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
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
复制标题
DOI：
10.1088/0004-637x/739/1/45
复制
发表时间：
2011-04
期刊：
影响因子：
--
通讯作者：
N. F. Schreiber;A. Shapley;R. Genzel;N. Bouché;G. Cresci;R. Davies;D. Erb;S. Genel;D. Lutz
中科院分区：
文献类型：
--
作者：
N. F. Schreiber;A. Shapley;R. Genzel;N. Bouché;G. Cresci;R. Davies;D. Erb;S. Genel;D. Lutz
利用超大望远镜SINFONI现有的近红外积分场光谱，研究了6个z-∼-2恒星形成星系在1.6μm深、高分辨率哈勃空间望远镜NIC2/F160W成像中发现的发光恒星“团”的性质。单个星团对∼的贡献为0.5%-15%，中位数为≈2%；星团光的总贡献范围为10%-25%。本征团大小和恒星质量的中位数是∼1kpc和∼109M☉，在其他研究中通过静止紫外或线发射确定的团块范围内。考虑到宿主星系的全球性质，盘子集中的团块大小和质量与通过富含气体的湍流盘中的引力不稳定而形成团团的预期大体一致。通过将NIC2的数据与先进的巡天相机/F814W成像相结合，我们可以推断出每个星系内适度的颜色、M/L和恒星年龄变化。在这两个物体中，在不同波长识别的集束并不完全重叠；NIC2识别的集束往往比AC或Hα识别的集束更红/更老，而没有静止帧光学对应物。有证据表明，有一种系统性的趋势，即群体中年龄较大的人以较小的半乳中心半径为中心，这与群体向内迁移将物质输送到中心区域的情景一致。从对半径≲1-3kpc处类凸起成分的限制来看，我们样本中的五个圆盘似乎都不包含致密的大质量恒星核，我们也没有发现凸起恒星质量分数随星系恒星年龄的变化趋势。有必要进行进一步的观测，以探索恒星凸起的形成和团块在这一过程中的作用。
We study the properties of luminous stellar “clumps” identified in deep, high-resolution Hubble Space Telescope NIC2/F160W imaging at 1.6 μm of six z ∼ 2 star-forming galaxies with existing near-infrared integral field spectroscopy from SINFONI at the Very Large Telescope. Individual clumps contribute ∼0.5%–15% of the galaxy-integrated rest-frame ≈5000 Å emission, with median of ≈2%; the total contribution of clump light ranges from 10% to 25%. The median intrinsic clump size and stellar mass are ∼1 kpc and ∼109 M☉, 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 through gravitational instabilities in gas-rich, turbulent disks given the host galaxies' global properties. By combining the NIC2 data with Advanced Camera for Surveys (ACS)/F814W imaging available for one source, and adaptive-optics-assisted SINFONI Hα 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 Hα-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 toward the central regions. From constraints on a bulge-like component at radii ≲ 1–3 kpc, 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 buildup of stellar bulges and the role of clumps in this process.