Monday, March 09, 2015 at 4:00 PM

JILA Auditorium

Brice Ménard, Johns Hopkins University

"De-projecting astronomical surveys"

Abstract:

Observations of the sky are inherently a 2-dimensional measurement of flux density on the sphere of the sky. For astrophysical studies, however, one usually needs the knowledge of 3d positions, for example to convert an angle into a physical scale or a brightness into a luminosity. In the context of extragalactic surveys, distance or redshift information is usually done with photometric redshifts​ which rely on strong assumptions and often lead to problematic estimates​. In this talk I will how it is possible to instead use clustering measurements and infer redshift​s​ for any type of extragalactic​ sources. I will show applications of this "clustering-redshift" technique ​to​ various datasets at UV, optical, IR and radio wavelengths​, and show a number​ of surprises.

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