Searcharxiv⌕ Search
Home/Archive/arXiv

arXiv · 0706.1551

Study of the Flux and Spectral Variations in the VHE Emission from the Blazar Markarian 501, with the MAGIC Telescope

D. Paneque
View original source ↗Read source document ↗Export metadata ↓

Abstract

The blazar Markarian 501 (Mrk 501) was observed above 100 GeV with the MAGIC Telescope during May, June and July 2005. The high sensitivity of the instrument made possible the detection of the source with high significance in each of the observing nights. During this observational campaign, the emitted gamma-ray flux from Mkn 501 was found to vary by one order of magnitude, and showed a high correlation with spectral changes. Intra-night flux variability was also observed, with flux-doubling times of ~2 minutes. The data showed a clear evidence of a spectral peak (in the nuFnu representation) during the nights when the gamma-ray activity was highest. The location of this spectral feature was found to be correlated with the emitted gamma-ray flux. In these proceedings we discuss some of the results of this unprecedented spectral and temporal analysis of Mrk 501 observations in the very high energy range.

Explore related subjects

astro-ph

Keep this discovery

BibTeXRIS

D. Paneque. 2007-06-11. Study of the Flux and Spectral Variations in the VHE Emission from the Blazar Markarian 501, with the MAGIC Telescope. https://doi.org/10.1063/1.2757290

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related papers

arXiv2017

Pulsar Magnetic Field Oscillation Model and Verification Methods

We constructed the magnetic field oscillation model (hereafter the MO model) by analogizing the periodically reversing phenomenon of the solar magnetic field to pulsars. Almost all kinds of pulsar radiation phenomena are best explained using the MO model, especially polarization characteristics, glitch, generation rate, the geodetic precession of pulsars and the configuration of pulsar-wind nebula of the Crab. The MO model also provides satisfactory explanation for other characteristics of pulsars, e.g., interpulse, spin-down, pulse nulling, beat and pulse drift, the loss rate of the rotating energy, and the accuracy of frequency. We present eight verification methods for the MO model. In addition to pulsars, our MO model can also be used to explain the pulse emission from non-compact stars such as the ultracool dwarf TVLM 513-46546 and the magnetic chemically peculiar star CU Virginis.

astro-ph↗
arXiv2017

Cosmological parameters from WMAP 5-year temperature maps

I calculate a hybrid cross-power spectrum estimator from the WMAP 5-year CMB temperature maps, discuss the goodness of fit, and then constrain cosmological parameters. The spectrum and results are generally consistent with previous results, though the power spectrum error bars are slightly smaller and there are small shifts at high ell. The small improvement in error bars is obtained at very low numerical cost but does not significantly improve parameter constraints. I discuss the accuracy of the likelihood model and how constraints on the optical depth translate into constraints on the reionization history allowing for helium reionization. In the appendices I propose a simple reionization parameterization that determines the history in terms of a mid-point reionization redshift, and suggest a new likelihood approximation for chi-squared-like distributions with varying skewness.

astro-ph↗
arXiv2017

The Statistics of Radio Astronomical Polarimetry: Bright Sources and High Time Resolution

A four-dimensional statistical description of electromagnetic radiation is developed and applied to the analysis of radio pulsar polarization. The new formalism provides an elementary statistical explanation of the modal broadening phenomenon in single pulse observations. It is also used to argue that the degree of polarization of giant pulses has been poorly defined in past studies. Single and giant pulse polarimetry typically involves sources with large flux densities and observations with high time resolution, factors that necessitate consideration of source-intrinsic noise and small-number statistics. Self noise is shown to fully explain the excess polarization dispersion previously noted in single pulse observations of bright pulsars, obviating the need for additional randomly polarized radiation. Rather, these observations are more simply interpreted as an incoherent sum of covariant, orthogonal, partially polarized modes. Based on this premise, the four-dimensional covariance matrix of the Stokes parameters may be used to derive mode-separated pulse profiles without any assumptions about the intrinsic degrees of mode polarization. Finally, utilizing the small-number statistics of the Stokes parameters, it is established that the degree of polarization of an unresolved pulse is fundamentally undefined; therefore, previous claims of highly polarized giant pulses are unsubstantiated. Unpublished supplementary material is appended after the bibliography.

astro-ph↗