Evolutionary Population Synthesis for Binary Stellar Population at High Spectral Resolution: Integrated Spectral Energy Distributions and Absorption-feature Indices

Abstract

Using EPS we present high resolution (0.3 Å, HRes) ISEDs from 3000 to 7000 Åand Lick/IDS absorption-line indices, for an extensive set of instantaneous burst binary stellar populations (BSPs) with binary interactions. The ages of the BSPs are in the range 1 - 15 Gyr and the metallicities are in the range 0.004 - 0.03. This HRes synthesis results can satisfy the needs of modern spectroscopic galaxy surveys, and are available on request. By comparing the synthetic continuum of BSPs at high and low resolution (LRes) we show that there is a good agreement for Z=0.02 and a tolerable disagreement for non-solar metallicity. The strength of the Balmer lines at HRes is greater than that at LRes for all metallicities. The comparison of Lick/IDS absorption-line indices at LRes and HRes, both of which are obtained by the fitting functions (FFs), shows that the discrepancies in all indices except for TiO_1 and TiO_2 are insignificant for BSPs with Z=0.004 and Z=0.02. The HRes Ca4227, Fe5015 and Mg_b indices are redder than the corresponding LRes one for BSPs with Z=0.01 and Z=0.03, this effect lowers the derived age and metallicity of the BSP. The high resolution Mg_1, Fe5709 and Fe5782 indices are bluer than those at LRes, it raises the age and metallicity. The discrepancy in these six indices is greater for BSPs with Z=0.03 in comparison to Z=0.01. At HRes we compare the Lick/IDS spectral absorption indices obtained by using the FFs with those measured directly from the synthetic spectra, and see that Ca4455, Fe4668, Mg_b and Na D indices obtained by the use of the FFs are redder for all metallicities, Fe5709 is redder at Z=0.03 and becomes to be bluer at Z=0.01 and 0.004, and other indices are bluer for all metallicities than the corresponding values measured directly from the synthetic spectra.