Constraints on the assembly and dynamics of galaxies. II. Properties of kiloparsec-scale clumps in rest-frame optical emission of z ~ 2 star-forming galaxies
N. M. Förster Schreiber, A. E. Shapley, R. Genzel, N. Bouché, G. Cresci, R. Davies, D. K. Erb, S. Genel, D. Lutz, S. Newman, K. L. Shapiro, C. C. Steidel, A. St… 展开作者
N. M. Förster Schreiber, A. E. Shapley, R. Genzel, N. Bouché, G. Cresci, R. Davies, D. K. Erb, S. Genel, D. Lutz, S. Newman, K. L. Shapiro, C. C. Steidel, A. Sternberg, L. J. Tacconi
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29 pages, 11 figures. Revised version accepted for publication in the Astrophysical Journal
We study the properties of luminous stellar clumps identified in deep, high resolution HST/NIC2 F160W imaging at 1.6um of six z~2 star-forming galaxies with existing near-IR integral field spectroscopy from SINFONI at the VLT. Individual clumps contribute ~0.5%-15% of the galaxy-integrated rest-frame ~5000A emission, with median of about 2%; the total contribution of clump light ranges from 10%-25%. The median intrinsic clump size and stellar mass are ~1kpc and log(Mstar[Msun])~9, in the ranges for clumps identified in rest-UV or line emission in other studies. The clump sizes and masses in the subset of disks are broadly consistent with expectations for clump formation via gravitational instabilities in gas-rich, turbulent disks given the host galaxies' global properties. By combining the NIC2 data with ACS/F814W imaging available for one source, and AO-assisted SINFONI Halpha data for another, we infer modest color, M/L, and stellar age variations within each galaxy. In these two objects, sets of clumps identified at different wavelengths do not fully overlap; NIC2-identified clumps tend to be redder/older than ACS- or Halpha-identified clumps without rest-frame optical counterparts. There is evidence for a systematic trend of older ages at smaller galactocentric radii among the clumps, consistent with scenarios where inward migration of clumps transports material towards the central regions. From constraints on a bulge-like component at radii <1-3kpc, none of the five disks in our sample appears to contain a compact massive stellar core, and we do not discern a trend of bulge stellar mass fraction with stellar age of the galaxy. Further observations are necessary to probe the build-up of stellar bulges and the role of clumps in this process.
Metal-enriched, sub-kiloparsec gas clumps in the circumgalactic medium of a faint z = 2.5 galaxy
本文报道了在一个明亮的类星体背景视线上偶然探测到一个红移为2.5、碰撞参数为50 kpc的0.2 L $^*$，Lyman-$α$发射星系。类星体的高解析度光谱显示出一个部分莱曼极限吸收系统（$N_\mathrm{HI}=10^{16.94\pm0.10}$ cm $^{-2}$），有许多与前景星系相同红移的相关金属吸收线。使用光电离模型，仔细对待测量误差和边缘化的电离辐射光谱的形状和归一化的不确定性，我们推导出的总氢柱密度$N_\mathrm{H}=10^{19.4\pm0.3}$厘米$^{-2}$，并表明，所有的吸收云金属富集，与$Z=0.1$ - $0.6 Z_\odot$。这些金属丰度和系统的大速度宽度（$436$ km $\,$ s $^{-1}$）表明气体是由外流风产生的。使用膨胀壳模型，我们估计质量流出率为$\sim5 M_\odot\,$年$^{-1}$。我们的光电离模型产生非常小的尺寸（$<$ 100-500 pc）的吸收云，我们认为这是典型的高柱密度吸收环星系介质（CGM）。考虑到这些小尺寸和极端的运动学，目前还不清楚这些团块如何在CGM中存活而不被流体动力学不稳定性破坏。小的云大小意味着，即使是最先进的宇宙学模拟需要超过$1000$倍的质量分辨率的改善，以解决相关的流体动力学冷气体在CGM。
Dynamical clock of the Helmi stream -- Analysis of the clumping of stars in the orbital frequency-space
National Astronomical Observatory of Japan（日本国立天文台）；The Graduate University for Advanced Studies, SOKENDAI（综合研究大学院大学（SOKENDAI））；The Institute of Statistical Mathematics（统计数学研究所）
Galaxy and Halo Root Systems: Fingerprints of Mass Assembly
Institute for Astronomy, University of Hawaiì at Mānoa（夏威夷大学马诺阿分校天文学研究所）；Blue Marble Space（蓝大理石空间）；UNAM, Universidad Nacional Autónoma de México, Instituto de Astronomía（墨西哥国立自治大学天文学研究所）
Evolution of the mass, size, and star formation rate in high-redshift merging galaxies MIRAGE - A new sample of simulations with detailed stellar feedback
LEGGOS I: The JWST LEGGOS Survey -- LEnsing and Galaxy Growth: Observing Substructures -- Unpacks the Nature of Clumpy Star Formation and Quenching in Gravitationally Lensed Galaxies beyond Cosmic Noon
University of Washington（华盛顿大学）；University of Pittsburgh（匹兹堡大学）；University of Arizona（亚利桑那大学）；Eureka Scientific（尤里卡科学公司）；University of Cincinnati（辛辛那提大学）；NASA Goddard Space Flight Center（美国国家航空航天局戈达德太空飞行中心）
Spatially resolved Halpha maps and sizes of 57 strongly star-forming galaxies at z~1 from 3D-HST: evidence for rapid inside-out assembly of disk galaxies
Spatially resolved metallicity and ionization in the merging system Gz9p3 at z=9.3
Stockholm University（斯德哥尔摩大学）；Centro de Astrobiología (CAB), CSIC-INTA（天体生物学中心（CAB），西班牙国家研究委员会-国家航空技术研究所）；Space Telescope Science Institute (STScI)（太空望远镜科学研究所）；University of Copenhagen（哥本哈根大学）；UK Astronomy Technology Centre, Royal Observatory Edinburgh（英国天文学技术中心，爱丁堡皇家天文台）
Complex gas kinematics in compact, rapidly assembling star-forming galaxies
我们已经获得了6个紧凑的、强烈的恒星形成星系的深、高分辨率光谱观测，它们的红移在z~0.1-0.3之间，其中大多数也被称为绿豆星系。值得注意的是，这些星系在光谱区域显示出复杂的发射线轮廓，包括Hα，[NII] $λλ6548, 6584$和[SII] $λλ6717, 6731$，由不同运动学分量在几kpc的空间范围上的叠加组成：一个非常宽的发射线下的一个以上的较窄的组件。对于至少两个观测到的星系，这些多个分量中的一些在它们的2D光谱中被空间分辨，而对于另一个星系，在距离星系约7 kpc的相同退行速度下检测到一个缺乏恒星连续体的微弱分离Hα斑点。单个较窄的Hα分量显示出高的内禀速度色散（σ~30-80 km s $^{-1}$），结合未锐化的遮蔽HST图像，表明恒星形成是在几个致密和湍流团块的集合中进行的，相对速度高达~500 km s $^{-1}$。在所有情况下，广泛的Hα成分表明大的膨胀速度（全宽零强度FWZI $\ge$ 1000 km s $^{-1}$）和非常高的光度（高达~10 $^{42}$ erg s $^{-1}$），可能显示出来自SNe的高能外流的印记。这些有趣的结果强调了绿豆对于研究远近低质量星系集合的重要性。
