Contents of: VI/111/./abstract/GSTACEY_IRBSEDS1.abs

The following document lists the file abstract/GSTACEY_IRBSEDS1.abs from catalogue VI/111.
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We propose to use ISOPHT-S, ISOPHT-P and the SWS grating to obtain
low resolution spectra and photometry from 2.5 to 25 um of a sample
of 50 IRAS galaxies.  We have two primary scientific goals.  First,
we will use the PAH and silicate dust bands and available spectral
lines to discern the origins of the large IR luminosities of these
galaxies: starbursts or active galactic nuclei(AGNs).  Strong PAH
emission is indicative of a starburst nucleus, while the mid-IR
line ratios derived from the species [ArII], [ArIII], [SIV], and
[NeII] reflect the earliest stellar type still on the main sequence,
hence the age of the starburst.  Lack of PAH emission, together
with emission from more highly ionized species like [ArV], [ArVI],
[MgIV], and [MgVIII], signal the presence of an AGN.  Lines from
the refractories (e.g. [NiII]), trace shocks likely associated with
supernovae, or galaxy-wide collisions.  Second, our proposed
2.5 to 25 um spectrophotometry is essential to validate the use
of far-IR colors as luminosity indicators in the deep cosmological
surveys proposed both in the ISO core program (6.75 and 15 um surveys)
and in the proposed WIRE mission (12 and 25 um surveys).  Nearly
all the sources detected in these two cosmological surveys will have
intrinsic far-IR luminosities in excess of 10^10 L(solar).  Therefore,
our two scientific goals (discerning AGNs from starbursts, and
providing calibration for deep surveys) are complementary:  they both
require a statistically significant sample of IR luminous galaxies at
modest redshifts.  We have selected 50 galaxies from the IRAS Bright
Galaxy Survey with far-IR luminosities at and above 1.5 x 10^10
L(solar).  The proposed observations will therefore investigate both
the origins of the IR luminosity and provide a framework for
understanding the evolution of IR-luminous galaxies in the early
Universe.

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