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- Title
Detection of the Geminga pulsar with MAGIC hints at a power-law tail emission beyond 15 GeV.
- Authors
MAGIC Collaboration; Acciari, V. A.; Ansoldi, S.; Antonelli, L. A.; Arbet Engels, A.; Asano, K.; Baack, D.; Babić, A.; Baquero, A.; Barres de Almeida, U.; Barrio, J. A.; Becerra González, J.; Bednarek, W.; Bellizzi, L.; Bernardini, E.; Bernardos, M.; Berti, A.; Besenrieder, J.; Bhattacharyya, W.; Bigongiari, C.
- Abstract
We report the detection of pulsed gamma-ray emission from the Geminga pulsar (PSR J0633+1746) between 15 GeV and 75 GeV. This is the first time a middle-aged pulsar has been detected up to these energies. Observations were carried out with the MAGIC telescopes between 2017 and 2019 using the low-energy threshold Sum-Trigger-II system. After quality selection cuts, ∼80 h of observational data were used for this analysis. To compare with the emission at lower energies below the sensitivity range of MAGIC, 11 years of Fermi-LAT data above 100 MeV were also analysed. From the two pulses per rotation seen by Fermi-LAT, only the second one, P2, is detected in the MAGIC energy range, with a significance of 6.3σ. The spectrum measured by MAGIC is well-represented by a simple power law of spectral index Γ = 5.62 ± 0.54, which smoothly extends the Fermi-LAT spectrum. A joint fit to MAGIC and Fermi-LAT data rules out the existence of a sub-exponential cut-off in the combined energy range at the 3.6σ significance level. The power-law tail emission detected by MAGIC is interpreted as the transition from curvature radiation to Inverse Compton Scattering of particles accelerated in the northern outer gap.
- Subjects
PULSAR detection; COMPTON scattering; SCATTERING (Physics); MAGIC; TAILS; GAMMA ray astronomy; PULSARS
- Publication
Astronomy & Astrophysics / Astronomie et Astrophysique, 2020, Vol 643, p1
- ISSN
0004-6361
- Publication type
Article
- DOI
10.1051/0004-6361/202039131