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Abstract: The nature of galaxies selected at submillimeter wavelengths SMGs, S 850 > 3mJy, some of the bolometrically most luminous objects at high redshifts, isstill elusive. In particular their star formation histories and source ofemission are not accurately constrained. In this paper we introduce a newapproach to analyse the SMG data. Namely, we present the first self-consistentUV-to-radio spectral energy distribution fits of 76 SMGs with spectroscopicredshifts using all photometric datapoints from ultraviolet to radiosimultaneously. We find that they are highly star-forming median starformation rate 713 MSun yr^-1 for SMGs at z>0.5, moderately dust-obscuredmedian A V~2 mag, hosting significant stellar populations median stellarmass 3.7x10^11 MSun of which only a minor part has been formed in the ongoingstarburst episode. This implies that in the past, SMGs experienced eitheranother starburst episode or merger with several galaxies. The properties ofSMGs suggest that they are progenitors of present-day elliptical galaxies. Wefind that these bright SMGs contribute significantly to the cosmic starformation rate density ~20% and stellar mass density ~30-50% at redshifts2-4. Using number counts at low fluxes we find that as much as 80% of thecosmic star formation at these redshifts took place in SMGs brighter than 0.1mJy. We find evidence that a linear infrared-radio correlation holds for SMGsin an unchanged form up to redshift of 3.6, though its normalization is offsetfrom the local relation by a factor of ~2.1 towards higher radio luminosities.We present a compilation of photometry data of SMGs and determinations ofcosmic SFR and stellar mass densities.



Autor: Michał J. Michałowski, Jens Hjorth, Darach Watson

Fuente: https://arxiv.org/







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