On the Impact of Inclination-Dependent Attenuation on Derived Star-Formation Histories: Results from Disk Galaxies in the GOODS Fields

We develop and implement a new inclination-dependent attenuation prescription for spectral energy distribution (SED) fitting and study its impact on derived star-formation histories. Our procedure utilizes the attenuation curves from Tuffs et al. (2004). We apply our procedure within the SED fitting code Lightning to 162 disk-dominated galaxies in the Great Observatories Origins Deep Survey (GOODS) North and South fields. To compare with more traditional fitting procedures, we also fit the SEDs with the inclination-independent Calzetti et al. (2000) attenuation curve. We find that both the inclination-dependent and Calzetti et al. (2000) fits recover comparable FUV-band attenuation and recent star-formation rates at all inclinations, albeit with large dispersions of ~0.40 magnitudes and ~0.38 dex, respectively. However, we find that the difference between A_V values derived from our inclination-dependent and Calzetti et al. (2000) fits are strongly correlated with inclination (p-value < 10^-30). For galaxies with i < 50 degrees (i > 80 degrees), derived A_V values are 0.22 ± 0.12 magnitudes lower (0.2-0.65 magnitudes higher) for our inclination-dependent model compared to traditional methods. Further, we show that the ratio of stellar masses between fits also has a highly significant (p-value < 10^-20) trend with inclination. For i=0-65 degrees, stellar masses are comparable between fits with a minor dispersion of ~0.10 dex. However, for galaxies with i > 70 degrees, derived stellar masses can be drastically lower using Calzetti et al. (2000) fits (up to a factor of 2.88 at 90 degrees) compared to the inclination-dependent fits.