http://arxiv.org/abs/2005.02757
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 ($10^{10} < M^/M_{\odot} < 10^{10.5}$) galaxies is statistically significantly different in different environments such that, the galaxies in clusters are older than the filament galaxies by 1-1.5 Gyr, while their counterparts in the voids are younger than filament galaxies by $\sim 1$ Gyr. The massive galaxies ($M^/M_{\odot} > 10^{10.5}$), 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.
J. Tiwari, S. Mahajan and K. Singh
Thu, 7 May 20
3/62
Comments: Accepted for publication in New Astronomy. 18 pages, 11 figures
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