The APOGEE Library of Infrared SSP Templates (A-LIST): High-Resolution Simple Stellar Population Spectral Models in the H-Band

TL;DR

The paper introduces A-LIST, a high-resolution, empirical near-infrared stellar population spectral library spanning various ages, metallicities, and alpha abundances, enabling improved galaxy stellar population analysis.

Contribution

A-LIST is the first high-resolution, empirical near-IR SSP spectral library covering a wide parameter space, enhancing spectral modeling capabilities for unresolved stellar populations.

Findings

Accurately fits M31 globular cluster spectra with metallicities within 0.1 dex.

Recovers ages of models within approximately 1.5 Gyr.

Provides the highest resolution near-IR SSP models based on empirical stellar spectra.

Abstract

Integrated light spectroscopy from galaxies can be used to study the stellar populations that cannot be resolved into individual stars. This analysis relies on stellar population synthesis (SPS) techniques to study the formation history and structure of galaxies. However, the spectral templates available for SPS are limited, especially in the near-infrared. We present A-LIST (APOGEE Library of Infrared SSP Templates), a new set of high-resolution, near-IR SSP spectral templates spanning a wide range of ages (2-12 Gyr), metallicities ($\rm -2.2 < [M/H] < +0.4$) and $\alpha$ abundances ($\rm -0.2 < [\alpha/M] < +0.4$). This set of SSP templates is the highest resolution ($R\sim22500$) available in the near infrared, and the first such based on an empirical stellar library. Our models are generated using spectra of $\sim$300,000 stars spread across the Milky Way, with a wide range of metallicities and abundances, from the APOGEE survey. We show that our model spectra provide accurate fits to M31 globular cluster spectra taken with APOGEE, with best-fit metallicities agreeing with those of previous estimates to within $\sim$0.1 dex. We also compare these model spectra to lower-resolution E-MILES models and demonstrate that we recover the ages of these models to within $\sim$1.5 Gyr. This library is available in https://github.com/aishashok/ALIST-library.