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arXiv 1806.07578astro-ph.GA
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NGC4993和其他短GRB宿主星系的线比和连续谱SED的模拟

Modelling line ratios and continuum SED of NGC4993 and other short GRB host galaxies

Marcella Contini

摘要:

我们提出了一个详细的光谱建模NGC 4993-GW 170817的宿主星系-和其他SGRB宿主星系。为了确定它们的物理条件和元素丰度,我们从文献中收集了光谱和光度数据。观察数据有时会丢失,这使我们无法完全约束模型。然而,对于大多数SGRB宿主,报告了[OIII]5007/Hb和[NII]6548/Ha线比率。用复合模型(光电离+激波)对NGC 4993的分析证实,活动星系核(很可能是LINER或LLAGN)是气体光电离源。激波速度和震前密度与活动星系核的窄线区相似。O/H和N/H具有太阳能值。对于样品的其他SGRB,我们发现O/H比接近太阳,而N/H在红移接近0.4时覆盖了更大的值范围。在NGC 4993中,一个老的恒星星族,其特征是黑体温度为Tbb= 4000 K,相对于韧致辐射的SED的相对贡献比大多数本地AGN和SB星系高出100倍以上。对于组成样品的其他SGRB,Tbb的范围在SGRB 100206 A的2000 K和SGRB 111117 A的8000 K之间。

英文摘要:

We present a detailed spectral modelling of NGC4993 -- the host galaxy of GW170817 -- and other SGRB host galaxies. In order to determine their physical conditions and the element abundances, we have gathered spectroscopic and photometric data from the literature. The observation data are sometimes missing preventing us from fully constraining the model. However, for most of the SGRB hosts the [OIII]5007/Hb and [NII]6548/Ha line ratios are reported. The analysis of NGC4993 by a composite model (photoionization+shock) confirms that an AGN, most probably a LINER or a LLAGN, is the gas photoionization source. Shock velocities and preshock densities are similar to those found in the narrow line region of AGN. O/H and N/H have solar values. For the other SGRB of the sample we have found that O/H ratios are nearly solar, while N/H cover a much larger range of values at redshifts close to 0.4. In NGC4993, the relative contribution to the SED of an old stellar population, characterized by a black body temperature of Tbb=4000K, with respect to Bremsstrahlung is higher by a factor >100 than in most of the local AGN and SB galaxies. For the other SGRB composing the sample, Tbb ranges between 2000K for SGRB100206A and 8000K for SGRB111117A.

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。

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