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High velocity dispersion in a rare grand-design spiral galaxy at redshift z = 2.18

机译:在红移z = 2.18时在罕见的宏伟设计旋涡星系中进行高速色散

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摘要

Although grand-design spiral galaxies are relatively common in the local Universe, only one has been spectroscopically confirmed~1 to lie at redshift z> 2 (HDFX 28; z= 2.011); and it may prove to be a major merger that simply resembles a spiral in projection. The rarity of spirals has been explained as a result of disks being dynamically 'hot' at z > 2 (refs 2-5), which may instead favour the formation of commonly observed clumpy structures. Alternatively, current instrumentation may simply not be sensitive enough to detect spiral structures comparable to those in the modern Universe. At z< 2, the velocity dispersion of disks decreases, and spiral galaxies are more numerous by z≈ 1 (refs 7, 13-15). Here we report observations of the grand-design spiral galaxy Q2343-BX442 at z= 2.18. Spectroscopy of ionized gas shows that the disk is dynamically hot, implying an uncertain origin for the spiral structure. The kinematics of the galaxy are consistent with a thick disk undergoing a minor merger, which can drive the formation of short-lived spiral structure~(16-18). A duty cycle of <100Myr for such tidally induced spiral structure in a hot massive disk is consistent with its rarity.
机译:尽管在当地宇宙中,大型设计的旋涡星系相对普遍,但光谱确认只有1个位于红移z> 2(HDFX 28; z = 2.011)。并可能证明这是一次大型合并,看起来就像是螺旋式的投影。由于磁盘在z> 2时动态“变热”(参考文献2-5),已经解释了螺旋的稀有性,而这反而可能有利于形成通常观察到的块状结构。或者,当前的仪器可能根本不够灵敏,无法检测到与现代宇宙中可比的螺旋结构。在z <2时,盘的速度色散减小,并且螺旋星系以z≈1的数量更多(参考文献7、13-15)。在这里,我们报告了z = 2.18时的大设计旋涡星系Q2343-BX442的观测结果。电离气体的光谱显示圆盘是动态变热的,这意味着螺旋结构的起源不确定。银河系的运动学与厚盘经历小合并是一致的,这可以推动短寿命螺旋结构的形成[16-18]。在热的大容量磁盘中,这种潮汐引起的螺旋结构的工作循环<100Myr与它的稀有性一致。

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  • 来源
    《Nature》 |2012年第7407期|p.338-340|共3页
  • 作者单位

    Dunlap Institute for Astronomy & Astrophysics, University of Toronto, 50 St George Street, Toronto M5S3H4, Ontario, Canada;

    Department of Physics and Astronomy, University of California, Los Angeles,California 90095, USA;

    California Institute of Technology, MS 249-17, Pasadena, California 91125, USA;

    Department of Physics and Astronomy, University of California, Riverside, California 92521, USA;

    Steward Observatory, 933 North Cherry Ave, Tucson, Arizona 85721, USA;

    Department of Physics, University of Wisconsin-Milwaukee, Milwaukee, Wisconsin 53211, USA;

  • 收录信息 美国《科学引文索引》(SCI);美国《工程索引》(EI);美国《生物学医学文摘》(MEDLINE);美国《化学文摘》(CA);
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  • 正文语种 eng
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