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Today's Colloquium: The Simple Structure but Puzzling Evolution of Massive Galaxies - Matthew Auger (University of Cambridge)

Submitter: colloquium
Description: Massive early-type galaxies show a remarkable amount of homology, and the structure of early-type galaxies over a wide mass range can be very well described by just two parameters. Nevertheless, the origin of this simple structure has eluded explanation. In particular, the existence of very compact massive early-type galaxies at z ~ 2 -- and their almost complete absence in the local universe -- is impossible to reconcile with the once favoured major dry merger scenario of galaxy evolution. I will introduce the first results of a search for a new class of strong gravitational lenses that will provide unique insights on the plausible evolutionary scenarios for massive galaxy growth.

The lens system illustrated here, SDSS J0930+2855, is one of the new class of lenses that have bright, compact, and massive early-type galaxies acting as the background source. These lenses provide several advantages over 'classic' lensing systems, largely driven by the excellent sensitivity that can be obtained with modest telescope time due to the intrinsically luminous nature of the sources; this image of SDSSJ0930+2855 is a colour composite from Hubble Space Telescope B and I imaging, but in an infrared image the background source would clearly outshine the foreground lensing galaxy.

I will also highlight several other areas that will be significantly impacted by these new lenses, including: the search for cold dark matter substructures, the nature of dark matter in galaxy-scale haloes, and the equation of state of dark energy.
Copyright: Matthew Auger
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