Browsing Faculty of Natural and Agricultural Sciences by Subject "radiation mechanisms: non-thermal"

Now showing items 1-10 of 22

    • Accelerating high-energy pulsar radiation codes 

      Venter, C.; De Jager, O.C. (IOP Publishing, 2010)
      Curvature radiation (CR) is believed to be a dominant mechanism for creating gamma-ray emission from pulsars and is emitted by relativistic particles that are constrained to move along curved magnetic field lines. Additionally, ...

    • Constraining a general-relativistic frame-dragging model for pulsed radiation from a population of millisecond pulsars in 47 Tucanae using GLAST LAT 

      Venter, C.; De Jager, O.C. (IOP Publications, 2008)
      Although only 22 millisecond pulsars (MSPs) are currently known to exist in the globular cluster (GC) 47 Tucanae, this cluster may harbor 30-60 MSPs, or even up to ∼200. In this Letter, we model the pulsed curvature radiation ...

    • Discovery of TeV y-ray emission from PKS 0447-439 and derivation of an upper limit on its redshift 

      Abramowski, A.; Casanova, S.; Krüger, P.P.; Pekeur, N.W.; Sheidaei, F.; Venter, C.; Vorster, M.; H.E.S.S. Collaboration (EDP Sciences, 2013)
      Very high-energy γ-ray emission from PKS 0447−439 was detected with the H.E.S.S. Cherenkov telescope array in December 2009. This blazar is one of the brightest extragalactic objects in the Fermi bright source list and has ...

    • Discovery of variable VHE γ-ray emission from the binary system 1FGL J1018.6-5856 

      Abramowski, A.; Böttcher, M.; Davids, I.D.; Ivascenko, A.; Krüger, P.P.; Pekeur, N.W.; Seyffert, A.S.; Spanier, F.; Sushch, I.; Van der Walt, D.J.; Venter, C.; H.E.S.S. Collaboration (EDP Sciences, 2015)
      Re-observations with the HESS telescope array of the very high-energy (VHE) source HESS J1018–589 A that is coincident with the Fermi-LAT γ-ray binary 1FGL J1018.6–5856 have resulted in a source detection significance of ...

    • Discovery of very high energy γ-ray emission from the BL Lacertae object PKS 0301-243 with H.E.S.S. 

      Abramowski, A.; Böttcher, M.; Casanova, S.; Krüger, P.P.; Pekeur, N.W.; Sushch, I.; Venter, C.; Vorster, M.; H.E.S.S. Collaboration (EDP Sciences, 2013)
      The active galactic nucleus PKS 0301−243 (z = 0.266) is a high-synchrotron-peaked BL Lac object that is detected at high energies (HE, 100 MeV < E < 100 GeV) by Fermi/LAT. This paper reports on the discovery of PKS 0301−243 ...

    • H.E.S.S. reveals a lack of TeV emission from the supernova remnant Puppis A 

      Abramowski, A.; Böttcher, M.; Davids, I.D.; Ivascenko, A.; Krüger, P.P.; Pekeur, N.W.; Spanier, F.; Sushch, I.; Venter, C.; Vorster, M.; H.E.S.S. Collaboration (EDP Sciences, 2015)
      Context: Puppis A is an interesting ~4 kyr-old supernova remnant (SNR) that shows strong evidence of interaction between the forward shock and a molecular cloud. It has been studied in detail from radio frequencies to ...

    • Hadronic models of blazars require a change of the accretion paradigm 

      Zdziarski, Andrzej A.; Böttcher, Markus (Oxford University Press, 2015)
      We study hadronic models of broad-band emission of jets in radio-loud active galactic nuclei, and their implications for the accretion in those sources. We show that the models that account for broad-band spectra of blazars ...

    • HESS and Fermi-LAT discovery of γ-rays from the blazar 1ES 1312-423 

      Abramowski, A.; Casanova, S.; Krüger, P.P.; Pekeur, N.W.; Sushch, I.; Venter, C.; Vorster, M.; H.E.S.S. Collaboration (Oxford Univ Press, 2013)
      A deep observation campaign carried out by the High Energy Stereoscopic System (HESS) on Centaurus A enabled the discovery of γ-rays from the blazar 1ES 1312−423, 2° away from the radio galaxy. With a differential flux at ...

    • HESS observations of the Carina nebula and its enigmatic colliding wind binary Eta Carinae 

      Abramowski, A.; Büsching, I.; Casanova, S.; Pekeur, N.W.; Sheidaei, F.; Venter, C.; Vorster, M.; H.E.S.S. Collaboration (Oxford Univ Press, 2012)
      The massive binary system Eta Carinae and the surrounding HII complex, the Carina nebula, are potential particle acceleration sites from which very high energy (VHE; E ≥ 100 GeV) γ -ray emission could be expected. This ...

    • Leptonic and hadronic modeling of Fermi-detected blazars 

      Böttcher, M.; Reimer, A.; Sweeney, K.; Prakash, A. (IOP Science, 2013)
      We describe new implementations of leptonic and hadronic models for the broadband emission from relativistic jets in active galactic nuclei in a temporary steady state. For the leptonic model, a temporary equilibrium between ...