Dust in the Early (z>1) Universe

Abstract

Although dust emission at cosmological distances has only been detected a little more than a decade ago, remarkable progress has been achieved since then in characterizing the far-infrared emission of high-redshift systems. The mere fact that dust can be detected in galaxies at high redshift is remarkable for two reasons: (a) even at very early cosmic epochs (all the way to the first Gyr of the universe), dust production was apparently very effective, (b) due to the inverse K-correction (`the magic of (sub-)millimeter') is it actually possible to detect this dust emission using current facilities. Deep blind surveys using bolometer cameras on single dish telescopes have uncovered a population of massively starforming systems at z~2, the so-called submillimeter galaxies (SMGs). Follow-up radio and millimeter interferometric observations helped to characterize their main physical properties (such as far-infrared luminosities and implied star formation rates). Average FIR properties of fainter optically/NIR-selected classes of galaxies have been constrained using stacking techniques. Targeted observations of the rare quasars have provided evidence for major star formation activity in quasar host galaxies throughout cosmic times. Molecular gas and PAH features have been detected in both SMGs and quasars, providing additional evidence for major star formation episodes (SFR 500-3000 M_sun/yr) in the brightest systems. Even though remarkable progress has been achieved in recent years, current facilities fail to uncover the counterparts of even major local starbursts (such as Arp220) at any significant redshift (z>0.5). Only ALMA will be able to go beyond the tip of the iceberg to study the dust and FIR properties of typical star forming systems, all the way out to the epoch of cosmic reionization (z>>6).