Six More Ultra-faint Milky Way Companions Discovered in the DECam Local Volume Exploration Survey
Six More Ultra-faint Milky Way Companions Discovered in the DECam Local Volume Exploration Survey
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DOI：
10.3847/1538-4357/acdd78
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发表时间：
2022-09
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通讯作者：
W. Cerny;C. E. Mart'inez-V'azquez;A. Drlica-Wagner;A. Pace;B. Mutlu-Pakdil;T. Li;A. Riley;D. Crnojevi'c;C. Bom;J. Carballo-Bello;J. Carlin;A. Chiti;Y. Choi;M. Collins;Elise Darragh-Ford;P. Ferguson;M. Geha;D. Mart'inez-Delgado;P. Massana;S. Mau;G. Medina;R. Muñoz;E. Nadler;K. Olsen;A. Pieres;J. Sakowska;J. Simon;G. Stringfellow;A. K. Vivas;A. Walker;R. Wechsler
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作者：
W. Cerny;C. E. Mart'inez-V'azquez;A. Drlica-Wagner;A. Pace;B. Mutlu-Pakdil;T. Li;A. Riley;D. Crnojevi'c;C. Bom;J. Carballo-Bello;J. Carlin;A. Chiti;Y. Choi;M. Collins;Elise Darragh-Ford;P. Ferguson;M. Geha;D. Mart'inez-Delgado;P. Massana;S. Mau;G. Medina;R. Muñoz;E. Nadler;K. Olsen;A. Pieres;J. Sakowska;J. Simon;G. Stringfellow;A. K. Vivas;A. Walker;R. Wechsler
我们报告发现了六颗超微弱银河系卫星，这些卫星是通过使用暗能量相机 (DECam) 数据进行匹配滤波器搜索来识别的，这些数据是 DECam 局部体积探索 (DELVE) 调查第二次数据发布的一部分。利用深层 Gemini/GMOS-N 成像（针对四个候选系统）以及后续 DECam 成像（针对两个候选系统），我们描述了这些系统的形态和恒星种群。我们发现这些候选者都具有微弱的绝对星等（M V ≥ -3.2 mag）和古老的贫金属恒星群（τ > 10 Gyr，[Fe/H] 15 pc），而其他三个是致密的（r 1/2 < 10 pc）。根据这些特性，我们推断前三个系统（Boötes V、Leo Minor I 和 Virgo II）符合超微弱矮星系分类，而后三个系统（DELVE 3、DELVE 4 和 DELVE 5）可能是超微弱星团。利用盖亚卫星的数据，我们自信地测量了Boötes V、Leo Minor I和DELVE 4的自行，并初步检测到来自DELVE 3和DELVE 5的自行信号；未检测到 Virgo II 的信号。我们利用这些测量结果来探索新发现的系统与人马座矮球体、麦哲伦星云和巨大极地结构之间可能的关联，发现了一些看似合理的关联。我们的研究结果提供了维拉·鲁宾天文台即将发现的众多超微弱恒星系统的预览，并强调了对最微弱恒星系统进行分类的挑战。
We report the discovery of six ultra-faint Milky Way satellites identified through matched-filter searches conducted using Dark Energy Camera (DECam) data processed as part of the second data release of the DECam Local Volume Exploration (DELVE) survey. Leveraging deep Gemini/GMOS-N imaging (for four candidates) as well as follow-up DECam imaging (for two candidates), we characterize the morphologies and stellar populations of these systems. We find that these candidates all share faint absolute magnitudes (M V ≥ −3.2 mag) and old, metal-poor stellar populations (τ > 10 Gyr, [Fe/H] 15 pc), while the other three are compact (r 1/2 < 10 pc). From these properties, we infer that the former three systems (Boötes V, Leo Minor I, and Virgo II) are consistent with ultra-faint dwarf galaxy classifications, whereas the latter three (DELVE 3, DELVE 4, and DELVE 5) are likely ultra-faint star clusters. Using data from the Gaia satellite, we confidently measure the proper motion of Boötes V, Leo Minor I, and DELVE 4, and tentatively detect a proper-motion signal from DELVE 3 and DELVE 5; no signal is detected for Virgo II. We use these measurements to explore possible associations between the newly discovered systems and the Sagittarius dwarf spheroidal, the Magellanic Clouds, and the Vast Polar Structure, finding several plausible associations. Our results offer a preview of the numerous ultra-faint stellar systems that will soon be discovered by the Vera C. Rubin Observatory and highlight the challenges of classifying the faintest stellar systems.