Dust and gas in star-forming galaxies at z 3. Extending galaxy uniformity to 11.5 billion years
Daddi, E.; Elbaz, D.; Dickinson, M.; Magdis, G. E.; Rigopoulou, D.; Toft, S.; Valentino, F.; Huang, J. -S.; Dannerbauer, H.; Sargent, M.; Feruglio, C.; Bethermin, M.; Gomez Guijarro, C.
Denmark, Greece, United Kingdom, France, Italy, Spain, United States, China, Chile
Abstract
We present millimetre dust emission measurements of two Lyman-break galaxies at z 3 and construct for the first time fully sampled infrared spectral energy distributions (SEDs), from mid-IR to the Rayleigh-Jeans tail, of individually detected, unlensed, UV-selected, main sequence (MS) galaxies at z = 3. The SED modelling of the two sources confirms previous findings, based on stacked ensembles, of an increasing mean radiation field ⟨ U ⟩ with redshift, consistent with a rapidly decreasing gas metallicity in z> 2 galaxies. Complementing our study with CO[J = 3 → 2] emission line observations, we have measured the molecular gas mass reservoir (MH2) of the systems using three independent approaches: 1) CO line observations; 2) the dust to gas mass ratio vs. metallicity relation; and 3) a single band, dust emission flux on the Rayleigh-Jeans side of the SED. All techniques return consistent MH2 estimates within a factor of two or less, yielding gas depletion time-scales (τdep ≈ 0.35 Gyr) and gas-to-stellar mass ratios (MH2/M∗ ≈ 0.5-1) for our z 3 massive MS galaxies. The overall properties of our galaxies are consistent with trends and relations established at lower redshifts, extending the apparent uniformity of star-forming galaxies over the last 11.5 billion years.
Herschel is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia and with important participation from NASA.