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arXiv 1602.00737astro-ph.GA
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一个低红移高恒星形成率星系样本中的解析气体运动学

Resolved gas kinematics in a sample of low-redshift high star-formation rate galaxies

Mathew Varidel, Michael Pracy, Scott Croom, Matt Owers, Elaine Sadler

摘要:

我们使用附近六个(z~0.01-0.04)高恒星形成率(SFR~10-40太阳质量/年)星系样本的积分场光谱来研究亚银河系尺度上局部速度色散与恒星形成率之间的关系。低红移在一定程度上减轻了光束拖尾效应,该效应人为地使测量的色散膨胀,因为它将具有不同视线速度的区域组合成单个空间像素。我们比较的参数地图的速度色散与Halpha通量(代理本地恒星形成率),和速度梯度(代理的本地影响的光束涂抹)。我们发现,即使对于这些非常接近的星系,Halpha速度色散与速度梯度的相关性比与Halpha通量更强-这意味着光束拖尾仍然对速度色散测量有显着影响。我们得到了一个一阶非参数校正的未加权和通量加权平均速度色散通过拟合一个二维线性回归模型的spaxel-by-spectrometer的数据,其中的速度梯度和Halpha通量是独立的变量和速度色散是因变量,然后外推到零速度梯度。修正后的速度弥散分别比未修正的通量加权和未加权平均视线速度弥散值低1.3-4.5倍和1.3-2.7倍。这些修正大于先前引用的使用速度和速度色散场的圆盘模型来校正光束拖尾。修正后的通量加权速度频散值为sigma_m~20-50 km/s。

英文摘要:

We have used integral field spectroscopy of a sample of six nearby (z~0.01-0.04) high star-formation rate (SFR~10-40 solar masses per year) galaxies to investigate the relationship between local velocity dispersion and star formation rate on sub-galactic scales. The low redshift mitigates, to some extent, the effect of beam smearing which artificially inflates the measured dispersion as it combines regions with different line-of-sight velocities into a single spatial pixel. We compare the parametric maps of the velocity dispersion with the Halpha flux (a proxy for local star-formation rate), and the velocity gradient (a proxy for the local effect of beam smearing). We find, even for these very nearby galaxies, the Halpha velocity dispersion correlates more strongly with velocity gradient than with Halpha flux - implying that beam smearing is still having a significant effect on the velocity dispersion measurements. We obtain a first-order non parametric correction for the unweighted and flux weighted mean velocity dispersion by fitting a 2D linear regression model to the spaxel-by-spaxel data where the velocity gradient and the Halpha flux are the independent variables and the velocity dispersion is the dependent variable; and then extrapolating to zero velocity gradient. The corrected velocity dispersions are a factor of ~1.3-4.5 and ~1.3-2.7 lower than the uncorrected flux-weighted and unweighted mean line-of-sight velocity dispersion values, respectively. These corrections are larger than has been previously cited using disc models of the velocity and velocity dispersion field to correct for beam smearing. The corrected flux-weighted velocity dispersion values are sigma_m~20-50 km/s.

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