| 介紹 | We studied the large-scale distribution of the Lyman-Alpha Emitters at z=3.1 over the 1.4 deg^2 area at SSA22 field that involves one of the most conspicuous high-redshift "protocluster", or the high-density peak of star-forming galaxies known so far, at z=3.09.
Using Subaru Telescope, we have detected ~1500 emitters at z=3.1 including ~100 Lyman Alpha Blobs which are the extended Lyman Alpha emission halos. The "superstructre" of the emitters distributed over ~200 Mpc comoving scale contains the protocluster (density peak), its surrounding ~30Mpc-scale "belt-like" high density region whose significance is also very high (overdensity is 1.13±0.01, still ~10σ of the expected CDM fluctuation at such large scale), as well as the very under-dense “voids” of the emitters. We studied the distributions of the Ly Alpha luminosity, size, and equivalent width over the wide-range of density environment as well as the properties of the Ly Alpha Blobs in the field.
We have also obtained deep NIR image and spectra of the galaxies in the z=3.09 protocluster to study the properties of the massive galaxies and their activity. We have indeed detected the density peak of the K-band selected galaxies whose position coincides with the local peak of the LyAlpha emitters. Compared with the Coma cluster, ~30-40% of the stellar mass already formed in the protocluster. The massive galaxies are dominated by very red objects, little overlap with LBG and LyAlpha emitters, ~50% of them are quiescent (passively-evolving) spectra while many of the rest have very active and dusty star-formation activity. We're witnessing the formation of the cluster massive galaxies there.
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