Unveiling extended gamma-ray emission around HESS J1813-178

F Aharonian , F. Ait Benkhali , J Aschersleben , H Ashkar (1) , M Backes , A Baktash , V. Barbosa Martins , J Barnard , R Batzofin , Y Becherini (2) , D Berge , K Bernlöhr , B Bi , M Böttcher , C Boisson (3) , J Bolmont (4) , M de Bony de Lavergne (5) , J Borowska , M Bouyahiaoui , M Breuhaus , R Brose , F Brun (5) , B Bruno , T Bulik , C Burger-Scheidlin , S Caroff (6) , S Casanova , R Cecil , J Celic , M Cerruti (2) , P Chambery (7) , T Chand , A Chen , J Chibueze , O Chibueze , G Cotter , J. Damascene Mbarubucyeye , A Djannati-Ataï (2) , A Dmytriiev , V Doroshenko , S Einecke , J.-P Ernenwein (8) , K Feijen (2) , M Filipovic , G Fontaine (1) , M Füßling , S Funk , S Gabici (2) , Y.A Gallant (9) , S Ghafourizadeh , G Giavitto , D Glawion , J.F Glicenstein (5) , P Goswami (2) , G Grolleron (4) , M.-H Grondin (7) , J.A Hinton , W Hofmann , T.L Holch , M Holler , M Jamrozy , F Jankowsky , V Joshi , I Jung-Richardt , K Katarzynski , R Khatoon , B Khélifi (2) , S Klepser , W Kluzniak , Nu Komin , K Kosack (5) , D Kostunin , A Kundu , R.G Lang , S Le Stum (8) , F Leitl , A Lemière (2) , M Lemoine-Goumard (7) , J.-P Lenain (4) , F Leuschner , J Mackey , D Malyshev , D Malyshev , V Marandon (5) , P Marinos , G Martí-Devesa , R Marx , A Mehta , A Mitchell , R Moderski , L Mohrmann , A Montanari , E Moulin (5) , T Murach , M de Naurois (1) , J Niemiec , A. Priyana Noel , P O'Brien , S Ohm , L Olivera-Nieto , E de Ona Wilhelmi , M Ostrowski , S Panny , M Panter , R.D Parsons , D.A Prokhorov , G Pühlhofer , M Punch (2) , A Quirrenbach , M Regeard (2) , P Reichherzer (5) , A Reimer , O Reimer , H Ren , M Renaud (9) , B Reville , F Rieger , G Roellinghoff , B Rudak , V Sahakian , H Salzmann , M Sasaki , F Schüssler (5) , H.M Schutte , J.N.S Shapopi , A Specovius , S Spencer , R Steenkamp , S Steinmassl , C Steppa , I Sushch , H Suzuki , T Takahashi , T Tanaka , R Terrier (2) , M Tluczykont , N Tsuji , T Unbehaun , C van Eldik , M Vecchi , J Veh , C Venter , J Vink , T Wach , S.J Wagner , A Wierzcholska , M Zacharias , D Zargaryan , A.A Zdziarski , S Zouari (2) , N Zywucka

1 LLR - Laboratoire Leprince-Ringuet
2 APC (UMR_7164) - AstroParticule et Cosmologie
3 LUTH (UMR_8102) - Laboratoire Univers et Théories
4 LPNHE (UMR_7585) - Laboratoire de Physique Nucléaire et de Hautes Énergies
5 IRFU - Institut de Recherches sur les lois Fondamentales de l'Univers
6 LAPP - Laboratoire d'Annecy de Physique des Particules
7 LP2I - Bordeaux - Laboratoire de Physique des Deux Infinis Bordeaux
8 CPPM - Centre de Physique des Particules de Marseille
9 LUPM - Laboratoire Univers et Particules de Montpellier

HESS J1813$-$178 is a very-high-energy $\gamma$-ray source spatially coincident with the young and energetic pulsar PSR J1813$-$1749 and thought to be associated with its pulsar wind nebula (PWN). Recently, evidence for extended high-energy emission in the vicinity of the pulsar has been revealed in the Fermi Large Area Telescope (LAT) data. This motivates revisiting the HESS J1813$-$178 region, taking advantage of improved analysis methods and an extended data set. Using data taken by the High Energy Stereoscopic System (H.E.S.S.) experiment and the Fermi-LAT, we aim to describe the $\gamma$-ray emission in the region with a consistent model, to provide insights into its origin. We performed a likelihood-based analysis on 32 hours of H.E.S.S. data and 12 years of Fermi-LAT data and fit a spectro-morphological model to the combined datasets. These results allowed us to develop a physical model for the origin of the observed $\gamma$-ray emission in the region. In addition to the compact very-high-energy $\gamma$-ray emission centered on the pulsar, we find a significant yet previously undetected component along the Galactic plane. With Fermi-LAT data, we confirm extended high-energy emission consistent with the position and elongation of the extended emission observed with H.E.S.S. These results establish a consistent description of the emission in the region from GeV energies to several tens of TeV. This study suggests that HESS J1813$-$178 is associated with a $\gamma$-ray PWN powered by PSR J1813$-$1749. A possible origin of the extended emission component is inverse Compton emission from electrons and positrons that have escaped the confines of the pulsar and form a halo around the PWN.

Domaines: Astrophysique [astro-ph]

F Aharonian, F. Ait Benkhali, J Aschersleben, H Ashkar, M Backes, et al.. Unveiling extended gamma-ray emission around HESS J1813-178. Astron.Astrophys., 2024, 686, pp.A149. ⟨10.1051/0004-6361/202348374⟩. ⟨hal-04537734⟩