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The Large Area Telescope (LAT) on the Fermi satellite is the first gamma-ray instrument to discover pulsars directly via their gamma-ray emission. Roughly one third of the 117 gamma-ray pulsars detected by the LAT in its first three years…

High Energy Astrophysical Phenomena · Physics 2019-08-13 Pablo M. Saz Parkinson

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

Here we investigate to what extent unresolved \gr pulsars contribute to the galactic diffuse emission, and further whether unresolved \gr pulsars can be made responsible for the excess of diffuse galactic emission above 1 GeV which has been…

Astrophysics · Physics 2009-10-30 Martin Pohl

Cosmic rays can interact with the solar atmosphere and produce a slew of secondary messengers, making the Sun a bright gamma-ray source in the sky. Detailed observations with Fermi-LAT have shown that these interactions must be strongly…

High Energy Astrophysical Phenomena · Physics 2024-03-26 Zhe Li , Kenny C. Y. Ng , Songzhan Chen , Yuncheng Nan , Huihai He

We present the results of 2.5 years AGILE observations of PSR B1509-58. The modulation significance of the light-curve above 30 MeV is at a sigma confidence level and the light-curve is similar to those found earlier up to 30 MeV by \comp:…

High Energy Astrophysical Phenomena · Physics 2011-03-31 Maura Pilia , Alberto Pellizzoni

Context: Despite more than half a century of research, the dominant radiation mechanism of gamma-ray burst (GRB) prompt emission remains unsolved. Some progress has been made through the analyses of the observational spectra of Swift/BAT,…

High Energy Astrophysical Phenomena · Physics 2026-02-11 Yan-Zhi Meng , Shu-Qing Zhong , Jia-Hong Gu , Xin-Fei Li , Xiaozhou Zhao

We present a study on the gamma-ray emission detected by the AGILE-GRID from the region of the SNR G78.2+2.1 (Gamma Cygni). In order to investigate the possible presence of gamma rays associated with the SNR below 1 GeV, it is necessary to…

High Energy Astrophysical Phenomena · Physics 2019-06-19 G. Piano , M. Cardillo , M. Pilia , A. Trois , A. Giuliani , A. Bulgarelli , N. Parmiggiani , M. Tavani

A phenomenological model is presented to explain the light curves of gamma-ray bursts. Gamma-rays are produced in a narrow beam which sweeps through space due to the precession of a slaved accretion disc. The light curve expected from such…

Astrophysics · Physics 2009-10-31 Simon Portegies Zwart

The study of the gamma-ray radiation produced by cosmic rays that escape their accelerators is of paramount importance for (at least) two reasons: first, the detection of those gamma-ray photons can serve to identify the sources of cosmic…

High Energy Astrophysical Phenomena · Physics 2015-06-15 Stefano Gabici

A model is proposed for the observed combination of power-law and thermal emission of keV X-rays from rotationally powered pulsars. For gamma-ray pulsars with accelerators very many stellar radii above the neutron star surface, 100 MeV…

Astrophysics · Physics 2009-10-30 F. Y. -H. Wang , M. Ruderman , J. P. Halpern , T. Zhu

We study the gamma-ray emission patterns and light curves in dissipative pulsar magnetospheres. We produce the gamma-ray light curves by using the geometric method and the particle trajectory method. For the geometric method, assuming the…

High Energy Astrophysical Phenomena · Physics 2019-04-10 Gang Cao , Xiongbang Yang

Recent observations from the Swift gamma-ray burst mission indicate that a fraction of gamma ray bursts are characterized by a canonical behaviour of the X-ray afterglows. We present an effective theory which allows us to account for X-ray…

Astrophysics · Physics 2008-11-26 Paolo Cea

Several groups of authors have analyzed Fermi LAT data in a region around the Galactic Center finding an unaccounted gamma-ray excess over diffuse backgrounds in the GeV energy range. It has been argued that it is difficult or even…

High Energy Astrophysical Phenomena · Physics 2015-06-23 Jovana Petrovic , Pasquale D. Serpico , Gabrijela Zaharijas

We explore the multiwavelength radiation properties of the light curves and energy spectra in the dissipative magnetospheres of pulsars. The dissipative magnetospheres are simulated by the pseudo-spectral method with the combined force-free…

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

Pulsars are the most numerous class of Galactic gamma-ray sources detected by the Fermi Large Area Telescope (LAT). Young pulsars occasionally experience sudden timing discontinuities called glitches, characterized by rapid changes in…

High Energy Astrophysical Phenomena · Physics 2026-01-08 Giovanni Cozzolongo , Alessio Fiori , Massimiliano Razzano , Pablo M. Saz Parkinson

Based on the Fermi observational data we reveal meaningful constraints for the dependence of the macroscopic conductivity $(\sigma)$ of dissipative pulsar magnetosphere models on the corresponding spin-down rate, $\dot{\mathcal{E}}$. Our…

High Energy Astrophysical Phenomena · Physics 2017-06-28 Constantinos Kalapotharakos , Alice K. Harding , Demosthenes Kazanas , Gabriele Brambilla

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

Data from the Fermi-LAT reveal two large gamma-ray bubbles, extending 50 degrees above and below the Galactic center, with a width of about 40 degrees in longitude. The gamma-ray emission associated with these bubbles has a significantly…

High Energy Astrophysical Phenomena · Physics 2011-01-03 Meng Su , Tracy R. Slatyer , Douglas P. Finkbeiner

If gamma-ray bursts originate in our Galaxy, they probably involve violent disturbances in the magnetospheres of neutron stars. Any event of this kind is likely to trigger the sudden expulsion of magnetic flux and plasma at relativistic…

Astrophysics · Physics 2016-06-08 Mitchell C. Begelman , P. Meszaros , Martin J. Rees

Pulsars are rapidly-rotating neutron stars born out of the death of stars. A diffuse nebula is formed when particles stream from these neutron stars and interact with the ambient medium. These pulsar wind nebulae (PWNe) are visible across…

High Energy Astrophysical Phenomena · Physics 2014-01-28 Joshua Lande
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