Related papers: When A Standard Candle Flickers
The Gamma ray Burst Monitor (GBM) on board Fermi has been providing continuous data to the astronomical community since 2008 August 12. In this paper we present the results of the analysis of the first three years of these continuous data…
The status of the INTEGRAL cross-calibration is presented for a standard X-ray astronomy source, the Crab Nebula, as well as for some weaker sources. The relative flux normalization for the different INTEGRAL instruments is discussed…
We analyze the effect of polarized diffuse emission in the calibration of wide-beam mm-wave polarimeters, when using the Crab Nebula as a reference source for both polarized brightness and polarization angle. We show that, for CMB…
As one of the most energetic and brightest events, gamma-ray bursts (GRBs) have been used as a standard candle for cosmological probe. Based on the relevant features of GRBs light curves, a plateau phase followed a decay phase, we obtain…
The MAGIC stereoscopic system collected 69 hours of Crab Nebula data between October 2009 and April 2011. Analysis of this data sample using the latest improvements in the MAGIC stereoscopic software provided an unprecedented precision of…
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…
The ~400 MeV flaring emission from the Crab Nebula is naturally explained as the result of an abrupt reduction in the mass-loading of the pulsar wind. Very few particles are then available to carry the current required to maintain wave…
High-energy radiation of young pulsar wind nebulae (PWNe) is known to be variable. This is most prominently exemplified by the Crab nebula which can undergo both rapid brightenings and dimmings. Two pulsars in the Large Magellanic Cloud,…
We present spectral analysis of the Crab Nebula obtained with the {\it Chandra} X-ray observatory. The X-ray spectrum is characterized by a power-law whose index varies across the nebula. The variation can be discussed in terms of the…
The Crab Pulsar Wind Nebula is the best studied source of $\gamma$-ray astrophysics. The contribution of the various soft radiation fields to the Inverse Compton component of its high energy emission, the strenght of the internal magnetic…
We studied the evolution of the X-ray and gamma-ray spectra of the Crab pulsar utilizing the 11-year observations from the Rossi X-ray Timing Explorer (RXTE) and 9-year observations from the Fermi Gamma-ray Space Telescope (FGST). By…
The Crab nebula was observed with the H.E.S.S. stereoscopic Cherenkov-telescope array between October 2003 and January 2005 for a total of 22.9 hours (after data quality selection). Observations were made with three operational telescopes…
An axisymmetric model for the Crab Nebula is constructed to examine the flow dynamics in the nebula. The model is based on that of Kennel and Coroniti (1984), although we assume that the kinetic-energy-dominant wind is confined in an…
A plausible model for the Crab Nebula is one in which a particle dominated, highly relativistic wind from the pulsar passes through a shock front in which the particles attain a power law energy distribution. The electrons and positrons…
We present TeV gamma-ray observations of the Crab Nebula, the standard reference source in ground-based gamma-ray astronomy, using data from the High Altitude Water Cherenkov (HAWC) Gamma-Ray Observatory. In this analysis we use two…
Pulsars are well studied all over the electromagnetic spectrum, and the Crab pulsar may be the most studied object in the sky. Nevertheless, a high-quality optical to near-infrared spectrum of the Crab or any other pulsar has not been…
We report on gamma-ray observations of the Crab Pulsar and Nebula using 8 months of survey data with the Fermi Large Area Telescope (LAT). The high quality light curve obtained using the ephemeris provided by the Nancay and Jodrell Bank…
The Crab Nebula has been observed by the HEGRA (High-Energy Gamma-Ray Astronomy) stereoscopic system of imaging air Cherenkov telescopes (IACTs) for a total of about 200 hrs during two observational campaigns: from September 1997 to March…
Observations of the Crab Nebula have proven to be the best tool to calibrate and to characterize the performance of a Cherenkov telescope. Scientifically, it is interesting to measure the energy spectrum of the Crab Nebula close to the…
The Crab Nebula, also known as Tau A, is a polarized astronomical source at millimeter wavelengths. It has been used as a stable light source for polarization angle calibration in millimeter-wave astronomy. However, it is known that its…