On the Impact of Inclination-Dependent Attenuation on Derived Star Formation Histories: Results from Disk Galaxies in the Great Observatories Origins Deep Survey Fields

TL;DR

This study introduces an inclination-dependent attenuation model for spectral energy distribution fitting and demonstrates its impact on derived star formation histories and stellar masses in disk galaxies, revealing biases in traditional methods.

Contribution

The paper develops and applies an inclination-dependent attenuation prescription within SED fitting, highlighting its effects on star formation rates and stellar mass estimates compared to traditional inclination-independent methods.

Findings

Inclination-dependent attenuation affects optical attenuation (AV) estimates.

Traditional methods underestimate stellar masses in highly inclined galaxies.

Inclination-dependent models provide more accurate stellar mass estimates for edge-on disks.

Abstract

We develop and implement an inclination-dependent attenuation prescription for spectral energy distribution (SED) fitting and study its impact on derived star-formation histories. We apply our prescription within the SED fitting code Lightning to a clean sample of 82, z=0.21-1.35 disk-dominated galaxies in the Great Observatories Origins Deep Survey North and South fields. To compare our inclination-dependent attenuation prescription with more traditional fitting prescriptions, we also fit the SEDs with the inclination-independent Calzetti et al. (2000) attenuation curve. From this comparison, we find that fits to a subset of 58, z < 0.7 galaxies in our sample, utilizing the Calzetti et al. (2000) prescription, recover similar trends with inclination as the inclination-dependent fits for the far-UV-band attenuation and recent star-formation rates. However, we find a difference between prescriptions in the optical attenuation (AV) that is strongly correlated with inclination (p-value < 10^-11). For more face-on galaxies, with i < 50 deg, (edge-on, i = 90 deg), the average derived AV is 0.31 +\- 0.11 magnitudes lower (0.56 +\- 0.16 magnitudes higher) for the inclination-dependent model compared to traditional methods. Further, the ratio of stellar masses between prescriptions also has a significant (p-value < 10^-2) trend with inclination. For i = 0-65 deg, stellar masses are systematically consistent between fits, with log(Mstar_inc/Mstar_Calzetti) = -0.05 +/- 0.03 dex and scatter of 0.11 dex. However, for i = 80-90 deg, derived stellar masses are lower for the Calzetti et al. (2000) fits by an average factor of 0.17 +\- 0.03 dex and scatter of 0.13 dex. Therefore, these results suggest that SED fitting assuming the Calzetti et al. (2000) attenuation law potentially underestimates stellar masses in highly inclined disk-dominated galaxies.