Suraphong Yuma, Masami Ouchi, Alyssa B. Drake, Chris Simpson, Kazuhiro Shimasaku, Kimihiko Nakajima, Yoshiaki Ono, Rieko Momose, Masao Mori, Masayuki Umemura
We present the first volume-limited search for extended metal-line [OII]{\lambda}{\lambda}3726,3729 nebulae, or [OII] blobs, at z=1.2 using deep narrowband imaging with a survey volume of 1.9x10^5 Mpc^3 on the 1 deg^2 sky of Subaru-XMM Deep Survey (SXDS) field. We discover a giant [OII] blob, dubbed '[OII] blob 1', with a spatial extent over ~75 kpc at a spectroscopic redshift of z=1.18, and also identify a total of thirteen [OII] blobs with a size of >30 kpc. Our optical spectrum of [OII] blob 1 presents [NeV]{\lambda}3426 line at the 6{\sigma} level, indicating that this object harbors an obscured type-2 AGN. The presence of gas outflows in this object is suggested by two marginal detections of FeII{\lambda}2587 absorption and FeII*{\lambda}2613 emission lines both of which are blueshifted at as large as 500-600 km/s. The [OII] luminosity of this object, 1.5x10^{43} erg/s, is significantly brighter than the values expected from deduced star formation rates. These results indicate that the heating source of [OII] blob 1 is not star formation, but AGN feedback and associated shock excitation. The number density of [OII] blob 1-type giant blobs is estimated to be ~5x10^{-6} Mpc^{-3} at z~1.2, which is comparable with that of outflowing AGNs at a similar redshift, suggesting that giant [OII] blobs are produced only by AGN activity. On the other hand, the number density of normal [OII] blobs, 6x10^{-5} Mpc^{-3}, compared to that of z~1 galaxies in the blue cloud in the same M_B range, may imply that 3% of star-forming galaxies at z~1 are quenching star formation through outflows involving extended [OII] emission.
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http://arxiv.org/abs/1306.5246
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