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Several important mechanisms that explain the coherent pulsar radio emission rely on streaming (or beam) instabilities of the relativistic pair plasma in a pulsar magnetosphere. However, it is still not clear whether a streaming instability…

High Energy Astrophysical Phenomena · Physics 2021-06-02 Alina C. Manthei , Jan Benáček , Patricio A. Muñoz , Jörg Büchner

We present initial pulsar results from the first station of the Long Wavelength Array (LWA1) obtained during the commissioning period of LWA1 and early science results. We present detections of periodic emission from 44 previously known…

Instrumentation and Methods for Astrophysics · Physics 2015-08-06 K. Stovall , P. S. Ray , J. Blythe , J. Dowell , T. Eftekhari , A. Garcia , T. J. W. Lazio , M. McCrackan , F. K. Schinzel , G. B. Taylor

We operate the six German stations of the LOw Frequency ARray as standalone telescopes to observe more than 100 pulsars every week. To date, we have collected almost four years of high-quality data at an unprecedented weekly cadence. This…

Solar and Stellar Astrophysics · Physics 2018-08-22 Caterina Tiburzi , Joris Verbiest

The following results of dissertation are submitted for defense: 1. Precise measurements of coordinates and proper motion of the pulsar PSR 0329+54 using the VLBI method. 2. Establishing of the reason for the discrepancy between the…

Instrumentation and Methods for Astrophysics · Physics 2024-01-25 Alexander Evgenievich Rodin

Blazars present highly variable $\gamma$-ray emission. This variability, which can range from a few minutes to several years, is also observed at other wavelengths across the entire electromagnetic spectrum. We make use of the first 12…

High Energy Astrophysical Phenomena · Physics 2024-03-05 P. Peñil , J. Otero-Santos , M. Ajello , S. Buson , A. Domínguez , L. Marcotulli , N. Torres-Albà , J. Becerra González , J. A. Acosta-Pulido

The phenomenon of pulsar nulling, observed as the temporary inactivity of a pulsar, remains poorly understood both observationally and theoretically. Most observational studies that quantify nulling employ a variant of Ritchings (1976)'s…

High Energy Astrophysical Phenomena · Physics 2023-09-15 Akash Anumarlapudi , Joseph K. Swiggum , David L. Kaplan , Travis D. J. Fichtenbauer

Emission spectrum is calculated for a weak axisymmetric pulsar. Also calculated are the observed spectrum, efficiency, and the observed efficiency. The underlying flow of electrons and positrons turns out to be curiously intricate.

High Energy Astrophysical Phenomena · Physics 2013-09-27 Andrei Gruzinov

Nonlinear radio waves modulate the plasma, scatter on the modulations, and develop an intermittent power spectrum -- perhaps. Rudiments of theory, numerical simulations, and qualitative modeling of nonlinear scattering are presented.…

High Energy Astrophysical Phenomena · Physics 2020-02-10 Andrei Gruzinov

Active galactic nuclei come in many varieties. A minority of them are radio-loud, and exhibit two opposite prominent plasma jets extending from the proximity of the supermassive black hole up to megaparsec distances. When one of the…

High Energy Astrophysical Phenomena · Physics 2021-06-14 Claudia M. Raiteri , Massimo Villata

Polarization measurements provide strong constraints on models for emission from rotation-powered pulsars. We present multiwavelength polarization predictions showing that measurements over a range of frequencies can be particularly…

High Energy Astrophysical Phenomena · Physics 2017-05-24 Alice K. Harding , Constantinos Kalapotharakos

Understanding the jitter noise resulting from single-pulse phase and shape variations is important for the detection of gravitational waves using pulsar timing array. We presented measurements of jitter noise and single-pulse variability of…

High Energy Astrophysical Phenomena · Physics 2024-01-24 S. Q. Wang , N. Wang , J. B. Wang , G. Hobbs , H. Xu , B. J. Wang , S. Dai , S. J. Dang , D. Li , Y. Feng , C. M. Zhang

Recent suggestions for a modification of general relativity to provide an alternative approach to gravity in connection with the dark energy (matter) problem imply a long range vector component of the gravitational field. This could lead to…

Astrophysics · Physics 2008-03-14 C. Sivaram

The energy source of a pulsar's non-thermal emission is the rotational energy loss of the neutron star. The rotational energy of the neutron star is transformed into the pulsar radiation by a long sequence of processes. The processes of…

Astrophysics · Physics 2007-05-23 Vladimir V. Usov

Most of pulsar nulling observations were conducted at frequencies lower than 1400~MHz. We aim to understand the nulling behaviors of pulsars at relatively high frequency, and to check if nulling is caused by a global change of pulsar…

High Energy Astrophysical Phenomena · Physics 2021-01-04 P. F. Wang , J. L. Han , L. Han , B. Y. Cai , C. Wang , T. Wang , X. Chen , D. J. Zhou , Y. Z. Yu , J. Han , J. Xu , X. Y. Gao , T. Hong , L. G. Hou , B. Dong

Millisecond and binary pulsars are the most stable astronomical standards of frequency. They can be applied to solving a number of problems in astronomy and time-keeping metrology including the search for a stochastic gravitational wave…

Solar and Stellar Astrophysics · Physics 2015-05-14 Sergei Kopeikin

The mechanisms of emission and changes in rotation frequency ('glitching') of the Vela pulsar (J0835-4510) are not well understood. Further insight into these mechanisms can be achieved by long-term studies of integrated pulse width, timing…

High Energy Astrophysical Phenomena · Physics 2016-03-21 J. L. Palfreyman , J. M. Dickey , S. P. Ellingsen , I. R. Jones , A. W. Hotan

The origin of pulsar radio emission is one of the old puzzles in theoretical astrophysics. In this Letter we present a global kinetic plasma simulation which shows from first-principles how and where radio emission can be produced in pulsar…

High Energy Astrophysical Phenomena · Physics 2023-12-12 Ashley Bransgrove , Andrei M. Beloborodov , Yuri Levin

Pulsars are rotating neutron stars, sweeping the emission regions from the magnetic poles across our line of sight. Isolated neutron stars lose angular momentum through dipole radiation and (possibly) particle winds, hence they slow down…

Astrophysics · Physics 2007-05-23 R Dodson , D. R. Lewis , P. M. McCulloch

High time-resolution observations of pulsars were carried out at 35 MHz, using the Gauribidanur Radio Telescope (India), to study the spectra of intrinsic pulse-to-pulse fluctuations. Our sample consists of a few bright pulsars, each of…

Astrophysics · Physics 2007-05-23 Ashish Asgekar , A. A. Deshpande

The extreme variability of blazars, in both timescale and amplitude, is generally explained as the effect of a relativistic jet closely aligned to the observer's line-of-sight. Due to causality arguments, variability characteristics…