DETECTION OF THE 158 μm [C II] TRANSITION AT z = 1.3: EVIDENCE FOR A GALAXY-WIDE STARBURST (original) (raw)

We report the detection of 158 µm [CII] fine-structure line emission from MIPS J142824.0+352619, a hyperluminous (L IR ∼ 10 13 L ⊙) starburst galaxy at z = 1.3. The line is bright, and corresponds to a fraction L [CII] /L FIR ≈ 2 × 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 ∼ 10 4.2 cm −3 , and that are illuminated by a far-UV radiation field ∼10 3.2 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] /L FIR ratio is higher than observed in local ULIRGs or in the few high-redshift QSOs detected in [CII], but the L [CII] /L FIR and L CO /L FIR 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.