Fermi Establishes Classical Novae as a Distinct Class of Gamma-Ray Sources

TL;DR

This paper demonstrates that classical novae are a distinct class of gamma-ray sources, revealing unexpected high-energy particle acceleration processes during thermonuclear explosions on white dwarfs.

Contribution

It establishes classical novae as a new, separate class of gamma-ray emitters, expanding the understanding of high-energy phenomena in our galaxy.

Findings

Classical novae are gamma-ray sources with soft spectra.

Detected gamma-ray novae last 2-3 weeks.

High-energy particle acceleration occurs during nova explosions.

Abstract

A classical nova results from runaway thermonuclear explosions on the surface of a white dwarf that accretes matter from a low-mass main-sequence stellar companion. In 2012 and 2013, three novae were detected in gamma rays and stood in contrast to the first gamma-ray detected nova V407 Cygni 2010, which belongs to a rare class of symbiotic binary systems. Despite likely differences in the compositions and masses of their white dwarf progenitors, the three classical novae are similarly characterized as soft spectrum transient gamma-ray sources detected over 2-3 week durations. The gamma-ray detections point to unexpected high-energy particle acceleration processes linked to the mass ejection from thermonuclear explosions in an unanticipated class of Galactic gamma-ray sources.