Composite Spectra of Emission-line Galaxies from eBOSS

Guangtun Zhu, the eBOSS collaboration

The eBOSS survey is obtaining spectra of about 200,000 emission line galaxies (ELGs) at redshifts z>0.6, providing a unique rich dataset of rest-frame near-UV spectroscopy for astrophysical applications. For target selection purposes, the ELG pilot survey observed about 12,000 ELGs, among which about 8,600 are at 0.6<z<1.2. Zhu et al. (2015) presented the composite spectra of these galaxies, and in particular, investigated the blueshifted resonant absorption lines (Fe II, Mg II) and non-resonant emission lines (Fe II*) in the NUV; these are the signatures of ubiquitous galactic-scale outflows associated with star formation activities. Because the composite spectra are of great interest to the community, here we make them publicly available as a value-added product.