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Recent kinetic simulations sparked a debate regarding the emission mechanism responsible for pulsed GeV $\gamma$-ray emission from pulsars. Some models invoke curvature radiation, while other models assume synchrotron radiation in the…

High Energy Astrophysical Phenomena · Physics 2022-02-16 Monica Barnard , Christo Venter , Alice K. Harding , Constantinos Kalapotharakos , Tyrel J. Johnson

The Fermi Large Area Telescope has revolutionised the $\gamma$-ray pulsar field, increasing the population to over 250 detected pulsars. The majority display spectra with exponential cutoffs in a narrow range around a few GeV. Models…

High Energy Astrophysical Phenomena · Physics 2021-03-22 M. Barnard

We report on analysis of timing and spectroscopy of the Vela pulsar using eleven months of observations with the Large Area Telescope on the Fermi Gamma-Ray Space Telescope. The intrinsic brightness of Vela at GeV energies combined with the…

High Energy Astrophysical Phenomena · Physics 2015-05-18 A. A. Abdo

We demonstrate a method for quantitatively comparing gamma-ray pulsar light curves with magnetosphere beaming models. With the Fermi LAT providing many pulsar discoveries and high quality pulsar light curves for the brighter objects, such…

High Energy Astrophysical Phenomena · Physics 2015-03-13 Roger W. Romani , Kyle P. Watters

The second pulsar catalogue of the Fermi Large Area Telescope (LAT) will contain in excess of 100 gamma-ray pulsars. The light curves (LCs) of these pulsars exhibit a variety of shapes, and also different relative phase lags with respect to…

High Energy Astrophysical Phenomena · Physics 2015-01-22 M. Breed , C. Venter , A. K. Harding , T. J. Johnson

$\gamma$-ray spectra of pulsars have been mostly studied in a phenomenological way, by fitting them to a cut-off power-law function. Here, we analyze a model where pulsed emission comes from synchro-curvature processes in a gap. We…

High Energy Astrophysical Phenomena · Physics 2015-06-24 Daniele Viganò , Diego F. Torres

The light curves and spectral properties of more than 200 $\gamma$-ray pulsars have been measured in unsurpassed detail in the eight years since the launch of the hugely successful Fermi Large Area Telescope (LAT) $\gamma$-ray mission. We…

High Energy Astrophysical Phenomena · Physics 2017-02-20 Monica Barnard , Christo Venter , Alice K. Harding

We study the pulsar energy-dependent $\gamma$-ray light curves and spectra from curvature radiation in the dissipative magnetospheres. The dissipative magnetospheres with the combined force-free (FFE) and Aristotelian (AE) are computed by a…

High Energy Astrophysical Phenomena · Physics 2024-03-12 Gang Cao , Xiongbang Yang

Pulsars emit pulsed emission across the entire electromagnetic spectrum and their light curve phenomenology is strongly dependent on energy. This is also true for the gamma-ray waveband. Continued detections by Fermi Large Area Telescope in…

High Energy Astrophysical Phenomena · Physics 2018-11-29 Monica Barnard , Christo Venter , Alice K. Harding , Constantinos Kalapotharakos

Pulsed gamma rays have been detected with the Fermi Large Area Telescope (LAT) from more than 20 millisecond pulsars (MSPs), some of which were discovered in radio observations of bright, unassociated LAT sources. We have fit the radio and…

High Energy Astrophysical Phenomena · Physics 2011-11-04 Tyrel J. Johnson , Alice K. Harding , Christo Venter

The Vela pulsar is one of the most exciting gamma-ray sources and has been at the forefront of high-energy pulsar science since the detection of gamma-ray pulsations at the radio period by SAS-2 in 1975. With the unprecedented angular…

High Energy Astrophysical Phenomena · Physics 2009-12-22 T. J. Johnson , Ö. Çelik , M. Kerr , A. K. Harding , G. A. Caliandro

Since the era of the Fermi/LAT and atmospheric Cerenkov telescopes, pulsars are known to emit high and very high-energy photons, in the MeV-GeV range and sometimes up to TeV. To date, it is still unclear where and how these photons are…

High Energy Astrophysical Phenomena · Physics 2019-02-13 Jérôme Pétri

Gamma-ray emission from pulsars is thought to arise from accelerating regions in pulsar's outer magnetosphere. The shape of the light curves is thus sensitive to the details of the magnetic geometry of the magnetosphere. In this work, we…

High Energy Astrophysical Phenomena · Physics 2009-11-03 Xue-Ning Bai , Anatoly Spitkovsky

We investigate the $\gamma$-ray emission from a outer-gap accelerator, which is located in the outer-magnetosphere of a pulsar. The charge depletion from the Goldreich-Julian density causes a large electric field along the magnetic field…

Astrophysics · Physics 2009-11-10 J. Takata , S. Shibata , K. Hirtotani

In recent years, surprise discoveries of pulsed emission from the Crab and Vela pulsars above 100 GeV have drawn renewed attention to this largely unexplored region of the energy range. In this paper, we discuss example light curves due to…

High Energy Astrophysical Phenomena · Physics 2018-08-22 Christo Venter , Monica Barnard , Alice K. Harding , Constantinos Kalapotharakos

The equatorial current sheets outside the light cylinder(LC) are thought as the promising site of the high energy emission based on the results of the recent numerical simulations. We explore the pulsar light curves and energy spectra by…

High Energy Astrophysical Phenomena · Physics 2021-03-17 Xiongbang Yang , Gang Cao

The Vela pulsar represents a distinct group of {\gamma}-ray pulsars. Fermi {\gamma}-ray observations reveal that it has two sharp peaks (P1 and P2) in the light curve with a phase separation of 0.42 and a third peak (P3) in the bridge. The…

High Energy Astrophysical Phenomena · Physics 2011-06-17 Y. J. Du , J. L. Han , G. J. Qiao , C. K. Chou

We compare population synthesis results for inner and outer magnetosphere emission models with the various characteristics measured in the first LAT pulsar catalogue for both the radio-loud and radio-weak or radio-quiet gamma-ray pulsars.…

High Energy Astrophysical Phenomena · Physics 2015-05-27 Marco Pierbattista , Isabelle Grenier , Alice Harding , Peter L. Gonthier

The Large Area Telescope (LAT) on Fermi, launched on 2008 June 11, is a space telescope to explore the high energy gamma-ray universe. The instrument covers the energy range from 20 MeV to 300 GeV with greatly improved sensitivity and…

High Energy Astrophysical Phenomena · Physics 2010-06-18 Damien Parent

The Vela pulsar is the brightest persistent source in the GeV sky and thus is the traditional first target for new gamma-ray observatories. We report here on initial Fermi Large Area Telescope observations during verification phase pointed…

Astrophysics · Physics 2009-11-13 A. A. Abdo
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