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arXiv 1005.4036astro-ph.HEastro-ph.CO
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千禧年模拟中长伽马射线暴的宿主星系

Host galaxies of long gamma-ray bursts in the Millennium Simulation

Nora E. Chisari, Patricia B. Tissera, Leonardo J. Pellizza

摘要:

在这项工作中,我们研究了长伽马射线暴(LGRB)的宿主星系的性质使用的星系目录构建的千禧年模拟。我们开发了一个LGRB合成模型的基础上的假设,这些事件起源于大质量恒星的生命结束后的Bracksar模型,包括对祖星的金属丰度的约束的可能性。设计了一个完整的可观测性管道,用于计算一个星系被观测识别为LGRB宿主的概率估计。这个新的工具使我们能够建立一个可观测的主机星系目录,这是需要重现当前的恒星质量分布的观察主机。这个可观测性管道预测,祖星的最小质量应该是~75太阳质量,以便能够重现BATSE观测。在我们的观测目录中的系统能够再现观测到的宿主星系的性质,即恒星质量,颜色,光度,恒星形成活动和金属丰度作为红移的函数。在z>2时,我们的模型预测可观测的宿主星系将与全球星系群非常相似。我们发现,在平均气体金属丰度低于0.6太阳质量的可观测宿主星系中,约有88%的恒星质量在10^8.5-10^10.3太阳质量之间,与观测结果非常吻合。有趣的是,在我们的模型中,可观测的宿主星系主要保持在这个质量范围内,而不管红移如何,因为较低的恒星质量系统被观测到的概率较低,而质量较大的系统则金属含量太高。可观测的宿主星系被预测优先居住在10^11-10^11.5太阳质量范围内的暗物质晕中,对红移的依赖性很弱。

英文摘要:

(abridged) In this work, we investigate the nature of the host galaxies of long Gamma-Ray bursts (LGRBs) using a galaxy catalogue constructed from the Millennium Simulation. We developed an LGRB synthetic model based on the hypothesis that these events originate at the end of the life of massive stars following the collapsar model, with the possibility of including a constraint on the metallicity of the progenitor star. A complete observability pipeline was designed to calculate a probability estimation for a galaxy to be observationally identified as a host for LGRBs detected by present observational facilities. This new tool allows us to build an observable host galaxy catalogue which is required to reproduce the current stellar mass distribution of observed hosts. This observability pipeline predicts that the minimum mass for the progenitor stars should be ~75 solar masses in order to be able to reproduce BATSE observations. Systems in our observable catalogue are able to reproduce the observed properties of host galaxies, namely stellar masses, colours, luminosity, star formation activity and metallicities as a function of redshift. At z>2, our model predicts that the observable host galaxies would be very similar to the global galaxy population. We found that ~88 per cent of the observable host galaxies with mean gas metallicity lower than 0.6 solar have stellar masses in the range 10^8.5-10^10.3 solar masses in excellent agreement with observations. Interestingly, in our model observable host galaxies remain mainly within this mass range regardless of redshift, since lower stellar mass systems would have a low probability of being observed while more massive ones would be too metal-rich. Observable host galaxies are predicted to preferentially inhabit dark matter haloes in the range 10^11-10^11.5 solar masses, with a weak dependence on redshift.

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