Ly-alpha Emission from Galaxy Formation
Claude-André Faucher-Giguère (Harvard) - Nov 16, 2009 at 12:10 pm
Astronomers have exquisite observations of both galaxies (by directly
imaging their stars) and of the intergalactic medium (in absorption
spectra of background sources). While we know that the galactic
baryons must have been accreted from the IGM, we currently have
virtually no direct observations of the galaxy assembly process
itself. Contrary to the classical picture of galaxy formation in which
the accreting gas is shock-heated to the virial temperature of the
halo before cooling, recent simulations show that most of the gas is
instead accreted in cold streams, with temperatures T~10^4-10^5 K. At
these temperatures, the accretion streams will radiate primarily in
the Ly-alpha line and may be accessible to current observations. I
will present new results combining cosmological hydrodynamical
simulations with Ly-alpha radiative transfer, including the expected
Ly-alpha luminosities, spectra, and morphologies of the accretion
streams. I will discuss whether these streams may have already been
detected in the form of extended 'Ly-alpha blobs'.
The seminar will be held in 544 Campbell Hall.
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