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arXiv 1603.03432astro-ph.GA
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KMOS ^3D:早期恒星形成盘中质量收支的动力学约束

KMOS^3D: Dynamical constraints on the mass budget in early star-forming disks

S. Wuyts, N. M. Förster Schreiber, E. Wisnioski, R. Genzel, A. Burkert, K. Bandara, A. Beifiori, S. Belli, R. Bender, G. B. Brammer, J. Chan, R. Davies, M. Foss… 展开作者

S. Wuyts, N. M. Förster Schreiber, E. Wisnioski, R. Genzel, A. Burkert, K. Bandara, A. Beifiori, S. Belli, R. Bender, G. B. Brammer, J. Chan, R. Davies, M. Fossati, A. Galametz, S. K. Kulkarni, P. Lang, D. Lutz, J. T. Mendel, I. G. Momcheva, T. Naab, E. J. Nelson, R. P. Saglia, S. Seitz, L. J. Tacconi, K. Tadaki, H. Übler, P. G. van Dokkum, D. J. Wilman, E. Wuyts

摘要:

我们利用KMOS/VLT对240个恒星形成盘在0.6 < z < 2.6的深积分场光谱观测来动态地限制它们的质量预算。我们的样本由大质量($\gtrsim 10^{9.8} M_\odot$)星系组成,大小为$R_e \gtrsim 2$ kpc。通过对比观测到的速度和色散曲线的动力学模型,我们发现,平均而言,恒星的内容贡献$32^{+8}_{-7}\%$的总动力学质量,与星系之间的显着传播(第68百分位数范围f_star ~ 18 - 62%)。包括从CO和尘埃标度关系推断的分子气体,估计的重子质量加起来占我们样本中典型星系总质量的$56^{+17}_{-12}\%$,在z > 2时达到~ 90%。我们的结论是,重子构成了大部分的质量内的磁盘区域的高红移恒星形成的磁盘星系,与典型的磁盘在z > 2强烈重子占主导地位的$R_e$。在我们的样本中,在星系之间观察到恒星和重子质量分数的大量物体与物体之间的变化,大于它们各自测量中的形式不确定性所能解释的。在这两种情况下,质量分数与表面密度的测量最强相关。高$Σ_{star}$星系的特征是恒星质量分数更接近于1,并且具有高推断气体或重子表面密度的系统为恒星和分子气体以外的其他质量成分留下的空间更少。我们的发现可以被解释为更多的扩展磁盘进一步探测(更多的光盘探测更远)到它们所在的暗物质晕。

英文摘要:

We exploit deep integral-field spectroscopic observations with KMOS/VLT of 240 star-forming disks at 0.6 < z < 2.6 to dynamically constrain their mass budget. Our sample consists of massive ($\gtrsim 10^{9.8} M_\odot$) galaxies with sizes $R_e \gtrsim 2$ kpc. By contrasting the observed velocity and dispersion profiles to dynamical models, we find that on average the stellar content contributes $32^{+8}_{-7}\%$ of the total dynamical mass, with a significant spread among galaxies (68th percentile range f_star ~ 18 - 62%). Including molecular gas as inferred from CO- and dust-based scaling relations, the estimated baryonic mass adds up to $56^{+17}_{-12}\%$ of total for the typical galaxy in our sample, reaching ~ 90% at z > 2. We conclude that baryons make up most of the mass within the disk regions of high-redshift star-forming disk galaxies, with typical disks at z > 2 being strongly baryon-dominated within $R_e$. Substantial object-to-object variations in both stellar and baryonic mass fractions are observed among the galaxies in our sample, larger than what can be accounted for by the formal uncertainties in their respective measurements. In both cases, the mass fractions correlate most strongly with measures of surface density. High $Σ_{star}$ galaxies feature stellar mass fractions closer to unity, and systems with high inferred gas or baryonic surface densities leave less room for additional mass components other than stars and molecular gas. Our findings can be interpreted as more extended disks probing further (and more compact disks probing less far) into the dark matter halos that host them.

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