The effects of binary interactions on parameter determinations for early-type galaxies

TL;DR

This study examines how binary interactions in stellar population models influence the estimation of galaxy parameters, finding significant effects on age determination but not on photometric redshift or metallicity for early-type galaxies.

Contribution

It provides a comparative analysis of stellar population models with and without binary interactions, highlighting their impact on galaxy age estimations and star formation rates.

Findings

Binary interactions do not affect photometric redshift estimation.

Neglecting binary interactions leads to underestimating ETG ages.

Including binary interactions increases age estimates in about 33% of ETGs.

Abstract

Based on stellar population models without (SSP) and with (BSP) binary interactions, we investigate the effects of binary interactions on parameter determinations for early-type galaxies (ETGs). We present photometric redshift (photo-z), age and spectral type for photometric data sample by fitting observed magnitudes with the SSP and BSP models. Our results show that binary interactions have no effect on photo-z estimation. Once we neglect binary interactions, the age of ETGs will be underestimated, by contrast, the effects on the age estimations can be negligible for other type of galaxies. For ETG sample, we derive their properties by fitting their spectra with the SSP and BSP models. When comparing these galaxy properties, we find no variation of the overall metallicities for ETGs among the SSP and BSP models. Moreover, the inclusion of binary interactions can affect age estimations. Our results show that the BSP-fitted ages in ~33.3% of ETG sample are around 0.5-1.0 Gyr larger than the SSP-fitted ages; ~44.2\% are only 0.1-0.5 Gyr larger; the rest ~22.5% are approximately equal. By comparisons, we find the difference of the star formation rate between the SSP and BSP models is large at the late evolution stage.