Galaxy Zoo and SPARCFIRE: constraints on spiral arm formation mechanisms from spiral arm number and pitch angles
Galaxy Zoo and SPARCFIRE: constraints on spiral arm formation mechanisms from spiral arm number and pitch angles
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Galaxy Zoo和SPARCFIRE：从旋臂数量和螺距角度对旋臂形成机制的约束
DOI：
10.1093/mnras/stx2137
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发表时间：
2017
影响因子：
4.8
通讯作者：
R. Smethurst
中科院分区：
文献类型：
--
作者：
R. E. Hart;S. Bamford;W. Hayes;C. Cardamone;W. Keel;S. Kruk;C. Lintott;K. Masters;B. Simmons;R. Smethurst
本文研究了旋涡星系的形态特征，包括旋臂数和俯仰角的测量。利用星系动物园2，选择了6222个SDSS螺旋星系的恒星质量完整样本。我们使用机器视觉算法sparcfire来识别旋臂特征并测量其相关的几何形状。一个支持向量机分类器来识别可靠的螺旋特征，我们能够估计我们的样本的一半的螺距角。我们使用这些机器测量来校准手臂松紧度的视觉估计，从而估计整个样本的俯仰角。螺旋臂的属性进行比较，相对于各种星系的属性。星系的星星形成性质随臂数而显著变化，但与俯仰角无关。我们发现，拥有强棒的星系的旋臂比无棒星系的旋臂要松得多（4°-6°）。考虑到这一点，与多臂结构相关的旋臂比双臂星系中的旋臂要松（2°）。与此平均趋势相反，具有较大膨胀与总恒星质量比的星系显示出更少和更松散的旋臂。这种效应主要是由星系盘驱动的，因此具有更大质量盘的星系包含更多具有更紧密螺距角的螺旋臂。这意味着星系中心的质量集中并不是星系间螺距角和旋臂数变化的主要原因，这反过来又表明并非所有的旋臂都受经典密度波或模态理论的支配。
In this paper, we study the morphological properties of spiral galaxies, including measurements of spiral arm number and pitch angle. Using Galaxy Zoo 2, a stellar mass-complete sample of 6222 SDSS spiral galaxies is selected. We use the machine vision algorithm sparcfire to identify spiral arm features and measure their associated geometries. A support vector machine classifier is employed to identify reliable spiral features, with which we are able to estimate pitch angles for half of our sample. We use these machine measurements to calibrate visual estimates of arm tightness, and hence estimate pitch angles for our entire sample. The properties of spiral arms are compared with respect to various galaxy properties. The star formation properties of galaxies vary significantly with arm number, but not pitch angle. We find that galaxies hosting strong bars have spiral arms substantially (4°-6°) looser than unbarred galaxies. Accounting for this, spiral arms associated with many-armed structures are looser (by 2°) than those in two-armed galaxies. In contrast to this average trend, galaxies with greater bulge-to-total stellar mass ratios display both fewer and looser spiral arms. This effect is primarily driven by the galaxy disc, such that galaxies with more massive discs contain more spiral arms with tighter pitch angles. This implies that galaxy central mass concentration is not the dominant cause of pitch angle and arm number variations between galaxies, which in turn suggests that not all spiral arms are governed by classical density waves or modal theories.
影响因子：
4.9
作者：
Bundy, Kevin;Bershady, Matthew A.;Zhang, Kai
通讯作者：
Zhang, Kai