论文标题
通过恒星种群合成确定活性银河核中的星形形成率
Determining star-formation rates in Active Galactic Nuclei hosts via stellar population synthesis
论文作者
论文摘要
主动银河核（AGN）反馈对宿主星系的影响及其在淬火或增强恒星形成中的作用，由于通常基于年轻星星的光电量化的假设，无法用于主动的星系，因此无法使用AGN来源。因此，我们研究了从恒星种群中得出的SFR及其与源自气体的关系，用于170个AGN宿主的样本和291个星系的匹配对照样品。我们比较了通过HA发射线（SFRG）根据诊断图（诊断图）电离的区域获得的SFR密度值与从最后1至100〜MYR中从恒星种群合成（SFRSTARS）获得的区域进行了比较。我们发现，在过去的20〜MYR中的SFRSTARS紧密复制了SFRG，尽管通过转换获得了更好的匹配：LOG（SFRSTARS）=（0.870 +/- 0.004）log（SFRG）+（0.007 +/- 0.006），这对AGN主机和非活动都有效。我们还比较了通过气体HA/HB比获得的红色比与通过恒星种群合成中的完整光谱拟合得出的红色。我们发现，气体和恒星消光之间的比率在2.64 <a_vgas/a_vstar} <2.85范围内，与先前的文献结果近似一致，用于较小的样品。我们将差异解释为是由于恒星的变红由影响较不明显的老年人群的恒星发红，而气体的红色变红却更大，因为它与年轻的恒星种群相关，使其更深地埋在灰尘中。
The effect of active galactic nuclei (AGN) feedback on the host galaxy, and its role in quenching or enhancing star-formation, is still uncertain due to the fact that usual star-formation rate (SFR) indicators -- emission-line luminosities based on the assumption of photoionisation by young stars -- cannot be used for active galaxies as the ionising source is the AGN. We thus investigate the use of SFR derived from the stellar population and its relation with that derived from the gas for a sample of 170 AGN hosts and a matched control sample of 291 galaxies. We compare the values of SFR densities obtained via the Ha emission line (SFRg) for regions ionised by hot stars according to diagnostic diagrams with those obtained from stellar population synthesis (SFRstars) over the last 1 to 100~Myr. We find that the SFRstars over the last 20~Myrs closely reproduces the SFRg, although a better match is obtained via the transformation: log(SFRstars) = (0.870+/-0.004) log(SFRg) +(0.007+/-0.006), which is valid for both AGN hosts and non-active galaxies. We also compare the reddening obtained via the gas Ha/Hb ratio with that derived via the full spectral fitting in the stellar population synthesis. We find that the ratio between the gas and stellar extinction is in the range 2.64 < A_Vgas/A_Vstar} < 2.85, in approximate agreement with previous results from the literature, obtained for smaller samples. We interpret the difference as being due to the fact that the reddening of the stars is dominated by that affecting the less obscured underlying older population, while the reddening of the gas is larger as it is associated to a younger stellar population buried deeper in the dust.
