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Type: Journal article
Title: Discovery of gamma-ray emission from the extragalactic pulsar wind nebula N 157B with HESS
Author: Maxted, N.
Nicholas, B.
Rowell, G.
Citation: Astronomy and Astrophysics, 2012; 545:L2-1-L2-5
Publisher: EDP Sciences
Issue Date: 2012
ISSN: 0004-6361
Statement of
H.E.S.S. Collaboration, A. Abramowski ... N. Maxted ... B. Nicholas ... G. Rowell ... et al.
Abstract: We present the significant detection of the first extragalactic pulsar wind nebula (PWN) detected in gamma rays, N 157B, located in the large Magellanic Cloud (LMC). Pulsars with high spin-down luminosity are found to power energised nebulae that emit gamma rays up to energies of several tens of TeV. N 157B is associated with PSR J0537−6910, which is the pulsar with the highest known spin-down luminosity. The High Energy Stereoscopic System telescope array observed this nebula on a yearly basis from 2004 to 2009 with a dead-time corrected exposure of 46 h. The gamma-ray spectrum between 600 GeV and 12 TeV is well-described by a pure power-law with a photon index of 2.8 ± 0.2(sub)stat ± 0.3(sub)syst and a normalisation at 1 TeV of (8.2 ± 0.8(sub)stat ± 2.5(sub)syst) × 10⁻¹³ cm-2 s⁻¹ TeV⁻¹. A leptonic multi-wavelength model shows that an energy of about 4 × 10⁴⁹ erg is stored in electrons and positrons. The apparent efficiency, which is the ratio of the TeV gamma-ray luminosity to the pulsar’s spin-down luminosity, 0.08% ± 0.01%, is comparable to those of PWNe found in the Milky Way. The detection of a PWN at such a large distance is possible due to the pulsar’s favourable spin-down luminosity and a bright infrared photon-field serving as an inverse-Compton-scattering target for accelerated leptons. By applying a calorimetric technique to these observations, the pulsar’s birth period is estimated to be shorter than 10 ms.
Keywords: gamma rays: general; pulsars: individual: PSR J0537-6910; ISM: supernova remnants; Magellanic Clouds
Rights: © ESO 2012
RMID: 0020123303
DOI: 10.1051/0004-6361/201219906
Appears in Collections:Chemistry and Physics publications

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