arXiv 2007.013102020-07astro-ph.GA

$z\sim6$恒星形成星系中Ly $α$空间偏移的大小和普遍性

The Size and Pervasiveness of Ly$α$-UV Spatial Offsets in Star-Forming Galaxies at $z\sim6$

B. C. Lemaux, S. Fuller, M. Bradač, L. Pentericci, A. Hoag, V. Strait, T. Treu, C. Alvarez, P. Bolan, P. J. Gandhi, T. Jones, C. Mason, D. Pelliccia, B. Ribeiro… 展开作者

B. C. Lemaux, S. Fuller, M. Bradač, L. Pentericci, A. Hoag, V. Strait, T. Treu, C. Alvarez, P. Bolan, P. J. Gandhi, T. Jones, C. Mason, D. Pelliccia, B. Ribeiro, R. E. Ryan, K. B. Schmidt, E. Vanzella, Y. Khusanova, O. Le Fèvre, L. Guaita, N. P. Hathi, A. Koekemoer, J. Pforr

备注：: 21 pages, 7 figures, 2 tables. Updated with the accepted MNRAS version that includes minor changes to the text and two tables
DOI：: 10.1093/mnras/stab924

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摘要：

我们研究了65透镜和无透镜星系的再电离时代（$5\leq z\leq7$），在这些红移的第一个这样的研究，紫外线连续光谱和LY $α$发射之间的投影空间偏移，以了解这些偏移的潜力混淆估计的LY $α$性能的星系中观察到的狭缝光谱。虽然我们发现，在我们的样本中，约40%的星系显示出显着的投影空间偏移（$|Δ_{Lyα-UV}|$），我们发现一个适度的平均偏移0.61 $\pm$ 0.08千秒差距。我们的样本的一小部分，约10%，表现出2-4 kpc的偏移量，尺寸大于这些红移的典型星系的有效半径。一个内部的比较和比较研究在较低的红移产生没有显着的证据的演变$|Δ_{Lyα-UV}|$与红移。在我们自己的样本中，紫外线明亮的星系显示出的偏移量比它们较暗的星系大三倍，分别为0.89 $\pm$ 0.18和0.27 $\pm$ 0.05千秒差距。我们认为，偏移量可能不是合并过程的结果，而是由于内部各向异性过程导致恒星的反馈促进Ly $α$荧光和/或从附近或流出的气体的后向散射。通过简单模拟的模拟观测，量化了由于各种观测设置的偏移效应而导致的Ly $α$通量的减少。结果发现，对于平均偏移量的星系，Ly $α$光子的损失，如果校正的话，除了最窄的狭缝宽度（<0.4“）之外，不是所有星系的限制因素。然而，对于最大的偏移量，如果这种偏移量大部分垂直于狭缝长轴，在狭缝宽度为$\leq$ 1“的情况下，狭缝损失被发现是非常严重的，例如詹姆斯韦伯太空望远镜/NIRSpec观测计划。（节略）

英文摘要：

We study the projected spatial offset between the ultraviolet continuum and Ly$α$ emission for 65 lensed and unlensed galaxies in the Epoch of Reionization ($5\leq z\leq7$), the first such study at these redshifts, in order to understand the potential for these offsets to confuse estimates of the Ly$α$ properties of galaxies observed in slit spectroscopy. While we find that ~40% of galaxies in our sample show significant projected spatial offsets ($|Δ_{Lyα-UV}|$), we find a modest average offset of 0.61$\pm$0.08 kpc. A small fraction of our sample, ~10%, exhibits offsets of 2-4 kpc, sizes that are larger than the effective radii of typical galaxies at these redshifts. An internal comparison and a comparison to studies at lower redshift yielded no significant evidence of evolution of $|Δ_{Lyα-UV}|$ with redshift. In our own sample, UV-bright galaxies showed offsets a factor of three greater than their fainter counterparts, 0.89$\pm$0.18 vs. 0.27$\pm$0.05 kpc, respectively. We argue that offsets are likely not the result of merging processes, but are rather due to internal anisotropic processes resulting from stellar feedback facilitates Ly$α$ fluorescence and/or backscattering from nearby or outflowing gas. The reduction in the Ly$α$ flux due to offset effects for various observational setups was quantified through mock observations of simple simulations. It was found that the loss of Ly$α$ photons for galaxies with average offsets is not, if corrected for, a limiting factor for all but the narrowest slit widths (<0.4''). However, for the largest offsets, if such offsets are mostly perpendicular to the slit major axis, slit losses were found to be extremely severe in cases where slit widths of $\leq$1'' were employed, such as those planned for James Webb Space Telescope/NIRSpec observations. (abridged)

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