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首页> 外文期刊>Astronomy and astrophysics >Probing the merger history of red early-type galaxies with their faint stellar substructures
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Probing the merger history of red early-type galaxies with their faint stellar substructures

机译:探索红色早期型星系及其暗淡的恒星亚结构的合并历史

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Several detailed observations, such as those carried out at the Canada-France-Hawaii Telescope (CFHT), have revealed prominent Low Surface Brightness (LSB) fine structures that lead to a change in the apparent morphology of galaxies. Previous photometry surveys have developed observational techniques which make use of the diffuse light detected in the external regions of galaxies. In these studies, the outer perturbations have been identified and classified. These include tidal tails, stellar streams, and shells. These structures serve as tracers for interacting events and merging events and retain some memory of the mass assembly of galaxies. Cosmological numerical simulations are required to estimate their visibility timescale, among other properties, in order to reconstruct the merger history of galaxies. In the present work, we analyze a hydrodynamical cosmological simulation to build up a comprehensive interpretation of the properties of fine structures. We present a census of several types of LSB fine structures compiled using a visual inspection of individual snapshots at various points in time. We reconstruct the evolution of the number of fine structures detected around an early-type galaxy and we compare it with the merger history of the galaxy. We find that most fine structures are associated with major and intermediate mass merger events. Their survival timescale ranges between 0.7 and 4 Gyr. Shells and streams remain visible for a longer time, while tidal tails have a shorter lifetime. These estimates for the survival time of collisional debris provide clues for the interpretation of the shape and frequency of fine structures observed in deep images with regard to their mass assembly. We find that the detectability of stellar streams is most sensitive at the surface brightness limit, demonstrating greater visibility at the deepest surface brightness level used in our simulation. We see between two and three times more streams based on a surface brightness cut of 33 mag arcsec~(?2)than with 29 mag arcsec~(?2). We find that the detection of shells is strongly dependent upon the projection angle.
机译:几项详细的观测,例如在加拿大-法国-夏威夷望远镜(CFHT)上进行的观测,揭示了突出的低表面亮度(LSB)精细结构,导致了星系的表观形态发生了变化。先前的光度学调查已经开发了观测技术,该技术利用了在星系外部区域中检测到的漫射光。在这些研究中,外部扰动已被识别和分类。这些包括潮汐的尾巴,恒星流和贝壳。这些结构充当相互作用事件和合并事件的示踪剂,并保留了星系质量集合的某些记忆。为了重建星系合并历史,需要进行宇宙学数值模拟以估计其可见性时间尺度以及其他属性。在当前的工作中,我们分析了流体力学的宇宙学模拟,以建立对精细结构特性的全面解释。我们提供了对几种LSB精细结构的普查,这些结构是通过在各个时间点对单个快照进行视觉检查而编译的。我们重建了在早期类型星系周围检测到的精细结构数量的演化,并将其与星系合并历史进行了比较。我们发现大多数精细结构都与主要和中间的大规模合并事件相关。它们的生存时间范围为0.7至4 Gyr。贝壳和溪流保持可见的时间更长,而潮汐的尾巴寿命较短。这些对碰撞碎片生存时间的估计为解释在深部图像中观察到的精细结构的质量和组装质量提供了线索。我们发现,恒星流的可检测性在表面亮度极限处最敏感,这表明在我们的模拟中使用的最深表面亮度水平下,可见性更高。根据表面亮度削减33 mag arcsec〜(?2),我们看到的流是29 mag arcsec〜(?2)的流的2至3倍。我们发现,对壳的检测在很大程度上取决于投影角度。

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