Study of high-energy particle acceleration in Tycho with gamma-ray observations

TL;DR

This paper presents an updated analysis of gamma-ray observations of Tycho supernova remnant, providing new insights into cosmic-ray acceleration with increased exposure and improved low-energy sensitivity data from VERITAS and Fermi-LAT.

Contribution

It offers the first combined analysis of extensive gamma-ray data from VERITAS and Fermi-LAT for Tycho, enhancing understanding of particle acceleration mechanisms.

Findings

Extended gamma-ray data set with doubled exposure.

Improved low-energy sensitivity in TeV measurements.

Insights into hadronic cosmic-ray acceleration in Tycho.

Abstract

Gamma-ray emission from supernova remnants (SNRs) can provide a unique window to observe the cosmic-ray acceleration believed to take place in these objects. Tycho is an especially good target for investigating hadronic cosmic-ray acceleration and interactions because it is a young type Ia SNR that is well studied in other wavelengths, and it is located in a relatively clean environment. Several different theoretical models have been advanced to explain the broadband spectral energy emission of Tycho from radio to the gamma-ray emission detected by the Fermi-LAT in the GeV and by VERITAS in the TeV. We will present an update on the high-energy gamma-ray studies of Tycho with $\sim150$ hours of VERITAS and $\sim77$ months of the Fermi-LAT observations, which represents about a factor of two increase in exposure over previously published data. VERITAS data also include exposure with an upgraded camera, which made it possible to extend the TeV measurements toward lower energy, thanks to its improved low energy sensitivity. We will interpret these observations in the context of the particle acceleration in Tycho and proposed emission models.