Gamma-ray halo around 3C 279: looking through the Sun on the 8th of October

TL;DR

This paper explores how solar occultations of gamma-ray sources, especially 3C 279, can reveal detailed astrophysical information, including halo sizes, using data from EGRET and Fermi telescopes.

Contribution

It introduces a novel method to analyze gamma-ray halos through solar occultations, with specific application to 3C 279 using Fermi data.

Findings

Fermi can constrain the size of gamma-ray halos around 3C 279.

EGRET data provides insights into gamma-ray source structures.

Solar occultation technique offers a new approach for astrophysical measurements.

Abstract

We discuss how the solar occultations of bright sources of energetic gamma rays can be used to extract non-trivial physical and astrophysical information, including the angular size of the image when it is significantly smaller than the experiment's angular resolution. We analyze the EGRET data and discuss prospects for other instruments. The Fermi Gamma Ray Space Telescope will be able to constrain the size of a possible halo around 3C~279 from observations it makes on the 8th of October each year.