Issue |
A&A
Volume 627, July 2019
|
|
---|---|---|
Article Number | A100 | |
Number of page(s) | 16 | |
Section | Interstellar and circumstellar matter | |
DOI | https://doi.org/10.1051/0004-6361/201935458 | |
Published online | 08 July 2019 |
H.E.S.S. and Suzaku observations of the Vela X pulsar wind nebula★
1
Centre for Space Research, North-West University,
Potchefstroom
2520, South Africa
2
Institut für Experimentalphysik, Universität Hamburg,
Luruper Chaussee 149,
22761
Hamburg, Germany
3
Max-Planck-Institut für Kernphysik,
PO Box 103980,
69029
Heidelberg,
Germany
4
Dublin Institute for Advanced Studies,
31 Fitzwilliam Place,
Dublin 2,
Ireland
5
High Energy Astrophysics Laboratory,
RAU,
123 Hovsep Emin St Yerevan
0051, Armenia
6
Yerevan Physics Institute,
2 Alikhanian Brothers St.,
375036
Yerevan,
Armenia
7
Institut für Physik, Humboldt-Universität zu Berlin,
Newtonstr. 15,
12489
Berlin, Germany
8
Department of Physics, University of Namibia, Private Bag 13301,
Windhoek
12010, Namibia
9
GRAPPA, Anton Pannekoek Institute for Astronomy, University of Amsterdam,
Science Park 904,
1098
XH Amsterdam, The Netherlands
10
Department of Physics and Electrical Engineering, Linnaeus University,
351 95
Växjö,
Sweden
11
Institut für Theoretische Physik, Lehrstuhl IV: Weltraum und Astrophysik, Ruhr-Universität Bochum,
44780
Bochum, Germany
12
Institut für Astro- und Teilchenphysik, Leopold-Franzens-Universität Innsbruck,
6020
Innsbruck, Austria
13
School of Physical Sciences, University of Adelaide,
Adelaide
5005, Australia
14
LUTH, Observatoire de Paris, PSL Research University, CNRS, Université Paris Diderot,
5 place Jules Janssen,
92190
Meudon, France
15
CNRS/IN2P3, Laboratoire de Physique Nucléaire et de Hautes Energies, LPNHE, Sorbonne Université, Université Paris Diderot, Sorbonne Paris Cité,
4 place Jussieu,
75l252
Paris,
France
16
Laboratoire Univers et Particules de Montpellier, Université Montpellier, CNRS/IN2P3,
CC 72, Place Eugène Bataillon,
34095
Montpellier Cedex 5, France
17
IRFU, CEA, Université Paris-Saclay,
91191
Gif-sur-Yvette, France
18
Astronomical Observatory, The University of Warsaw,
Al. Ujazdowskie 4,
00-478
Warsaw,
Poland
19
Aix-Marseille Université, CNRS/IN2P3, CPPM,
Marseille, France
20
Instytut Fizyki Ja̧drowej PAN, ul. Radzikowskiego 152,
31-342
Kraków,
Poland
21
School of Physics, University of the Witwatersrand, 1 Jan Smuts Avenue,
Braamfontein,
Johannesburg
2050
South Africa
22
Laboratoire d’Annecy de Physique des Particules, Université Grenoble Alpes, Université Savoie Mont Blanc, CNRS, LAPP,
74000
Annecy,
France
23
Landessternwarte, Universität Heidelberg, Königstuhl,
69117
Heidelberg, Germany
24
CNRS/IN2P3, Centre d’Études Nucléaires de Bordeaux Gradignan, Université Bordeaux,
33175
Gradignan, France
25
Institut für Astronomie und Astrophysik, Universität Tübingen,
Sand 1,
72076
Tübingen, Germany
26
Laboratoire Leprince-Ringuet, Ecole Polytechnique, CNRS/IN2P3,
91128
Palaiseau, France
27
APC, AstroParticule et Cosmologie, Université Paris Diderot, CNRS/IN2P3, CEA/Irfu,
Observatoire de Paris, Sorbonne Paris Cité, 10, rue Alice Domon et Léonie Duquet,
75205
Paris Cedex 13,
France
28
Université Grenoble Alpes, CNRS, IPAG,
38000
Grenoble, France
29
Department of Physics and Astronomy, The University of Leicester, University Road,
Leicester,
LE1 7RH, UK
30
Nicolaus Copernicus Astronomical Center, Polish Academy of Sciences, ul. Bartycka 18,
00-716
Warsaw,
Poland
31
Institut für Physik und Astronomie, Universität Potsdam,
Karl-Liebknecht-Strasse 24/25,
14476
Potsdam, Germany
32
Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen Centre for Astroparticle Physics,
Erwin-Rommel-Str. 1,
91058
Erlangen, Germany
33
DESY,
15738
Zeuthen,
Germany
34
Obserwatorium Astronomiczne, Uniwersytet Jagielloński,
ul. Orla 171,
30-244
Kraków, Poland
35
Centre for Astronomy, Faculty of Physics, Astronomy and Informatics, Nicolaus Copernicus University,
