arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 1903.09282astro-ph.GA
收藏

SDSS:邻近星系的内部密度斜率

SDSS--IV MaNGA : The Inner Density Slopes of nearby galaxies

Ran Li, Hongyu Li, Shi Shao, Shengdong Lu, Kai Zhu, Chunxiang Wang, Liang Gao, Shude Mao, Aaron A. Dutton, Junqiang Ge, Yunchong Wang, Alexie Leauthaud, Zheng Z… 展开作者

Ran Li, Hongyu Li, Shi Shao, Shengdong Lu, Kai Zhu, Chunxiang Wang, Liang Gao, Shude Mao, Aaron A. Dutton, Junqiang Ge, Yunchong Wang, Alexie Leauthaud, Zheng Zheng, Kevin Bundy, Joel R. Brownstein

摘要:

我们推导出质量加权总密度斜率内的有效(半光)半径,$γ'$,超过2000附近的星系从SDSS-IV的MANGA调查使用牛仔裤各向异性模型应用到IFU的意见。我们的星系跨越了恒星质量($10^9$ $M_{\rm \odot}< M_* < 10^{12}$ M $_{\odot}$)和速度色散(30 km/s $< σ_v <$ 300 km/s)的广泛范围。我们发现,对于速度色散为$σ_v>100$ km/s的星系,密度斜率有一个平均值$\langle γ^{\prime} \rangle = 2.24$和一个色散$σ_γ=0.22$,几乎与速度色散无关。在$σ\sim 100$ km/s处,$γ'-σ_v$关系出现明显的翻转,低于此值,密度斜率随$σ_v$迅速减小。我们的分析表明,大部分矮星系(低于$M_* = 10^{10}$ M $_{\odot}$)的总密度斜率小于1,这意味着他们可能居住在冷暗物质晕与浅密度斜率。我们比较了我们的结果与星系的流体动力学模拟的EAGLE,Illustris和IllustrisTNG项目,并发现所有的模拟预测浅的密度斜率的大质量星系与高$σ_v$。最后,我们探讨了$γ'$对星系晕中星系位置的依赖性,即中心星系与卫星星系,并发现对于相同的速度色散,$γ'$的振幅高出卫星星系约0.1。

英文摘要:

We derive the mass weighted total density slopes within the effective (half-light) radius, $γ'$, for more than 2000 nearby galaxies from the SDSS-IV MaNGA survey using Jeans-anisotropic-models applied to IFU observations. Our galaxies span a wide range of the stellar mass ($10^9$ $M_{\rm \odot}< M_* < 10^{12}$ M$_{\odot}$) and the velocity dispersion (30 km/s $< σ_v <$ 300 km/s). We find that for galaxies with velocity dispersion $σ_v>100$ km/s, the density slope has a mean value $\langle γ^{\prime} \rangle = 2.24$ and a dispersion $σ_γ=0.22$, almost independent of velocity dispersion. A clear turn over in the $γ'-σ_v$ relation is present at $σ\sim 100$ km/s, below which the density slope decreases rapidly with $σ_v$. Our analysis shows that a large fraction of dwarf galaxies (below $M_* = 10^{10}$ M$_{\odot}$) have total density slopes shallower than 1, which implies that they may reside in cold dark matter halos with shallow density slopes. We compare our results with that of galaxies in hydrodynamical simulations of EAGLE, Illustris and IllustrisTNG projects, and find all simulations predict shallower density slopes for massive galaxies with high $σ_v$. Finally, we explore the dependence of $γ'$ on the positions of galaxies in halos, namely centrals vs. satellites, and find that for the same velocity dispersion, the amplitude of $γ'$ is higher for satellite galaxies by about 0.1.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

↑