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arXiv 2001.02955astro-ph.GA
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2型LINER的光谱学

Optical spectroscopy of type-2 LINERs

L. Hermosa-Muñoz, S. Cazzoli, I. Márquez, J. Masegosa

摘要:

第二类低电离窄发射线区(LINER)已被光学分类与帕洛玛数据作为不存在广泛的组成部分,在巴耳末发射线与宽线区(BLR)的活动星系核(AGN)。我们揭示了存在不同的运动学成分的发射线在核区域的一个样本的本地(z $\leq$ 0.022)2型LINERS。我们专注于通过检测(或不检测)起源于BLR的广泛组分来分析其真实性质。此外,我们寻找可能存在的非旋转运动,如外流。我们已经应用了一个分解的核发射线使用光谱分析的9型2 LINER的中分辨率数据从哈勃太空望远镜(HST)档案检索的光谱。这项研究是用帕洛玛天文台双摄谱仪的档案光谱完成的。的发射线拟合揭示了一个广泛的组成部分的存在下,与BLR在6的9个星系的空间数据,和2的8个从地面光谱。在HST/STIS数据中测量的两个星系(NGC 4486和NGC 4594)的速度色散表明存在外流。结果表明,空间分辨率在BLR的检测中起着重要作用,因为它在地基数据中似乎被稀释了(即使在去除恒星贡献之后)。对于发射线诊断也是如此,因为污染物光有助于降低朝向标准BPT的星形形成区域的发射线比率。我们建议将NGC 4594重新分类为1型LINER,因为在空间和地面光谱中都可以看到BLR分量。我们发现NGC 4486的BLR分量的结果不明确。我们样本中的适度流出检测可能表明它们不像1型LINER那样频繁。

英文摘要:

Type-2 Low-ionization Narrow Emission-line Regions (LINERs) have been optically classified with the Palomar data as not presenting a broad component in the Balmer emission lines associated to the Broad Line Region (BLR) of the Active Galactic Nuclei (AGN). We unveil the presence of different kinematic components of emission lines in the nuclear region of a sample of local (z$\leq$0.022) type-2 LINERs. We focus on the analysis of their true nature by means of the detection (or not) of a broad component originated in the BLR. Additionally, we search for the possible presence of non-rotational motions such as outflows. We have applied a decomposition of the nuclear emission lines using a spectroscopic analysis of the optical spectra of 9 type-2 LINERs of intermediate-resolution data retrieved from the Hubble Space Telescope (HST) archive. The study is completed with archival spectra from the Double Spectrograph from the Palomar Observatory. The emission line fitting reveals the presence of a broad component associated to the BLR in 6 out of the 9 galaxies for the space-based data, and for 2 out of the 8 from the ground-based spectra. The velocity dispersion of two galaxies (NGC 4486 and NGC 4594) measured in HST/STIS data suggest the presence of outflows. The results indicate that the spatial resolution plays a major role in the detection of the BLR, as it appears diluted in the ground-based data (even after removing stellar contribution). This is also true for the emission line diagnostics, as the contaminant light contributes to lower emission line ratios towards the star-forming area of standard BPTs. We propose to reclassify NGC4594 as a type-1 LINER, since a BLR component is seen in both space- and ground-based spectra. We find ambiguous results for the BLR component of NGC 4486. The modest outflow detection in our sample may indicate that they are not as frequent as for type-1 LINERs.

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