Detection of the 158 micron [CII] Transition at z=1.3: Evidence for a Galaxy-Wide Starburst
Abstract
We report the detection of 158 micron [CII] fine-structure line emission from MIPS J142824.0+352619, a hyperluminous (LIR ~ 1013 Lsun) starburst galaxy at z=1.3. The line is bright, and corresponds to a fraction L[CII]/LFIR = 2 x 10-3 of the far-IR (FIR) continuum. The [CII], CO, and FIR continuum emission may be modeled as arising from photodissociation regions (PDRs) that have a characteristic gas density of n ~ 104.2 cm-3, and that are illuminated by a far-UV radiation field ~103.2 times more intense than the local interstellar radiation field. The mass in these PDRs accounts for approximately half of the molecular gas mass in this galaxy. The L[CII]/LFIR ratio is higher than observed in local ULIRGs or in the few high-redshift QSOs detected in [CII], but the L[CII]/LFIR and LCO/LFIR ratios are similar to the values seen in nearby starburst galaxies. This suggests that MIPS J142824.0+352619 is a scaled-up version of a starburst nucleus, with the burst extended over several kiloparsecs.