arXivDaily arXiv每日学术速递 周一至周五更新
arXiv周末暂无论文更新,休息一下吧,周末愉快~~
arXiv 1901.07556astro-ph.GA
收藏

恒星形成历史的随机模拟I:恒星形成主序星的散布

Stochastic modeling of star-formation histories I: the scatter of the star-forming main sequence

Neven Caplar, Sandro Tacchella

摘要:

我们提出了一个框架,作为一个随机过程的星系的恒星形成历史建模。我们定义这个随机过程,通过功率谱密度的功能形式的一个破碎的幂律。恒星形成历史在短时间尺度上是相关的,这种相关性的强度由幂律斜率$α$描述,并且它们在与功率谱密度$τ_{\rm break}$中的中断的时间尺度成比例的时间尺度上去相关以类似于白噪声。我们使用这个框架来探索随机过程的性质,我们假设,产生的对数正态分布的恒星形成率和恒星质量之间的关系,所谓的星系恒星形成的主要序列。具体而言,我们将展示如何测量的归一化和宽度($σ_{\rm MS}$)的主序列,在几个通带,探测不同的时间尺度,给出了约束的参数的基础功率谱密度。我们首先得到这些结果分析一个简化的情况下,我们通过平均在最近的恒星形成历史的观测模型。然后,我们运行数值模拟,以找到更现实的观测情况下的结果。作为一个概念的证明,我们使用观测估计的主要序列分散在$z\sim0$和$M_{\star}\approx10^{10}~M_{\odot}$测量H $α$,UV+IR和U波段,并显示这些点的组合,以$τ_{\rm break}=178^{+104}_{-66}$百万年,当假设$α=2$。这意味着星系的恒星形成历史失去了它们以前在$\sim200$ Myr时间尺度上活动的“记忆”,突出了作用于星系动力学时间尺度的重子效应的重要性。

英文摘要:

We present a framework for modelling the star-formation histories of galaxies as a stochastic process. We define this stochastic process through a power spectrum density with a functional form of a broken power-law. Star-formation histories are correlated on short timescales, the strength of this correlation described by a power-law slope, $α$, and they decorrelate to resemble white noise over a timescale that is proportional to the timescale of the break in the power spectrum density, $τ_{\rm break}$. We use this framework to explore the properties of the stochastic process that, we assume, gives rise to the log-normal scatter about the relationship between star-formation rate and stellar mass, the so-called galaxy star-forming main sequence. Specifically, we show how the measurements of the normalisation and width ($σ_{\rm MS}$) of the main sequence, measured in several passbands that probe different timescales, give a constraint on the parameters of the underlying power spectrum density. We first derive these results analytically for a simplified case where we model observations by averaging over the recent star-formation history. We then run numerical simulations to find results for more realistic observational cases. As a proof of concept, we use observational estimates of the main sequence scatter at $z\sim0$ and $M_{\star}\approx10^{10}~M_{\odot}$ measured in H$α$, UV+IR and the u-band, and show that combination of these point to $τ_{\rm break}=178^{+104}_{-66}$ Myr, when assuming $α=2$. This implies that star-formation histories of galaxies lose "memory" of their previous activity on a timescale of $\sim200$ Myr, highlighting the importance of baryonic effects that act over the dynamical timescales of galaxies.

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。

↑