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Date and Time of the Query: 2019-06-27 T06:17:52 PDT
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For refcode 2014ApJ...794..129H:
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2014ApJ...794..129H MOSFIRE and LDSS3 Spectroscopy for an [O II] Blob at z = 1.18: Gas Outflow and Energy Source Harikane, Yuichi; Ouchi, Masami; Yuma, Suraphong; Rauch, Michael; Nakajima, Kimihiko; Ono, Yoshiaki Abstract. We report our Keck/MOSFIRE and Magellan/Low-Dispersion Survey Spectrograph spectroscopy for an [O II] Blob, O II B 10, that is a high-z galaxy with spatially extended [O II] lambdalambda3726, 3729 emission over 30 kpc recently identified by a Subaru large-area narrowband survey. The systemic redshift of O II B 10 is z = 1.18 securely determined with [O III] lambdalambda4959, 5007 and Hbeta emission lines. We identify Fe II lambda2587 and Mg II lambdalambda2796, 2804 absorption lines blueshifted from the systemic redshift by 80 +/- 50 and 260 +/- 40 km s^--1^, respectively, which indicates gas outflow from O II B 10 with the velocity of ~80-260 km s^--1^. This outflow velocity is comparable with the escape velocity, 250 +/- 140 km s^--1^, estimated under the assumption of a singular isothermal halo potential profile. Some fraction of the outflowing gas could escape from the halo of O II B 10, suppressing O II B 10's star-formation (SF) activity. We estimate a mass loading factor, eta, that is a ratio of mass outflow rate to SF rate, and obtain eta > 0.8 +/- 0.1, which is relatively high compared with low-z starbursts including U/LIRGs and active galactic nuclei (AGNs). The major energy source of the outflow is unclear with the available data. Although no signature of AGNs is found in the X-ray data, O II B 10 falls in the AGN/star-forming composite region in the line diagnostic diagrams. It is possible that the outflow is powered by SF and a type-2 AGN with narrow FWHM emission line widths of 70-130 km s^--1^. This is the first detailed spectroscopic study of oxygen-line blobs that includes analyses of the escape velocity, the mass loading factor, and the presence of an AGN, and is a significant step to understanding the nature of oxygen-line blobs and the relation between gas outflow and SF quenching at high redshift. Key words: galaxies: evolution, galaxies: formation, galaxies: high-redshift
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