A Search for Massive Galaxy Population in a Protocluster of LAEs at z = 2.39 near the Radio Galaxy 53W002
A Search for Massive Galaxy Population in a Protocluster of LAEs at z = 2.39 near the Radio Galaxy 53W002
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DOI：
10.3847/1538-4357/ac6257
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发表时间：
2021-09
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影响因子：
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通讯作者：
Naoki Yonekura;M. Kajisawa;Erika Hamaguchi;K. Mawatari;Toru Yamada
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作者：
Naoki Yonekura;M. Kajisawa;Erika Hamaguchi;K. Mawatari;Toru Yamada
利用Subaru望远镜上Suprime-Cam和MOIRCS的B、V、i′、J、H和Ks波段成像数据，在射电星系53 W 002附近z = 2.39的Lyα发射体（LAEs）的已知大尺度高密度结构中寻找大质量星系群。在70.2arcmin ~ 2的巡天范围内，通过对62个原星系团成员的JHK s波段颜色和光谱能量分布（SED）拟合分析（JHK s -selected galaxies），我们选择了62个原星系团成员候选者，并将SED拟合估计的物理性质与COSMOS场中的一个比较样本进行了比较。我们发现，在Ks 2或V-Ks> 4的53 W 002场中，JHK s -选择星系的数密度显著过量。特别是，在53 W 002场中Ks 2的JHK s选择星系的数密度是比较样本的9倍。大部分Ks为2的星系都是质量大于1011 M的大质量星系，它们的比星星形成率（sSFR）为10−11-10−10 yr−1，表明星星的形成尚未完全停止。我们还发现，在15-20 Mpc范围内，MS = 5 × 1010 M ~（-1）到1011 M ~（-1）的静止星系的密度过剩和sSFR 1011 M ~（-1）并不位于LAEs的密度峰值处，而是沿沿着与LAEs结构相似的方向广泛分布。另一方面，sSFR < 10−11 yr−1的静止星系明显避开了LAEs的结构。我们的研究结果表明，大质量星系也存在于这个原星系团中发现的LAEs的中等过密度和它们的星星形成活动依赖于在原星系团中的位置。
We searched for massive galaxy population in the known large-scale high-density structure of Lyα emitters (LAEs) at z = 2.39 near the radio galaxy 53W002 by using imaging data from B,V,i′,J,H,andKs bands taken with Suprime-Cam and MOIRCS on the Subaru telescope. We selected 62 protocluster member candidates by their JHK s -band colors and spectral energy distribution (SED) fitting analysis (JHK s -selected galaxies) in our survey field of 70.2arcmin2 and compared their physical properties estimated from the SED fitting with a comparison sample in the COSMOS field. We found significant number density excesses for the JHK s -selected galaxies in the 53W002 field at K s 2, or V − K s > 4. In particular, the number density of the JHK s -selected galaxies with K s 2 in the 53W002 field is nine times higher than the comparison sample. Most of those with K s 2 are massive galaxies with M s > 1011 M ⊙, and their specific star formation rates (sSFRs) of 10−11–10−10 yr−1 suggest that the star formation has not yet stopped completely. We also found a density excess of quiescent galaxies with M s = 5 × 1010 M ⊙ to 1011 M ⊙ and sSFR 1011 M ⊙ are not located at the density peaks of LAEs but widely distributed along a similar direction to the structure of LAEs over ∼15–20 comoving Mpc. On the other hand, the quiescent galaxies with sSFR < 10−11 yr−1 clearly avoid the structure of LAEs. Our results suggest that massive galaxies also exist in this protocluster discovered by the moderate overdensity of LAEs and their star formation activities depend on location in the protocluster.