Morphologies of galaxies within voids,Astronomy & Astrophysics

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Morphologies of galaxies within voids
Astronomy & Astrophysics ( IF 5.4 ) Pub Date : 2024-12-17 , DOI: 10.1051/0004-6361/202450809
M. Argudo-Fernández, C. Gómez Hernández, S. Verley, A. Zurita, S. Duarte Puertas, G. Blázquez Calero, J. Domínguez-Gómez, D. Espada, E. Florido, I. Pérez, L. Sánchez-Menguiano

Context. Among the largest structures in which matter is distributed in the Universe, we find cosmic voids, which are large, under-dense regions almost devoid of galaxies. The study of these structures and the galaxies that inhabit them, the void galaxies, provides key information for understanding galaxy evolution.Aims. In this work we investigate the effects of the environment on the evolution of void galaxies. In particular, we study their morphology and explore its dependence on the location within the void where the galaxies reside, as well as on the properties of the void, such as its size and the galaxy number density.Methods. The sample of void galaxies that we use in this study is based on the catalogue of cosmic voids and void galaxies in the Sloan Digital Sky Survey Data Release 7 (SDSS-DR7). As we are interested in studying the morphology of void galaxies, we select galaxies in the redshift range of 0.005 ≤ z ≤ 0.080, and use the public galaxy morphologies of the SDSS sample together with deep learning algorithms to divide the sample into early- and late-type void galaxies. We analyse the fractions of galaxies of each morphological type as a function of the void-centric distance, the size of the voids, and the density of galaxies in each void.Results. There is a higher abundance of late-type galaxies with respect to early-type galaxies within voids, which remains nearly constant from the inner to the outer part of the voids. We do not find any dependence of the fraction of early- and late-type galaxies on void size or on the number-density of galaxies in the voids.Conclusions. Galaxies in voids follow the morphology–density relation, in the sense that the majority of the galaxies in voids (the most under-dense large-scale environments) are late-type galaxies. However, we find no difference between voids with lower or higher volume number-density of galaxies: the fractions of early- and late-type galaxies do not depend on the density of the voids. The physical processes responsible for the evolution from late towards earlier types (such as external environmental quenching) are not sufficiently effective in voids or are so slow (internal secular quenching) that their contributions do not appear in the morphology–density relation.

中文翻译：

空隙中星系的形态

上下文。在宇宙中物质分布的最大结构中，我们发现了宇宙空隙，它们是几乎没有星系的大而密度不足的区域。对这些结构和居住在其中的星系（虚空星系）的研究为理解星系演化提供了关键信息。目标。在这项工作中，我们研究了环境对虚空星系演化的影响。特别是，我们研究了它们的形态，并探索了它对星系在虚空内的位置以及虚空特性（如其大小和星系数量密度）的依赖性。方法。我们在这项研究中使用的空星系样本是基于斯隆数字巡天数据版本 7 （SDSS-DR7）中的宇宙空洞和空星系目录。由于我们对研究虚空星系的形态感兴趣，我们选择了 0.005 ≤ z ≤ 0.080 的红移范围内的星系，并使用 SDSS 样本的公共星系形态以及深度学习算法将样本分为早期和晚期空星系。我们分析了每种形态类型的星系分数，作为以空洞为中心的距离、空洞的大小以及每个空隙中星系密度的函数。结果。相对于虚空内的早期星系，晚期星系的丰度更高，从虚空的内部到外部几乎保持不变。我们没有发现早期和晚期星系的比例与空隙大小或空隙中星系的数量密度有任何依赖性。结论。虚空中的星系遵循形态-密度关系，从某种意义上说，虚空中的星系（密度最低的大尺度环境）中的大多数星系都是晚期星系。然而，我们发现星系体积数密度较低或较高的空隙之间没有差异：早期和晚期星系的分数不取决于空隙的密度。负责从晚期到早期类型的演化的物理过程（例如外部环境猝灭）在空隙中不够有效，或者非常缓慢（内部长期猝灭），以至于它们的贡献不会出现在形态-密度关系中。