| Description |
Gamma-Ray Bursts (GRBs) are so luminous that they can shine through highlyobscured galaxies, nearby and in the remote universe. GRBs enableidentification of galaxies independently of their luminosity, thus singlingout a population that is a potentially powerful probe of galaxy evolution.Only a minority of the host galaxies of GRBs (GRBHs) have been so far detectedat sub-millimeter (submm) or mid-infrared (mid-IR) wavelengths; however, inthis minority the inferred star-formation rates (SFRs) can be as high as ~500Msun/year, implying that they are similar to submm galaxies. On the otherhand, the frequent non-detections argue against a population dominated bymassive and strongly starbursting galaxies. One way to resolve this dilemmawould be warm dust. At redshifts 2-4, warm dust (40-50K) would be difficult todetect in the submm bands because its peak would be too blue, and also in themid-IR, because its peak emission would be far too red. We propose to breakthis possible dust-temperature redshift conspiracy with Herschel PACS+SPIREphotometry of 14 GRBHs with redshifts reaching 4.4. The sample was selectedon the basis of prior Spitzer IRAC (or MIPS) detections. We already have inhand a large amount of ancillary multiwavelength data with which we candetermine stellar ages and masses. We will construct spectral energydistributions from the UV to the far-IR and use them to derive bolometricluminosities and SFRs, and constrain dust mass, dust temperature, and grainproperties. We will compare the dust properties with the stellar component ofthe galaxies, and analyze the GRBHs in the context of other high-z galaxypopulations. Such a program is now possible thanks to the unique ability ofHerschel to study dust emission in galaxies over a wide range of redshifts.Ultimately our proposed study of GRBHs will open a new window on the study ofgalaxy formation and evolution. |
