Browsing Research Output by Author "c79e97e2-d64a-4a28-80c0-832a204e545f"

Now showing items 1-19 of 19

    • 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.; H.E.S.S. Collaboration (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 ...

    • Cloud ablation by a relativistic jet and the extended flare in CTA 102 in 2016 and 2017 

      Zacharias, M.; Böttcher, M.; Jankowsky, F.; Lenain, J.-P.; Wagner, S.J. (IOP, 2017)
      In late 2016 and early 2017, the flat spectrum radio quasar CTA 102 exhibited a very strong and long-lasting outburst. The event can be described by a roughly two-month long increase of the baseline flux in the monitored energy ...

    • The complex VHE and multiwavelength flaring activity of the FSRQ PKS 1510-089 in May 2015 

      Zacharias, M.; Böttcher, M.; Chakraborty, N.; Cologna, G.; Jankowsky, F. (AIP, 2017)
      The blazar PKS 1510-089 was the first of the flat spectrum radio quasar type, which had been detected simultaneously by a ground based Cherenkov telescope (H.E.S.S.) and the LAT instrument on board the Fermi satellite. ...

    • 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.; H.E.S.S. Collaboration (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 ...

    • The extended flare in CTA 102 in 2016 and 2017 within a hadronic model through cloud ablation by the relativistic jet 

      Zacharias, M.; Böttcher, M.; Jankowsky, F.; Lenain, J.-P.; Wagner, S.J. (IOP Publishing, 2019)
      The flat-spectrum radio quasar CTA 102 (redshift 1.037) exhibited a tremendously bright four-month-long outburst from late 2016 to early 2017. In a previous paper, we interpreted the event as the ablation of a gas cloud ...

    • 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.; H.E.S.S. Collaboration (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 ...

    • 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.; H.E.S.S. Collaboration (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.; H.E.S.S. Collaboration (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 ...

    • Observation of the extremely bright flare of the FSRQ 3C279 with H.E.S.S. II 

      Romoli, C.; Zacharias, M.; Meyer, M.; Ait Benkhali, F.; Jacholkowska, A. (PoS, 2017)
      In June 2015, the Flat Spectrum Radio Quasar 3C 279 underwent an extremely bright gamma-ray flare, with an increase of the flux above 100 MeV by a factor 10 in less than 1 day, revealing an intrinsic variability timescale ...

    • 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.; H.E.S.S. Collaboration (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.; H.E.S.S. Collaboration (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 ...

    • 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, D.J.; Van Rensburg, C.; Venter, C.; Wadiasingh, Z.; Zacharias, M.; H.E.S.S. Collaboration (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.; H.E.S.S. Collaboration (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 ...

    • 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.; H.E.S.S. Collaboration (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.; H.E.S.S. Collaboration (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) ...

    • Target of opportunity observations of blazars with H.E.S.S. 

      Schüssler, F.; Böttcher, M.; Davids, I.D.; Zacharias, M.; Seglar-Arroyo, M. (PoS, 2017)
      The very-high-energy (VHE, E>100 GeV) extragalactic sky is dominated by blazars, a class of active galactic nuclei which show rapid variability at all wavelengths. Target of Opportunity (ToO) observations triggered by ...

    • VHE γ-ray discovery and multiwavelength study of the blazar 1ES 2322-409 

      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.; H.E.S.S. Collaboration (Oxford Univ Press, 2019)
      A hotspot at a position compatible with the BL Lac object 1ES 2322−409 was serendipitously detected with H.E.S.S. during observations performed in 2004 and 2006 on the blazar PKS 2316−423. Additional data on 1ES 2322−409 ...

    • The y-ray spectrum of the core of Centaurus A as observed with H.E.S.S. and Fermi-LAT 

      Abdalla, H.; Barnard, M.; Böttcher, M.; Garrigoux, T.; Ivaschenko, 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.; H.E.S.S. Collaboration; Fermi LAT (EDP Sciences, 2018)
      Centaurus A (Cen A) is the nearest radio galaxy discovered as a very-high-energy (VHE; 100 GeV–100 TeV) γ-ray source by the High Energy Stereoscopic System (H.E.S.S.). It is a faint VHE γ-ray emitter, though its VHE flux ...