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Description
We present nebular emission associated with 198 strong Mg II absorbers at 0.35<=z<=1.1 in the fibre spectra of quasars from the Sloan Digital Sky Survey. Measured [OII] luminosities (L_[OII]_) are typical of sub-L* galaxies with derived star formation rate (uncorrected for fibre losses and dust reddening) in the range of 0.5-20M_{sun}_/yr. Typically less than ~3 per cent of the MgII systems with rest equivalent width, W_2796_>=2{AA}, show L_[OII]_>=0.3L*_[OII]_. The detection rate is found to increase with increasing W_2796_ and z. No significant correlation is found between W_2796_ and L_[OII]_ even when we restrict the samples to narrow z ranges. A strong correlation is seen between L_[OII]_ and z. While this is expected from the luminosity evolution of galaxies, we show that finite fibre size plays a very crucial role in this correlation. The measured nebular line ratios (like [OIII]/[OII] and [OIII]/H {beta}) and their z evolution are consistent with those of galaxies detected in deep surveys. Based on the median stacked spectra, we infer the average metallicity (logZ~8.3), ionization parameter (logq~7.5) and stellar mass (log (M/M_{sun}_)~9.3). The MgII systems with nebular emission typically have W_2796_>=2{AA}, MgII doublet ratio close to 1 and W(FeII{lambda}2600)/W_2796_~0.5 as often seen in damped Ly {alpha} and 21-cm absorbers at these redshifts. This is the biggest reported sample of [OII] emission from MgII absorbers at low-impact parameters ideally suited for probing various feedback processes at play in z<=1 galaxies.
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