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arXiv 1502.07965astro-ph.GA
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局部亮红外星系的恒星形成历史

Star-formation histories of local luminous infrared galaxies

Miguel Pereira-Santaella, Almudena Alonso-Herrero, Luis Colina, Daniel Miralles-Caballero, Pablo G. Pérez-González, Santiago Arribas, Enrica Bellocchi, Sara Caz… 展开作者

Miguel Pereira-Santaella, Almudena Alonso-Herrero, Luis Colina, Daniel Miralles-Caballero, Pablo G. Pérez-González, Santiago Arribas, Enrica Bellocchi, Sara Cazzoli, Tanio Díaz-Santos, Javier Piqueras López

摘要:

本文分析了29个红外光度在10^11 Lsun和10^11.8 Lsun之间的本星系和单个星系的从紫外到远红外和H $α$的积分光谱能量分布(SED)。我们结合了新的窄带H $α$ +[NII]和宽带g,r光学成像与北欧光学望远镜(NOT),档案GALEX,2 MASS,斯皮策和赫歇尔数据。SED(光度测量和积分H $α$通量)已与MAGPHYS代码的修改版本进行了拟合,该代码使用了紫外-近红外范围的恒星星族合成模型和红外辐射的热发射模型,并考虑了吸收和再发射辐射之间的能量平衡。从SED拟合,我们得出这些星系的恒星形成历史(SFH)。其中近一半的恒星形成率在最后几个Gyr期间似乎近似恒定。在另一半,目前的恒星形成率似乎比1 Gyr前增加了3-20倍。具有恒定SFH的天体往往比星暴质量更大,并且它们与主序星(M-S)星系的预期性质相容。同样,导出的SFH表明,我们所有的物体都是大约1 Gyr前的M-S星系,恒星质量在10^10.1到10^11.5 Msun之间。拟合出了平均消光系数(A_v=0.6-3 mag)和多环芳烃(PAH)光度与L(IR)比值(0.03-0.16)。我们将A_v与总IR和H $α$光度结合成一个图,该图可用于识别在过去1亿年中SFR快速变化(增加或减少)的天体。

英文摘要:

We present the analysis of the integrated spectral energy distribution (SED) from the ultraviolet (UV) to the far-infrared and H$α$ of a sample of 29 local systems and individual galaxies with infrared (IR) luminosities between 10^11 Lsun and 10^11.8 Lsun. We have combined new narrow-band H$α$+[NII] and broad-band g, r optical imaging taken with the Nordic Optical Telescope (NOT), with archival GALEX, 2MASS, Spitzer, and Herschel data. The SEDs (photometry and integrated H$α$ flux) have been fitted with a modified version of the MAGPHYS code using stellar population synthesis models for the UV-near-IR range and thermal emission models for the IR emission taking into account the energy balance between the absorbed and re-emitted radiation. From the SED fits we derive the star-formation histories (SFH) of these galaxies. For nearly half of them the star-formation rate appears to be approximately constant during the last few Gyrs. In the other half, the current star-formation rate seems to be enhanced by a factor of 3-20 with respect to that occured ~1 Gyr ago. Objects with constant SFH tend to be more massive than starbursts and they are compatible with the expected properties of a main-sequence (M-S) galaxy. Likewise, the derived SFHs show that all our objects were M-S galaxies ~1 Gyr ago with stellar masses between 10^10.1 and 10^11.5 Msun. We also derived from our fits the average extinction (A_v=0.6-3 mag) and the polycyclic aromatic hydrocarbons (PAH) luminosity to L(IR) ratio (0.03-0.16). We combined the A_v with the total IR and H$α$ luminosities into a diagram which can be used to identify objects with rapidly changing (increasing or decreasing) SFR during the last 100 Myr.

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