标题： 维持螺旋星系中的恒星形成率 - 用于THINGS星系的超新星驱动湍流吸积盘模型 显示英文标题

标题： Sustaining star formation rates in spiral galaxies - Supernova-driven turbulent accretion disk models applied to THINGS galaxies

摘要： 气体盘的螺旋星系可以描述为具有团块的吸积盘，而没有粘度与实际气体热状态的耦合。 由Vollmer & Beckert (2003)提出的包含出现和扩展团块的湍流盘模型包含自由参数，这些参数可以通过对个别星系的分子气体、原子气体和恒星形成率的观测来约束。 利用来自THINGS、HERACLES、SINGS和GALEX数据的18个邻近螺旋星系的径向分布，将观测到的恒星形成效率、分子分数和速度弥散与模型进行比较。 观测到的速度弥散径向减小可以通过模型再现。 在该模型框架下，内盘的减少是由于恒星质量分布主导了引力势。 在模型中引入恒星形成效率的径向断裂显著改善了拟合效果。 这种恒星形成制度的变化是通过将恒星形成率公式中的自由落体时间替换为分子形成时间尺度来实现的。 根据恒星形成公式，断裂半径位于星系盘中分子气体主导区和原子气体主导区之间的过渡区域附近，或更接近光学半径。 发现只有质量较小的星系（log (M (M_solar)) <~ 10）才能通过盘内的径向气体吸积来平衡恒星形成导致的气体损失。 因此，这些星系可以访问其具有大角动量的气体储层。 另一方面，大质量星系的恒星形成由从假想的电离气体球形晕或卫星吸积的外部气体质量吸积率决定。 显示英文摘要

摘要： Gas disks of spiral galaxies can be described as clumpy accretion disks without a coupling of viscosity to the actual thermal state of the gas. The model description of a turbulent disk consisting of emerging and spreading clumps (Vollmer & Beckert 2003) contains free parameters, which can be constrained by observations of molecular gas, atomic gas and the star formation rate for individual galaxies. Radial profiles of 18 nearby spiral galaxies from THINGS, HERACLES, SINGS, and GALEX data are used to compare the observed star formation efficiency, molecular fraction, and velocity dispersion to the model. The observed radially decreasing velocity dispersion can be reproduced by the model. In the framework of this model the decrease in the inner disk is due to the stellar mass distribution which dominates the gravitational potential. Introducing a radial break in the star formation efficiency into the model improves the fits significantly. This change in star formation regime is realized by replacing the free fall time in the prescription of the star formation rate with the molecule formation timescale. Depending on the star formation prescription, the break radius is located near the transition region between the molecular-gas-dominated and atomic-gas-dominated parts of the galactic disk or closer to the optical radius. It is found that only less massive galaxies (log (M (M_solar)) <~ 10) can balance gas loss via star formation by radial gas accretion within the disk. These galaxies can thus access their gas reservoirs with large angular momentum. On the other hand, the star formation of massive galaxies is determined by the external gas mass accretion rate from a putative spherical halo of ionized gas or from satellite accretion.