Issue |
A&A
Volume 673, May 2023
|
|
---|---|---|
Article Number | A148 | |
Number of page(s) | 15 | |
Section | Interstellar and circumstellar matter | |
DOI | https://doi.org/10.1051/0004-6361/202245776 | |
Published online | 24 May 2023 |
Detection of extended γ-ray emission around the Geminga pulsar with H.E.S.S.
1
Dublin Institute for Advanced Studies,
31 Fitzwilliam Place,
Dublin 2, Ireland
2
Max-Planck-Institut für Kernphysik,
PO Box 103980,
69029
Heidelberg, Germany
3
Landessternwarte, Universität Heidelberg,
Königstuhl,
69117
Heidelberg, Germany
4
Kapteyn Astronomical Institute, University of Groningen,
Landleven 12,
9747 AD
Groningen, The Netherlands
5
Laboratoire Leprince-Ringuet, École Polytechnique, CNRS, Institut Polytechnique de Paris,
91128
Palaiseau, France
6
University of Namibia, Department of Physics,
Private Bag 13301,
Windhoek
10005, Namibia
7
Centre for Space Research, North-West University,
Potchefstroom
2520, South Africa
8
DESY,
15738
Zeuthen, Germany
9
School of Physics, University of the Witwatersrand,
1 Jan Smuts Avenue, Braamfontein,
Johannesburg
2050, South Africa
10
Université de Paris, CNRS, Astroparticule et Cosmologie,
75013
Paris, France
11
Department of Physics and Electrical Engineering, Linnaeus University,
351 95
Växjö, Sweden
12
Institut für Physik, Humboldt-Universität zu Berlin,
Newtonstr. 15,
12489
Berlin, Germany
13
Institut für Astronomie und Astrophysik, Universität Tübingen,
Sand 1,
72076
Tübingen, Germany
14
Laboratoire Univers et Théories, Observatoire de Paris, Université PSL, CNRS, Université de Paris,
92190
Meudon, France
15
Sorbonne Université, Université Paris Diderot, Sorbonne Paris Cité, CNRS/IN2P3, Laboratoire de Physique Nucléaire et de Hautes Énergies, LPNHE,
4 Place Jussieu,
75252
Paris, France
16
IRFU, CEA, Université Paris-Saclay,
91191
Gif-sur-Yvette, France
17
Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen Centre for Astroparticle Physics,
Erwin-Rommel-Str. 1,
91058
Erlangen, Germany
18
Astronomical Observatory, The University of Warsaw,
Al. Ujazdowskie 4,
00-478
Warsaw, Poland
19
Université Savoie Mont Blanc, CNRS, Laboratoire d’Annecy de Physique des Particules - IN2P3,
74000
Annecy, France
20
Instytut Fizyki Jądrowej PAN,
ul. Radzikowskiego 152,
31-342
Kraków, Poland
21
Université Bordeaux, CNRS,
LP2I Bordeaux, UMR 5797,
33170
Gradignan, France
22
University of Oxford, Department of Physics,
Denys Wilkinson Building, Keble Road,
Oxford
OX1 3RH, UK
23
Laboratoire Univers et Particules de Montpellier, Université Montpellier, CNRS/IN2P3,
CC 72, Place Eugène Bataillon,
34095
Montpellier Cedex 5, France
24
Institut für Physik und Astronomie, Universität Potsdam,
Karl-Liebknecht-Strasse 24/25,
14476
Potsdam, Germany
25
School of Physical Sciences, University of Adelaide,
Adelaide
5005, Australia
26
Aix Marseille Université, CNRS/IN2P3, CPPM,
Marseille, France
27
School of Science, Western Sydney University,
Locked Bag 1797,
Penrith South DC, NSW
2751, Australia
28
Institut für Astro- und Teilchenphysik, Leopold-Franzens-Universität Innsbruck,
6020
Innsbruck, Austria
29
Universität Hamburg, Institut für Experimentalphysik,
Luruper Chaussee 149,
D 22761
Hamburg, Germany
30
Obserwatorium Astronomiczne, Uniwersytet Jagielloński,
ul. Orla 171,
30-244
Kraków, Poland
31
Institute of Astronomy, Faculty of Physics, Astronomy and Informatics, Nicolaus Copernicus University,
Grudziadzka 5,
87-100
Torun, Poland
32
Nicolaus Copernicus Astronomical Center, Polish Academy of Sciences,
ul. Bartycka 18,
00-716
Warsaw, Poland
33
GRAPPA, Anton Pannekoek Institute for Astronomy, University of Amsterdam,
Science Park 904,
1098 XH
Amsterdam, The Netherlands
34
Department of Physics, University of the Free State,
PO Box 339,
Bloemfontein
9300, South Africa
35
Department of Physics and Astronomy, The University of Leicester,
University Road,
Leicester
LE1 7RH, UK
36
Yerevan Physics Institute,
2 Alikhanian Brothers St.,
375036
Yerevan, Armenia
37
Department of Physics, Konan University,
8-9-1 Okamoto, Higashinada, Kobe,
Hyogo
658-8501, Japan
38
Kavli Institute for the Physics and Mathematics of the Universe (WPI), The University of Tokyo Institutes for Advanced Study (UTIAS), The University of Tokyo,
5-1-5 Kashiwa-no-Ha, Kashiwa,
Chiba,
277-8583, Japan
39
RIKEN,
2-1 Hirosawa, Wako,
Saitama
351-0198, Japan
Received:
23
December
2022
Accepted:
4
April
2023
Geminga is an enigmatic radio-quiet γ-ray pulsar located at a mere 250 pc distance from Earth. Extended very-high-energy γ-ray emission around the pulsar was discovered by Milagro and later confirmed by HAWC, which are both water Cherenkov detector-based experiments. However, evidence for the Geminga pulsar wind nebula in gamma rays has long evaded detection by imaging atmospheric Cherenkov telescopes (IACTs) despite targeted observations. The detection of γ-ray emission on angular scales ≳2º poses a considerable challenge for the background estimation in IACT data analysis. With recent developments in understanding the complementary background estimation techniques of water Cherenkov and atmospheric Cherenkov instruments, the H.E.S.S. IACT array can now confirm the detection of highly extended γ-ray emission around the Geminga pulsar with a radius of at least 3º in the energy range 0.5–40 TeV. We find no indications for statistically significant asymmetries or energy-dependent morphology. A flux normalisation of (2.8 ± 0.7) × 10−12 cm−2 s−1 TeV−1 at 1 TeV is obtained within a 1º radius region around the pulsar. To investigate the particle transport within the halo of energetic leptons around the pulsar, we fitted an electron diffusion model to the data. The normalisation of the diffusion coefficient obtained of D0 = 7.6−1.2+1.5 × 1027 cm2 s−1, at an electron energy of 100 TeV, is compatible with values previously reported for the pulsar halo around Geminga, which is considerably below the Galactic average.
Key words: gamma rays: general / acceleration of particles / pulsars: general / diffusion
© The Authors 2023
Open Access article, published by EDP Sciences, under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
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