Abstract
We present a spectroscopic catalogue of 40 luminous starburst galaxies at z=0.7--1.7 (median z=1.3). 19 of these are submillimetre galaxies (SMGs) and 21 are submillimetre-faint radio galaxies (SFRGs). This sample helps to fill in the redshift desert at z=1.2--1.7 in previous studies as well as probing a lower luminosity population of galaxies. Radio fluxes are used to determine star-formation rates for our sample which range from around 50 to 500 M$_\odot$ yr$^{-1}$ and are generally lower than those in z$\sim$2 SMGs. We identify nebular [OII] 3727 emission in the rest-UV spectra and use the linewidths to show that SMGs and SFRGs in our sample have larger linewidths and therefore dynamical masses than optically selected star-forming galaxies at similar redshifts. The linewidths are indistinguishable from those measured in the z$\sim$2 SMG populations suggesting little evolution in the dynamical masses of the galaxies between redshift 1--2. [NeV] and [NeIII] emission lines are identified in a subset of the spectra indicating the presence of an active galactic nucleus (AGN). In addition, a host of interstellar absorption lines corresponding to transitions of MgII and FeII ions are also detected. These features show up prominently in composite spectra and we use these composites to demonstrate that the absorption lines are present at an average blueshift of $-240\pm$50 kms$^{-1}$ relative to the systemic velocities of the galaxies derived from [OII]. This indicates the presence of large-scale outflowing interstellar gas in these systems (Abridged)
Highlights
Submillimetre galaxies (SMGs) selected based on their 850-μm fluxes (Blain et al 1999; Chapman et al 2005; Coppin et al 2006; Weiß et al 2009) play an important role in the overall star formation history of the Universe
The sample of submillimetre galaxies (SMGs) and Sub-mm-faint radio galaxies (SFRGs) with secure redshifts that are analysed in this study has been summarized in Tables 2 and 3
It can clearly be seen that this spectroscopic sample of SMGs and SFRGs helps us to effectively fill in the redshift desert at z ∼ 1.5
Summary
Submillimetre (sub-mm) galaxies (SMGs) selected based on their 850-μm fluxes (Blain et al 1999; Chapman et al 2005; Coppin et al 2006; Weiß et al 2009) play an important role in the overall star formation history of the Universe. They are thought to be the highredshift counterparts of the most infrared luminous systems in the local Universe such as the luminous infrared galaxies (LIRGs) and ultraluminous infrared galaxies (ULIRGs) and progenitors of the. Radio observations of SFRGs indicate that they are very similar to SMGs in terms of radio morphology and size (Casey et al 2011) Together, these two populations have an SFR density at redshifts ∼1–3 that is roughly comparable to the rest-frame UV selected population. These galaxies represent a reasonably complete sample of infrared luminous galaxies at the main epoch of galaxy formation
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