Browsing Research Output by Author "Büsching, I."
Now showing items 1-20 of 71
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The 2010 very high energy γ-ray flare and 10 years of multi-wavelength observations of M 87
Abramowski, A.; Büsching, I.; De Jager, O.C.; Sheidaei, F.; Venter, C.; Vorster, M.; H.E.S.S. Collaboration (IOP Publishing, 2012)The giant radio galaxy M 87 with its proximity (16 Mpc), famous jet, and very massive black hole ((3 – 6) × 109 M☉) provides a unique opportunity to investigate the origin of very high energy (VHE; E > 100 GeV) γ-ray ... -
Are anomalous cosmic rays the main contribution to the low-energy galactic cosmic ray spectrum?
Scherer, K.; Ferreira, S.E.S.; Büsching, I.; Potgieter, M.S.; Fichtner, H. (IOP Publishing, 2008)While the high-energy part of the Galactic cosmic ray spectrum is well observed, its nature at energies below about 1 GeV nucleon-1 is still not known well. Recent in situ measurements made with the Voyager 1 spacecraft in ... -
Constraints on injection parameters of cosmic rays in the Galactic center from resolved HESS observations
De Jager, O.C.; Büsching, I. (Elsevier Ltd., 2008) -
Constraints on the gamma-ray emission from the cluster-scale AGN outburst in the hydra A galaxy cluster
Abramowski, A.; Büsching, I.; Casanova, S.; Pekeur, N.W.; Sheidaei, F.; Venter, C.; Vorster, M.; H.E.S.S. Collaboration (EDP Sciences, 2012)Context. In some galaxy clusters, powerful active galactic nuclei (AGN) have blown bubbles with cluster scale extent into the ambient medium. The main pressure support of these bubbles is not known to date, but cosmic rays ... -
Constraints on the multi-TeV particle population in the Coma galaxy cluster with HESS observations
Aharonian, F.; Büsching, I.; Davids, I.D.; De Jager, O.C.; Holleran, M.; Raubenheimer, B.C.; Venter, C.; H.E.S.S. Collaboration (EDP Sciences, 2009)Aims. Galaxy clusters are key targets in the search for ultra high energy particle accelerators. The Coma cluster represents one of the best candidates for such a search owing to its high mass, proximity, and the established ... -
Contributions from nearby pulsars to the local cosmic ray electron spectrum
Büsching, I.; Venter, C.; De Jager, O.C. (Elsevier, 2008)PSR J0437-4715 is one of the closest millisecond pulsars (MSPs) to Earth, lying at a distance of _140 pc. This pulsar has a characteristic age of 4.9 Gyr and a relatively low spindown power of _1034 ergs/s. During its ... -
Contributions from nearby pulsars to the local cosmic ray electron spectrum
Büsching, I.; Venter, C.; De Jager, O.C. (Elsevier, 2008)PSR J0437-4715 is one of the closest millisecond pulsars (MSPs) to Earth, lying at a distance of ∼140 pc. This pulsar has a characteristic age of 4.9 Gyr and a relatively low spindown power of ∼1034 ergs/s. During its ... -
A cosmic-ray positron anisotropy due to two middle-aged, nearby pulsars?
Büsching, I.; De Jager, O.C.; Potgieter, M.S.; Venter, C. (IOP Publishing, 2008)Geminga and B0656+14 are the closest pulsars with characteristic ages in the range of 100 kyr to 1 Myr. They both have spin-down powers of the order 3 × 1034 ergs s–1 at present. The winds of these pulsars had most probably ... -
Detection of gamma rays from a starburst galaxy
Acero, F.; Büsching, I.; Davids, I.D.; De Jager, O.C.; Raubenheimer, B.C.; Venter, C.; H.E.S.S. Collaboration (AAAS, 2009)Starburst galaxies exhibit in their central regions a highly increased rate of supernovae, the remnants of which are thought to accelerate energetic cosmic rays up to energies of ~1015 electron volts. We report the detection ... -
Detection of very high energy radiation from HESS J1908+063 confirms the Milagro unidentified source MGRO J1908+06
Aharonian, F.; Büsching, I.; De Jager, O.C.; Holleran, M.; Raubenheimer, B.C.; Venter, C.; H.E.S.S. Collaboration (EDP Sciences, 2009)Aims. Detection of a $\gamma$-ray source above 300 GeV is reported, confirming the unidentified source MGRO J1908+06, discovered by the Milagro collaboration at a median energy of 20 TeV. Methods. The source was observed ... -
Detection of very-high-energy y-ray emission from the vicinity of PSR B1706-44 and G 343.1-2.3 with H.E.S.S.
