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Context. LS I +61 303 is a member of the select group of gamma-ray binaries: galactic binary systems that contain a massive star and a compact object, show a changing milliarcsecond morphology and a similar broad spectral energy…

High Energy Astrophysical Phenomena · Physics 2015-06-05 A. Cañellas , B. C. Joshi , J. M. Paredes , C. H. Ishwara-Chandra , J. Moldón , V. Zabalza , J. Martí , M. Ribó

A new pulsar, 1SAX J1452.8-5949, was discovered during a BeppoSAX galactic plane survey on 1999 July 20 at R.A.=14h 52m 49s, Dec=-59 49' 18'' (J2000) with a 90% confidence uncertainty radius of 50''. Coherent pulsations were detected with a…

The extreme synchrotron BL Lac object H2356-309, located at a redshift of z = 0.165, was observed from June to December 2004 with a total exposure of approx. 40 h live-time with the H.E.S.S. (High Energy Stereoscopic System) array of…

Astrophysics · Physics 2009-11-11 Aharonian et al.

We report the discovery of eight gamma-ray pulsars in blind frequency searches using the LAT, onboard the Fermi Gamma-ray Space Telescope. Five of the eight pulsars are young (tau_c<100 kyr), energetic (Edot>10^36 erg/s), and located within…

We performed deep observations to search for radio pulsations in the directions of 375 unassociated Fermi Large Area Telescope (LAT) gamma-ray sources using the Giant Metrewave Radio Telescope (GMRT) at 322 and 607 MHz. In this paper we…

We report the first detection of >100 MeV gamma rays associated with a behind-the-limb solar flare, which presents a unique opportunity to probe the underlying physics of high-energy flare emission and particle acceleration. On 2013 October…

Solar and Stellar Astrophysics · Physics 2015-06-03 Melissa Pesce-Rollins , Nicola Omodei , Vahe' Petrosian , Wei Liu , Fatima Rubio da Costa , Alice Allafort , Qingrong Chen

With the installation of a new 28-m diameter imaging atmospheric Cherenkov telescope in the middle of the array, the H.E.S.S. instrument has entered since 2012 into its Phase II. The fifth large-size telescope is particularly important to…

High Energy Astrophysical Phenomena · Physics 2019-08-14 Matteo Cerruti , Jean-Philippe Lenain , Heike Prokoph

The Fermi Large Area Telescope has detected over 260 gamma-ray pulsars. About one quarter of these are labeled as radio-quiet. In the population of nonrecycled gamma-ray pulsars, the fraction of radio-quiet pulsars is higher, about one…

High Energy Astrophysical Phenomena · Physics 2021-10-13 J. -M. Grießmeier , D. A. Smith , G. Theureau , T. J. Johnson , M. Kerr , L. Bondonneau , I. Cognard , M. Serylak

Observations of the HBL blazar 1RXS J023832.6-311658 were made in 2013, 2015 and 2016 with the High Energy Stereoscopic System (H.E.S.S.). An excess of very high energy (VHE: > 100 GeV) gamma rays is clearly observed. The spectral energy…

High Energy Astrophysical Phenomena · Physics 2019-08-14 Florian Gaté

Very high energy (VHE; >100 GeV) gamma-ray observations of PG 1553+113 were made with the High Energy Stereoscopic System (HESS) in 2005 and 2006. A strong signal, ~10 standard deviations, is detected by HESS during the 2 years of…

Astrophysics · Physics 2007-10-01 HESS Collaboration , W. Benbow , C. Boisson , R. Buehler , H. Sol

The detection of gamma-rays from the source HESS J1745-290 in the Galactic Center (GC) region with the H.E.S.S. array of Cherenkov telescopes in 2004 is presented. After subtraction of the diffuse gamma-ray emission from the GC ridge, the…

Astrophysics · Physics 2012-08-27 H. E. S. S. collaboration , : , F. A. Aharonian

Geminga is an enigmatic radio-quiet gamma-ray pulsar located at a mere 250 pc distance from Earth. Extended very-high-energy gamma-ray emission around the pulsar has been detected by multiple water Cherenkov detector based instruments.…

High Energy Astrophysical Phenomena · Physics 2023-09-01 A. M. W. Mitchell , S. Caroff

The Crab pulsar is the only astronomical pulsed source detected above 100 GeV. The emission mechanism of very high energy gamma-ray pulsation is not yet fully understood, although several theoretical models have been proposed. In order to…

High Energy Astrophysical Phenomena · Physics 2019-08-14 T. Y. Saito , S. Bonnefoy , K. Hirotani , R. Zanin

We report on the discovery of X-ray pulsations from the Be/X-ray system LS 992/RX J0812.4-3114 during an RXTE observation. From a timing analysis of the source we obtained a barycentric pulse period of 31.8851 \pm 0.0004 s. The pulse…

Astrophysics · Physics 2009-10-31 Pablo Reig , Paul Roche

We have used the 150 MHz radio continuum survey (TGSS ADR) from the Giant Metrewave Radio Telescope (GMRT) to search for phase-averaged emission toward all well-localized radio pulsars north of -53deg Declination. We detect emission toward…

High Energy Astrophysical Phenomena · Physics 2016-10-05 D. A. Frail , P. Jagannathan , K. P. Mooley , H. T. Intema

Discovered after the end of the Compton Gamma-Ray Observatory mission, the radio pulsar PSR J2021+3651 was long considered a likely counterpart of the high-energy gamma-ray source 2CG 075+00 = 3EG J2021+3716 = GeV J2020+3658, but it could…

We present a heliopause spectrum for galactic electrons over an energy range from 1 MeV to 50 GeV at 122 AU from the Sun. This spectrum can be considered the lowest possible local interstellar spectrum (LIS). This is obtained by using a…

Solar and Stellar Astrophysics · Physics 2013-08-08 M. S. Potgieter , R. R. Nndanganeni , E. E. Vos , M. Boezio

HESS J1813-178 is one of the brightest sources detected during the first HESS Galactic Plane survey. The compact source, also detected by MAGIC, is believed to be a pulsar wind nebula powered by one of the most powerful pulsars known in the…

High Energy Astrophysical Phenomena · Physics 2023-09-01 T. Wach , A. M. W. Mitchell , V. Joshi , S. Funk

In January 2009, multiple short bursts of soft gamma-rays were detected from the direction of the anomalous X-ray pulsar 1E 1547.0-5408 by different satellites. Here we report on the observations obtained with the INTEGRAL SPI-ACS detector…

High Energy Astrophysical Phenomena · Physics 2011-02-11 S. Mereghetti , D. Gotz , G. Weidenspointner , A. von Kienlin , P. Esposito , A. Tiengo , G. Vianello , G. L. Israel , L. Stella , R. Turolla , N. Rea , S. Zane

More than 100 millisecond pulsars (MSPs) have been discovered in radio observations of gamma-ray sources detected by the Fermi Large Area Telescope (LAT), but hundreds of pulsar-like sources remain unidentified. Here we present the first…