Spectral Energy Distributions of Infrared Bright Galaxies
Sukanya Chakrabarti (Harvard/CfA) - 17 Apr at 12:00 noon
The dusty infrared bright galaxies now commonly dubbed as LIRGs
and ULIRGS (luminous and ultraluminous infrared galaxies) were discovered
in large numbers by the IRAS satellite. They've intrigued observers and
theorists by the unexpectedly large amounts of infrared
radiation they produce (L_IR ~ 10^11 Lsun - 10^12 Lsun). Since they are
often heavily obscured in the optical and radiate most of their energy in the mid
and far-infrared, the infrared SED is a commonly used tool to study these
systems.
Here, we use a new approach to study their infrared SEDs. We calculate the
infrared SEDs from simulations of major galaxy mergers and study the
effect of AGN and starburst feedback on the evolution of the SED as a
function of time. We use a self-consistent three-dimensional radiative
equilibrium code to calculate the emergent SEDs and images. We find that
feedback processes critically determine the evolution of the SED. AGN
feedback in particular is very effective at dispersing gas mass and
rapidly injecting energy into the ISM. In general, simulations performed
with AGN feedback have warmer spectra, particularly in their most luminous
phases, compared to (otherwise equivalent) simulations performed with
starburst feedback. This suggests that the IRAS warm-cold classification
of ULIRGs maybe naturally explained within the context of a dynamical
model where AGN feedback disperses gas mass effectively enough to produce
warm SEDs.
The seminar will be held in 544 Campbell Hall.
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