Issue |
A&A
Volume 383, Number 3, MarchI 2002
|
|
---|---|---|
Page(s) | 755 - 762 | |
Section | Cosmology (including clusters of galaxies) | |
DOI | https://doi.org/10.1051/0004-6361:20011785 | |
Published online | 15 March 2002 |
Contribution of starburst mergers at
to the strong
evolution of infrared and submillimeter deep surveys
Purple Mountain Observatory, Academia Sinica, China; National Astronomical Observatories of China National Astronomical Observatory of Japan, Mitaka, Tokyo 181-8588, Japan
Corresponding author: ypwang@pmo.ac.cn
Received:
20
July
2001
Accepted:
29
November
2001
Recent far-infrared and submillimetre waveband observations
revealed a large number of Ultraluminous
Infrared Galaxies (ULIGs) with infrared luminosities >
.
These sources are
proposed to lie at redshifts above one, and in normally interacting systems with
very dusty environments. We discussed in a previous paper that a population with a
fast evolving infrared burst phase triggered by gas-rich mergers
at
predicted successfully the steep slope of faint IRAS
60 μm source counts within the flux range of 100 mJy ~ 1 Jy, still leaving
the infrared background level at this wavelength compatible with the upper limit from recent
high energy TeV γ ray detection of Mrk 501. To extend the model to mid and far infrared wavelengths, we adopt a reasonable
template spectral energy distribution typical for nearby-infrared-bright starburst galaxies (
),
such as Arp 220. We construct the SED
for the dusty starburst mergers at
by a simple dust extinction law and a thermal continuum assumption for the far-infrared
emission. Since the radiation process at mid-infrared for these starburst merging systems is still uncertain, we assume
it is similar to the MIR continuum of Arp 220, but modify it by the observed flux correlation of ULIGs from IRAS and ISOCAM
deep surveys.
We show in this paper that the strong evolution of the European Large Area ISO Survey (ELAIS)
at 90 μm, ISO 170 μm and the Submillimeter deep survey at 850 μm could be sufficiently accounted for by
such an evolutionary scenario, especially the hump of the ISOCAM 15 μm source count around 0.4 mJy.
From current best fit results, we find that the dust temperature of those extremely bright starburst merging system at
would be higher than that of Arp 220 for a
reconciliation of the multi-wavelength infrared deep surveys. We thus propose
that the infrared burst phase of dusty starburst galaxies or AGNs from gas-rich mergers
at
could contribute significantly to the strong evolution of the IRAS
60 μm, the ISO 15 μm, 90 μm, 170 μm, as well as the SCUBA 850 μm number
counts, while being compatible with the current observational limits of the cosmic infrared background and the redshift distributions.
The major difference of our current model prediction is that we see a fast convergence of the differential number counts
at 60 μm
below 50 mJy, which is about a factor of two brighter than other model predictions. Future infrared satellites like Astro-F or
SIRTF would give strong constraints to the models.
Key words: galaxies: evolution / galaxies: interaction / galaxies: starburst / galaxies: Seyfert
© ESO, 2002
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