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首页> 外文期刊>The Astrophysical journal >MODELING THE DISTRIBUTION OF Mg II ABSORBERS AROUND GALAXIES USING BACKGROUND GALAXIES AND QUASARS
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MODELING THE DISTRIBUTION OF Mg II ABSORBERS AROUND GALAXIES USING BACKGROUND GALAXIES AND QUASARS

机译:利用背景星系和类星体模拟星系周围Mg II吸收剂的分布

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摘要

We present joint constraints on the distribution of Mg II absorption around high redshift galaxies obtained by combining two orthogonal probes, the integrated Mg II absorption seen in stacked background galaxy spectra and the distribution of parent galaxies of individual strong Mg II systems as seen in the spectra of background quasars. We present a suite of models that can be used to predict, for different two- and three-dimensional distributions, how the projected Mg II absorption will depend on a galaxy's apparent inclination, the impact parameter b and the azimuthal angle between the projected vector to the line of sight and the projected minor axis. In general, we find that variations in the absorption strength with azimuthal angles provide much stronger constraints on the intrinsic geometry of the Mg II absorption than the dependence on the inclination of the galaxies. In addition to the clear azimuthal dependence in the integrated Mg II absorption that we reported earlier in Bordoloi et?al., we show that strong equivalent width Mg II absorbers (Wr (2796) ≥ 0.3 ?) are also asymmetrically distributed in azimuth around their host galaxies: 72% of the absorbers in Kacprzak et?al., and 100% of the close-in absorbers within 35?kpc of the center of their host galaxies, are located within 50° of the host galaxy's projected semi minor axis. It is shown that either composite models consisting of a simple bipolar component plus a spherical or disk component, or a single highly softened bipolar distribution, can well represent the azimuthal dependencies observed in both the stacked spectrum and quasar absorption-line data sets within 40?kpc. Simultaneously fitting both data sets, we find that in the composite model the bipolar cone has an opening angle of ~100° (i.e., confined to within 50° of the disk axis) and contains about two-thirds of the total Mg II absorption in the system. The single softened cone model has an exponential fall off with azimuthal angle with an exponential scale length in opening angle of about 45°. We conclude that the distribution of Mg II gas at low impact parameters is not the same as that found at high impact parameters. At larger impact parameters beyond 40?kpc, there is evidence for a much more symmetric distribution, significantly different from that closer in to the galaxies.
机译:我们提出了结合两个正交探针获得的高红移星系周围Mg II吸收分布的联合约束条件,在堆叠背景星系光谱中看到的积分Mg II吸收以及在光谱中看到的各个强Mg II系统的母星系的分布类星体的集合。我们提供了一套模型,可用于预测不同的二维和三维分布,预计的Mg II吸收量将如何取决于星系的视倾角,撞击参数b以及投影向量与目标之间的方位角。视线和投影的短轴。通常,我们发现,吸收强度随方位角的变化对Mg II吸收的本征几何的约束比对星系倾斜的依赖性强得多。除了我们早些时候在Bordoloi等人报道的对Mg II吸收的明显的方位角依赖性外,我们还显示出强大的等效宽度Mg II吸收剂(Wr(2796)≥0.3?)也围绕它们的方位不对称分布宿主星系:在Kacprzak等人中,有72%的吸收体以及距离其宿主星系中心35?kpc内的100%的近距离吸收体都位于宿主星系的投影半短轴的50°范围内。结果表明,由简单的双极分量加上球形或圆盘分量组成的复合模型,或者单个高度软化的双极分布,都可以很好地表示在40?范围内的叠加光谱和类星体吸收线数据集中观察到的方位角依赖性。 kpc。同时拟合这两个数据集,我们发现在复合模型中,双极锥的张开角约为100°(即,限制在圆盘轴的50°以内),并且包含三分之二的Mg II吸收总量。系统。单个软化的圆锥模型具有一个带有方位角的指数衰减,在打开角度约为45度时具有指数刻度长度。我们得出的结论是,低冲击参数下的Mg II气体分布与高冲击参数下的分布不同。有证据表明,在超过40kkpc的较大撞击参数下,有更对称的分布证据,这与更靠近银河系的分布明显不同。

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