TeV Solar Gamma Rays as a probe for the Solar Internetwork Magnetic Fields

TL;DR

This paper proposes that TeV solar gamma rays, affected by solar magnetic fields, can serve as a new probe to study magnetic fields below the solar photosphere, which are otherwise difficult to measure directly.

Contribution

The study introduces a semi-analytic model demonstrating how large horizontal magnetic fields below the photosphere influence TeV gamma rays, offering a novel method to probe these hidden magnetic regions.

Findings

Magnetic fields below the photosphere can explain observed TeV gamma rays.

High-energy gamma rays are significantly affected by subsurface magnetic fields.

Proposes gamma rays as a new diagnostic tool for solar magnetic fields.

Abstract

The magnetic fields that emerge from beneath the solar surface and permeate the solar atmosphere are the key drivers of space weather and, thus, understanding them is important to human society. Direct observations, used to measure magnetic fields, can only probe the magnetic fields in the photosphere and above, far from the regions the magnetic fields are being enhanced by the solar dynamo. Solar gamma rays produced by cosmic rays interacting with the solar atmosphere have been detected from GeV to TeV energy range, and revealed that they are significantly affected by solar magnetic fields. However, much of the observations are yet to be explained by a physical model. Using a semi-analytic model, we show that magnetic fields at and below the photosphere with a large horizontal component could explain the $\sim$1 TeV solar gamma rays observed by HAWC. This could allow high-energy solar gamma rays to be a novel probe for magnetic fields below the photosphere.