HII镓的近红外光谱图谱
A Spectral Atlas of HII Galaxies in the Near-Infrared
摘要：
最近的模型表明，TP-AGB星应占主导地位的近红外光谱的人口0.3至2 Gyr老，留下独特的签名，可用于检测年轻/中间恒星星族的星系。然而，在近红外光谱中没有恒星形成星系的同质数据库可以充分探索这些结果。考虑到这一点，我们研究了23个HII和星爆星系样本的近红外光谱，旨在表征这些物体在0.8-2.4微米区域内最突出的光谱特征和连续体形状。光谱指数推导出相关的吸收线/频带和文献中相同的样品的光学指数进行比较。我们发现光学和近红外指数之间没有相关性。这可能是由于这两组数据之间的孔径差异。这一结果进一步得到了子样本星系在近红外光谱中发射线的缺失或弱化的支持，而在光学光谱中，发射线是强而清晰的，这意味着这些星系中的许多电离源不是核，而是环核或位于热点。我们探测到的重要特征预测的恒星星族占主导地位的TP-AGB，如CN 1.1微米和CO 2.3微米。在至少一个星系（NGC 4102）中，首次探测到1.4微米的CN带。我们还检测到TiO和ZrO波段，以前从未报道过在河外来源。的连续发射的形状被发现是强烈相关的存在/缺乏的发射线。导出了一个恒星形成星系的观测模板，作为星暴星系中恒星星族的基准，用来比较不同类型星系，特别是活动星系核和高红移星系的近红外光谱。
英文摘要：
Recent models show that TP-AGB stars should dominate the NIR spectra of populations 0.3 to 2 Gyr old, leaving unique signatures that can be used to detect young/intermediate stellar population in galaxies. However, no homogeneous database of star-forming galaxies is available in the NIR to fully explore these results. With this in mind, we study the NIR spectra of a sample of 23 HII and starburst galaxies, aimed at characterizing the most prominent spectral features and continuum shape in the 0.8-2.4 micron region of these objects. Spectral indices are derived for the relevant absorption lines/bands and a comparison with optical indices of the same sample available in the literature is made. We found no correlation between the optical and the NIR indexes. This is probably due to the differences in aperture between these two sets of data. That result is further supported by the absence or weakness of emission lines in the NIR for a subsample galaxies, while in the optical the emission lines are strong and clear, which means that the ionisation source in many of these galaxies is not nuclear, but circumnuclear or located in hot spots. We detected important signatures predicted for a stellar population dominated by the TP-AGBs, like CN 1.1 micron and CO 2.3 micron. In at least one galaxy (NGC 4102) the CN band at 1.4 micron was detected for the first time. We also detect TiO and ZrO bands that have never been reported before in extragalactic sources. The shape of the continuum emission is found to be strongly correlated to the presence/lack of emission lines. An observational template for the star-forming galaxies is derived to be used as a benchmark of stellar population(s) in starburst galaxies against which to compare near-IR spectroscopy of different types of galaxies, especially those with AGN activity and/or those at high-redshift.
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