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arXiv 0710.4448astro-ph
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12μ mSeyfert星系的Spitzer-IRS高分辨光谱:I.首批成果

Spitzer-IRS high resolution spectroscopy of the 12μm Seyfert galaxies: I. First results

Silvia Tommasin, Luigi Spinoglio, Matthew A. Malkan, Howard Smith, Eduardo Gonzalez-Alfonso, Vassilis Charmandaris

摘要:

本文给出了12 μ m活动星系样品中29个(约四分之一)Seyfert星系的首次高分辨Spitzer IRS 9- 37 μ m光谱,并对它们进行了讨论。高分辨率光谱是通过相应的离源观测获得的。这允许出色的背景扣除,以便准确测量弱发射线的连续谱水平和强度。其结果是几个新的组合的发射线比,线/连续和连续/连续的比率,原来是有效的诊断AGN组件的强度在这些星系的红外发射。已知的谱线比[NeV]/[NeII]、[OIV]/[NeII],以及[NeIII]/[NeII]和[NeV]/[SiII]都可以有效地用来测量活动星系核的优势。我们扩展的分析,已经做了使用6.2um的PAH发射功能,11.25um的PAH功能,这也与活动星系核的优势反相关的等效宽度。我们测量到11.25 μ m的PAH特征与H_2S(1)有一个恒定的比值,约为10:1,与Seyfert类型无关。使用在约19 μ m处的两个光谱仪通道的精确通量测量的比率,具有相差4倍的孔径面积,我们测量了源扩展性,并将其与发射线和PAH特征等效宽度相关联。源的扩展性给出了活动星系核优势的另一种度量,并与[NeII]和PAH发射的EW相关。利用H $_2$的转动跃迁,我们能够估算出所观测星系中温暖分子成分的温度(200- 300 K)和质量(1-10 x 10^6 M_sun),或者说是它们的重要极限。

英文摘要:

The first high resolution Spitzer IRS 9-37um spectra of 29 Seyfert galaxies (about one quarter) of the 12um Active Galaxy Sample are presented and discussed. The high resolution spectroscopy was obtained with corresponding off-source observations. This allows excellent background subtraction, so that the continuum levels and strengths of weak emission lines are accurately measured. The result is several new combinations of emission line ratios, line/continuum and continuum/continuum ratios that turn out to be effective diagnostics of the strength of the AGN component in the IR emission of these galaxies. The line ratios [NeV]/[NeII], [OIV]/[NeII], already known, but also [NeIII]/[NeII] and [NeV]/[SiII] can all be effectively used to measure the dominance of the AGN. We extend the analysis, already done using the 6.2um PAH emission feature, to the equivalent width of the 11.25um PAH feature, which also anti-correlates with the dominance of the AGN. We measure that the 11.25um PAH feature has a constant ratio with the H_2 S(1) irrespective of Seyfert type, approximately 10 to 1. Using the ratio of accurate flux measurements at about 19um with the two spectrometer channels, having aperture areas differing by a factor 4, we measured the source extendness and correlated it with the emission line and PAH feature equivalent widths. The extendness of the source gives another measure of the AGN dominance and correlates both with the EWs of [NeII] and PAH emission. Using the rotational transitions of H$_2$ we were able to estimate temperatures (200-300K) and masses (1-10 x 10^6 M_sun), or significant limits on them, for the warm molecular component in the galaxies observed.

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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