Abramowski, A.; Büsching, I.; Davids, I.D.; De Jager, O.C.; Holleran, M.; Venter, C.; H.E.S.S. Collaboration (EDP Sciences, 2011)The γ-ray pulsar PSRB1706−44 and the adjacent supernova remnant (SNR) candidate G343.1−2.3 were observed by H.E.S.S. during a dedicated observation campaign in 2007. As a result of this observation campaign, a new source ... -
Discovery of a VHE gamma-ray source coincident with the supernova remnant CTB 37A
Aharonian, F.; Büsching, I.; De Jager, O.C.; Holleran, M.; Raubenheimer, B.C.; Venter, C.; H.E.S.S. Collaboration (EDP Sciences, 2008)Aims. The supernova remnant (SNR) complex CTB 37 is an interesting candidate for observations with very high energy (VHE) γ-ray telescopes such as HESS. In this region, three SNRs are seen. One of them is potentially ... -
Discovery of extended VHE Y-ray emission from the vicinity of the young massive stellar cluster Westerlund 1
Abramowski, A.; Büsching, I.; De Jager, O.C.; Sheidaei, F.; Venter, C.; Vorster, M.; H.E.S.S. Collaboration (EDP Sciences, 2012)Aims. Results obtained in very-high-energy (VHE; E≥100GeV) γ-ray observations performed with the H.E.S.S. telescope array are used to investigate particle acceleration processes in the vicinity of the young massive stellar ... -
Discovery of hard-spectrum y-ray emission from the BL Lacertae object 1ES 0414+009
Abramowski, A.; Büsching, I.; De Jager, O.C.; Sheidaei, F.; Venter, C.; Vorster, M.; H.E.S.S. Collaboration (EDP Sciences, 2012)Context. 1ES 0414 + 009 (z = 0.287) is a distant high-frequency-peaked BL Lac object, and has long been considered a likely emitter of very-high-energy (VHE, E > 100 GeV) γ-rays due to its high X-ray and radio flux. Aims. ... -
Discovery of the source HESS J1356-645 associated with the young and energetic PSR J1357-6429
Abramowski, A.; Büsching, I.; De Jager, O.C.; Venter, C.; Vorster, M.; H.E.S.S. Collaboration (EDP Sciences, 2011)Context. Several newly discovered very-high-energy (VHE; E > 100 GeV) γ-ray sources in the Galaxy are thought to be associated with energetic pulsars. Among them, middle-aged (≳104 yr) systems exhibit large centre-filled ... -
Discovery of very high energy gamma-ray emission coincident with molecular clouds in the W 28 (G6.4-0.1) field
Aharonian, F.; Büsching, I.; De Jager, O.C.; Holleran, M.; Raubenheimer, B.C.; Venter, C.; H.E.S.S. Collaboration (EDP Sciences, 2008)Aims. Observations of shell-type supernova remnants (SNRs) in the GeV to multi-TeV γ-ray band, coupled with those at millimetre radio wavelengths, are motivated by the search for cosmic-ray accelerators in our Galaxy. The ... -
Discovery of very high energy y-ray emission from Centaurus A with HESS.
Aharonian, F.; Büsching, I.; De Jager, O.C.; Holleran, M.; Raubenheimer, B.C.; Venter, C.; H.E.S.S. Collaboration (IOP Publishing, 2009)We report the discovery of faint very high energy (VHE; E > 100 GeV) γ-ray emission from the radio galaxy Centaurus A in observations performed with the High Energy Stereoscopic System (H.E.S.S.) experiment, an imaging ... -
Discovery of very-high-energy gamma-ray emission from the vicinity of PSR J1913+1011 with HESS
Aharonian, F.; Büsching, I.; Holleran, M.; Raubenheimer, B.C.; Venter, C.; H.E.S.S. Collaboration (EDP Sciences, 2008)The HESS experiment, an array of four Imaging Atmospheric Cherenkov Telescopes with high sensitivity and large field-of-view, has been used to search for emitters of very-high-energy (VHE, >100 GeV) $\gamma$-rays along the ... -
Discovery of VHE emission towards the Carina arm region with the H.E.S.S. telescope array: HESS J1018-589
Abramowski, A.; Büsching, I.; Casanova, S.; De Jager, O.C.; Pekeur, N.W.; Sheidaei, F.; Venter, C.; Vorster, M.; H.E.S.S. Collaboration (EDP Sciences, 2012)The Carina arm region, containing the supernova remnant SNR G284.3–1.8, the high-energy (HE; E > 100 MeV) binary 1FGL J1018.6–5856 and the energetic pulsar PSR J1016–5857 and its nebula, has been observed with the H.E.S.S. ... -
Discovery of VHE gamma-rays from the high-frequency-peaked BL Lacertae object RGB J0152+017
Aharonian, F.; Büsching, I.; De Jager, O.C.; Holleran, M.; Raubenheimer, B.C.; Venter, C.; H.E.S.S. Collaboration (EDP Sciences, 2008)Aims. The BL Lac object RGB J0152+017 (z=0.080) was predicted to be a very high-energy (VHE; >100 GeV) $\gamma$-ray source, due to its high X-ray and radio fluxes. Our aim is to understand the radiative processes by ...