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SUMMARY:A Color-Independent Approach to Galaxy and Quasar Evolution throug
 h Absorption Spectroscopy - Jens-Kristian Krogager\, University of Lyon (C
 RAL)
DTSTART:20220318T113000Z
DTEND:20220318T123000Z
UID:TALK168056@talks.cam.ac.uk
CONTACT:Ricarda Beckmann
DESCRIPTION:Quasars are widely used in astrophysics to probe various envir
 onments\, ranging from large-scale studies of clustering and the intergala
 ctic medium to galactic-scale studies of the interstellar and circumgalact
 ic media. Moreover\, quasars are intriguing objects on their own and many 
 aspects of quasar evolution and the multitude of observational phenomena a
 re still not fully understood. One main limitation to quasar studies in ge
 neral is the pre-selection for spectroscopic observations. The largest spe
 ctroscopic quasar samples to date have been selected based primarily on op
 tical colors with inhomogeneous inclusion of multi-wavelength data to incr
 ease purity. Such identifications may lead to potential biases in the deri
 ved quasar demographic and can have severe consequences for foreground abs
 orption studies. Various other methods for selecting quasars based on diff
 erent parts of the quasar energy distribution have been employed (e.g.\, r
 adio\, X-ray or IR)\, yet current samples are much smaller than optically-
 selected samples. In this talk\, I will highlight our efforts to obtain th
 e first color-independent quasar sample by selecting candidate quasars pur
 ely based on astrometry from Gaia. This method allows us to select a sampl
 e of optically bright quasars with no further assumptions on the spectral 
 shape. The talk will focus on the implications for studies of foreground a
 bsorption systems as well as the quasar demographic in general.
LOCATION:via zoom 
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