that super spirals represent the small fraction of giant galaxies that, unlike giant ellipticals, were not transformed by major mergers. High rotation velocities up to 630 km/s at 40 kpc indicate massive dark halos, consistent with the high observed merger rate. Because of their giant sizes and other extreme properties, super spirals present a unique laboratory for studying galaxy scaling laws. The mere existence of such giant disk galaxies constrains the applicability of star formation quenching mechanisms to galaxy evolution.

For more information, please contact Althea E. Keith by phone at 626-395-4973 or by email at [email protected].