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We present a determination of the distributions of photon spectral index and gamma-ray flux - the so called LogN-LogS relation - for the 352 blazars detected with a greater than approximately seven sigma detection threshold and located…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-28 J. Singal , V. Petrosian , M. Ajello

Pulsars emerge in the Fermi era as a sizable population of gamma-ray sources. Millisecond pulsars (MSPs) constitute an older subpopulation whose sky distribution extends to high Galactic latitudes, and it has been suggested that unresolved…

High Energy Astrophysical Phenomena · Physics 2011-08-24 Jennifer M. Siegal-Gaskins , Rebecca Reesman , Vasiliki Pavlidou , Stefano Profumo , Terry P. Walker

Pulsars' gamma-ray luminosities are thought to exceed their radio luminosities by several orders of magnitude: a notion that is based on the assumption that the decay with distance of the flux of gamma-ray pulses obeys the inverse-square…

High Energy Astrophysical Phenomena · Physics 2022-01-25 Houshang Ardavan

The Large Area Telescope aboard the Fermi spacecraft has detected more than 200 $\gamma$-ray pulsars since its launch in 2008. By concurrently fitting standard geometric model light curves onto Fermi and radio data, researchers have…

High Energy Astrophysical Phenomena · Physics 2018-08-30 M. C. Bezuidenhout , C. Venter , A. S. Seyffert , A. K. Harding

We present results of our pulsar population synthesis of ordinary isolated and millisecond pulsars in the Galactic plane. Over the past several years, a program has been developed to simulate pulsar birth, evolution and emission using Monte…

Astrophysics · Physics 2008-11-26 Peter L. Gonthier , Sarah A. Story , Brian D. Clow , Alice K. Harding

The origin of the extragalactic $\gamma$-ray background permeating throughout the Universe remains a mystery forty years after its discovery. The extrapolated population of blazars can account for only half of the background radiation at…

High Energy Astrophysical Phenomena · Physics 2016-07-25 Xiawei Wang , Abraham Loeb

Due to the low gamma-ray fluxes from pulsars above 50 GeV and the small collecting area of space-based telescopes, the gamma-ray emission discovered by the Fermi-LAT in $\sim$150 pulsars is largely unexplored at these energies. In this…

High Energy Astrophysical Phenomena · Physics 2015-05-20 A. McCann

The error in the Solar system ephemeris will lead to dipolar correlations in the residuals of pulsar timing array for widely separated pulsars. In this paper, we utilize such correlated signals, and construct a Bayesian data-analysis…

Instrumentation and Methods for Astrophysics · Physics 2018-02-16 Y. J. Guo , K. J. Lee , R. N. Caballero

Employing Fermi-LAT gamma ray observations, several independent groups have found excess extended gamma ray emission at the Galactic center (GC). Both, annihilating dark matter (DM) or a population of $\sim 10^3$ unresolved millisecond…

High Energy Astrophysical Phenomena · Physics 2013-12-12 Chris Gordon , Oscar Macias

Traditional pulsar surveys have primarily employed time-domain periodicity searches. However, these methods are susceptible to effects like scattering, eclipses and orbital motion. At lower radio frequencies (<= 300 MHz), factors such as…

High Energy Astrophysical Phenomena · Physics 2024-11-20 S. Sett , M. Sokolowski , E. Lenc , N. D. R. Bhat

Using a likelihood analysis (updated since McLaughlin & Cordes 2000) and EGRET detections, upper limits and diffuse background measurements, we find a best-fit luminosity law for the gamma-ray pulsar population. We find that roughly 30 of…

Astrophysics · Physics 2007-05-23 M. A. McLaughlin , J. M. Cordes

Among the current sample of over 2000 radio pulsars known primarily in the disk of our Galaxy, millisecond pulsars now number almost 200. Due to the phenomenal success of blind surveys of the Galactic field, and targeted searches of Fermi…

Astrophysics of Galaxies · Physics 2015-06-11 Duncan R. Lorimer

The "blazar simplified view" is a new paradigm that explains well the diverse statistical properties of blazars observed over the entire electromagnetic spectrum on the basis of minimal assumptions on blazars' physical and geometrical…

High Energy Astrophysical Phenomena · Physics 2015-05-20 Paolo Giommi , Paolo Padovani

We use Fermi Gamma-ray Space Telescope detections and upper limits on non-recycled pulsars obtained from the Large Area Telescope (LAT) to constrain how the gamma-ray luminosity L depends on the period P and the period derivative \dot{P}.…

Solar and Stellar Astrophysics · Physics 2015-06-17 B. B. P. Perera , M. A. McLaughlin , J. M. Cordes , M. Kerr , T. H. Burnett , A. K. Harding

(abridged) Thanks to the recent discovery by Fermi of about fifty new gamma-ray pulsars, it becomes possible to look for statistical properties of their pulsed high-energy emission, especially their light-curves and phase-resolved spectra.…

High Energy Astrophysical Phenomena · Physics 2015-05-20 Jérôme Pétri

The Fermi satellite has recently detected gamma ray emission from the central regions of our Galaxy. This may be evidence for dark matter particles, a major component of the standard cosmological model, annihilating to produce high-energy…

High Energy Astrophysical Phenomena · Physics 2015-10-07 Timothy D. Brandt , Bence Kocsis

We compare radio profile widths of young, energetic gamma-ray-detected and non-gamma-ray-detected pulsars. We find that the latter typically have wider radio profiles, with the boundary between the two samples exhibiting a dependence on the…

High Energy Astrophysical Phenomena · Physics 2016-11-15 Simon C. Rookyard , Patrick Weltevrede , Simon Johnston , Matthew Kerr

The Fermi Gamma-ray Space Telescope has revealed a diffuse $\gamma$-ray background at energies from 0.1 GeV to 1 TeV, which can be separated into Galactic emission and an isotropic, extragalactic component. Previous efforts to understand…

High Energy Astrophysical Phenomena · Physics 2021-09-17 Matt A. Roth , Mark R. Krumholz , Roland M. Crocker , Silvia Celli

Since the launch of the Large Area Telescope (LAT) on board the Fermi spacecraft in June 2008, the number of observed gamma-ray pulsars has increased dramatically. A large number of these are also observed at radio frequencies. Constraints…

High Energy Astrophysical Phenomena · Physics 2012-01-24 A. S. Seyffert , C. Venter , T. J. Johnson , A. K. Harding

Star-forming galaxies are predicted to contribute considerably to the cosmic gamma-ray background (CGB) as they are confirmed gamma-ray emitters and are the most numerous population of gamma-ray sources, although individually faint. Even…

High Energy Astrophysical Phenomena · Physics 2009-12-18 Shin'ichiro Ando , Vasiliki Pavlidou
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