THE FATE OF A RED NUGGET: IN SITU STAR FORMATION OF SATELLITES AROUND A MASSIVE COMPACT GALAXY
THE FATE OF A RED NUGGET: IN SITU STAR FORMATION OF SATELLITES AROUND A MASSIVE COMPACT GALAXY
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DOI：
10.3847/0004-637x/816/2/87
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发表时间：
2015-11
期刊：
影响因子：
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通讯作者：
T. Morishita;T. Ichikawa
中科院分区：
文献类型：
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作者：
T. Morishita;T. Ichikawa
为了研究局域大质量星系的吸积相，我们在一个大质量致密星系（M *<$3.9 × 10 10 M <$？>），光谱法证实（z spec = 1.9213？>）在eXtreme深场，这最初已在Szomoru等人报道。我们检测到1369卫星候选人的投影维里半径（r vir 300？> kpc）的紧凑星系在所有综合先进相机的调查图像，与5？> - 极限星等m ACS <$30.6？> ABmag相当于1.6 × 10 7 M？在红移。用12张多波段图像测量的光度红移确认了候选卫星中的34颗。大多数卫星被发现具有与恒星形成星系一致的静止坐标系颜色。我们研究了恒星质量和星星形成速率之间的关系（星星形成主序列），发现在低质量端（）有一个更陡的斜率，而更大质量的卫星则与以前研究报告的序列一致。在不确定性的星星形成和光度红移，我们推测可能的情况下，紧凑的星系演变成一个本地的大质量星系的方式显着的大小和质量的增长。虽然卫星中现有的恒星总质量的合并不足以解释观测和模拟预测的质量增长，但卫星中原位形成的星星的贡献可以弥补这一不足。假设大多数卫星保持观测到的原位星星形成，然后在它们吸积之前熄灭，例如，环境淬火，紧凑的星系将成为一个大质量的早期类型的星系符合当地的大小质量关系。
To study the accretion phase for local massive galaxies, we search accreting satellites around a massive compact galaxy ( M * ∼ 3.9 × 10 10 M ⊙ ?> ), spectroscopically confirmed ( z spec = 1.9213 ?> ) in the eXtreme Deep Field, which has been originally reported in Szomoru et al. We detect 1369 satellite candidates within the projected virial radius ( r vir ∼ 300 ?> kpc) of the compact galaxy in the all-combined Advanced Camera for Surveys image, with a 5 ?> -limiting magnitude of m ACS ∼ 30.6 ?> ABmag, which corresponds to ∼ 1.6 × 10 7 M ⊙ ?> at the redshift. The photometric redshift measured with 12 multi-band images confirms 34 satellites out of the candidates. Most of the satellites are found to have rest-frame colors consistent with star-forming galaxies. We investigate the relation between stellar mass and star formation rate (the star formation main sequence), and find a steeper slope at the low-mass end ( ), while more massive satellites are consistently on the sequence reported in previous studies. Within the uncertainties of star formation and photometric redshift, we conjecture possible scenarios for the compact galaxy which evolves to a local massive galaxy by way of significant size and mass growth. While the merging of the existing total stellar mass in the satellites is not enough to explain the mass growth predicted by observations and simulations, the contribution by in situ star formation in the satellites could compensate for the deficit. Provided that most satellites keep the observed in situ star formation and then quench before they accrete by, e.g., environmental quenching, the compact galaxy would become a massive early-type galaxy consistent with the local size–mass relation.