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Recent observations by the Fermi Large Area Telescope (LAT) and the High Energy Stereoscopic System (H.E.S.S.) have revealed globular clusters (GC) to be sources of high-energy (HE) and very-high-energy (VHE) gamma-rays. It has been…

High Energy Astrophysical Phenomena · Physics 2014-12-15 P L Prinsloo , C Venter , I Büsching , A Kopp

Using a simplified model of cascade pair creation over pulsar polar caps presented in two previous papers, we investigate the expected gamma-ray output from pulsars' low altitude particle acceleration and pair creation regions. We divide…

Astrophysics · Physics 2009-11-07 J. A. Hibschman

A novel design for a compact gamma-ray spectrometer is presented. The proposed system allows for spectroscopy of high-flux multi-MeV gamma-ray beams with MeV energy resolution in a compact design. In its basic configuration, the…

Instrumentation and Detectors · Physics 2015-06-19 D. J. Corvan , G. Sarri , M. Zepf

Intriguing sub-TeV tails in the pulsed $\gamma$-ray emission from the Crab pulsar have been recently discovered by the MAGIC and VERITAS Collaborations. They were not clearly predicted by any pulsar model. It is at present argued that this…

High Energy Astrophysical Phenomena · Physics 2016-02-12 W. Bednarek

A significant amount of the millisecond pulsars has been discovered within binary systems. In several such binary systems the masses of the companion stars have been derived allowing to distinguish two classes of objects, called the Black…

High Energy Astrophysical Phenomena · Physics 2016-02-12 W. Bednarek

(abridged) Gamma-ray binaries are massive stars with compact object companions that are observed to emit most of their energy in the gamma-ray range. One of these binaries is known to contain a radio pulsar, PSR B1259-63. Synchrotron and…

High Energy Astrophysical Phenomena · Physics 2015-05-27 Jérôme Pétri , Guillaume Dubus

The vast majority of the pulsars detected by the Fermi Large Area Telescope (LAT) display spectra with exponential cutoffs falling in a narrow range around a few GeV. Early spectral modelling predicted spectral cutoff energies of up to 100…

High Energy Astrophysical Phenomena · Physics 2016-03-08 M. Breed , C. Venter , A. K. Harding

A two-dimensional electrodynamic model is used to study particle acceleration and non-thermal emission mechanisms in the pulsar magnetospheres. We solve distribution of the accelerating electric field with the emission process and the…

Astrophysics · Physics 2009-11-13 J. Takata , H. -K. Chang , S. Shibata

The seven known gamma-ray pulsars represent a very small fraction of the more than 1000 presently known radio pulsars, yet they can give us valuable information about pulsar particle acceleration and energetics. Although the theory of…

Astrophysics · Physics 2007-05-23 Alice K. Harding

Air-Cherenkov telescopes have detected pulsations at energies above 50 GeV from a growing number of Fermi pulsars. These include the Crab, Vela, PSR B1706-44 and Geminga, with the first two having pulsed detections above 1 TeV. In some…

High Energy Astrophysical Phenomena · Physics 2022-01-05 Alice K. Harding , Christo Venter , Constantinos Kalapotharakos

The study of pulsars in the three and a half decades since their discovery has highlighted a handful of issues critical to their understanding. To date there is no consensus on the physical mechanism for their radio radio emission, despite…

Astrophysics · Physics 2009-11-10 Matthew G. Baring

The observed spectra of 9 pulsars for which multiwavelength data are available from radio to $X$- or $\gamma$-ray bands (Crab, Vela, Geminga, B0656+14, B1055-52, B1509-58, B1706-44, B1929+10, and B1951+32) are compared with the spectrum of…

Astrophysics of Galaxies · Physics 2009-08-11 H. Ardavan , A. Ardavan , J. Singleton , J. Fasel , W. Junor , J. Middleditch , M. R. Perez , A. Schmidt , P. Sengupta , P. Volegov

Until now X-radiation from nine millisecond pulsars has been detected. In the present paper we summarize the observations and show the results of a re-analysis of archival ROSAT data. In addition we present the results of recent…

Astrophysics · Physics 2007-05-23 W. Becker , J. Trümper

We present Keck spectroscopic measurements of the millisecond pulsar binary J2215+5135. These data indicate a neutron-star (NS) mass M_NS=1.6Mo, much less than previously estimated. The pulsar heats the companion face to T_D~9000K; the…

High Energy Astrophysical Phenomena · Physics 2015-08-19 Roger W. Romani , Melissa L. Graham , Alexei V. Filippenko , Matthew Kerr

