最大的恒星形成星系。基于反馈驱动的Turbulence的星爆调节
Maximally Star-Forming Galactic Disks I. Starburst Regulation Via Feedback-Driven Turbulence
摘要：
盘状星系中心的恒星形成速率通常大大超过半径较大的星系。我们调查的想法，这些中央恒星爆发是自我调节，注入ISM的恒星形成平衡的引力约束气体的动量通量。对于大多数恒星爆发，超新星是最大的贡献者的动量通量，湍流提供了主要的压力支持的分子ISM。如果形成的每颗恒星质量的动量反馈为p_*/m_* ~ 3000 km/s，则在气体主导垂直重力的区域，预测的恒星形成速率为Sigma_SFR=2 pi G Sigma ^2 m_*/p_* ~0.1（Sigma/100 Msun/pc^2）^2 Msun/kpc^2/yr。我们将这一预测与模拟包含反馈的恒星形成的垂直分辨盘的数值模拟进行了比较，发现气体表面密度σ ~ 10^2-10^3 Msun/pc ^2的结果非常吻合。我们还比较了汇编的恒星形成率和气体含量从本地和高红移星系（合并和正常星系），找到良好的协议，提供的X_CO下降微弱的Sigma和Sigma_SFR增加。稠密湍流气体中的恒星形成率也与重力自由落体时间有关;如果每自由落体时间的效率为0.01，则反馈驱动的湍流速度色散为v_z = 0.4 × 10_ff p_*/m_* ~ 10 km/s，与Sigma或Sigma_SFR相对无关。湍流调节的星暴（由动力学动量反馈控制）是更大的自我调节计划的一部分;初级原子低西格玛外盘可能有恒星形成由紫外线加热反馈调节，而在极高西格玛的区域可能由辐射反馈调节，这些辐射被重新处理成捕获的IR。
英文摘要：
Star formation rates in the centers of disk galaxies often vastly exceed those at larger radii. We investigate the idea that these central starbursts are self-regulated, with the momentum flux injected to the ISM by star formation balancing the gravitational force confining the gas. For most starbursts, supernovae are the largest contributor to the momentum flux, and turbulence provides the main pressure support for the predominantly-molecular ISM. If the momentum feedback per stellar mass formed is p_*/m_* ~ 3000 km/s, the predicted star formation rate is Sigma_SFR=2 pi G Sigma^2 m_*/p_* ~0.1(Sigma/100Msun/pc^2)^2 Msun/kpc^2/yr in regions where gas dominates the vertical gravity. We compare this prediction with numerical simulations of vertically-resolved disks that model star formation including feedback, finding good agreement for gas surface densities Sigma ~ 10^2-10^3 Msun/pc^2. We also compare to a compilation of star formation rates and gas contents from local and high-redshift galaxies (both mergers and normal galaxies), finding good agreement provided that X_CO decreases weakly as Sigma and Sigma_SFR increase. Star formation rates in dense, turbulent gas are also expected to depend on the gravitational free-fall time; if the efficiency per free-fall time is epsilon_ff ~ 0.01, the turbulent velocity dispersion driven by feedback is expected to be v_z = 0.4 epsilon_ff p_*/m_* ~ 10 km/s, relatively independent of Sigma or Sigma_SFR. Turbulence-regulated starbursts (controlled by kinetic momentum feedback) are part of the larger scheme of self-regulation; primarily-atomic low-Sigma outer disks may have star formation regulated by UV heating feedback, whereas regions at extremely high Sigma may be regulated by feedback of radiation that is reprocessed into trapped IR.
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