Crepuscular Rays from the Highly Inclined Active Galactic Nucleus in IC 5063

TL;DR

This paper reports the discovery of large-scale radial rays in the active galaxy IC 5063, likely caused by dusty scattering and shadowing effects from the nucleus, similar to crepuscular rays observed near sunset.

Contribution

First observation of crepuscular-ray-like structures in an active galactic nucleus using HST, suggesting dust scattering and shadowing as their origin.

Findings

Radial rays extend over 11 kpc from the nucleus.

Bright rays are from dust scattering of AGN emission.

Dark rays may be shadowing by a warped torus.

Abstract

On Earth near sunset, the sun may cast "crepuscular rays" such that clouds near the horizon obscure the origin of light scattered in bright rays. In principle, AGN should be able to produce similar effects. Using new Hubble Space Telescope (HST) near-infrared and optical observations, we show that the active galaxy IC 5063 contains broad radial rays extending to $\gtrsim$11 kpc from the nucleus. We argue that the bright rays may arise from dusty scattering of continuum emission from the active nucleus, while the dark rays are due to shadowing near the nucleus, possibly by a warped torus. We also consider alternative AGN-related and stellar origins for the extended light.