Image of a black hole illuminated by a parabolic screen

TL;DR

This paper presents an analytical model of a parabolic screen illuminating a black hole, revealing unique shadow structures influenced by gravitational lensing and the screen's geometry, with implications for black hole imaging.

Contribution

The study introduces a novel analytical model of a parabolic screen illuminating a black hole, avoiding edge effects and analyzing shadow structures for Schwarzschild and Kerr black holes.

Findings

Black hole shadows differ significantly with the parabolic screen model.

Photon emission from the back side of the screen affects shadow appearance.

Shadow shapes vary with observer angle and black hole spin.

Abstract

An analytical model of a parabolic screen illuminating a black hole is proposed. This allows to avoid naturally the appearance of edge effects associated with photons moving along the plane of the screen. The temperature distribution along the radius of the screen corresponds to that for a relativistic disk (Novikov-Thorne disk). It is shown that the structure of the emerging black hole shadow differs significantly from the case when the photon source is a remote screen, since in the model considered, the photons subjected to strong gravitational lensing of the black hole are emitted by the "back side" of the screen, which would not be visible in the absence of a black hole. In the thin screen approximation, the shadow of a Schwarzschild black hole has been constructed in cases when the angle between the axis of symmetry of the illuminating screen and the direction towards the observer is 5, 30, 60, and 80 degrees. For the Kerr black hole, images are shown for angles of 60 and 80 degrees.