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arXiv 1808.04279astro-ph.GA
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Herschel参考巡天中Galerkin的核谱与积分谱

Nuclear vs. Integrated Spectroscopy of Galaxies in the Herschel Reference Survey

G. Gavazzi, G. Consolandi, S. Belladitta, A. Boselli, M. Fossati

摘要:

上下文在本宇宙的一组完整星系中,确定活动星系核(AGN)相对于其它光谱类,如类HII区(HII)、过渡天体(TRAN)、被动星系核(PAS)和退休星系核(RET)的相对频率,对于鉴别星系核区的电离源具有重要意义。目标。在这里,我们的目标是提供一个光谱表征的星系核属于赫歇尔参考巡天(HRS),体积和幅度有限的样本代表当地的宇宙,这已成为一个基准的本地和高z的研究,半解析模型和宇宙学模拟。核光谱分类和全球星系尺度上确定的分类之间的比较提供了有关星系属性如何从核到外部区域变化的信息。此外,外推的全球恒星形成(SF)的性能相比,由H α光度学计算的SDSS光纤光谱可以是有用的测试方法的基础上确定的全球恒星形成率(SFR)的本地星系的孔径校正。方法.通过收集文献中已有的核谱学资料,并结合Loiano 1.52 m望远镜的新观测资料,分析了HRS星系的322个核谱。结果使用两个诊断图(BPT和WHAN),我们提供了HRS星系的核和综合光谱分类。结论.我们发现活动星系核所占的比例随着恒星质量的增加而增加,当logM > 10.0 M时,\odot或66%的LTG是活动星系核或TRAN。

英文摘要:

Context. The determination of the relative frequency of active galactic nuclei (AGN) versus other spectral classes, for example, HII region-like (HII), transition objects (TRAN), passive (PAS), and retired (RET), in a complete set of galaxies in the local Universe is of primary importance to discriminate the source of ionization in the nuclear region of galaxies. Aims. Here we aim to provide a spectroscopic characterization of the nuclei of galaxies belonging to the Herschel Reference Survey (HRS), a volume and magnitude limited sample representative of the local Universe, which has become a benchmark for local and high-z studies, for semianalytical models and cosmological simulations. The comparison between the nuclear spectral classification and the one determined on the global galactic scale provides information about how galaxy properties change from the nuclear to the outer regions. Moreover, the extrapolation of the global star formation (SF) properties from the SDSS fiber spectroscopy compared to the one computed by Halpha photometry can be useful for testing the method based on aperture correction for determining the global star formation rate (SFR) for local galaxies. Methods. By collecting the existing nuclear spectroscopy available from the literature, complemented with new observations obtained using the Loiano 1.52m telescope, we analyze the 322 nuclear spectra of HRS galaxies. Results. Using two diagnostic diagrams (the BPT and the WHAN) we provide a nuclear and an integrated spectral classification for the HRS galaxies. Conclusions. We find that the fraction of AGNs increases with stellar mass, such that at logM > 10.0 M\odot or 66% of the LTGs are AGNs or TRAN.

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