Powderday: Dust Radiative Transfer for Galaxy Simulations

TL;DR

Powderday is an open-source, flexible dust radiative transfer tool that integrates with galaxy simulations, enabling detailed modeling of galaxy spectral energy distributions and dust effects with high customization.

Contribution

It introduces a versatile, runtime-flexible radiative transfer package that interfaces seamlessly with various galaxy formation simulation codes and includes novel dust modeling approaches.

Findings

Model for SFR-infrared luminosity relation including AGN effects

Impact of circumstellar dust on galaxy mid-infrared emission

Galaxy inclination angle influences dust attenuation laws

Abstract

We present Powderday, a flexible, fast, open-source dust radiative transfer package designed to interface with galaxy formation simulations. Powderday builds on FSPS population synthesis models, Hyperion dust radiative transfer, and employs yt to interface between different software packages. We include our stellar population synthesis modeling on the fly, which allows for significant run-time flexibility in the assumed stellar physics. We include a model for nebular line emission that can employ either precomputed Cloudy lookup tables (for efficiency), or direct photoionization calculations for all young stars (for flexibility). The dust content follows either observationally-motivated prescriptions, direct modeling from galaxy formation simulations, or a novel approach that includes the dust content via learning-based algorithms from the SIMBA cosmological galaxy formation simulation. AGN can additionally be included via a range of prescriptions. The output of these models are broadband SEDs, as well as filter-convolved images. Powderday is designed to eliminate last-mile efforts by researchers that employ different hydrodynamic galaxy formation models, and seamlessly interfaces with GIZMO, AREPO, GASOLINE, CHANGA, and ENZO. We demonstrate the capabilities of the code via three applications: a model for the star formation rate (SFR) - infrared luminosity relation in galaxies (including the impact of AGN); the impact of circumstellar dust around AGB stars on the mid-infrared emission from galaxy SEDs; and the impact of galaxy inclination angle on dust attenuation laws.