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Synchrotron circular polarization of a non-thermal power-law electron distribution in gamma-ray bursts (GRBs) has been studied. However, some numerical simulations have shown that the resulting distribution of electrons is a combination of…

High Energy Astrophysical Phenomena · Physics 2025-05-29 Kangfa Cheng , Jirong Mao , Xiaohong Zhao , Hongbang Liu , Zhegeng Chen , Gaojin Yu , Zhifu Chen

The radio continuum spectra of 14 star-forming galaxies are investigated by fitting nonthermal (synchrotron) and thermal (free-free) radiation laws. The underlying radio continuum measurements cover a frequency range of ~325 MHz to 24.5 GHz…

Astrophysics of Galaxies · Physics 2018-03-28 Uli Klein , Ute Lisenfeld , Simon Verley

The flux density spectra of radio pulsars are known to be steep and, to first order, described by a power-law relationship of the form S_{\nu} \propto \nu^{\alpha}, where S_{\nu} is the flux density at some frequency \nu and \alpha is the…

Solar and Stellar Astrophysics · Physics 2015-06-15 Samuel D. Bates , Duncan R. Lorimer , Joris P. W. Verbiest

We discuss the recent detection of pulsed gamma-ray emission from the Crab Pulsar above 100 GeV with the VERITAS array of atmospheric Cherenkov telescopes. Gamma-ray emission at theses energies is not expected in present pulsar models. We…

High Energy Astrophysical Phenomena · Physics 2019-08-13 Andrew McCann

We present a census of 100 pulsars, the largest below 100 MHz, including 94 normal pulsars and six millisecond pulsars, with the Long Wavelength Array (LWA). Pulse profiles are detected across a range of frequencies from 26 to 88 MHz,…

High Energy Astrophysical Phenomena · Physics 2025-03-31 Pratik Kumar , Greg B. Taylor , Kevin Stovall , Jayce Dowell , Stephen M. White

We present a power spectral analysis of the Crab pulsar's timing noise, mainly using radio measurements from Jodrell Bank taken over the period 1982-1989. The power spectral analysis is complicated by nonuniform data sampling and the…

Astrophysics · Physics 2009-11-07 D. Matthew Scott , Mark H. Finger , Colleen A. Wilson

We have carried out new, high-frequency, high-time-resolution observations of the Crab pulsar. Combining these with our previous data, we characterize bright single pulses associated with the Main Pulse, both the Low-Frequency and…

High Energy Astrophysical Phenomena · Physics 2016-12-14 T. H. Hankins , J. A. Eilek , G. Jones

We report our analysis of the Fermi Large Area Telescope data for 39 millisecond pulsars (MSPs) listed in the second $\gamma$-ray pulsar catalog. Spectra of the pulsars are obtained. We fit the spectra with a function of a power law with…

High Energy Astrophysical Phenomena · Physics 2016-11-09 Yi Xing , Zhongxiang Wang

A number of Anomalous X-ray Pulsars (AXPs) have recently been detected in the optical/IR wavelengths. We use their inferred brightness to place general constraints on any model for this emission within the magnetar framework. We find that…

Astrophysics · Physics 2007-05-23 Feryal Ozel

We present HST/STIS far-UV observations of the Crab nebula and its pulsar. Broad, blueshifted absorption arising in the nebula is seen in C IV 1550, reaching about 2500 km/s. This can be interpreted as evidence for a fast outer shell, and…

We present first results from a LOFAR census of non-recycled pulsars. The census includes almost all such pulsars known (194 sources) at declinations ${\rm Dec}> 8^\circ$ and Galactic latitudes $|{\rm Gb}| > 3^\circ$, regardless of their…

Millisecond pulsars (MSPs) are a growing class of gamma-ray emitters. Pulsed gamma-ray signals have been detected from more than 40 MSPs with the Fermi Large Area Telescope (LAT). The wider radio beams and more compact magnetospheres of…

High Energy Astrophysical Phenomena · Physics 2014-06-24 T. J. Johnson , C. Venter , A. K. Harding , L. Guillemot , D. A. Smith , M. Kramer , O. Celik , P. R. den Hartog , E. C. Ferrara , X. Hou , J. Lande , P. S. Ray

Radio emission models of colliding wind binaries (CWBs) have been discussed by Dougherty et al. (2003). We extend these models by considering the temporal and spatial evolution of the energy distribution of relativistic electrons as they…

Astrophysics · Physics 2009-11-11 J. M. Pittard , S. M. Dougherty , R. F. Coker , E. O'Connor , N. J. Bolingbroke

The general properties of the non-thermal non-pulsed X-ray emission of rotation powered pulsars are investigated in the context of a pulsar wind nebula model. An examination of the observed X-ray emission from a sample of 23 pulsars from…

Astrophysics · Physics 2016-08-30 K. S. Cheng , Ronald E. Taam , W. Wang

The spectra of only a few pulsars are known in the low-energy gamma-ray region around 1 Mev. We searched for point sources of gamma-radiation in the 0.3-1 and 1-8 Mev bandpasses at the location of known radio and X-ray pulsars. Single…

High Energy Astrophysical Phenomena · Physics 2011-04-21 Joseph F. Dolan

The high sensitivity and wide frequency coverage of the Murchison Widefield Array allow for the measurement of the spectral scaling of the pulsar scattering timescale, $\alpha$, from a single observation. Here we present three case studies…

High Energy Astrophysical Phenomena · Physics 2019-04-17 F. Kirsten , N. D. R. Bhat , B. W. Meyers , J. -P. Macquart , S. E. Tremblay , S. M. Ord

We describe a refined calculation of high energy emission from rotation-powered pulsars based on the Outer Gap model of Cheng, Ho \&~Ruderman (1986a,b). We have improved upon previous efforts to model the spectra from these pulsars (e. g.…

Astrophysics · Physics 2009-10-22 J. Chiang , R. W. Romani

We present the time-averaged characteristics of the Crab pulsar in the 0.75-30 MeV energy window using data from the imaging Compton Telescope COMPTEL aboard the Compton Gamma-Ray Observatory (CGRO) collected over its 9 year mission.…

Astrophysics · Physics 2009-11-07 L. Kuiper , W. Hermsen , G. Cusumano , R. Diehl , V. Schonfelder , A. Strong , K. Bennett , M. McConnell

Pulsars are famous for their rotational stability. Most of them steadily spin down and display a highly repetitive pulse shape. But some pulsars experience timing irregularities such as nulling, intermittency, mode changing and timing…

High Energy Astrophysical Phenomena · Physics 2015-09-23 Lev Arzamasskiy , Alexander Philippov , Alexander Tchekhovskoy

During 2002-2003 the number of IR-identified counterparts to the Anomalous X-ray Pulsars (AXPs) has grown to four (4U0142+614, 2E2259+584, 1E 1048-59 and 1RXS J170849-400910) out of the six assessed objects of this class, plus two…

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