Star formation in the local environments of high-redshift ultraluminous infrared galaxies

We present ananalysis of the megaparsec scale environments of a sample of ultraluminous infrared galaxies(ULIRGs) at redshift 1.7, using far-infrared data from the Herschel Space Telescope. We compare their environments to those of a sample of fainter sources in the far-infrared which have comparable red shifts, in order to determine whether the environments of the ULIRGs host a net over density of star formation in comparison to that of galaxies in the field. An overdensity could indicate the presence of possible companions forming in the vicinity of the ULIRGs, which may imply that these objects reside in protocluster environments. We search for evidence for an excess of far-infrared flux on megaparsec scales around the ULIRGs compared to the field, where the excess is modelled by a power law. This excess flux is then converted to a star formation rate density in solar masses per year per cubic megaparsec. The presence of excess infrared flux around these objects is detected, indicating that there is an overdensity of star formation in their local environments which may be a rising from obscured objects in the vicinity.