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arXiv 2201.11800astro-ph.GA
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低红移莱曼连续巡天。揭示低- $z$莱曼连续发光体的ISM特性

The Low-Redshift Lyman Continuum Survey. Unveiling the ISM properties of low-$z$ Lyman continuum emitters

Alberto Saldana-Lopez, Daniel Schaerer, John Chisholm, Sophia R. Flury, Anne E. Jaskot, Gábor Worseck, Kirill Makan, Simon Gazagnes, Valentin Mauerhofer, Anne V… 展开作者

Alberto Saldana-Lopez, Daniel Schaerer, John Chisholm, Sophia R. Flury, Anne E. Jaskot, Gábor Worseck, Kirill Makan, Simon Gazagnes, Valentin Mauerhofer, Anne Verhamme, Ricardo O. Amorín, Harry C. Ferguson, Mauro Giavalisco, Andrea Grazian, Matthew J. Hayes, Timothy M. Heckman, Alaina Henry, Zhiyuan Ji, Rui Marques-Chaves, Stephan R. McCandliss, M. S. Oey, Göran Östlin, Laura Pentericci, Trinh X. Thuan, Maxime Trebitsch, Eros Vanzella, Xinfeng Xu

摘要:

结合66个来自低红移莱曼连续巡天(LzLCS)的紫外(UV)光谱和辅助数据以及早期研究的23个LyC观测数据,我们在$z \sim 0.3$上形成了一个恒星形成星系的统计样本,以研究冷星际介质(ISM)气体在电离辐射泄漏中的作用。我们首先限制大质量恒星的内容(年龄和金属丰度)和紫外线衰减,通过拟合恒星连续与简单的恒星星族模型的组合。该模型,连同准确的LyC通量测量,允许确定每个星系($f_{\rm esc}^{\rm abs}$)的绝对LyC光子逃逸分数。我们测量了多个HI和低电离态(LIS)谱线的等效宽度和剩余通量,以及采用栅栏模型的几何覆盖率。$f_{\rm esc}^{\rm abs}$跨度很大,中位数(0.16,0.84分位数)为0.04(0.02,0.20),在LyC检测到的89个星系中有50个。HI和LIS谱线等效宽度与UV光度和衰减成比例,与谱线的剩余通量成反比。HI和LIS剩余通量的相关性,表明中性气体的LIS过渡空间跟踪。我们发现所观察到的吸收线和紫外衰减的趋势主要是由覆盖分数驱动的。不均匀的气体覆盖表明LyC光子通过ISM中的低柱密度通道逃逸。紫外线的等效宽度和剩余通量与$f_{\rm esc}^{\rm abs}$密切相关:强LyC泄漏显示弱吸收线、低紫外线衰减和大的Ly $α$等效宽度。我们最后表明,同时进行的紫外吸收线和尘埃衰减测量可以预测,平均而言,逃逸分数的星系和方法可以适用于星系在很宽的红移范围。

英文摘要:

Combining 66 ultraviolet (UV) spectra and ancillary data from the Low-Redshift Lyman Continuum Survey (LzLCS) and 23 LyC observations by earlier studies, we form a statistical sample of star-forming galaxies at $z \sim 0.3$ to study the role of the cold interstellar medium (ISM) gas in the leakage of ionizing radiation. We first constrain the massive star content (ages and metallicities) and UV attenuation, by fitting the stellar continuum with a combination of simple stellar population models. The models, together with accurate LyC flux measurements, allow to determine the absolute LyC photon escape fraction for each galaxy ($f_{\rm esc}^{\rm abs}$). We measure the equivalent widths and residual fluxes of multiple HI and low-ionization state (LIS) lines, and the geometrical covering fraction adopting the picket-fence model. The $f_{\rm esc}^{\rm abs}$ spans a wide range, with a median (0.16, 0.84 quantiles) of 0.04 (0.02, 0.20), and 50 out of the 89 galaxies detected in the LyC. The HI and LIS line equivalent widths scale with the UV luminosity and attenuation, and inversely with the residual flux of the lines. The HI and LIS residual fluxes are correlated, indicating that the neutral gas is spatially traced by the LIS transitions. We find the observed trends of the absorption lines and the UV attenuation are primarily driven by the covering fraction. The non-uniform gas coverage demonstrates that LyC photons escape through low-column density channels in the ISM. The equivalent widths and residual fluxes of the UV lines strongly correlate with $f_{\rm esc}^{\rm abs}$: strong LyC leakers show weak absorption lines, low UV attenuation, and large Ly$α$ equivalent widths. We finally show that simultaneous UV absorption line and dust attenuation measurements can predict, on average, the escape fraction of galaxies and the method can be applied to galaxies across a wide redshift range.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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