Institute of Astronomy

Quasars Probing Quasars: Thinking Outside of the Grid

SpeakerTalk DateTalk Series
Joseph F. Hennawi, Max-Planck-Institut für Astronomie, Heidelberg28 October 2010Institute of Astronomy Colloquia

Abstract

Over the next decade, astronomers will invest billions of dollars on
new instruments to study galaxy formation and evolution at large
cosmological lookback times. However, cosmological simulations of
galaxy formation cannot resolve the relevant physics required to
robustly predict the observables which have been the focus of studies
of high-redshift galaxies. I will argue that observations of the
diffuse gas in the outskirts of galaxies provide a much fruitful
comparison to theory, because hydrodynamics at moderate overdensities
is much easier to simulate than molecule or star-formation. I will
introduce a novel technique whereby a foreground quasar (and massive
galaxy) can be studied in absorption against a background quasar,
resolving scales as small as 30kpc. This experiment reveals a rich
absorption spectrum which contains a wealth of information about the
physical conditions of diffuse gas around massive
proto-galaxies. These types of measurements will allow us to determine
the initial conditions for galaxy formation. Absorption line modeling
techniques will be reviewed, and I'll discuss the implications of
these new observations for galaxy formation and feedback scenarios.

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