Now showing items 1-20 of 24

    • The 2014 TeV γ-ray flare of Mrk 501 seen with H.E.S.S.: temporal and spectral constraints on Lorentz invariance violation 

      Abdalla, H.; Arcaro, C.; Backes, M.; Barnard, M.; Böttcher, M.; Chandra, S.; Krüger, P.P.; Ndiyavala, H.; Seyffert, A.S.; Spanier, F.; Van der Walt, D.J.; Van Rensburg, C.; Venter, C.; Wadiasingh, Z.; Zacharias, M. (IOP Publishing, 2019)
      The blazar Mrk 501 (z = 0.034) was observed at very-high-energy (VHE, E gsim 100 GeV) gamma-ray wavelengths during a bright flare on the night of 2014 June 23–24 (MJD 56832) with the H.E.S.S. phase-II array of Cherenkov ...
    • Characterising the VHE diffuse emission in the central 200 parsecs of our Galaxy with H.E.S.S. 

      Abdalla, H.; Barnard, M.; Böttcher, M.; Davids, I.D.; Garrigoux, T.; Ivascenko, A.; Krüger, P.P.; Pekeur, N.W.; Richter, S.; Seyffert, A.S.; Spanier, F.; Sushch, I.; Van der Walt, D.J.; Van Rensburg, C.; Venter, C.; Wadiasingh, Z.; Zacharias, M. (EDP Sciences, 2018)
      The diffuse very high-energy (VHE; >100 GeV) γ-ray emission observed in the central 200 pc of the Milky Way by H.E.S.S. was found to follow dense matter distribution in the central molecular zone (CMZ) up to a longitudinal ...
    • Constraints on particle acceleration in SS433/W50 from MAGIC and H.E.S.S. observations 

      Ahnen, M.L.; Munar-Adrover, P.; Abdalla, H.; Barnard, M.; Böttcher, M.; Davids, I.D.; Garrigoux, T.; Ivascenko, A.; Krüger, P.P.; Pekeur, N.W.; Richter, S.; Van der Walt, D.J.; Van Rensburg, C.; Venter, C.; Wadiasingh, Z.; Seyffert, A.S.; Spanier, F.; Sushch, I. (EDP Sciences, 2018)
      Context. The large jet kinetic power and non-thermal processes occurring in the microquasar SS 433 make this source a good candidate for a very high-energy (VHE) gamma-ray emitter. Gamma-ray fluxes above the sensitivity ...
    • Deeper H.E.S.S. observations of Vela Junior (RX J0852.0-4622): morphology studies and resolved spectroscopy 

      Abdalla, H.; Barnard, M.; Böttcher, M.; Davids, I.D.; Garrigoux, T.; Ivascenko, A.; Krüger, P.P.; Pekeur, N.W.; Richter, S.; Seyffert, A.S.; Sushch, I.; Spanier, F.; Van der Walt, D.J.; Van Rensburg, C.; Venter, C.; Wadiasingh, Z. (EDP Sciences, 2018)
      Aims. We study γ-ray emission from the shell-type supernova remnant (SNR) RX J0852.0−4622 to better characterize its spectral properties and its distribution over the SNR. Methods. The analysis of an extended High Energy ...
    • Detection of variable VHE γ-ray emission from the extra-galactic γ-ray binary LMC P3 

      Abdalla, H.; Barnard, M.; Böttcher, M.; Garrigoux, T.; Ivascenko, A.; Krüger, P.P.; Ndiyavala, H.; Pekeur, N.W.; Seyffert, A.S.; Spanier, F.; Sushch, I.; Van der Walt, D.J.; Van Rensburg, C.; Venter, C.; Wadiasingh, Z.; Zacharias, M. (EDP Sciences, 2018)
      Context. Recently, the high-energy (HE, 0.1–100 GeV) γ-ray emission from the object LMC P3 in the Large Magellanic Cloud (LMC) has been discovered to be modulated with a 10.3-day period, making it the first extra-galactic ...
    • Extended VHE γ-ray emission towards SGR1806-20, LBV 1806-20, and stellar cluster Cl* 1806-20 

      Abdalla, H.; Barnard, M.; Böttcher, M.; Davids, I.D.; Garrigoux, T.; Ivascenko, A.; Krüger, P.P.; Pekeur, N.W.; Seyffert, A.S.; Spanier, F.; Sushch, I.; Van der Walt, J.; Venter, C.; Wadiasingh, Z. (EDP Sciences, 2018)
      Using the High Energy Spectroscopic System (H.E.S.S.) telescopes we have discovered a steady and extended very high-energy (VHE) γ-ray source towards the luminous blue variable candidate LBV 1806−20, massive stellar cluster ...
    • First ground-based measurement of sub-20 GeV to 100GeV y-Rays from the Vela pulsar with H.E.S.S. II 

