$alpha$-MC: Self-consistent $alpha$-enhanced stellar population models covering a wide range of age, metallicity, and wavelength
Minjung Park, Charlie Conroy, Benjamin D. Johnson, Joel Leja, Aaron Dotter, Phillip A. Cargile
arXiv:2410.21375v1 Announce Type: new
Abstract: We present new stellar population models, $alpha$-MC, self-consistently taking into account non-solar $rm [alpha/Fe]$ abundances for both isochrones and stellar spectra. The $alpha$-MC models are based on $alpha$-enhanced MIST isochrones and C3K spectral libraries, which are publicly available in FSPS. Our new models cover a wide range of ages ($rm log (age/yr) = 5.0 – 10.3$), metallicities ($rm [Fe/H]=[-2.5,+0.5]$ in steps of 0.25, $rm [alpha/Fe]=-0.2,+0.0,+0.2,+0.4,+0.6$), and wavelengths ($0.1-2.5,rm mu m$). We investigate the separate and combined effects of $alpha$-enhanced isochrones and stellar spectral libraries on simple stellar populations (SSPs), including their broadband colors, spectral indices, and full spectra. We find that the primary effect of $alpha$-enhancement in isochrones is to lower the overall continuum levels and redden the continuum shapes, while $alpha$-enhancement in stellar spectra mainly affects individual spectral lines. At constant $rm [Fe/H]$, $alpha$-enhancement has significant impacts on the broadband colors by $rm sim 0.1-0.4,mag$ across all ages ($rm 0.01 – 10,Gyr$). The effects of $alpha$-enhancement on colors at fixed $rm [Z/H]$ are smaller, by $rm sim 0.1-0.2,mag$. The spectral indices involving $alpha$-elements, Ca4227 and Mg b, increase with $rm [alpha/Fe]$ (both at fixed $rm [Fe/H]$ and fixed $rm [Z/H]$) due to enhanced $alpha$-abundances. At constant $rm [Fe/H]$, $alpha$-enhancement weakens most Fe-sensitive and Hydrogen Balmer lines. Our new self-consistent $alpha$-enhanced models will be essential in deriving accurate physical properties of high-redshift galaxies, where $alpha$-enhancement is expected to be common.arXiv:2410.21375v1 Announce Type: new
Abstract: We present new stellar population models, $alpha$-MC, self-consistently taking into account non-solar $rm [alpha/Fe]$ abundances for both isochrones and stellar spectra. The $alpha$-MC models are based on $alpha$-enhanced MIST isochrones and C3K spectral libraries, which are publicly available in FSPS. Our new models cover a wide range of ages ($rm log (age/yr) = 5.0 – 10.3$), metallicities ($rm [Fe/H]=[-2.5,+0.5]$ in steps of 0.25, $rm [alpha/Fe]=-0.2,+0.0,+0.2,+0.4,+0.6$), and wavelengths ($0.1-2.5,rm mu m$). We investigate the separate and combined effects of $alpha$-enhanced isochrones and stellar spectral libraries on simple stellar populations (SSPs), including their broadband colors, spectral indices, and full spectra. We find that the primary effect of $alpha$-enhancement in isochrones is to lower the overall continuum levels and redden the continuum shapes, while $alpha$-enhancement in stellar spectra mainly affects individual spectral lines. At constant $rm [Fe/H]$, $alpha$-enhancement has significant impacts on the broadband colors by $rm sim 0.1-0.4,mag$ across all ages ($rm 0.01 – 10,Gyr$). The effects of $alpha$-enhancement on colors at fixed $rm [Z/H]$ are smaller, by $rm sim 0.1-0.2,mag$. The spectral indices involving $alpha$-elements, Ca4227 and Mg b, increase with $rm [alpha/Fe]$ (both at fixed $rm [Fe/H]$ and fixed $rm [Z/H]$) due to enhanced $alpha$-abundances. At constant $rm [Fe/H]$, $alpha$-enhancement weakens most Fe-sensitive and Hydrogen Balmer lines. Our new self-consistent $alpha$-enhanced models will be essential in deriving accurate physical properties of high-redshift galaxies, where $alpha$-enhancement is expected to be common.