Physical conditions of the interstellar medium of high-redshift, strongly lensed submillimetre galaxies from the Herschel-ATLAS

摘要: We present Herschel-Spectral and Photometric Imaging Receiver (SPIRE) Fourier transform spectrometer (FTS) radio follow-up observations of two Herschel-Astrophysical Terahertz Large Area Survey (H-ATLAS)-detected strongly lensed distant galaxies. In one the targeted galaxies H-ATLAS J090311.6+003906 (SDP.81), we detect [O iii] 88 μm [C ii] 158 lines at a signal-to-noise ratio ∼5. do not have any positive line identification in other fainter target J091305.0−005343 (SDP.130). Currently, SDP.81 is faintest submillimetre galaxy with detections FTS, continuum flux just below 200 mJy 200–600 wavelength range. The derived redshift from z = 3.043 ± 0.012, agreement ground-based CO measurements. This first detection by Herschel higher than 0.05. Comparing observed ratios grid photodissociation region (PDR) models different physical conditions, derive PDR cloud density n ≈ 2000 cm−3 far-ultraviolet ionizing radiation field G0≈ (in units Habing – local Galactic interstellar 1.6 × 10−6 W m−2). Using CO-derived molecular mass properties, estimate effective radius emitting to be 500–700 pc. These characteristics are typical for star-forming, high-redshift indicate that deviates significantly far-infrared/radio (FIR/radio) correlation, which hints some fraction emission coming an active galactic nucleus (AGN). constraints on source size millimetre-wave put very conservative upper limit possible AGN contribution less 33 per cent. indications, together high iii]/FIR i] 63 μm/[C μm, suggest likely originate AGN.