powderday: Dust Radiative Transfer for Galaxy Simulations

Abstract

We present POWDERDAY (available at https://github.com/dnarayanan/powderday), a flexible, fast, open-source dust radiative transfer package designed to interface with both idealized and cosmological galaxy formation simulations. POWDERDAY builds on FSPS stellar population synthesis models, and HYPERION dust radiative transfer, and employs YT to interface between different software packages. We include our stellar population synthesis modeling on the fly, allowing significant flexibility in the assumed stellar physics and nebular line emission. The dust content follows either simple observationally motivated prescriptions (i.e., constant dust-tometals ratios, or dust-to-gas ratios that vary with metallicity), direct modeling from galaxy formation simulations that include dust physics, as well as a novel approach that includes the dust content via learning-based algorithms from the SIMBA cosmological galaxy formation simulation. Active galactic nuclei (AGNs) can additionally be included via a range of prescriptions. The output of these models are broadband (912 Å-1 mm) spectral energy distributions (SEDs), as well as filter-convolved monochromatic 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-infrared luminosity relation in galaxies (including the impact of AGNs), 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.

First Light And Reionisation Epoch Simulations (FLARES) II: The Photometric Properties of High-Redshift Galaxies

“…The S (Davé et al 2019) suite of simulations shows a higher normalisation of the SFR function than E at high-redshift. In Lovell et al (2021b) (where they post-processed S galaxies using P , (Narayanan et al 2021)) they find reasonable agreement with observationally inferred 850 m number counts, which they partly attribute to the higher SFRs. So the lower star formation rate at high-redshift is a likely cause of the deficit in IR luminosities in our model.…”

“…There are numerous codes (e.g. S (Jonsson 2006), R -3 (Dullemond et al 2012), (Camps & Baes 2015), P (Narayanan et al 2021), etc) available, most relying on sophisticated Monte-Carlo methods. For this study we use the publicly available code , version 9 (Camps & Baes 2020).…”

Effects of Spatial Discretization in Lyα Line Radiation Transfer Simulations

“…Forward modeling hence requires detailed dust RT calculations, a nontrivial undertaking (Steinacker et al 2013). In the past few years, several advanced tools for the forward modeling of simulated galaxies including dust have been developed (e.g., Jonsson 2006;Baes et al 2011;Robitaille 2011;Reissl et al 2016;Narayanan et al 2021). These tools have been applied to generate synthetic ultraviolet to submillimeter observations for many cosmological hydrodynamics simulations in order to test their fidelity or make detailed observational predictions (Torrey et al 2015;Camps et al 2016Trayford et al 2017;Liang et al 2018;Ma et al 2019;Rodriguez-Gomez et al 2019;Baes et al 2020;Shen et al 2020;Trčka et al 2020;Vogelsberger et al 2020b).…”

The IRX–β relation of high-redshift galaxies

“…Synthetic SED and multifrequency imaging of the simulated sample can be produced through dust radiative transfer (RT) modelling (e.g. Hayward & Smith 2015;Snyder et al 2015;Torrey et al 2015;Camps et al 2018;Narayanan et al 2021). Subsequently, various observational properties of galaxies can be derived and a direct comparison to observations becomes possible.…”