Thomas Nicole, Davé Romeel
Institute for Computational Cosmology, Department of Physics, University of Durham, South Road, Durham DH1 3LE, UK.
Centre for Extragalactic Astronomy, Department of Physics, Durham University, Durham DH1 3LE, UK.
Mon Not R Astron Soc. 2022 Aug 6;515(4):5539-5555. doi: 10.1093/mnras/stac2175. eCollection 2022 Oct.
We investigate the environmental properties of the = 0 radio galaxy population using the simba cosmological hydrodynamic simulation. We identify centrals and satellites from a population of high and low excitation radio galaxies (HERGs and LERGs) in simba, and study their global properties. We find that [Formula: see text] of radio galaxies are satellites, and that there are insignificant differences in the global properties of LERGs based on their central/satellite classification. HERG satellites display lower values of star formation, 1.4 GHz radio luminosity, and Eddington fractions than HERG centrals. We further investigate the environments of radio galaxies and show that HERGs typically live in less dense environments, similar to star-forming galaxies. The environments of high-mass LERGs are similar to non-radio galaxies, but low-mass LERGs live in underdense environments similar to HERGs. LERGs with overmassive black holes reside in the most dense environments, while HERGs with overmassive black holes reside in underdense environments. The richness of a LERG's environment decreases with increasing Eddington fraction, and the environments of all radio galaxies do not depend on radio luminosity for [Formula: see text]. Complementing these results, we find that LERGs cluster on the same scale as the total galaxy population, while multiple HERGs are not found within the same dark matter halo. Finally, we show that high density environments support the growth of HERGs rather than LERGs at = 2. Simba predicts that with more sensitive surveys, we will find populations of radio galaxies in environments much similar to the total galaxy population.
我们使用SIMBA宇宙学流体动力学模拟来研究z = 0射电星系群体的环境特性。我们从SIMBA中的高激发和低激发射电星系（HERG和LERG）群体中识别出中心星系和卫星星系，并研究它们的整体特性。我们发现射电星系的[公式：见正文]是卫星星系，并且基于中心/卫星分类，LERG的整体特性没有显著差异。HERG卫星星系的恒星形成、1.4 GHz射电光度和爱丁顿分数的值低于HERG中心星系。我们进一步研究射电星系的环境，结果表明HERG通常生活在密度较低的环境中，类似于恒星形成星系。高质量LERG的环境与非射电星系相似，但低质量LERG生活在与HERG相似的低密度环境中。拥有超大质量黑洞的LERG存在于密度最高的环境中，而拥有超大质量黑洞的HERG存在于低密度环境中。LERG环境的丰富度随着爱丁顿分数的增加而降低，并且对于[公式：见正文]，所有射电星系的环境不依赖于射电光度。作为这些结果的补充，我们发现LERG在与总星系群体相同的尺度上聚集，而在同一个暗物质晕中未发现多个HERG。最后，我们表明在z = 2时，高密度环境支持HERG而非LERG的增长。SIMBA预测，通过更灵敏的观测，我们将在与总星系群体非常相似的环境中发现射电星系群体。
