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arXiv 1401.8091astro-ph.GAastro-ph.CO
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恒星质量在10**8-10**10 Msol范围内星系中星暴周期的定量约束

Quantitative constraints on starburst cycles in galaxies with stellar masses in the range 10**8-10**10 Msol

Guinevere Kauffmann

摘要:

我们用4000个星散点和H $δ_A$指数,结合由发射线通量测量得到的SFR/M*,来约束恒星质量在10**8-10**10 Msol范围内的星系的近期恒星形成历史。爆发星系中的总SFR密度的分数是恒星质量的强函数,从10**8 Msol的恒星质量的0.85下降到M* = 10**10 Msol的星系的0.25。低质量星系并不都是年轻的。对于恒星质量小于10**9 Msol的星系,其半质量形成时间的分布范围很广,跨度为1-10 Gyr。恒星形成率在爆发星族范围内的峰谷变化范围为10-25。在低质量星系中,爆发的平均持续时间与星系的动力学时间相当。星系结构与估计的爆发质量分数相关,但在低质量和高质量星系中以不同的方式。具有大爆发质量分数的高质量星系更集中在中心,这表明凸起的形成正在起作用。在低质量星系中,恒星表面质量密度作为F_{burst}的函数而减小。这些结果与Teyssier等人(2013)的观测预测非常一致,并进一步证明了尖点晕问题可以通过星系生命周期中多次恒星爆发的能量输入来解决。我们注意到,没有令人信服的证据表明本地宇宙中恒星形成星系数量的IMF变化。

英文摘要:

We have used 4000 Å break and H$δ_A$ indices in combination with SFR/M* derived from emission line flux measurements, to constrain the recent star formation histories of galaxies with stellar masses in the range 10**8-10**10 Msol. The fraction of the total SFR density in galaxies with ongoing bursts is a strong function of stellar mass, declining from 0.85 at a stellar mass of 10**8 Msol to 0.25 for galaxies with M* = 10**10 Msol. Low mass galaxies are not all young. The distribution of half mass formation times for galaxies with stellar masses less than 10**9 Msol is broad, spanning the range 1-10 Gyr. The peak-to-trough variation in star formation rate among the bursting population ranges lies in the range 10-25. In low mass galaxies, the average duration of the burst is comparable to the dynamical time of the galaxy. Galaxy structure is correlated with estimated burst mass fraction, but in different ways in low and in high mass galaxies. High mass galaxies with large burst mass fractions are more centrally concentrated, indicating that bulge formation is at work. In low mass galaxies, stellar surface mass densities decrease as a function of F_{burst}. These results are in good agreement with the observational predictions of Teyssier et al (2013) and lend further credence to the idea that the cuspy halo problem can be solved by energy input from multiple starbursts over the lifetime of the galaxy. We note that there is no compelling evidence for IMF variations in the population of star-forming galaxies in the local Universe.

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