Grudziadzka 5,
87-100
Torun, Poland
36
Department of Physics, University of the Free State,
PO Box 339,
Bloemfontein
9300, South Africa
37
Department of Physics, Rikkyo University, 3-34-1 Nishi-Ikebukuro, Toshima-ku,
Tokyo
171-8501, Japan
38
Kavli Institute for the Physics and Mathematics of the Universe (Kavli IPMU), The University of Tokyo Institutes for Advanced Study (UTIAS), The University of Tokyo,
5-1-5 Kashiwa-no-Ha,
Kashiwa City,
Chiba
277-8583, Japan
39
Department of Physics, The University of Tokyo,
7-3-1 Hongo,
Bunkyo-ku,
Tokyo
113-0033, Japan
40
RIKEN,
2-1 Hirosawa,
Wako,
Saitama
351-0198, Japan
41
School of Science, The University of New South Wales, Australian Defence Force Academy,
Canberra
2610, Australia
42
Now at Institut de Ciències del Cosmos (ICC UB), Universitat de Barcelona (IEEC-UB), Martí Franquès 1,
E08028
Barcelona, Spain
43
Now at Physik Institut, Universität Zürich,
Winterthurerstrasse 190,
CH-8057
Zürich, Switzerland
44
Now at IRAP, Université de Toulouse, CNRS, UPS, CNES, 9 avenue Colonel-Roche,
31028
Toulouse,
Cedex 4,
France
e-mail: luigi.tibaldo@irap.omp.eu
Received:
13
March
2019
Accepted:
17
May
2019
Context. Pulsar wind nebulae (PWNe) represent the most prominent population of Galactic very-high-energy gamma-ray sources and are thought to be an efficient source of leptonic cosmic rays. Vela X is a nearby middle-aged PWN, which shows bright X-ray and TeV gamma-ray emission towards an elongated structure called the cocoon.
Aims. Since TeV emission is likely inverse-Compton emission of electrons, predominantly from interactions with the cosmic microwave background, while X-ray emission is synchrotron radiation of the same electrons, we aim to derive the properties of the relativistic particles and of magnetic fields with minimal modelling.
Methods. We used data from the Suzaku XIS to derive the spectra from three compact regions in Vela X covering distances from 0.3 to 4 pc from the pulsar along the cocoon. We obtained gamma-ray spectra of the same regions from H.E.S.S. observations and fitted a radiative model to the multi-wavelength spectra.
Results. The TeV electron spectra and magnetic field strengths are consistent within the uncertainties for the three regions, with energy densities of the order 10−12 erg cm−3. The data indicate the presence of a cutoff in the electron spectrum at energies of ~ 100 TeV and a magnetic field strength of ~6 μG. Constraints on the presence of turbulent magnetic fields are weak.
Conclusions. The pressure of TeV electrons and magnetic fields in the cocoon is dynamically negligible, requiring the presence of another dominant pressure component to balance the pulsar wind at the termination shock. Sub-TeV electrons cannot completely account for the missing pressure, which may be provided either by relativistic ions or from mixing of the ejecta with the pulsar wind. The electron spectra are consistent with expectations from transport scenarios dominated either by advection via the reverse shock or by diffusion, but for the latter the role of radiative losses near the termination shock needs to be further investigated in the light of the measured cutoff energies. Constraints on turbulent magnetic fields and the shape of the electron cutoff can be improved by spectral measurements in the energy range ≳ 10 keV.
Key words: stars: winds, outflows / gamma rays: stars / radiation mechanisms: non-thermal / acceleration of particles / pulsars: individual: PSR B0833-45
Spectra are only available at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/627/A100
© H.E.S.S. Collaboration 2019
Open Access article, published by EDP Sciences, under the terms of the Creative Commons Attribution License (http://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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