Colloquium on 26 January 2017
Dust-obscured galaxies under the cosmic zoom lens in the Herschel Astrophysical Terahertz Large Area Survey

Details

Title: Dust-obscured galaxies under the cosmic zoom lens in the Herschel Astrophysical Terahertz Large Area Survey
Speaker: Dr Mattia Negrello (University of Cardiff)
Date: Thursday, 26 January 2017
Time: 11:00 - 0:00
Venue: SAAO Auditorium

Abstract

The Herschel Astrophysical Terahertz Large Area Survey (H-ATLAS) is the widest-area extragalactic survey undertaken with the Herschel space observatory, covering around 600 square degrees of the sky from far-infrared to sub-millimetre wavelengths. One of its scientific goals is the systematic search of gravitationally lensed dust-obscured galaxies using a simple and efficient method that was first proposed in the 90s, which exploits the steep number counts of sub-mm selected galaxies.
After discussing the importance of gravitational lensing in the study of distant galaxies and the key role played by dust-obscured galaxies in our understanding of galaxy formation and evolution, I will review the status of the search of lensed galaxies in H-ATLAS and of the associated campaign of follow-up multiwavelength observations. I will then show and discuss some examples of dust-obscured lensed galaxies discovered so far. In particular I will focus on SDP.81, the first gravitational lensing event we identified in H-ATLAS, in which the spatial resolution offered by follow-up observations with the Atacama Large Millimetre Array (~30 milliarcsec) and the extra “zoom-in” provided by gravitational lensing allow us to probe scales of just few tens of parsecs in a z=3 galaxy!
The talk is meant for a wide audience so please come along even if you are not very familiar with far-infrared/sub-mm astronomy and/or gravitational lensing.
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