科研之友
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摘要
We present the results of near-infrared spectroscopic observations of the K-band-selected candidate galaxies in the protocluster at z = 3.09 in the SSA22 field. We observed 67 candidates with KAB < 24 and confirmed redshifts of the 39 galaxies at 2.0 < z(spec) < 3.4. Of the 67 candidates, 24 are certainly protocluster members with 3.04 <= z(spec) <= 3.12, which are massive red galaxies that have been unidentified in previous optical observations of the SSA22 protocluster. Many distant red galaxies (J -K-AB > 1.4), hyper extremely red objects (J -K-AB > 2.1), Spitzer MIPS 24 mu m sources, active galactic nuclei (AGNs) as well as the counterparts of Ly alpha blobs and the AzTEC/ASTE 1.1mm sources in the SSA22 field are also found to be protocluster members. The mass of the SSA22 protocluster is estimated to be similar to 2-5 x 10(14) M circle dot, and this system is plausibly a progenitor of the most massive clusters of galaxies in the current universe. The reddest (J -K-AB >= 2.4) protocluster galaxies are massive galaxies with M-star similar to 10(11) M circle dot showing quiescent star formation activities and plausibly dominated by old stellar populations. Most of these massive quiescent galaxies host moderately luminous AGNs detected by X-ray. There are no significant differences in the [O (III)]lambda 5007/H beta emission line ratios and [O (III)]lambda 5007 line widths and spatial extents of the protocluster galaxies from those of massive galaxies at z similar to 2-3 in the general field.
- 出版日期2015-1-20
- 单位中国科学院国家天文台
