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arXiv 1802.02332astro-ph.GA
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致密恒星形成星系中的恒星形成率

Star-formation rate in compact star-forming galaxies

I. Y. Izotova, Y. I. Izotov

AI总结:

本研究利用多波段光度数据估算约14000个SDSS DR12暴发性致密恒星形成星系的终生平均恒星形成率,推导其与零龄星暴SFR的关联系数,对比常用SFR的差异并提出更适用的测定关系。

摘要:

我们利用Hβ发射线、远紫外(FUV)和中红外22微米连续谱光度数据,对从斯隆数字巡天(Sloan Digital Sky Survey, SDSS)第12次数据发布(Data Release 12, DR12)中选出的约14000个暴发性致密恒星形成星系(compact star-forming galaxies, CSFGs)样本,估算了在星系整个生命周期内平均的恒星形成率<SFR>。研究发现,将<SFR>与零星暴年龄下由Hβ光度推导的恒星形成率SFR_0相关联的平均系数为0.04。我们将<SFR>与一些常用的SFR进行了比较,后者是基于约1亿年(Myr)期间的连续恒星形成假设推导得出的,结果显示后者比<SFR>高2-3倍。研究表明,采用紫外和红外波段两个恒星形成指标的几何平均值推导、并归算到零星暴年龄的SFR之间的关系,与使用单一恒星形成指标的关系相比,离散度显著更低。我们认为,本文提出的<SFR>测定关系更适用于CSFGs,因为它们考虑了这类星系光度的正确时间演化。另一方面,我们也证明,常用的SFR关系可用于对暴发性致密星系生命周期内平均的<SFR>进行近似估算,误差在约2倍范围内。

英文摘要:

We use the data for the Hbeta emission-line, far-ultraviolet (FUV) and mid-infrared 22 micron continuum luminosities to estimate star formation rates <SFR> averaged over the galaxy lifetime for a sample of about 14000 bursting compact star-forming galaxies (CSFGs) selected from the Data Release 12 (DR12) of the Sloan Digital Sky Survey (SDSS). The average coefficient linking <SFR> and the star formation rate SFR_0 derived from the Hbeta luminosity at zero starburst age is found to be 0.04. We compare <SFR>s with some commonly used SFRs which are derived adopting a continuous star formation during a period of ~100 Myr, and find that the latter ones are 2-3 times higher. It is shown that the relations between SFRs derived using a geometric mean of two star-formation indicators in the UV and IR ranges and reduced to zero starburst age have considerably lower dispersion compared to those with single star-formation indicators. We suggest that our relations for <SFR> determination are more appropriate for CSFGs because they take into account a proper temporal evolution of their luminosities. On the other hand, we show that commonly used SFR relations can be applied for approximate estimation within a factor of ~2 of the <SFR> averaged over the lifetime of the bursting compact galaxy.

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