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Age and Metallicity of galaxies in different environments of the Coma supercluster
New Astronomy ( IF 1.9 ) Pub Date : 2020-11-01 , DOI: 10.1016/j.newast.2020.101417
Juhi Tiwari , Smriti Mahajan , Kulinder Pal Singh

We analyse luminosity-weighted ages and metallicity (Z) of galaxies in a continuous range of environments, i.e. clusters, filaments and voids prevalent in the Coma supercluster ($\sim 100 h^{-1}$ Mpc). Specifically, we employ two absorption line indices, H$\beta$ and $\langle\rm{Fe}\rangle$ as tracers of age and metallicity of galaxies. We find that the stellar-phase metallicity of galaxies declines with increasing age as a function of stellar mass ($M^*$) as well as environment. On the filaments, metallicity of galaxies varies as a function of their distance from the spine of the filament, such that galaxies closer to the centre of the filaments have lower metallicity relative to their counterparts 1 Mpc away from it. The mean age of intermediate mass galaxies ($10^{10} 10^{10.5}$), on the other hand show no such difference for the galaxies in clusters and filaments, but their counterparts in voids are found to be younger by $\sim 0.5$ Gyr. At fixed age however, Z of galaxies is independent of their $M^*$ in all environments, except the most massive ($M^*/M_{\odot} \gtrsim 10^{10.7}$), oldest galaxies ($\gtrsim 9$ Gyr) which show a sharp decline in their Z with $M^*$. Our results support a scenario where galaxies in the nearby Universe have grown by accreting smaller galaxies or primordial gas from the large-scale cosmic web.

中文翻译:

彗发超星系团不同环境下星系的年龄和金属性

我们分析了连续环境范围内星系的光度加权年龄和金属丰度 (Z),即彗发超星系团 ($\sim 100 h^{-1}$ Mpc) 中普遍存在的星团、细丝和空隙。具体来说,我们采用两个吸收线指数 H$\beta$ 和 $\langle\rm{Fe}\rangle$ 作为星系年龄和金属丰度的示踪剂。我们发现,作为恒星质量($M^*$)和环境的函数,星系的恒星相金属丰度随着年龄的增加而下降。在细丝上,星系的金属丰度随它们与细丝脊椎的距离而变化,因此靠近细丝中心的星系相对于距离它 1 Mpc 的对应星系具有较低的金属丰度。中等质量星系的平均年龄($10^{10} 10^{10.5}$),另一方面,星团和细丝中的星系没有这种差异,但发现它们在空隙中的对应物年轻 $\sim 0.5$ Gyr。然而,在固定年龄时,星系的 Z 在所有环境中都独立于它们的 $M^*$,除了质量最大的 ($M^*/M_{\odot} \gtrsim 10^{10.7}$)、最古老的星系 ($ \gtrsim 9$ Gyr),它们的 Z 值随着 $M^*$ 急剧下降。我们的结果支持附近宇宙中的星系通过从大规模宇宙网吸积较小的星系或原始气体而增长的情景。最古老的星系 ($\gtrsim 9$ Gyr),它们的 Z 值随着 $M^*$ 急剧下降。我们的结果支持这样一种情景,即附近宇宙中的星系通过从大规模宇宙网吸积较小的星系或原始气体而增长。最古老的星系 ($\gtrsim 9$ Gyr),它们的 Z 值随着 $M^*$ 急剧下降。我们的结果支持附近宇宙中的星系通过从大规模宇宙网吸积较小的星系或原始气体而增长的情景。
更新日期:2020-11-01
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