z>4亚毫米星系中的多环芳烃和中红外连续辐射
Polycyclic Aromatic Hydrocarbon and Mid-Infrared Continuum Emission in a z>4 Submillimeter Galaxy
摘要：
报道了用斯皮策空间望远镜上的红外光谱仪在z=4.055的亚毫米星系GN 20中探测到6.2um多环芳烃（PAH）和静止坐标系4- 7 um连续谱辐射。这表示在z>4时首次检测到PAH排放。多环芳烃发射特征的强度与~ 1600 Msun/yr的非常高的恒星形成率相一致。我们发现，这种强烈的恒星爆发的权力至少1/3的微弱的潜在的6微米连续辐射，与一个额外的，显着的（也许是占主导地位的）的贡献，由于幂律一样的热尘埃源，我们解释可能是一个微弱的，尘埃遮蔽的活动星系核（AGN）。如果以前未探测到的活动星系核是康普顿厚度的，则推断的6 μ m活动星系核连续发光度与钱德拉X射线天文台测量的硬X射线发射的敏感上限一致。这与在光学/红外波段发现的星系及其核心被严重的尘埃遮蔽是一致的。尽管强大的幂律分量增强中红外连续辐射，强烈的星爆与光子占主导地位的地区，引起PAH的排放似乎占主导地位的总能量输出在红外。GN 20是已知的所有红移中最明亮的星暴星系之一，嵌入在一个丰富的恒星形成星系的原星团中。这项调查提供了一个更好的了解能源的权力，这种特殊的系统，这代表了极端结束的大规模星系形成在早期宇宙的时间。
英文摘要：
We report the detection of 6.2um polycyclic aromatic hydrocarbon (PAH) and rest-frame 4-7um continuum emission in the z=4.055 submillimeter galaxy GN20, using the Infrared Spectrograph (IRS) on board the Spitzer Space Telescope. This represents the first detection of PAH emission at z>4. The strength of the PAH emission feature is consistent with a very high star formation rate of ~1600Msun/yr. We find that this intense starburst powers at least ~1/3 of the faint underlying 6um continuum emission, with an additional, significant (and perhaps dominant) contribution due to a power-law-like hot dust source, which we interpret to likely be a faint, dust-obscured active galactic nucleus (AGN). The inferred 6um AGN continuum luminosity is consistent with a sensitive upper limit on the hard X-ray emission as measured by the Chandra X-Ray Observatory if the previously undetected AGN is Compton-thick. This is in agreement with the finding at optical/infrared wavelengths that the galaxy and its nucleus are heavily dust-obscured. Despite the strong power-law component enhancing the mid-infrared continuum emission, the intense starburst associated with the photon-dominated regions that give rise to the PAH emission appears to dominate the total energy output in the infrared. GN20 is one of the most luminous starburst galaxies known at any redshift, embedded in a rich protocluster of star-forming galaxies. This investigation provides an improved understanding of the energy sources that power such exceptional systems, which represent the extreme end of massive galaxy formation at early cosmic times.
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。
