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# ICRC2015

July 29, 2015 to August 6, 2015
World Forum
Europe/Amsterdam timezone

## H.E.S.S. observations of LS 5039

Aug 1, 2015, 11:15 AM
15m
Amazon (World Forum)

### Amazon

#### World Forum

Churchillplein 10 2517 JW Den Haag The Netherlands
Oral contribution GA-EX

### Speaker

Christian Mariaud (LLR - Ecole Polytechnique)

### Description

LS 5039 is a gamma-ray binary system observed in a broad energy range, from radio to TeV energies, which exhibits both flux and spectral modulation folded on its orbital period of $\sim 3.9$~d. The X-ray and very-high-energy (VHE, E > 100 GeV) gamma-ray fluxes display a maximum/minimum at inferior/superior conjunction, with spectra becoming respectively harder/softer, a behavior which is completely reversed in the high-energy domain (HE, 0.1 < E < 100 GeV). The GeV spectrum cuts-off at a few GeVs, with a new hard component emerging at E > 10 GeV that is compatible with the low-energy tail of the TeV emission. The low 10 — 100 GeV flux, however, makes the GeV and TeV components difficult to reconcile within a single particle population emitting scenario. Here we report on new observations of LS 5039 conducted with the H.E.S.S. telescopes from 2009 to 2015. This new data set allows for an unprecedentedly-deep phase-folded coverage of the source at TeV energies, as well as an extension of the VHE spectral range down to $\sim 100$~GeV. Our results will be discussed in the context of VHE emission/absorption processes operating in the system and its connection with the emission observed at X-ray and GeV energies.
Collaboration H.E.S.S. 909

### Primary authors

Carlo Romoli (Dublin Institute for Advanced Studies) Christian Mariaud (LLR - Ecole Polytechnique) Mr Felix Aharonian (DIAS/MPIK) Guillaume Dubus (UJF Grenoble) Markus Boettcher (Centre for Space Research) Mathieu de Naurois (CNRS) Pol Bordas (Max-Planc-Institut fur Kernphysik) Victor Zabalza (University of Leicester)

### Presentation materials

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