A comparative study of satellite galaxies in Milky Way-like galaxies from HSC, DECaLS, and SDSS
A comparative study of satellite galaxies in Milky Way-like galaxies from HSC, DECaLS, and SDSS
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DOI：
10.1093/mnras/staa3495
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发表时间：
2020-09
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通讯作者：
Wenting Wang;M. Takada;Xiangchong Li;S. Carlsten;Ting-Wen Lan;Jingjing Shi;H. Miyatake;S. More-S.-Mor
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作者：
Wenting Wang;M. Takada;Xiangchong Li;S. Carlsten;Ting-Wen Lan;Jingjing Shi;H. Miyatake;S. More-S.-Mor
我们对卫星星系的光度函数(LFS)进行了全面和统计的研究，计算了来自HSC、Decal和SDSS的光度星系和孤立中心星系(ICGS)周围的星系对，以及SDSS/DR7光谱样本中的星系对。不同调查的结果显示出很好的一致性。卫星LFS可以测量到$M_V\sim&10$，对于小到$8.5<；\log_{10}M_\ast/M_\odot<；9.2$和$9.2<；\log_{10}M_\ast/M_\odot<；9.9$，这意味着在LMC质量ICGS周围平均有3-8颗卫星具有$M_V<；-10$。卫星LFS的亮端截止值和卫星丰度对主星和伴星之间的星等差都很敏感，这表明星等差较大的星系平均拥有质量较小的暗物质晕。通过选择恒星质量与我们的MW相似的初级恒星，我们发现：i)ICGS的平均卫星LFS与其伴星有不同的星等差距，以及不同颜色或颜色组合的星系对的平均LFS都比MW卫星Lf更陡峭；ii)-15<；M_V<；-10美元的卫星比我们MW的卫星多；iii)ICGS周围平均有1.5到2.5颗卫星，M_V<；-16美元，与我们的MW一致。因此，微波及其卫星系统在我们的微波质量系统样本中是不典型的。因此，我们的MW不能很好地代表其他MW质量的星系。仅基于兆瓦卫星的强烈宇宙学意义有待于在银河系外发现更暗的卫星。有趣的是，在局地宇宙中，在40~MPC的范围内，中波卫星的低频是典型的中波质量系统，这可能意味着局地体积是一个低密度区域。
We conduct a comprehensive and statistical study of the luminosity functions (LFs) for satellite galaxies, by counting photometric galaxies from HSC, DECaLS and SDSS around isolated central galaxies (ICGs) and galaxy pairs from the SDSS/DR7 spectroscopic sample. Results of different surveys show very good agreement. The satellite LFs can be measured down to $M_V\sim-10$, and for central primary galaxies as small as $8.5<\log_{10}M_\ast/M_\odot<9.2$ and $9.2<\log_{10}M_\ast/M_\odot<9.9$, which implies there are on average 3--8 satellites with $M_V<-10$ around LMC-mass ICGs. The bright end cutoff of satellite LFs and the satellite abundance are both sensitive to the magnitude gap between the primary and its companions, indicating galaxy systems with larger magnitude gaps are on average hosted by less massive dark matter haloes. By selecting primaries with stellar mass similar to our MW, we discovered that i) the averaged satellite LFs of ICGs with different magnitude gaps to their companions and of galaxy pairs with different colour or colour combinations all show steeper slopes than the MW satellite LF; ii) there are more satellites with $-15<M_V<-10$ than those in our MW; iii) there are on average 1.5 to 2.5 satellites with $M_V<-16$ around ICGs, consistent with our MW. Thus the MW and its satellite system are atypical of our sample of MW-mass systems. In consequence, our MW is not a good representative of other MW-mass galaxies. Strong cosmological implications based on only MW satellites await additional discoveries of fainter satellites in extra-galactic systems. Interestingly, the MW satellite LF is typical among other MW-mass systems within 40~Mpc in the local Universe, perhaps implying the Local Volume is an under-dense region.