Observing supermassive black holes in virtual reality

Jordy Davelaar,Ziri Younsi,Heino Falcke,Daniel Kok,Monika Mościbrodzka,Thomas Bronzwaer

doi:10.1186/s40668-018-0023-7

Abstract

We present a 360∘ (i.e., 4π steradian) general-relativistic ray-tracing and radiative transfer calculations of accreting supermassive black holes. We perform state-of-the-art three-dimensional general-relativistic magnetohydrodynamical simulations using the BHAC code, subsequently post-processing this data with the radiative transfer code RAPTOR. All relativistic and general-relativistic effects, such as Doppler boosting and gravitational redshift, as well as geometrical effects due to the local gravitational field and the observer’s changing position and state of motion, are therefore calculated self-consistently. Synthetic images at four astronomically-relevant observing frequencies are generated from the perspective of an observer with a full 360∘ view inside the accretion flow, who is advected with the flow as it evolves. As an example we calculated images based on recent best-fit models of observations of Sagittarius A*. These images are combined to generate a complete 360∘ Virtual Reality movie of the surrounding environment of the black hole and its event horizon. Our approach also enables the calculation of the local luminosity received at a given fluid element in the accretion flow, providing important applications in, e.g., radiation feedback calculations onto black hole accretion flows. In addition to scientific applications, the 360∘ Virtual Reality movies we present also represent a new medium through which to interactively communicate black hole physics to a wider audience, serving as a powerful educational tool.

Highlights

Active Galactic Nuclei (AGN) are strong sources of electromagnetic radiation from the radio up to γ -rays
Synthetic observational data was generated by ray-tracing radiative transfer codes which calculate the emission originating from the accreting black hole and measured by a far away observer by solving the equations of radiative transfer along geodesics, i.e., the paths of photons as they propagate around the black hole in either static spacetimes (e.g. Broderick 2006; Noble et al 2007; Dexter and Agol 2009; Shcherbakov and Huang 2011; Vincent et al 2011; Younsi et al 2012; Chan et al 2013, 2017; Younsi and Wu 2015; Dexter 2016; Schnittman et al 2016; Moscibrodzka and Gammie 2017; Bronzwaer et al 2018) or dynamical spacetimes (Kelly et al 2017; Schnittman et al 2018)
As an example astrophysical case we model the supermassive black hole Sgr A*, the methods presented in this work are generally applicable to any black hole as long as the radiation field’s feedback onto the accreting plasma has a negligible effect on the plasma’s magnetohydrodynamical properties, which is the case for Low Luminosity AGNs or low/hard state X-ray binaries

Summary

Introduction

Active Galactic Nuclei (AGN) are strong sources of electromagnetic radiation from the radio up to γ -rays. As an example astrophysical case we model the supermassive black hole Sgr A*, the methods presented in this work are generally applicable to any black hole as long as the radiation field’s feedback onto the accreting plasma has a negligible effect on the plasma’s magnetohydrodynamical properties, which is the case for Low Luminosity AGNs or low/hard state X-ray binaries. The trajectory of this camera consists of two phases: a hovering trajectory, where the observer moves with a.

Methods

Black holes and gravitational lensing

Discussion and conclusion