Probing Evolutionary Population Synthesis Models in the Near Infrared with Early Type Galaxies

TL;DR

This study evaluates the effectiveness of different spectral libraries in near-infrared stellar population synthesis of early type galaxies, highlighting the importance of high spectral resolution models for consistent results across optical and NIR data.

Contribution

It demonstrates that higher spectral resolution models yield more reliable and consistent stellar population analysis in the near-infrared, compared to lower resolution libraries.

Findings

Low-resolution libraries produce inconsistent NIR results.

High-resolution models agree well with each other and literature.

Higher spectral resolution improves optical and NIR result consistency.

Abstract

We performed a near-infrared (NIR, $\sim$1.0$\mu$m-2.4$\mu$m) stellar population study in a sample of early type galaxies. The synthesis was performed using five different evolutionary population synthesis libraries of models. Our main results can be summarized as follows: low spectral resolution libraries are not able to produce reliable results when applied to the NIR alone, with each library finding a different dominant population. The two newest higher resolution models, on the other hand, perform considerably better, finding consistent results to each other and to literature values. We also found that optical results are consistent with each other even for lower resolution models. We also compared optical and NIR results, and found out that lower resolution models tend to disagree in the optical and in the NIR, with higher fraction of young populations in the NIR and dust extinction $\sim$1 magnitude higher than optical values. For higher resolution models, optical and NIR results tend do aggree much better, suggesting that a higher spectral resolution is fundamental to improve the quality of the results.