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arXiv 2402.15099astro-ph.GAastro-ph.CO
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理解恒星形成星系的射电光度函数及其宇宙学演化

Understanding the radio luminosity function of star-forming galaxies and its cosmological evolution

Charles Jose, Luke Chamandy, Anvar Shukurov, Kandaswamy Subramanian, Luiz Felippe S. Rodrigues, Carlton M. Baugh

AI总结:

本研究结合GALFORM半解析模型与磁场发电机模型,探究恒星形成星系RLF的红移演化,发现湍动速度与恒星形成率相关的模型能较好解释$0 \leq z \leq 2$的观测结果,小尺度磁场在高红移RLF中占主导。

摘要:

我们利用GALFORM(一种星系形成半解析模型)和星系内磁场演化的发电机模型,探究恒星形成星系的射电光度函数(RLF)的红移演化。假设磁场与宇宙射线之间能量均分,我们推导了每个样本星系的同步辐射光度。在湍动速度与恒星形成率相关的模型中,红移范围$0 \leq z \leq 2$内的RLF与观测结果吻合良好。在更高红移处,星系的结构、星际物质及湍动状态与$z\lesssim2$时差异显著,因此适用于低红移的湍动与磁场模型不再适用。$0 \leq z \leq 2$范围内RLF的强红移演化可归因于高红移处具有大星系盘体积和强磁场的星系数量增加。另一方面,在湍动速度为常数或是$z$的显函数的模型中,观测到的RLF红移演化无法被很好地重现。星际湍动与外流参数的演化是RLF变化的主要(但并非唯一)驱动因素。我们发现小尺度和大尺度磁场均对RLF有贡献,但小尺度磁场在高红移处占主导。因此,偏振观测对于区分这两种成分、更好地理解星系及其非热成分的演化至关重要。

英文摘要:

We explore the redshift evolution of the radio luminosity function (RLF) of star-forming galaxies using GALFORM, a semi-analytic model of galaxy formation and a dynamo model of the magnetic field evolving in a galaxy. Assuming energy equipartition between the magnetic field and cosmic rays, we derive the synchrotron luminosity of each sample galaxy. In a model where the turbulent speed is correlated with the star formation rate, the RLF is in fair agreement with observations in the redshift range $0 \leq z \leq 2$. At larger redshifts, the structure of galaxies, their interstellar matter and turbulence appear to be rather different from those at $z\lesssim2$, so that the turbulence and magnetic field models applicable at low redshifts become inadequate. The strong redshift evolution of the RLF at $0 \leq z \leq 2$ can be attributed to an increased number, at high redshift, of galaxies with large disc volumes and strong magnetic fields. On the other hand, in models where the turbulent speed is a constant or an explicit function of $z$, the observed redshift evolution of the RLF is poorly captured. The evolution of the interstellar turbulence and outflow parameters appear to be major (but not the only) drivers of the RLF changes. We find that both the small- and large-scale magnetic fields contribute to the RLF but the small-scale field dominates at high redshifts. Polarisation observations will therefore be important to distinguish these two components and understand better the evolution of galaxies and their nonthermal constituents.

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。

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