Age and Metallicity of galaxies in different environments of the Coma supercluster. (arXiv:2005.02757v1 [astro-ph.GA])
<a href="http://arxiv.org/find/astro-ph/1/au:+Tiwari_J/0/1/0/all/0/1">Juhi Tiwari</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Mahajan_S/0/1/0/all/0/1">Smriti Mahajan</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Singh_K/0/1/0/all/0/1">Kulinder Pal Singh</a>
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 $langlerm{Fe}rangle$ 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.
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 $langlerm{Fe}rangle$ 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.
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