Probing the gamma-ray emission from HESS J1834-087 using H.E.S.S. and Fermi LAT observations

Abstract

Previous observations with HESS have revealed the existence of an extended very-high-energy (VHE; E>100 GeV) gamma-ray source, HESS J1834-087, coincident with the SNR W41. The origin of the gamma-ray emission has been further investigated with HESS and the Fermi-LAT. The gamma-ray data provided by 61h (HESS) and 4 yrs (Fermi LAT) of observations cover over 5 decades in energy (1.8GeV - 30TeV). The morphology and spectrum of the TeV and GeV sources have been studied and multi-wavelength data have been used to investigate the origin of the observed emission. The TeV source can be modeled with a sum of two components: one point-like and one significantly extended (sig_TeV = 0.17°), both centered on SNR W41 and exhibiting spectra described by a power law of index 2.6. The GeV source detected with Fermi is extended (sig_GeV =0.15°) and morphologically matches the VHE emission. Its spectrum can be described by a power-law with index 2.15 and joins smoothly the one of the whole TeV source. A break appears in the spectra around 100 GeV. Two main scenarios are proposed to explain the emission: a pulsar wind nebula (PWN) or the interaction of SNR W41 with a molecular cloud. X-ray observations suggest the presence of a point-like source (pulsar candidate) near the center of the SNR and non-thermal X-ray diffuse emission which could arise from a potential PWN. The PWN scenario is supported by the match of of the TeV and GeV positions with the putative pulsar. However, the overall spectrum is reproduced by a 1-zone leptonic model only if an excess of low-energy electrons is injected by a high spin-down power pulsar. This low-energy component is not needed if the point-like TeV source is unrelated to the extended GeV and TeV sources. The interacting SNR scenario is supported by the spatial coincidence between the gamma-ray sources, the detection of OH maser lines and the hadronic modeling.

12 pages, 8 figures, Accepted for publication in Astronomy & Astrophysics

References in corpus (10)

• Observations of the Crab Nebula with H.E.S.S
• The Boston University-Five College Radio Astronomy Observatory Galactic Ring Survey
• Particle acceleration in relativistic collisionless shocks: Fermi process at last?
• Background Modelling in Very-High-Energy gamma-ray Astronomy
• Detection of 16 Gamma-Ray Pulsars Through Blind Frequency Searches Using the Fermi LAT
• Pulsar Wind Nebulae in the Chandra Era
• First detection of a VHE gamma-ray spectral maximum from a Cosmic source: H.E.S.S. discovery of the Vela X nebula
• Pulsar Timing for the Fermi Gamma-ray Space Telescope
• The Distances of SNR W41 and overlapping HII regions
• VLA and XMM-Newton observations of the SNR W41/TeV Gamma-ray source HESS J1834-087

Cited by in corpus (9)

• Background model systematics for the Fermi GeV excess
• Learning About the Magnetar Swift J1834.9-0846 from its Wind Nebula
• Gamma-ray upper limits on magnetars with 6 years of Fermi-LAT observations
• Observational constraints on the maximum energies of accelerated particles in supernova remnants: low maximum energies and a large variety
• Towards observing reverberating and superefficient pulsar wind nebulae
• Study on the escape timescale of high-energy particles from supernova remnants through thermal X-ray properties
• The Interaction Between the Supernova Remnant W41 and the Filamentary Infrared Dark Cloud G23.33-0.30
• H.E.S.S.: The High Energy Stereoscopic System
• Multiwavelength study of non-thermal emission in the Swift J1834.9-0846/W41 region