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arXiv 1301.0653astro-ph.CO
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恒星星族合成的星盘质光比分布:应用于NGC 5278(KPG 390 A)的旋转曲线分解

Disk Mass-to-Light ratio distribution from stellar population synthesis: Application to rotation curve decomposition of NGC 5278 (KPG 390A)

P. Repetto, Eric E. Martínez-García, M. Rosado, R. F. Gabbasov

摘要:

在这项工作中,我们扩展了对螺旋星系NGC 5278的质量分布的研究,进行一维和二维的膨胀盘分解,以确定哪些组件构成该星系中的重子质量。我们的分析没有发现任何隆起,相反,我们发现一个明亮的来源,可能与中央活动星系核,和一个指数盘。利用宽波段光度观测和星族合成模型,确定了星盘对自转曲线的贡献,得到了星盘的二维质量分布。在NGC 5278的特殊情况下,我们发现,典型的假设,认为质量-光度比(M/L)的磁盘作为常数沿银河中心半径是不成立的。我们还从质量分布中提取了一个重子RC,以确定这个重子RC以及具有或多或少30%盘质量的重子RC(为了考虑盘质量误差)无法拟合整个RC。考虑重子RC和四种类型的暗物质晕:Hernquist、Burkert、Einasto和Navarro,Frenk & White,对NGC 5278进行了RC分解.我们的研究结果表明,Hernquist晕模型更好地我们所观察到的RC在确定的磁盘质量($M_d=5.6\times 10^{10}$太阳质量)的情况下,也与30%的磁盘质量。在盘质量增加30%的情况下,核心Einasto(n < 4)晕是最佳拟合模型。

英文摘要:

In this work we extend the study on the mass distribution of the spiral galaxy NGC 5278, performing 1D and 2D bulge-disk decomposition to determine which components constitute the baryonic mass in this galaxy. Our analysis does not detect any bulge, instead we find a bright source, probably related with the central AGN, and an exponential disk. We fix the stellar disk contribution to the rotation curve (RC) with broad band photometric observations and population synthesis models, to obtain 2D mass distribution of the stellar disk. In the particular case of NGC 5278, we find that the typical assumption of considering the mass-to-luminosity ratio (M/L) of the disk as constant along the galactocentric radius is not valid. We also extract a baryonic RC from the mass profile, to determine the inability of this baryonic RC and also of the baryonic RC with more and less 30% disk mass (in order to consider the disk mass errors) to fit the entire RC. We perform the RC decomposition of NGC 5278 considering the baryonic RC and four types of dark matter halos: Hernquist; Burkert; Einasto and Navarro, Frenk & White. Our results show that Hernquist halo models better our observed RC in the case of determined disk mass ($M_d=5.6\times 10^{10}$ solar masses) and also with 30% less disk mass. In the case of 30% more disk mass the cored Einasto (n < 4) halo is the best fitting model.

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