Formation and Evolution of Barred Galaxies

棒星系的形成和演化

• 批准号: 298620-2013
• 负责人: Martel, Hugo
• 金额: $ 1.82万
• 依托单位: Université Laval
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2017
• 资助国家: 加拿大
• 起止时间: 2017-01-01 至 2018-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=633453
• 关键词: Formation; Evolution; Barred; Galaxies

A large fraction of spiral galaxies contain bars. The presence of a bar can greatly affect the evolution of the host galaxy. The bar channels gas into the center of galaxies, where it is converted into stars. The nuclear reactions in these stars produce heavy elements (called "metals"), that are then ejected into the gas when the stars explode in supernovae. Also, if there is a supermassive black hole in the center of the galaxy, the gas flowing along the bar might fall onto the black hole, producing an active galactic nuclei (or AGN). We would therefore expect barred galaxies to have higher central star formation rates (SFR), higher central metallicity, and more intense AGN activity than unbarred galaxies. However, recent observations reveal a more complex picture. Only galaxies with strong bars show enhanced central star formation, and not all of them do: There appears to be significant differences between massive barred galaxies (stellar masses larger than 10-30 billion solar masses) and low-mass ones. All barred galaxies show an enhancement in central metallicity, but low-mass barred galaxies do not show a corresponding enhancement in central star formation. Some high-mass barred galaxies do, but not all of them. Instead, some massive galaxies with strong bars show a suppression of central star formation. This suggests that bars might, under some circumstances, quench star formation in the central regions, instead of boosting it. Also, we observe an anti-correlation between star formation and AGN activity in the center of barred galaxies. These observations reveal that galaxies of different masses, or with bars of different strength, can have drastically different star formation histories. To fully understand the evolution of these galaxies, we need to understand the interplay between the various physical processes driving this evolution. We propose to pursue a long-term project to study the evolution of barred galaxies. We will perform a series of numerical simulations of galaxy evolution. Our goal is to understand the physical processes that determine the history of star formation and metallicity in barred galaxies, and determine the role played by feedback in quenching star formation in some barred galaxies.

很大一部分螺旋星系包含条状星系。星系棒的存在可以极大地影响宿主星系的演化。气柱将气体输送到星系中心，在那里气体被转化为恒星。这些恒星中的核反应会产生重元素(称为“金属”)，当恒星在超新星中爆炸时，这些元素会被喷入气体中。此外，如果星系中心有一个超大质量的黑洞，沿着黑洞棒流动的气体可能会落到黑洞上，产生一个活跃的星系核(或AGN)。因此，我们预计封闭星系比非封闭星系有更高的中心恒星形成率(SFR)、更高的中心金属丰度和更强烈的活动星系核活动。然而，最近的观察揭示了一幅更复杂的图景。只有具有较强条状星系的星系显示出中央恒星形成的增强，但并不是所有星系都是如此：大质量条状星系(恒星质量大于100-300亿太阳质量)和低质量星系之间似乎存在显著差异。所有条状星系的中心金属丰度都有所增强，但低质量条状星系在中心恒星形成方面并没有相应的增强。一些高质量的黑洞星系有，但不是全部。相反，一些拥有强棒的大质量星系显示出对中央恒星形成的抑制。这表明，在某些情况下，星棒可能会抑制中心区域恒星的形成，而不是促进它的形成。此外，我们还观察到黑洞星系中心的恒星形成和活动星系核活动之间的反相关关系。这些观测揭示了不同质量的星系，或者具有不同强度的星棒的星系，可能有着截然不同的恒星形成历史。为了全面了解这些星系的演化，我们需要了解驱动这种演化的各种物理过程之间的相互作用。我们建议进行一个长期项目来研究禁止星系的演化。我们将进行一系列星系演化的数值模拟。我们的目标是了解决定条状星系中恒星形成和金属丰度历史的物理过程，并确定反馈在某些条状星系中猝灭恒星形成中所起的作用。