分类: 天文学 >> 天文学 提交时间: 2024-03-30
摘要: The atomic-to-molecular gas conversion is a critical step in the baryon cycle of galaxies, which sets the initial conditions for subsequent star formation and influences the multi-phase interstellar medium. We compiled a sample of 94 nearby galaxies with observations of multi-phase gas contents by utilizing public H I, CO, and optical IFU data from the MaNGA survey together with new FAST H I observations. In agreement with previous results, our sample shows that the global molecular-to-atomic gas ratio ($R_{\rm mol} \equiv$ log $M_{\rm H_2}/M_{\rm H\ I}$) is correlated with the global stellar mass surface density $\mu_*$ with a Kendall's $\tau$ coefficient of 0.25 and $p < 10^{-3}$, less tightly but still correlated with stellar mass and NUV$-$ r color, and not related to the specific star formation rate (sSFR). The cold gas distribution and kinematics inferred from the H I and CO global profile asymmetry and shape do not significantly rely on $R_{\rm mol}$. Thanks to the availability of kpc-scale observations of MaNGA, we decompose galaxies into H II, composite, and AGN-dominated regions by using the BPT diagrams. With increasing $R_{\rm mol}$, the fraction of H II regions within 1.5 effective radius decreases slightly; the density distribution in the spatially resolved BPT diagram also changes significantly, suggesting changes in metallicity and ionization states. Galaxies with high $R_{\rm mol}$ tend to have high oxygen abundance, both at one effective radius with a Kendall's $\tau$ coefficient of 0.37 ($p < 10^{-3}$) and their central regions. Among all parameters investigated here, the oxygen abundance at one effective radius has the strongest relation with global $R_{\rm mol}$, but the dependence of gas conversion on gas distribution and galaxy ionization states is weak.
分类: 信息科学与系统科学 >> 信息科学与系统科学基础学科 分类: 计算机科学 >> 计算机科学技术其他学科 分类: 工程与技术科学 >> 工程数学 提交时间: 2024-03-30
摘要: 什么是智能?是人工智能的核心问题之一,但是至今没有一个公认的定义。本文从智能与生命的关系视角提出:智能是生物体的基本能力和特征属性,是一种尽量用最小能量实现最大信息量,通过信息处理来适应环境、维持存在的能力。在此基础上,提出了智能是物质能量与信息之间的相互转换能力这一新观点,进一步提出了智能的测度计算方法、平均智能、综合智能等新概念,最后讨论了物质、能量与信息的定量转换关系,指出了智能的上界和能量转换为信息的下界,为便于实际应用,进一步给出一个无量纲的智能测度计算公式。为智能系统定量分析智能的高低给出了可行的计算方法。