We report the detection of a possible gamma-ray counterpart of the accreting millisecond pulsar SAX J1808.4-3658. The analysis of ~6 years of data from the Large Area Telescope on board the Fermi Gamma-ray Space Telescope (Fermi-LAT) within…

High Energy Astrophysical Phenomena · Physics 2016-01-27 E. de Ona Wilhelmi , A. Papitto , J. Li , N. Rea , D. F. Torres , L. Burderi , T. Di Salvo , R. Iaria , A. Riggio , A. Sanna

We report on an XMM-Newton observation of the accreting millisecond pulsar, IGR J17511-3057. Pulsations at 244.8339512(1) Hz are observed with an RMS pulsed fraction of 14.4(3)%. A precise solution for the P_orb=12487.51(2)s binary system…

High Energy Astrophysical Phenomena · Physics 2015-05-19 A. Papitto , A. Riggio , T. Di Salvo , L. Burderi , A. D'Aì , R. Iaria , E. Bozzo , M. T. Menna

We discuss here constraints on the particle acceleration models from the observed gamma-ray bursts spectra. The standard synchrotron shock model assumes that some fraction of available energy is given instantaneously to the electrons which…

Astrophysics · Physics 2010-11-11 Juri Poutanen , Boris E. Stern

The highest-energy known gamma-ray sources are all located within 0.5 degrees of extremely powerful pulsars. This raises the question of whether ultra-high-energy (UHE; $>$ 56 TeV) gamma-ray emission is a universal feature expected near…

High Energy Astrophysical Phenomena · Physics 2021-04-29 HAWC Collaboration , A. Albert , R. Alfaro , C. Alvarez , J. D. Álvarez , J. R. Angeles Camacho , J. C. Arteaga-Velázquez , K. P. Arunbabu , D. Avila Rojas , H. A. Ayala Solares , V. Baghmanyan , E. Belmont-Moreno , S. Y. BenZvi , C. Brisbois , K. S. Caballero-Mora , T. Capistrán , A. Carramiñana , S. Casanova , U. Cotti , J. Cotzomi , S. Coutiño de León , E. De la Fuente , C. de León , R. Diaz Hernandez , B. L. Dingus , M. A. DuVernois , M. Durocher , J. C. Díaz-Vélez , R. W. Ellsworth , K. Engel , C. Espinoza , K. L. Fan , M. Fernández Alonso , N. Fraija , A. Galván-Gámez , J. A. García-González , F. Garfias , G. Giacinti , M. M. González , J. A. Goodman , J. P. Harding , S. Hernandez , B. Hona , D. Huang , F. Hueyotl-Zahuantitla , P. Hüntemeyer , A. Iriarte , A. Jardin-Blicq , V. Joshi , D. Kieda , A. Lara , W. H. Lee , J. Lee , H. León Vargas , J. T. Linnemann , A. L. Longinotti , G. Luis-Raya , J. Lundeen , K. Malone , V. Marandon , O. Martinez , J. Martínez-Castro , J. A. Matthews , P. Miranda-Romagnoli , J. A. Morales-Soto , E. Moreno , M. Mostafá , A. Nayerhoda , L. Nellen , M. Newbold , M. U. Nisa , R. Noriega-Papaqui , L. Olivera-Nieto , N. Omodei , A. Peisker , Y. Pérez Araujo , E. G. Pérez-Pérez , C. D. Rho , Y. J. Roh , D. Rosa-González , E. Ruiz-Velasco , H. Salazar , F. Salesa Greus , A. Sandoval , M. Schneider , H. Schoorlemmer , J. Serna-Franco , A. J. Smith , R. W. Springer , P. Surajbali , M. Tanner , K. Tollefson , I. Torres , R. Torres-Escobedo , R. Turner , F. Ureña-Mena , L. Villaseñor , T. Weisgarber , E. Willox , H. Zhou

In the present paper a self-consistent theory, interpreting the VERITAS observations of the very high energy pulsed emission from the Crab pulsar is considered. The photon spectrum between 10MeV and 400GeV can be described by two power-law…

High Energy Astrophysical Phenomena · Physics 2012-08-13 Nino Chkheidze , George Machabeli , Zaza Osmanov

In 1993-1994 a series of observations of the X-ray pulsar GX 301-2 by HEXE onboard Mir-Kvant was made. A period of pulsations was measured (it varied between 675 and 678 s) and pulse profiles in different energy bands were produced. The…

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