      Abdalla, H.; Arcaro, C.; Barnard, M.; Böttcher, M.; Chandra, S.; Krüger, P.P.; Ndiyavala, H.; Seyffert, A.S.; Spanier, F.; Van der Walt, D.J.; Van Rensburg, C.; Venter, C.; Wadiasingh, Z.; Zacharias, M. (EDP Sciences, 2018)
      Aims. We report on the measurement and investigation of pulsed high-energy γ-ray emission from the Vela pulsar, PSR B0833−45, based on observations with the largest telescope of H.E.S.S., CT5, in monoscopic mode, and on ...
    • H.E.S.S. discovery of very high energy γ-ray emission from PKS 0625−354 

      Abdalla, H.; Barnard, M.; Davids, I.D.; Garrigoux, T.; Ivascenko, A.; Pekeur, N.W.; Seyffert, A.S.; Spanier, F.; Sushch, I.; Van der Walt, D.J.; Van Rensburg, C.; Venter, C.; Wadiasingh, Z. (Oxford Univ Press, 2018)
      PKS 0625−354 (z = 0.055) was observed with the four High Energy Stereoscopic System (H.E.S.S.) telescopes in 2012 during 5.5 h. The source was detected above an energy threshold of 200 GeV at a significance level of 6.1σ. ...
    • The H.E.S.S. Galactic plane survey 

      Abdalla, H.; Barnard, M.; Böttcher, M.; Garrigoux, T.; Ivascenko, A.; Krüger, P.P.; Pekeur, N.W.; Seyffert, A.S.; Spanier, F.; Sushch, I.; Van der Walt, D.J.; Van Rensburg, C.; Venter, C.; Wadiasingh, Z.; Zacharias, M. (EDP Sciences, 2018)
      We present the results of the most comprehensive survey of the Galactic plane in very high-energy (VHE) γ-rays, including a public release of Galactic sky maps, a catalog of VHE sources, and the discovery of 16 new sources ...
    • HESS J1741-302: a hidden accelerator in the Galactic plane 

      Abdalla, H.; Barnard, M.; Böttcher, M.; Garrigoux, T.; Ivascenko, A.; Krüger, P.P.; Pekeur, N.W.; Seyffert, A.S.; Spanier, F.; Sushch, I.; Van der Walt, D.J.; Van Rensburg, C.; Venter, C.; Wadiasingh, Z.; Zacharias, M. (EDP Sciences, 2018)
      The H.E.S.S. Collaboration has discovered a new very high energy (VHE, E > 0.1 TeV) γ-ray source, HESS J1741−302, located in the Galactic plane. Despite several attempts to constrain its nature, no plausible counterpart ...
    • Multi-messenger observations of a binary neutron star merger 

      Abdalla, H.; Böttcher, M.; Barnard, M. (IOP Publishing, 2017)
      On 2017 August 17 a binary neutron star coalescence candidate (later designated GW170817) with merger time 12:41:04 UTC was observed through gravitational waves by the Advanced LIGO and Advanced Virgo detectors. The Fermi ...
    • Particle transport within the pulsar wind nebula HESS J1825–137 

      Abdalla, H.; Arcaro, C.; Backes, M.; Barnard, M.; Böttcher, M.; Chand, T.; Chandra, S.; Ndiyavala, H.; Schutte, H.; Seyffert, A.S.; Van der Walt, D.J.; Van Rensburg, C.; Venter, C.; Wadiasingh, Z.; Zacharias, M. (EDP Sciences, 2019)
      Context. We present a detailed view of the pulsar wind nebula (PWN) HESS J1825–137. We aim to constrain the mechanisms dominating the particle transport within the nebula, accounting for its anomalously large size and ...
    • A polarized fast radio burst at low Galactic latitude 

      Petroff, E.; Abdalla, H.; Barnard, M.; Böttcher, M.; Davids, I.D.; Garrigoux, T.; Ivascenko, A.; Krüger, P.P.; Pekeur, N.W.; Seyffert, A.S.; Spanier, F.; Sushch, I.; Van der Walt, D.J.; Van Rensburg, C.; Venter, C.; Wadiasingh, Z. (Oxford Univ Press, 2017)
      We report on the discovery of a new fast radio burst (FRB), FRB 150215, with the Parkes radio telescope on 2015 February 15. The burst was detected in real time with a dispersion measure (DM) of 1105.6 ± 0.8 pc cm−3, a ...
    • The population of TeV pulsar wind nebulae in the H.E.S.S. Galactic Plane Survey 

      Abdalla, H.; Barnard, M.; Böttcher, M.; Davids, I.D.; Garrigoux, T.; Ivascenko, A.; Krüger, P.P.; Pekeur, N.W.; Seyffert, A.S.; Spanier, F.; Sushch, I.; Van der Walt, D.J.; Venter, C.; Wadiasingh, Z. (EDP Sciences, 2018)
      The nine-year H.E.S.S. Galactic Plane Survey (HGPS) has yielded the most uniform observation scan of the inner Milky Way in the TeV gamma-ray band to date. The sky maps and source catalogue of the HGPS allow for a systematic ...
    • Population study of Galactic supernova remnants at very high γ-ray energies with H.E.S.S. 

