FMOS near-IR spectroscopy of herschel-selected galaxies: Star formation rates, metallicity and dust attenuation at z ~ 1
Monthly Notices of the Royal Astronomical Society 426:3 (2012) 1782-1792
Authors:
IG Roseboom, A Bunker, M Sumiyoshi, L Wang, G Dalton, M Akiyama, J Bock, D Bonfield, V Buat, C Casey, E Chapin, DL Clements, A Conley, E Curtis-Lake, A Cooray, JS Dunlop, D Farrah, SJ Ham, E Ibar, F Iwamuro, M Kimura, I Lewis, E Macaulay, G Magdis, T Maihara, G Marsden, T Mauch, Y Moritani, K Ohta, SJ Oliver, MJ Page, B Schulz, D Scott, M Symeonidis, N Takato, N Tamura, T Totani, K Yabe, M Zemcov
Abstract:
We investigate the properties (e.g. star formation rate, dust attenuation, stellar mass and metallicity) of a sample of infrared (IR) luminous galaxies at z ~ 1 via near-IR spectroscopy with Subaru-FMOS. Our sample consists of Herschel SPIRE and Spitzer MIPS selected sources in the COSMOS field with photometric redshifts in the range of 0.7 < zphot < 1.8, which have been targeted in two pointings (0.5 deg2) with FMOS. We find a modest success rate for emission-line detections, with candidate Hα emission lines detected for 57 of 168 SPIRE sources (34 per cent). By stacking the near-IR spectra we directly measure the mean Balmer decrement for the Hα and Hβ lines, finding a value of 〈E(B - V)〉 = 0.51 ± 0.27 for 〈LIR〉 = 1012 L⊙ sources at 〈z〉 = 1.36. By comparing star formation rates estimated from the IR and from the dust-uncorrected Ha line we find a strong relationship between dust attenuation and star formation rate. This relation is broadly consistent with that previously seen in star-forming galaxies at z ~ 0.1. Finally, we investigate the metallicity via the N2 ratio, finding that z ~ 1 IR-selected sources are indistinguishable from the local mass-metallicity relation. We also find a strong correlation between dust attenuation and metallicity, with the most metal-rich IR sources experiencing the largest levels of dust attenuation. © 2012 The Authors, Monthly Notices of the Royal Astronomical Society.
