Browsing University of Galway Support Services by Subject "radiation mechanisms: non-thermal"
Now showing items 1-17 of 17
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A recent change in the optical and γ-ray polarization of the crab nebula and pulsar
(Oxford University Press (OUP), 2015-12-31)We report on observations of the polarization of optical and gamma-ray photons from the Crab nebula and pulsar system using the Galway Astronomical Stokes Polarimeter (GASP), the Hubble Space Telescope, Advanced Camera for ... -
A search for spectral hysteresis and energy-dependent time lags from x-ray and tev gamma-ray observations of mrk 421
(American Astronomical Society, 2016-12-22)Blazars are variable emitters across all wavelengths over a wide range of timescales, from months down to minutes. It is therefore essential to observe blazars simultaneously at different wavelengths, especially in the ... -
Circular polarization of synchrotron radiation in high magnetic fields
(Oxford University Press (OUP), 2015-04-01)The general model for incoherent synchrotron radiation has long been known, with the first theory being published by Westfold in 1959 and continued by Westfold and Legg in 1968. When this model was first developed, it was ... -
Fermilarge area telescope observations of markarian 421: the missing piece of its spectral energy distribution
(IOP Publishing, 2011-07-15)We report on the gamma-ray activity of the high-synchrotron-peaked BL Lacertae object Markarian 421 (Mrk 421) during the first 1.5 years of Fermi operation, from 2008 August 5 to 2010 March 12. We find that the Large Area ... -
Gamma-rays from the quasar pks 1441+25: story of an escape
(IOP Publishing, 2015-12-15)Outbursts from gamma-ray quasars provide insights on the relativistic jets of active galactic nuclei and constraints on the diffuse radiation fields that fill the universe. The detection of significant emission above 100 ... -
hst optical polarimetry of the vela pulsar and nebula
(Oxford University Press (OUP), 2014-09-30)Polarization measurements of pulsars offer a unique insight into the geometry of the emission regions in the neutron star magnetosphere. Therefore, they provide observational constraints on the different models proposed ... -
Insights into the high-energy γ-ray emission of markarian 501 from extensive multifrequency observations in thefermiera
(IOP Publishing, 2011-01-12)We report on the gamma-ray activity of the blazar Mrk 501 during the first 480 days of Fermi operation. We find that the average Large Area Telescope (LAT) gamma-ray spectrum of Mrk 501 can be well described by a single ... -
Inverse mapping of polarized optical emission from pulsars: basic formulation and determination of emission altitude
(Oxford University Press (OUP), 2011-08-22)We present an inverse mapping approach to determining the emission height of the optical photons from pulsars, which is directly constrained by empirical data. The model discussed is for the case of the Crab pulsar. Our ... -
Optical polarimetry of the inner crab nebula and pulsar
(Oxford University Press (OUP), 2013-06-20)Time-resolved polarization measurements of pulsars offer a unique insight into the geometry of their emission regions. Such measurements provide observational constraints on the different models proposed for the pulsar ... -
Simultaneous multiwavelength observations of markarian 421 during outburst
(IOP Publishing, 2009-08-26)We report on the results of two coordinated multiwavelength campaigns that focused on the blazar Markarian 421 during its 2006 and 2008 outbursts. These campaigns obtained UV and X-ray data using the XMM-Newton satellite, ... -
Spectral energy distribution of markarian 501: quiescent state versus extreme outburst
(IOP Publishing, 2011-02-03)The very high energy (VHE; E > 100 GeV) blazar Markarian 501 (Mrk 501) has a well-studied history of extreme spectral variability and is an excellent laboratory for studying the physical processes within the jets ... -
The 2010 very high energy γ-ray flare and 10 years of multi-wavelength observations of m 87
(IOP Publishing, 2012-02-02)The giant radio galaxy M 87 with its proximity (16 Mpc), famous jet, and very massive black hole ((3-6) x 10(9) M-circle dot) provides a unique opportunity to investigate the origin of very high energy (VHE; E > 100 ... -
The june 2008 flare of markarian 421 from optical to tev energies
(IOP Publishing, 2008-12-30)We present optical, X-ray, high-energy ((sic) 30 GeV) and very high energy ((sic) 100 GeV; VHE) observations of the high-frequency peaked blazar Mrk 421 taken between 2008 May 24 and June 23. A high-energy gamma-ray signal ... -
Unprecedented study of the broadband emission of mrk 421 during flaring activity in march 2010
(EDP Sciences, 2015-05-27)Context. Because of its proximity, Mrk 421 is one of the best sources on which to study the nature of BL Lac objects. Its proximity allows us to characterize its broadband spectral energy distribution (SED). Aims. The goal ... -
Upper limits from five years of blazar observations with the veritas cherenkov telescopes
(American Astronomical Society, 2016-05-18)Between the beginning of its full-scale scientific operations in 2007 and 2012, the VERITAS Cherenkov telescope array observed more than 130 blazars; of these, 26 were detected as very-high-energy (VHE; E > 100 GeV) ... -
Veritas observations of the unusual extragalactic transient swift j164449.3+573451
(IOP Publishing, 2011-08-24)We report on very high energy (>100 GeV) gamma-ray observations of Swift J164449.3+573451, an unusual transient object first detected by the Swift Observatory and later detected by multiple radio, optical, and X-ray ... -
Very-high energy observations of the galactic center region by veritas in 2010-2012
(IOP Publishing, 2014-07-16)The Galactic center is an interesting region for high-energy (0.1-100 GeV) and very-high-energy (E > 100 GeV) gamma-ray observations. Potential sources of GeV/TeV gamma-ray emission have been suggested, e.g., the ...