Dynamics of starbursting dwarf galaxies: I Zw 18
Dynamics of starbursting dwarf galaxies: I Zw 18
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DOI：
10.1051/0004-6361/201117867
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发表时间：
2011-07
影响因子：
6.5
通讯作者：
F. Lelli;M. Verheijen;F. Fraternali;Renzo Sancisi University of Groningen;U. Bologna;I. Bologna
中科院分区：
文献类型：
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作者：
F. Lelli;M. Verheijen;F. Fraternali;Renzo Sancisi University of Groningen;U. Bologna;I. Bologna
I Zw 18 is a prototype blue compact dwarf (BCD) galaxy, characterized by a strong starburst and extremely low metallicity (Z ~ 0.02 Z⊙).它长期以来一直被认为是本地宇宙中的候选年轻星系，但最近的研究发现它包含古老的恒星。我们分析了 21 厘米线的档案 VLA 观测结果，发现与星暴区域相关的 H i 形成了一个紧凑的快速旋转圆盘。 H i 柱密度非常高，高达~50-100 M⊙ pc-2（~0.6-1.2 × 1022 原子 cm-2）。旋转曲线平坦，内部陡峭上升，表明存在强烈的质量中心集中。具有暗物质晕的质量模型表明，重子可能主导内部区域的引力势。 A radial inflow/outflow motion of ~15 km s-1 is also present. I Zw 18 在气体分布、恒星分布和动力学方面似乎在结构上与典型的不规则矮星不同。它可以被认为是一个“微型”高表面亮度盘状星系。这些动力学特性必定与星暴密切相关。他们还为 BCD 后代问题提供了新的线索。 There is also extended H i emission towards the outlying stellar complex I Zw 18 C and a ~13.5 kpc H i tail.富含气体的矮星之间的相互作用/合并是星暴最可能的解释。
I Zw 18 is a prototype blue compact dwarf (BCD) galaxy, characterized by a strong starburst and extremely low metallicity (Z ~ 0.02 Z⊙). It has long been considered a candidate young galaxy in the Local Universe, but recent studies have found that it contains old stars. We analysed archival VLA observations of the 21 cm line and found that the H i associated to the starburst region forms a compact rapidly rotating disk. The H i column densities are very high, up to ~50-100 M⊙ pc-2 (~0.6-1.2 × 1022 atoms cm-2). The rotation curve is flat with a steep rise in the inner parts, indicating that there is a strong central concentration of mass. Mass models with a dark matter halo show that baryons may dominate the gravitational potential in the inner regions. A radial inflow/outflow motion of ~15 km s-1 is also present. I Zw 18 appears to be structurally different from typical dwarf irregulars in terms of its gas distribution, stellar distribution, and dynamics. It may be considered as a "miniature" high-surface-brightness disk galaxy. These dynamical properties must be tightly related to the starburst. They also shed new light on the question of the descendants of BCDs. There is also extended H i emission towards the outlying stellar complex I Zw 18 C and a ~13.5 kpc H i tail. An interaction/merger between gas-rich dwarfs is the most likely explanation of the starburst.