      Abdalla, H.; Barnard, M.; Böttcher, M.; Garrigoux, T.; Ivascenko, A.; Krüger, P.P.; Pekeur, N.W.; Seyffert, A.S.; Spanier, F.; Sushch, I.; Van der Walt, D.J.; Van Rensburg, C.; Venter, C.; Wadiasingh, Z.; Zacharias, M. (EDP Sciences, 2018)
      Shell-type supernova remnants (SNRs) are considered prime candidates for the acceleration of Galactic cosmic rays (CRs) up to the knee of the CR spectrum at E ≈ 3 × 1015 eV. Our Milky Way galaxy hosts more than 350 SNRs ...
    • A search for new supernova remnant shells in the Galactic plane with H.E.S.S. 

      Abdalla, H.; Barnard, M.; Böttcher, M.; Garrigoux, T.; Ivascenko, A.; Krüger, P.P.; Pekeur, N.W.; Richter, S.; Seyffert, A.S.; Spanier, F.; Sushch, I.; Van der Walt, D.J.; Van Rensburg, C.; Venter, C.; Wadiasingh, Z.; Zacharias, M.; Davids, I.D. (EDP Sciences, 2018)
      A search for new supernova remnants (SNRs) has been conducted using TeV γ-ray data from the H.E.S.S. Galactic plane survey. As an identification criterion, shell morphologies that are characteristic for known resolved TeV ...
    • A search for very high-energy flares from the microquasars GRS 1915+105, Circinus X-1, and V4641 Sgr using contemporaneous H.E.S.S. and RXTE observations 

      Abdalla, H.; Barnard, M.; Böttcher, M.; Davids, I.D.; Garrigoux, T.; Ivascenko, A.; Krüger, P.P.; Pekeur, N.W.; Seyffert, A.S.; Spanier, F.; Sushch, I.; Van der Walt, J.; Venter, C.; Wadiasingh, Z. (EDP Sciences, 2018)
      Context. Microquasars are potential γ-ray emitters. Indications of transient episodes of γ-ray emission were recently reported in at least two systems: Cyg X-1 and Cyg X-3. The identification of additional γ-ray-emitting ...
    • Search for γ-ray line signals from dark matter annihilations in the inner galactic halo from 10 years of observations with H.E.S.S. 

      Abdalla, H.; Barnard, M.; Böttcher, M.; Garrigoux, T.; Ivascenko, A.; Krüger, P.P.; Ndiyavala, H.; Pekeur, N.W.; Seyffert, A.S.; Spanier, F.; Sushch, I.; Van der Walt, J.; Van Rensburg, C.; Venter, C.; Wadiasingh, Z.; Zacharias, M. (APS, 2018)
      Spectral lines are among the most powerful signatures for dark matter (DM) annihilation searches in very-high-energy γ rays. The central region of the Milky Way halo is one of the most promising targets given its large ...
    • Searches for gamma-ray lines and 'pure WIMP' spectra from Dark Matter annihilations in dwarf galaxies with H.E.S.S. 

      Abdalla, H.; Arcaro, C.; Barnard, M.; Böttcher, M.; Chandra, S.; Krüger, P.P.; Ndiyavala, H.; Seyffert, A.S.; Spanier, F.; Van der Walt, D.J.; Van Rensburg, C.; Venter, C.; Wadiasingh, Z.; Zacharias, M. (IOP Publishing, 2018)
      Dwarf spheroidal galaxies are among the most promising targets for detecting signals of Dark Matter (DM) annihilations. The H.E.S.S. experiment has observed five of these systems for a total of about 130 hours. The data ...
    • The starburst galaxy NGC 253 revisited by H.E.S.S. and Fermi-LAT 

      Abdalla, H.; Arcaro, C.; Backes, M.; Barnard, M.; Böttcher, M.; Chandra, S.; Garrigoux, T.; Krüger, P.P.; Ndiyavala, H.; Seyffert, A.S.; Spanier, F.; Sushch, I.; Van der Walt, D.J.; Van Rensburg, C.; Venter, C.; Wadiasingh, Z.; Zacharias, M. (EDP Sciences, 2018)
      Context. NGC 253 is one of only two starburst galaxies found to emit γ-rays from hundreds of MeV to multi-TeV energies. Accurate measurements of the very-high-energy (VHE; E > 100 GeV) and high-energy (HE; E > 60 MeV) ...