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arXiv 2408.00865astro-ph.GA
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狮子座中的卫星群？利用DELVE早期数据第三版发现银河系卫星星系狮子座VI

A Pride of Satellites in the Constellation Leo? Discovery of the Leo VI Milky Way Satellite Galaxy with DELVE Early Data Release 3

Kavli Institute for Cosmological Physics, University of Chicago（芝加哥大学卡弗里宇宙学物理研究所）；Department of Physics, University of Chicago（芝加哥大学物理系）；Department of Astronomy, Yale University（耶鲁大学天文学系）；Fermi National Accelerator Laboratory（费米国家加速器实验室）；Department of Astronomy and Astrophysics, University of Chicago（芝加哥大学天文与天体物理学系）；McWilliams Center for Cosmology & Astrophysics, Carnegie Mellon University（卡内基梅隆大学麦克威廉斯宇宙学与天体物理中心）
C. Y. Tan, W. Cerny, A. Drlica-Wagner, A. B. Pace, M. Geha, A. P. Ji, T. S. Li, M. Adamów, D. Anbajagane, C. R. Bom, J. A. Carballo-Bello, J. L. Carlin, C. Chan… 展开作者

C. Y. Tan, W. Cerny, A. Drlica-Wagner, A. B. Pace, M. Geha, A. P. Ji, T. S. Li, M. Adamów, D. Anbajagane, C. R. Bom, J. A. Carballo-Bello, J. L. Carlin, C. Chang, Y. Choi, M. L. M. Collins, A. Doliva-Dolinsky, P. S. Ferguson, R. A. Gruendl, D. J. James, G. Limberg, M. Navabi, D. Martínez-Delgado, C. E. Martínez-Vázquez, G. E. Medina, B. Mutlu-Pakdil, D. L. Nidever, N. E. D. Noël, A. H. Riley, J. D. Sakowska, D. J. Sand, J. Sharp, G. S. Stringfellow, C. Tolley, D. L. Tucker, A. K. Vivas

备注：
25 pages, 14 figures, 2 tables. This version has been accepted for publication in ApJ and also includes a typo correction in Figure 8
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AI总结：

利用DELVE EDR3数据发现并光谱确认超微弱矮星系狮子座VI，测量其性质并排除其属于陨石坑-狮子座内落群。

摘要：

我们报告了在狮子座中发现并光谱确认的一个超微弱银河系（MW）卫星星系。该系统是通过暗能量相机（DECam）数据中的已解析恒星空间超密度发现的，数据来自DECam本地体积巡天（DELVE EDR3）第三版早期数据。其低光度（$M_V = -3.56_{-0.37}^{+0.47}$；$L_V = 2300_{-700}^{+1200} L_\odot$）、大尺寸（$R_{1/2} = 90_{-30}^{+30}$ pc）和大日心距离（$D = 111_{-6}^{+9}$ kpc）均与超微弱矮星系（UFD）族群一致。利用凯克望远镜/DEIMOS对系统的观测，我们光谱确认了九颗成员星，同时测量了暂定的质光比$700_{-500}^{+1400} M_\odot/L_\odot$和非零金属丰度弥散$\sigma_{[\rm Fe/H]}=0.19_{-0.11}^{+0.14}$，进一步证实了狮子座VI作为UFD的身份。尽管该系统具有高度椭圆的形状，$\epsilon = 0.54_{-0.29}^{+0.19}$，我们未发现其正在潮汐瓦解的决定性证据。此外，尽管狮子座VI在天空上靠近所提出的陨石坑-狮子座内落群成员，但其较小的日心距离和在能量-角动量空间中的不一致位置使得狮子座VI不太可能属于所提出的内落群。

英文摘要：

We report the discovery and spectroscopic confirmation of an ultra-faint Milky Way (MW) satellite in the constellation of Leo. This system was discovered as a spatial overdensity of resolved stars observed with Dark Energy Camera (DECam) data from an early version of the third data release of the DECam Local Volume Exploration survey (DELVE EDR3). The low luminosity ($M_V = -3.56_{-0.37}^{+0.47}$ ; $L_V = 2300_{-700}^{+1200} L_\odot$), large size ($R_{1/2} = 90_{-30}^{+30}$ pc), and large heliocentric distance ($D = 111_{-6}^{+9}$ kpc) are all consistent with the population of ultra-faint dwarf galaxies (UFDs). Using Keck/DEIMOS observations of the system, we were able to spectroscopically confirm nine member stars, while measuring a tentative mass-to-light ratio of $700_{-500}^{+1400} M_\odot/L_\odot$ and a non-zero metallicity dispersion of $σ_{[\rm Fe/H]}=0.19_{-0.11}^{+0.14}$, further confirming Leo VI's identity as an UFD. While the system has a highly elliptical shape, $ε= 0.54_{-0.29}^{+0.19}$, we do not find any conclusive evidence that it is tidally disrupting. Moreover, despite the apparent on-sky proximity of Leo VI to members of the proposed Crater-Leo infall group, its smaller heliocentric distance and inconsistent position in energy-angular momentum space make it unlikely that Leo VI is part of the proposed infall group.

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