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We have investigated the pulse shape evolution of the Crab pulsar emission in the hard X-ray domain of the electromagnetic spectrum. In particular, we have studied the alignment of the Crab pulsar phase profiles measured in the hard X-rays…

High Energy Astrophysical Phenomena · Physics 2014-11-20 S. Molkov , E. Jourdain , J. P. Roques

We present the results of the search for a correlation between giant radio pulses (GRPs) at 1.4 GHz and hard X-rays at 15-75 keV from the Crab pulsar. We made simultaneous ground and satellite observations of the Crab pulsar over 12 hours…

During 1997, the BL Lac object Mkn 501 went into an extraordinary state of high X-ray and TeV gamma-ray activity, lasting more than 6 months. In this paper we report on the TeV emission characteristics of the source in the subsequent years…

Astrophysics · Physics 2018-04-18 The HEGRA Collaboration , F. Aharonian , A. Akhperjanian , J. Barrio

We present a time-lapse sequence of 20 near-infrared (J- and K'-band) snapshots of the central 20x20 arcsec of the Crab pulsar wind nebula, taken at subarcsecond resolution with the Hokupa'a/QUIRC adaptive optics camera on the Gemini North…

The Crab Pulsar's radio emission is unusual, consisting predominantly of giant pulses, with durations of about a micro-second but structure down to the nano-second level, and brightness temperatures of up to $10^{37}\,$K. It is unclear how…

Recent XMM-Newton observations reveal an extended (150") low-surface brightness X-ray halo in the supernova remnant G21.5-0.9. The near circular symmetry, the lack of any limb brightening and the non-thermal spectral form, all favour an…

We present the results of a search for pulsed TeV emission from the Crab pulsar using the Whipple Observatory's 10m gamma-ray telescope. The direction of the Crab pulsar was observed for a total of 73.4 hours between 1994 November and 1997…

It has been over 24 years since the iconic Crab Nebula has been visited by the high spatial resolution eye of the Hubble Space Telescope. The expanding nebula is dynamic on these timescales, with many of the outer filaments of the nebula…

Solar and Stellar Astrophysics · Physics 2025-12-15 William P. Blair , Ravi Sankrit , Dan Milisavljevic , Tea Temim , J. Martin Laming , Patrick Slane , Ziwei Ding , Thomas Martin

We observed the Crab pulsar in October 2008 at the Copernico Telescope in Asiago - Cima Ekar with the optical photon counter Aqueye (the Asiago Quantum Eye) which has the best temporal resolution and accuracy ever achieved in the optical…

We present [O III] 4959,5007 emission line spectra (FWHM = 40 km/s) of the Crab Nebula's northern ejecta `jet'. These data, along with a recent [O III] image of the Crab, are used to build 3-dimensional models of the jet and adjacent…

High Energy Astrophysical Phenomena · Physics 2015-06-23 Christine S. Black , Robert A. Fesen

The fine structure and the variations of the optical pulse shape and phase of the Crab pulsar are studied on various time scales. The observations have been carried out on 4-m William Hershel and 6-m BTA telescopes with APD photon counter,…

Astrophysics · Physics 2008-11-26 S. Karpov , G. Beskin , A. Biryukov , V. Debur , V. Plokhotnichenko , M. Redfern , A. Shearer

We present broadband (3 -- 78 keV) NuSTAR X-ray imaging and spectroscopy of the Crab nebula and pulsar. We show that while the phase-averaged and spatially integrated nebula + pulsar spectrum is a power-law in this energy band, spatially…

It has been argued by Jacobson, Liberati and Mattingly that synchrotron radiation from the Crab Nebula imposes a stringent constraint on any modification of the dispersion relations of the electron that might be induced by quantum gravity.…

Astrophysics · Physics 2009-09-11 J. Ellis , N. E. Mavromatos , A. S. Sakharov

We report about very high energy (VHE) gamma-ray observations of the Crab Nebula with the MAGIC telescope. The gamma-ray flux from the nebula was measured between 60 GeV and 9 TeV. The energy spectrum can be described with a curved power…

Astrophysics · Physics 2009-06-23 MAGIC Collaboration , J. Albert

We present the results of a search for pulsed TeV emission from the Crab pulsar using the Whipple Observatory's 10 m gamma-ray telescope. The direction of the Crab pulsar was observed for a total of 73.4 hours between 1994 November and 1997…

We present a newly enlarged census of the compact radio population towards the Orion Nebula Cluster (ONC) using high-sensitivity continuum maps (3-10 $\mu$Jy bm$^{-1}$) from a total of $\sim30$ h centimeter-wavelength observations over an…

Astrophysics of Galaxies · Physics 2021-07-07 Jaime Vargas-González , Jan Forbrich , Sergio A. Dzib , John Bally

We have analyzed 16 years of observations dedicated to the Crab (pulsar + nebula) with the INTEGRAL SPI instrument to investigate its polarization properties. We find that the source presents a substantially polarized emission (PF = 24%) in…

High Energy Astrophysical Phenomena · Physics 2019-09-25 E. Jourdain , J. P. Roques

We report the flux densities of the evolving radio source SN1987A at 843 MHz measured from observations made with the Molonglo Observatory Synthesis Telescope between 1994 September and 2000 May. The radio light curve shows that the rate of…

Astrophysics · Physics 2009-10-31 Lewis Ball , D. F. Crawford , R. W. Hunstead , I. Klamer , V. J. McIntyre

Magnetic dissipation is frequently invoked as a way of powering the observed emission of relativistic flows in Gamma Ray Bursts and Active Galactic Nuclei. Pulsar Wind Nebulae provide closer to home cosmic laboratories which can be used to…

High Energy Astrophysical Phenomena · Physics 2015-06-05 S. S. Komissarov