CANDELS: THE PROGENITORS OF COMPACT QUIESCENT GALAXIES AT z ∼ 2
CANDELS: THE PROGENITORS OF COMPACT QUIESCENT GALAXIES AT z ∼ 2
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DOI：
10.1088/0004-637x/765/2/104
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发表时间：
2013-03-10
影响因子：
4.9
通讯作者：
Hsu, Li-Ting
中科院分区：
文献类型：
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作者：
Barro, Guillermo;Faber, S. M.;Hsu, Li-Ting
我们将高分辨率哈勃太空望远镜/WFC3图像与多波长光度测量相结合，跟踪宇宙组合近红外深河外遗产巡天两个视场中红移z = 1.4-3的大质量（M-* > 10(10)M（圆点））星系的结构和活动演化。我们探测到致密的恒星形成星系（cSFG），其数量密度、质量、大小和恒星形成率（SFR）使它们有资格成为 z = 1.5-3 处的致密、静止、大质量星系（cQG）的可能祖先。在 z 大于或等于 2 时，cSFG 的 SFR = 100-200M（圆点）yr(-1)，但它们的特定恒星形成速率（sSFR 类似于 10(-9)yr(-1)）通常是同一时期其他大质量 SFG 的一半，并且宿主 X 射线发光的活动星系核（AGN）为 30 倍（类似于30%）更频繁。这些特性表明，cSFG 是由富含气体的过程（合并或盘不稳定性）形成的，这些过程引发紧凑的星暴并为活动星系核提供能量，而活动星系核反过来又在动态时间尺度（大约 10（8）年）上淬灭了恒星的形成。 cSFG 在 z = 2-3 处连续形成，并逐渐淡化为 cQG，直至 z 类似于 1.5。在此纪元之后，cSFG 很少见，从而缩短了新 cQG 的形成。同时，直到 z = 1，现有的 cQG 继续扩大以匹配局部 QG 的大小，而气体较少的合并和其他长期机制则引导（较大的）SFG 作为后来到达红色序列的。总之，我们提出了 QG 形成的两种进化轨迹：早期（z 大于或类似于 2），快速猝灭的 cSFG 逐渐消失为 cQG，随后在静止阶段扩大的形成路径；以及晚到达（z 小于或类似于 2）路径，其中较大的 SFG 形成扩展的 QG，而不经过致密状态。
We combine high-resolution Hubble Space Telescope/WFC3 images with multi- wavelength photometry to track the evolution of structure and activity of massive (M-* > 10(10)M(circle dot)) galaxies at redshifts z = 1.4-3 in two fields of the Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey. We detect compact, star- forming galaxies (cSFGs) whose number densities, masses, sizes, and star formation rates (SFRs) qualify them as likely progenitors of compact, quiescent, massive galaxies (cQGs) at z = 1.5-3. At z greater than or similar to 2, cSFGs present SFR = 100-200M(circle dot) yr(-1), yet their specific star formation rates (sSFR similar to 10(-9) yr(-1)) are typically half that of other massive SFGs at the same epoch, and host X-ray luminous active galactic nuclei (AGNs) 30 times (similar to 30%) more frequently. These properties suggest that cSFGs are formed by gas- rich processes (mergers or disk- instabilities) that induce a compact starburst and feed an AGN, which, in turn, quench the star formation on dynamical timescales (few 10(8) yr). The cSFGs are continuously being formed at z = 2-3 and fade to cQGs down to z similar to 1.5. After this epoch, cSFGs are rare, thereby truncating the formation of new cQGs. Meanwhile, down to z = 1, existing cQGs continue to enlarge to match local QGs in size, while less-gas-rich mergers and other secular mechanisms shepherd (larger) SFGs as later arrivals to the red sequence. In summary, we propose two evolutionary tracks of QG formation: an early (z greater than or similar to 2), formation path of rapidly quenched cSFGs fading into cQGs that later enlarge within the quiescent phase, and a late-arrival (z less than or similar to 2) path in which larger SFGs form extended QGs without passing through a compact state.