Discovery of the binary pulsar PSR B1259-63 in very-high-energy gamma rays around periastron with HESS.

Aharonian, F; Akhperjanian, AG; Aye, KM; Bazer-Bachi, AR; Beilicke, M; Benbow, W; Berge, D; Berghaus, P; Bernlohr, K; Boisson, C; Bolz, O; Braun, I; Breitling, F; Brown, AM; Gordo, JB; Chadwick, PM; Chounet, LM; Cornils, R; Costamante, L; Degrange, B; Djannati-Atai, A; Drury, LO; Dubus, G; Emmanoulopoulos, D; Espigat, P; Feinstein, F; Fleury, P; Fontaine, G; Fuchs, Y; Funk, S; Gallant, YA; Giebels, B; Gillessen, S; Glicenstein, JF; Goret, P; Hadjichristidis, C; Hauser, M; Heinzelmann, G; Henri, G; Hermann, G; Hinton, JA; Hofmann, W; Holleran, M; Horns, D; de Jager, OC; Johnston, S; Khelifi, B; Kirk, JG; Komin, N; Konopelko, A; Latham, IJ; Le Gallou, R; Lemiere, A; Lemoine-Goumard, M; Leroy, N; Martineau-Huynh, O; Lohse, T; Marcowith, A; Masterson, C; McComb, TJL; de Naurois, M; Nolan, SJ; Noutsos, A; Orford, KJ; Osborne, JL; Ouchrif, M; Panter, M; Pelletier, G; Pita, S; Puhlhofer, G; Punch, M; Raubenheimer, BC; Raue, M; Raux, J; Rayner, SM; Redondo, I; Reimer, A; Reimer, O; Ripken, J;...

Abstract

We report the discovery of very-high-energy (VHE) $\gamma$-ray emission of the binary system PSR B1259-63 / SS 2883 of a radio pulsar orbiting a massive, luminous Be star in a highly eccentric orbit. The observations around the 2004 periastron passage of the pulsar were performed with the four 13 m Cherenkov telescopes of the HESS experiment, recently installed in Namibia and in full operation since December 2003. Between February and June 2004, a $\gamma$-ray signal from the binary system was detected with a total significance above $13\sigma$. The flux was found to vary significantly on timescales of days which makes PSR B1259-63 the first variable galactic source of VHE $\gamma$-rays observed so far. Strong emission signals were observed in pre- and post-periastron phases with a flux minimum around periastron, followed by a gradual flux decrease in the months after. The measured time-averaged energy spectrum above a mean threshold energy of 380 GeV can be fitted by a simple power law $F_0(E/1\,\rm TeV)^{-\Gamma}$ with a photon index $\Gamma = 2.7\pm0.2_\mathrm{stat}\pm0.2_\mathrm{sys}$ and flux normalisation $F_0 = (1.3 \pm 0.1_\mathrm{stat} \pm 0.3_\mathrm{sys}) \times 10^{-12}\,\rm TeV^{-1}\,\rm cm^{-2}\,\rm s^{-1}$. This detection of VHE $\gamma$-rays provides unambiguous evidence for particle acceleration to multi-TeV energies in the binary system. In combination with coeval observations of the X-ray synchrotron emission by the RXTE and INTEGRAL instruments, and assuming the VHE $\gamma$-ray emission to be produced by the inverse Compton mechanism, the magnetic field strength can be directly estimated to be of the order of 1 G.

Citation

Aharonian, F., Akhperjanian, A., Aye, K., Bazer-Bachi, A., Beilicke, M., Benbow, W., …Wagner, S. (2005). Discovery of the binary pulsar PSR B1259-63 in very-high-energy gamma rays around periastron with HESS. Astronomy & Astrophysics, 442(1), 1-10. https://doi.org/10.1051/0004-6361%3A20052983

• Journal Article Type: Article
• Publication Date: 2005-10
• Journal: Astronomy and astrophysics.
• Print ISSN: 0004-6361
• Electronic ISSN: 1432-0746
• Publisher: EDP Sciences
• Peer Reviewed: Peer Reviewed
• Volume: 442
• Issue: 1
• Pages: 1-10
• DOI: https://doi.org/10.1051/0004-6361%3A20052983
• Keywords: gamma-rays : observations; stars : pulsars : individual : PSR B1259-63ATMOSPHERIC CHERENKOV TELESCOPES; INVERSE COMPTON EMISSION; PSRB1259-63 SYSTEM; X-RAY; RADIO-EMISSION; OPTICAL-SYSTEM; CRAB-NEBULA;STAR SYSTEM; RADIATION; PASSAGE
• Public URL: https://durham-repository.worktribe.com/output/1598469