A DEEP HUBBLE SPACE TELESCOPE SEARCH FOR ESCAPING LYMAN CONTINUUM FLUX AT z ∼ 1.3: EVIDENCE FOR AN EVOLVING IONIZING EMISSIVITY
A DEEP HUBBLE SPACE TELESCOPE SEARCH FOR ESCAPING LYMAN CONTINUUM FLUX AT z ∼ 1.3: EVIDENCE FOR AN EVOLVING IONIZING EMISSIVITY
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深哈勃太空望远镜在 z ≤ 1.3 处寻找逃逸莱曼连续通量：不断变化的电离发射率的证据
DOI：
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发表时间：
2010
期刊：
影响因子：
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通讯作者：
C. Scarlata
中科院分区：
文献类型：
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作者：
B. Siana;H. Teplitz;H. Ferguson;T. Brown;M. Giavalisco;M. Dickinson;R. Chary;D. D. de Mello;C. Conselice;C. Bridge;J. Gardner;J. Colbert;C. Scarlata
我们获得了15个星暴星系在GOODS场中z = 1.3的深哈勃空间望远镜远紫外图像，以寻找逃逸的莱曼连续谱（LyC）光子。这些是在如此大的面积（4.83 arcmin 2）上最深的远紫外图像（mAB = 28.7，3σ，1″直径），并为任何红移的任何星系提供了一些最好的逃逸分数约束。我们没有探测到任何单个的星系，3σ极限的LyC（1500 nm）通量比静止坐标系UV（1500 nm）连续统通量暗50-149倍（以fν计）。校正平均星系际介质（IGM）衰减（因子102），以及恒星内禀莱曼破裂（因子103），这些限制转化为相对逃逸分数限制fesc，rel < [0.03，0.21]。叠加极限为fesc，rel（3σ）< 0.02。我们使用蒙特卡罗模拟来正确地解释视线IGM不透明度的预期分布。当包括以前在z = 1.3的观测的限制时，我们发现，在95%的置信水平下，不超过8%的z = 1.3的恒星形成星系的相对逃逸分数大于0.50。或者，如果大多数星系的逃逸LyC很低，但不为零，那么逃逸分数不会超过0.04。根据莱曼破裂星系（LBG）在z = 3的紫外弱区域有强的LyC辐射的证据，我们还叠加了我们星系中具有不同表面亮度的子区域，在fesc，rel < 0.03水平上没有检测到明显的LyC通量。叠加极限和蒙特卡罗模拟的极限都表明，z = 1.3时的平均电离辐射率（相对于非电离紫外辐射率）明显低于z = 1.3时在LBG中观察到的。如果恒星形成星系的电离辐射率确实随着红移而增加，这将有助于解释IGM在z>4时的高光电离率和IGM在z>6时的再电离率。
We have obtained deep Hubble Space Telescope far-UV images of 15 starburst galaxies at z ∼ 1.3 in the GOODS fields to search for escaping Lyman continuum (LyC) photons. These are the deepest far-UV images (mAB = 28.7, 3σ, 1″ diameter) over this large an area (4.83 arcmin2) and provide some of the best escape fraction constraints for any galaxies at any redshift. We do not detect any individual galaxies, with 3σ limits to the LyC (∼700 Å) flux 50–149 times fainter (in fν) than the rest-frame UV (1500 Å) continuum fluxes. Correcting for the mean intergalactic medium (IGM) attenuation (factor ∼2), as well as an intrinsic stellar Lyman break (factor ∼3), these limits translate to relative escape fraction limits of fesc,rel < [0.03, 0.21]. The stacked limit is fesc,rel(3σ) < 0.02. We use a Monte Carlo simulation to properly account for the expected distribution of line-of-sight IGM opacities. When including constraints from previous surveys at z ∼ 1.3 we find that, at the 95% confidence level, no more than 8% of star-forming galaxies at z ∼ 1.3 can have relative escape fractions greater than 0.50. Alternatively, if the majority of galaxies have low, but non-zero, escaping LyC, the escape fraction cannot be more than 0.04. In light of some evidence for strong LyC emission from UV-faint regions of Lyman break galaxies (LBGs) at z ∼ 3, we also stack sub-regions of our galaxies with different surface brightnesses and detect no significant LyC flux at the fesc,rel < 0.03 level. Both the stacked limits and the limits from the Monte Carlo simulation suggest that the average ionizing emissivity (relative to non-ionizing UV emissivity) at z ∼ 1.3 is significantly lower than has been observed in LBGs at z ∼ 3. If the ionizing emissivity of star-forming galaxies is in fact increasing with redshift, it would help to explain the high photoionization rates seen in the IGM at z>4 and reionization of the IGM at z>6.
影响因子：
8.7
作者：
Komatsu, E.;Smith, K. M.;Wright, E. L.
通讯作者：
Wright, E. L.