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arXiv 1401.3791astro-ph.GAastro-ph.CO
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在z = 4.7时由ALMA检测到的两个Ly-alpha发射体的性质的约束

Constraining the Nature of Two Ly-alpha Emitters detected by ALMA at z = 4.7

R. J. Williams, J. Wagg, R. Maiolino, C. Foster, M. Aravena, T. Wiklind, C. L. Carilli, R. G. McMahon, D. Riechers, F. Walter

摘要:

我们报告了两个Ly-alpha发射体(LAEs)同伴的光学VLT FORS 2光谱的准恒星物体(QSO)-亚毫米星系(SMG)系统BRI 1202 -0725在z = 4.7,这是最近发现的[CII] 158 μ m线的阿塔卡马大型毫米/亚毫米阵列(ALMA)。我们从两个源检测到Ly-alpha发射,因此确认这些Ly-alpha发射体候选者与BRI 1202 - 0725系统物理相关。我们还报告没有检测到任何高电离发射线(NV,Si IV,C IV和He II),并发现这些系统可能不会被类星体光电离,从而使原位恒星形成成为这些LAE的主要动力源。我们还发现,这两个LAEs的Ly-alpha发射比[CII]发射更宽(1300 km/s),比大多数LAEs更宽。此外,两个LAE都具有大致对称的Ly-alpha轮廓,这意味着两个系统都位于类星体产生的HII球体内。这是第一次利用附近的Ly-alpha发射体探测类星体的邻近区。我们讨论了这些星系的观测特性的背景下,最近的星系形成模型。

英文摘要:

We report optical VLT FORS2 spectroscopy of the two Ly-alpha emitters (LAEs) companions to the quasi-stellar object (QSO) - sub-millimetre galaxy (SMG) system BRI1202-0725 at z = 4.7, which have recently been detected in the [CII]158um line by the Atacama Large Millimetre/Sub-millimetre Array (ALMA). We detect Ly-alpha emission from both sources and so confirm that these Ly-alpha emitter candidates are physically associated with the BRI1202- 0725 system. We also report the lack of detection of any high ionisation emission lines (N V, Si IV, C IV and He II) and find that these systems are likely not photoionised by the quasar, leaving in situ star formation as the main powering source of these LAEs. We also find that both LAEs have Ly-alpha emission much broader (1300 km/s) than the [CII] emission and broader than most LAEs. In addition, both LAEs have roughly symmetric Ly-alpha profiles implying that both systems are within the HII sphere produced by the quasar. This is the first time that the proximity zone of a quasar is probed by exploiting nearby Ly-alpha emitters. We discuss the observational properties of these galaxies in the context of recent galaxy formation models.

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