Skylight: a new code for general-relativistic ray-tracing and radiative transfer in arbitrary spacetimes

TL;DR

Skylight is a versatile numerical code that performs general-relativistic ray-tracing and radiative transfer in arbitrary spacetimes, enabling accurate modeling of spectra and images near compact objects for astrophysical observations.

Contribution

It introduces a new flexible code capable of handling arbitrary geometries and coordinate systems for relativistic radiative transfer, with two integrated schemes and validated test cases.

Findings

Successfully reproduces spectra and light curves from accretion disks and neutron star hot spots.

Validates the code with multiple test cases demonstrating accuracy.

Provides a tool for detailed astrophysical modeling near compact objects.

Abstract

To reproduce the observed spectra and light curves originated in the neighborhood of compact objects requires accurate relativistic ray-tracing codes. In this work, we present Skylight, a new numerical code for general-relativistic ray tracing and radiative transfer in arbitrary space-time geometries and coordinate systems. The code is capable of producing images, spectra, and light curves from astrophysical models of compact objects as seen by distant observers. We incorporate two different schemes, namely Monte Carlo radiative transfer, integrating geodesics from the astrophysical region to distant observers, and camera techniques with backwards integration from the observer to the emission region. The code is validated by successfully passing several test cases, among them: thin accretion disks and neutron star hot spot emission.