THE MOST MASSIVE ULTRA-COMPACT DWARF GALAXY IN THE VIRGO CLUSTER
THE MOST MASSIVE ULTRA-COMPACT DWARF GALAXY IN THE VIRGO CLUSTER
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DOI：
10.1088/2041-8205/812/1/l2
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发表时间：
2015-08
期刊：
影响因子：
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通讯作者：
Chengze Liu;E. Peng;E. Toloba;J. C. Mihos;L. Ferrarese;K. 'Alamo-Mart'inez;Hong-Xin Zhang;P. Cot'e-P.
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作者：
Chengze Liu;E. Peng;E. Toloba;J. C. Mihos;L. Ferrarese;K. 'Alamo-Mart'inez;Hong-Xin Zhang;P. Cot'e-P.
我们利用下一代室女座星系团调查的成像和Keck/DEIMOS的光谱，报告了附近室女座星系团中最大质量超紧凑矮星系（UCD）的特性。这个天体（M59- ucd3）似乎与巨大的室女座星系M59 （NGC 4621）有关，其综合速度色散为78 km s−1 ？>，动态质量为3.7 × 10 8 M⊙,？有效半径（Re）为25pc。有效表面质量密度为9.4 × 10 10 M⊙kpc−2,？它是迄今为止发现的本地宇宙中密度最大的星系，超过了明亮的室女座UCD M60-UCD1的密度。M59-UCD3的总光度为M g′= - 14.2 ？>等，光谱能量分布与[Fe/H] = 0.0和[/ Fe] = + 0.2的古老（14 Gyr）恒星群一致。？我们还研究了M59周围的深度成像，发现了一个指向M59- ucd3的宽的低表面亮度流，它可能是UCD祖先的潮汐遗迹。这个UCD，以及M60-UCD1和M59cO等类似的天体，很可能代表了潮汐剥离星系的极端群体，它们更类似于更大、更大质量的致密早期型星系，而不是当今矮星系中的核星团。
We report on the properties of the most massive ultra-compact dwarf galaxy (UCD) in the nearby Virgo Cluster of galaxies using imaging from the Next Generation Virgo Cluster Survey and spectroscopy from Keck/DEIMOS. This object (M59-UCD3) appears to be associated with the massive Virgo galaxy M59 (NGC 4621), has an integrated velocity dispersion of 78 km s − 1 ?> , a dynamical mass of 3.7 × 10 8 M ⊙ , ?> and an effective radius (Re) of 25 pc. With an effective surface mass density of 9.4 × 10 10 M ⊙ kpc − 2 , ?> it is the densest galaxy in the local universe discovered to date, surpassing the density of the luminous Virgo UCD, M60-UCD1. M59-UCD3 has a total luminosity of M g ′ = − 14.2 ?> mag, and a spectral energy distribution consistent with an old (14 Gyr) stellar population with [Fe/H] = 0.0 and [ / Fe ] = + 0.2 . ?> We also examine deep imaging around M59 and find a broad low surface brightness stream pointing toward M59-UCD3, which may represent a tidal remnant of the UCD progenitor. This UCD, along with similar objects like M60-UCD1 and M59cO, likely represents an extreme population of tidally stripped galaxies more akin to larger and more massive compact early-type galaxies than to nuclear star clusters in present-day dwarf galaxies.