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arXiv 1609.09649astro-ph.GA
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高红移发光亚毫米星系中千秒差距尺度的尘埃盘

Kiloparsec-scale dust disks in high-redshift luminous submillimeter galaxies

J. A. Hodge, A. M. Swinbank, J. M. Simpson, I. Smail, F. Walter, D. M. Alexander, F. Bertoldi, A. D. Biggs, W. N. Brandt, S. C. Chapman, C. C. Chen, K. E. K. Co… 展开作者

J. A. Hodge, A. M. Swinbank, J. M. Simpson, I. Smail, F. Walter, D. M. Alexander, F. Bertoldi, A. D. Biggs, W. N. Brandt, S. C. Chapman, C. C. Chen, K. E. K. Coppin, P. Cox, A. C. Edge, T. R. Greve, R. J. Ivison, A. Karim, K. K. Knudsen, K. M. Menten, H. -W. Rix, E. Schinnerer, J. L. Wardlow, A. Weiss, P. van der Werf

摘要:

利用870 μ m阿塔卡玛大型毫米/亚毫米阵列(ALMA)对16个发光(L_IR ~ 4 × 10^12 L_sun)亚毫米星系(SMG)进行了高分辨率(0.16 $"$)成像。这张尘埃影像在1.3千秒差距的尺度上追踪了这些z~2.5星系中被尘埃遮蔽的恒星形成过程。发射具有$R_e=0.24" \pm 0.02"$的中值有效半径,对应于$R_{e}=1.8\pm$ 0.2 kpc的典型物理尺寸。我们推导出一个中值Sérsic指数为$n=0.9\pm0.2$,这意味着在目前的分辨率和灵敏度下,尘埃排放是显着的盘状。我们使用不同的加权方案与vibrium搜索0.12 $"$(~1.0 kpc)尺度上的团块,但我们发现在大多数情况下,没有显着的证据成团。事实上,我们使用模拟表明,所观察到的形态一般是一致的平滑指数盘,这表明在确定候选团块时,即使是温和的S/N干涉数据应谨慎。我们将我们的地图与HST H $_{160}$波段的图像进行比较,发现恒星的形态出现了明显的扩展和干扰,并表明主要的合并可能是我们观察到的致密尘埃盘形成的原因。模糊和未模糊的形态之间的鲜明对比也可能对假设尘埃与光学/近红外连续辐射位于同一位置的SED拟合例程产生影响。最后,我们讨论了当前恒星形成爆发改变观测到的星系大小和光剖面的潜力,表明这些SMG的$z\sim0$后代的恒星质量、有效半径和气体表面密度与当地观测到的最紧凑的大质量(M_* ~ 1-2 x 10^11 M_sun)早型星系一致。

英文摘要:

We present high-resolution (0.16$"$) 870um Atacama Large Millimeter/submillimeter Array (ALMA) imaging of 16 luminous (L_IR ~ 4 x 10^12 L_sun) submillimeter galaxies (SMGs) from the ALESS survey of the Extended Chandra Deep Field South. This dust imaging traces the dust-obscured star formation in these z~2.5 galaxies on ~1.3 kpc scales. The emission has a median effective radius of $R_e=0.24" \pm 0.02"$, corresponding to a typical physical size of $R_{e}=1.8\pm$0.2 kpc. We derive a median Sérsic index of $n=0.9\pm0.2$, implying that the dust emission is remarkably disk-like at the current resolution and sensitivity. We use different weighting schemes with the visibilities to search for clumps on 0.12$"$ (~1.0 kpc) scales, but we find no significant evidence for clumping in the majority of cases. Indeed, we demonstrate using simulations that the observed morphologies are generally consistent with smooth exponential disks, suggesting that caution should be exercised when identifying candidate clumps in even moderate S/N interferometric data. We compare our maps to comparable-resolution HST H$_{160}$-band images, finding that the stellar morphologies appear significantly more extended and disturbed, and suggesting that major mergers may be responsible for driving the formation of the compact dust disks we observe. The stark contrast between the obscured and unobscured morphologies may also have implications for SED fitting routines that assume the dust is co-located with the optical/near-IR continuum emission. Finally, we discuss the potential of the current bursts of star formation to transform the observed galaxy sizes and light profiles, showing that the $z\sim0$ descendants of these SMGs are expected to have stellar masses, effective radii, and gas surface densities consistent with the most compact massive (M_* ~ 1-2 x 10^11 M_sun) early-type galaxies observed locally.

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