arXivDaily arXiv每日学术速递 周一至周五更新
arXiv周末暂无论文更新,休息一下吧,周末愉快~~
arXiv 1104.2593astro-ph.CO
收藏

超致密矮星系的空间分辨动能

Spatially Resolved Kinematics of an Ultra-Compact Dwarf Galaxy

M. J. Frank, M. Hilker, S. Mieske, H. Baumgardt, E. K. Grebel, L. Infante

摘要:

我们提出了内部运动学的UCD 3,最明亮的已知超紧凑矮星系(UCD)在天炉座星系团,使这第一个UCD空间分辨光谱。我们的研究是基于在良好的视宁度条件(0.5 - 0.67弧秒半高宽)下,用VLT/FLAMES摄谱仪的ARGUS积分场单元获得的视宁度有限的观测结果。UCD 3的速度场显示出弱旋转的特征,与大质量球状星团中的速度场相当。它的速度色散分布与各向同性速度分布和质量遵循哈勃空间望远镜成像获得的光分布的假设完全一致。特别是,没有证据表明存在一个扩展的暗物质晕贡献了显著的质量分数(在R < 200 pc内>~ 33%),也没有证据表明中心黑洞的质量超过UCD质量的~ 5%。虽然这一结果并不排除UCD 3的银河系起源,但我们得出结论,它的内部运动学完全符合它是一个大质量星团。

英文摘要:

We present the internal kinematics of UCD3, the brightest known ultra-compact dwarf galaxy (UCD) in the Fornax cluster, making this the first UCD with spatially resolved spectroscopy. Our study is based on seeing-limited observations obtained with the ARGUS Integral Field Unit of the VLT/FLAMES spectrograph under excellent seeing conditions (0.5 - 0.67 arcsec FWHM). The velocity field of UCD3 shows the signature of weak rotation, comparable to that found in massive globular clusters. Its velocity dispersion profile is fully consistent with an isotropic velocity distribution and the assumption that mass follows the light distribution obtained from Hubble Space Telescope imaging. In particular, there is no evidence for the presence of an extended dark matter halo contributing a significant (>~33 per cent within R < 200 pc) mass fraction, nor for a central black hole more massive than ~5 per cent of the UCD's mass. While this result does not exclude a galaxian origin for UCD3, we conclude that its internal kinematics are fully consistent with it being a massive star cluster.

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。

↑