arXiv 1706.085402017-06-26astro-ph.GA

M51云尺度ISM结构与恒星形成

Cloud Scale ISM Structure and Star Formation in M51

Adam K. Leroy, Eva Schinnerer, Annie Hughes, J. M. Diederik Kruijssen, Sharon Meidt, Andreas Schruba, Jiayi Sun, Frank Bigiel, Gonzalo Aniano, Guillermo A. Blan… 展开作者

Adam K. Leroy, Eva Schinnerer, Annie Hughes, J. M. Diederik Kruijssen, Sharon Meidt, Andreas Schruba, Jiayi Sun, Frank Bigiel, Gonzalo Aniano, Guillermo A. Blanc, Alberto Bolatto, Mélanie Chevance, Dario Colombo, Molly Gallagher, Santiago Garcia-Burillo, Carsten Kramer, Miguel Querejeta, Jerome Pety, Todd A. Thompson, Antonio Usero

备注：: Accepted for publication in the Astrophysical Journal, 22 pages, 11 figures, email for access to data table before publication, for high resolution version before publication: http://www.astronomy.ohio-state.edu/~leroy.42/m51_cloudsf.pdf
DOI：: 10.3847/1538-4357/aa7fef

阅读 PDF

arXiv 页面 ↗HTML 原文 ↗

摘要：

我们比较了$40$ pc分辨率的分子气体的结构和螺旋星系M51盘上气体形成恒星的能力。我们将PAWS测量分解为$370$ pc和$1.1$ kpc分辨率元素，并在每个元素内估计分子气体耗尽时间（$τ_{\rm Dep}^{\rm mol}$），单位自由落体时间的恒星形成效率（$ε_{\rm ff}$）和分子气体的质量加权云尺度（40 pc）性质：表面密度、$Σ$、线宽、$σ$和$b\equivΣ/σ^2\proptoα_{\rm vir}^{-1}$，这是一个跟踪气体有界性的参数。我们表明，云尺度表面密度似乎是一个合理的代理平均体积密度。应用这一点，我们发现一个典型的恒星形成效率每自由落体时间，$ε_{ff} \left( \left< Σ_{40pc} \right> \right) \sim 0.3{-}0.36\%$，低于许多模型中采用的，并发现当地的云。此外，每自由落体时间的效率与$Σ$和$σ$反相关，与湍流恒星形成模型有一定的张力。在我们的分析中，每单位气体质量恒星形成率的最佳预测因子是$b \equiv Σ/ σ^2$，它用$τ_{\rm Dep}^{\rm mol} \propto b^{-0.9}$追踪自引力的强度。相关性的意义在于，具有较强自引力（较高的$b$）的气体以较高的速率（较低的$τ_{\rm Dep}^{\rm mol}$）形成恒星。星系的不同区域在$τ_{\rm Dep}^{\rm mol}$中大部分重叠，作为$b$的函数，因此低$b$解释了Meidt等人（2013）在内旋臂发现的令人惊讶的高$τ_{\rm Dep}^{\rm mol}$。

英文摘要：

We compare the structure of molecular gas at $40$ pc resolution to the ability of gas to form stars across the disk of the spiral galaxy M51. We break the PAWS survey into $370$ pc and $1.1$ kpc resolution elements, and within each we estimate the molecular gas depletion time ($τ_{\rm Dep}^{\rm mol}$), the star formation efficiency per free fall time ($ε_{\rm ff}$), and the mass-weighted cloud-scale (40 pc) properties of the molecular gas: surface density, $Σ$, line width, $σ$, and $b\equivΣ/σ^2\proptoα_{\rm vir}^{-1}$, a parameter that traces the boundedness of the gas. We show that the cloud-scale surface density appears to be a reasonable proxy for mean volume density. Applying this, we find a typical star formation efficiency per free-fall time, $ε_{ff} \left( \left< Σ_{40pc} \right> \right) \sim 0.3{-}0.36\%$, lower than adopted in many models and found for local clouds. More, the efficiency per free fall time anti-correlates with both $Σ$ and $σ$, in some tension with turbulent star formation models. The best predictor of the rate of star formation per unit gas mass in our analysis is $b \equiv Σ/ σ^2$, tracing the strength of self gravity, with $τ_{\rm Dep}^{\rm mol} \propto b^{-0.9}$. The sense of the correlation is that gas with stronger self-gravity (higher $b$) forms stars at a higher rate (low $τ_{\rm Dep}^{\rm mol}$). The different regions of the galaxy mostly overlap in $τ_{\rm Dep}^{\rm mol}$ as a function of $b$, so that low $b$ explains the surprisingly high $τ_{\rm Dep}^{\rm mol}$ found towards the inner spiral arms found by by Meidt et al. (2013).

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。

摘要：

英文摘要：

相关论文