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arXiv 1902.04580astro-ph.GA
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低表面亮度星系的形成和演化

The formation and evolution of low-surface-brightness galaxies

G. Martin, S. Kaviraj, C. Laigle, J. E. G. Devriendt, R. A. Jackson, S. Peirani, Y. Dubois, C. Pichon, A. Slyz

摘要:

我们对星系演化的统计理解,从根本上说是由位于当前广域巡天(mu ~ 23 mag arcsec^-2)表面亮度极限之上的天体驱动的。虽然理论和小的,深的调查都暗示了大量的低表面亮度星系(LSBG)比这些限制更暗,但它们的形成仍然知之甚少。我们使用Horizon-AGN(一种宇宙流体动力学模拟)来研究LSBG,特别是超弥散星系(UDG; μ> 24.5 mag arcsec^-2)的种群如何随着时间的推移而形成和演化。当M* > 10^8 MSun时,LSBG分别贡献了局部数密度、质量密度和光度密度的47%、7%和6%(当M* > 10^7 MSun时,约为85%/11%/10%)。今天的大射电星系群与高表面亮度星系(高表面亮度星系群; μ < 23 mag arcsec^-2)具有相似的暗物质比例和角动量,但有效半径更大(UDG为x2.5),致密的恒星形成气体比例更低(UDG比高表面亮度星系群少x6以上)。LSBG起源于与z > 2的HSBG相同的祖细胞。然而,LSBG祖先在早期形成恒星的速度更快。超新星能量注入的速率越高,它们的气体密度分布就越窄,这反过来又会产生更容易受到潮汐过程影响的较浅的恒星分布。在z ~ 1之后,潮汐扰动扩大了LSBG恒星的分布,并加热了它们的冷气体,形成了今天看到的弥散的、基本上缺乏气体的LSBG。在簇中,冲压压力剥离提供了一种额外的机制,有助于去除LSBG祖细胞中的气体。我们的研究结果提供了对星系人口形成的深入了解,这是全面了解星系演化的核心,这将是使用新的和即将到来的深宽调查研究的一个关键课题。

英文摘要:

Our statistical understanding of galaxy evolution is fundamentally driven by objects that lie above the surface-brightness limits of current wide-area surveys (mu ~ 23 mag arcsec^-2). While both theory and small, deep surveys have hinted at a rich population of low-surface-brightness galaxies (LSBGs) fainter than these limits, their formation remains poorly understood. We use Horizon-AGN, a cosmological hydrodynamical simulation to study how LSBGs, and in particular the population of ultra-diffuse galaxies (UDGs; mu > 24.5 mag arcsec^-2), form and evolve over time. For M* > 10^8 MSun, LSBGs contribute 47, 7 and 6 per cent of the local number, mass and luminosity densities respectively (~85/11/10 per cent for M* > 10^7 MSun). Today's LSBGs have similar dark-matter fractions and angular momenta to high-surface-brightness galaxies (HSBGs; mu < 23 mag arcsec^-2), but larger effective radii (x2.5 for UDGs) and lower fractions of dense, star-forming gas (more than x6 less in UDGs than HSBGs). LSBGs originate from the same progenitors as HSBGs at z > 2. However, LSBG progenitors form stars more rapidly at early epochs. The higher resultant rate of supernova-energy injection flattens their gas-density profiles, which, in turn, creates shallower stellar profiles that are more susceptible to tidal processes. After z ~ 1, tidal perturbations broaden LSBG stellar distributions and heat their cold gas, creating the diffuse, largely gas-poor LSBGs seen today. In clusters, ram-pressure stripping provides an additional mechanism that assists in gas removal in LSBG progenitors. Our results offer insights into the formation of a galaxy population that is central to a complete understanding of galaxy evolution, and which will be a key topic of research using new and forthcoming deep-wide surveys.

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。

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