THE LYMAN ALPHA MORPHOLOGY OF LOCAL STARBURST GALAXIES: RELEASE OF CALIBRATED IMAGES
THE LYMAN ALPHA MORPHOLOGY OF LOCAL STARBURST GALAXIES: RELEASE OF CALIBRATED IMAGES
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本地星暴星系的莱曼阿尔法形态：发布校准图像
DOI：
10.1088/0004-6256/138/3/923
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发表时间：
2008
期刊：
影响因子：
--
通讯作者：
H. Atek
中科院分区：
文献类型：
--
作者：
G. Östlin;M. Hayes;D. Kunth;J. Mas;C. Leitherer;A. Petrosian;H. Atek
我们展示了六个本地恒星形成星系样本的缩小和校准后的高分辨率莱曼阿尔法 (Lyα) 图像。选择目标来代表光度和金属度的范围，并包括已知的 Lyα 发射体和非发射体。远紫外成像是利用哈勃太空望远镜（HST）先进巡天相机的日盲通道在 F122M（Lyα 在线）和 F140LP（连续谱）滤光片中进行的。所得的 Lyα 图像是对恒星和星云连续体进行仔细建模的产物，通过支持 λ ≈ 2200、3300、4400、5500、Hα 和 8000 Å 的 HST 成像，结合 Starburst 99 进化合成模型以及连续体上的尘埃消光规定，促进了这一过程。总而言之，Lyα、Hα 和 UV 连续谱中所得的形态在质量上非常不同，我们表明大部分 Lyα 出现在共振散射事件产生的漫射成分中。根据积分 Hα 光度和重组理论计算得出的 Lyα 逃逸分数从未超过 14%。在每个像素中估计内部消光并用于校正 Lyα 通量。然而，消光校正太小（因子从 2.6 到无穷大），无法使新兴的全球 Lyα 光度与标准重组预测相一致。令人惊讶的是，当比较 Lyα 和 Hα 的全局等效宽度时，这两个量似乎是反相关的，这可能是由于星暴的机械反馈的演化所致。这需要在恒星形成率方面谨慎解释 Lyα 观测结果。所呈现的图像的物理分辨率比使用当前仪器在地面高红移下所能达到的物理分辨率高出3个数量级，因此我们的图像可以作为与原始星系形成的观测和建模进行比较的有用模板。因此，我们向社区提供简化的 Lyα、Hα 和连续体图像。
We present reduced and calibrated high resolution Lyman-alpha (Lyα) images for a sample of six local star-forming galaxies. Targets were selected to represent a range in luminosity and metallicity and to include both known Lyα emitters and nonemitters. Far ultraviolet imaging was carried out with the Solar Blind Channel of the Advanced Camera for Surveys on the Hubble Space Telescope (HST) in the F122M (Lyα online) and F140LP (continuum) filters. The resulting Lyα images are the product of careful modeling of both the stellar and nebular continua, facilitated by supporting HST imaging at λ ≈ 2200, 3300, 4400, 5500, Hα, and 8000 Å, combined with Starburst 99 evolutionary synthesis models, and prescriptions for dust extinction on the continuum. In all, the resulting morphologies in Lyα, Hα, and UV continuum are qualitatively very different and we show that the bulk of Lyα emerges in a diffuse component resulting from resonant scattering events. Lyα escape fractions, computed from integrated Hα luminosities and recombination theory, are found never to exceed 14%. Internal dust extinction is estimated in each pixel and used to correct Lyα fluxes. However, the extinction corrections are far too small (by factors from 2.6 to infinity) to reconcile the emerging global Lyα luminosities with standard recombination predictions. Surprisingly, when comparing the global equivalent widths of Lyα and Hα, the two quantities appear to be anticorrelated, which may be due to the evolution of mechanical feedback from the starburst. This calls for caution in the interpretation of Lyα observations in terms of star formation rates. The images presented have a physical resolution 3 orders of magnitude better than attainable at high redshifts from the ground with current instrumentation and our images may therefore serve as useful templates for comparing with observations and modeling of primeval galaxy formation. We therefore provide the reduced Lyα, Hα, and continuum images to the community.