Hadronic particle acceleration in the supernova remnant SN 1006 as traced by Fermi-LAT observations

¹ Univ. Bordeaux, CNRS, LP2i Bordeaux, UMR 5797, 33170 Gradignan, France
² AIM, CEA, CNRS, Université Paris-Saclay, Université de Paris, 91191 Gif sur Yvette, France
³ FSLAC IRL 2009, CNRS/IAC, La Laguna, Tenerife, Spain
⁴ Dipartimento di Fisica e Chimica E. Segrè, Università degli Studi di Palermo, Piazza del Parlamento 1, 90134 Palermo, Italy
⁵ INAF – Osservatorio Astronomico di Palermo, Piazza del Parlamento 1, 90134 Palermo, Italy

^★ Corresponding author; lemoine@lp2ib.in2p3.fr

Received: 21 August 2024
Accepted: 10 December 2024

Abstract

The supernova remnant SN 1006 is a source of high-energy particles detected in the radio, X-rays, and tera-electronvolt gamma rays. It was also announced as a source of gamma rays by Fermi-LAT, but only the north-east (NE) limb was detected at a significance level of more than 5σ. Using 15 years of Fermi-LAT observations and a thorough morphological analysis above 1 GeV, we report the detection of the NE rim at the 6σ level and the south–west (SW) rim at the 5.5σ level using radio templates from the GLEAM survey. The spectral analysis performed between 100 MeV and 1 TeV allows for the detection of a hard spectral index for the NE limb of 1.7 ± 0.1 ± 0.1, while the emission detected in the SW is reproduced well with a steeper spectral index of 2.2 ± 0.1 ± 0.1. A marginal detection (~3σ) of emission coincident with the bright north-west Hα filament is also described with a similar spectral index of ~2.1. We have successfully characterised the non-thermal multi-wavelength emission of the NE and SW limbs with a model in which inverse-Compton emission dominates in the NE, while proton-proton interactions becomes significant in the SW due to the enhanced density of the medium.