$z\sim4$恒星形成受到抑制的大质量星系的静止坐标系光学尺寸
The rest-frame optical sizes of massive galaxies with suppressed star formation at $z\sim4$
摘要：
本文介绍了用Subaru望远镜上的红外照相摄谱仪和AO 188在$K'$ -波段测量的大质量静止星系（QG）在$z\sim4$的静止标架光学尺寸。基于斯巴鲁XMM-牛顿深巡天（SXDS）中的深多波长星表，覆盖了从$u$ -波段到IRAC $8.0μm$超过0.7度$^2$的宽波长范围，我们评估了光度红移以识别具有抑制恒星形成的大质量（$M_{\star}\sim10^{11}\ M_\odot$）星系。这些星系在$z\sim4$处显示出一个显著的4000 $\rm Å$破裂特征，暗示着一个演化的恒星群。然后，我们进行后续的$K'$波段成像与自适应光学的五个最亮的星系（$K_{AB,total}=22.5\sim23.4$）。与低红移的QG相比，$z\sim4$的QG具有更小的有效半径$r_{eff}=0.2$到$1.8$ kpc的物理尺寸。通过堆叠四个最亮的物体测量的平均大小是$r_{eff}=0.7\rm\ kpc$。这是在$z\sim4$上首次测量QG的静止帧光学尺寸。我们使用模拟评估我们的尺寸测量的鲁棒性，发现我们的尺寸估计是合理准确的，预期系统偏差为$\sim0.2$ kpc。如果我们考虑到恒星质量的演化，在$z\sim4$的大质量QG很可能演化成今天最大的星系。我们发现它们的大小随宇宙时间以$\log(r_e/{\rm kpc})= -0.44+1.77 \log(t/\rm Gyr)$的形式演化。它们的大小增长与恒星质量的平方成正比，表明小的干合并驱动了大小-恒星质量增长。
英文摘要：
We present the rest-frame optical sizes of massive quiescent galaxies (QGs) at $z\sim4$ measured at $K'$-band with the Infrared Camera and Spectrograph (IRCS) and AO188 on the Subaru telescope. Based on a deep multi-wavelength catalog in the Subaru XMM-Newton Deep Survey Field (SXDS), covering a wide wavelength range from the $u$-band to the IRAC $8.0μm$ over 0.7 deg$^2$, we evaluate photometric redshift to identify massive ($M_{\star}\sim10^{11}\ M_\odot$) galaxies with suppressed star formation. These galaxies show a prominent 4000$\rm Å$ break feature at $z\sim4$, suggestive of an evolved stellar population. We then conduct follow-up $K'$-band imaging with adaptive optics for the five brightest galaxies ($K_{AB,total}=22.5\sim23.4$). Compared to lower redshift ones, QGs at $z\sim4$ have smaller physical sizes of effective radii $r_{eff}=0.2$ to $1.8$ kpc. The mean size measured by stacking the four brightest objects is $r_{eff}=0.7\rm\ kpc$. This is the first measurement of the rest-frame optical sizes of QGs at $z\sim4$. We evaluate the robustness of our size measurements using simulations and find that our size estimates are reasonably accurate with an expected systematic bias of $\sim0.2$ kpc. If we account for the stellar mass evolution, massive QGs at $z\sim4$ are likely to evolve into the most massive galaxies today. We find their size evolution with cosmic time in a form of $\log(r_e/{\rm kpc})= -0.44+1.77 \log(t/\rm Gyr)$. Their size growth is proportional to the square of stellar mass, indicating the size-stellar mass growth driven by minor dry mergers.
机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。
