X-ray Flux and Spectral Variability of the TeV Blazars Mrk 421 and PKS 2155-304

Gupta, Alok C.

doi:10.3390/galaxies8030064

Cited by 6 publications

(3 citation statements)

References 106 publications

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“…The object was a goal of several simultaneous MW observational campaigns over extended period of time (B lażejowski et al 2005;Fossati et al 2008;Lichti et al 2008;Donnarumma et al 2009;Horan et al 2009;Acciari et al 2011;Aleksić et al 2015a,b;Acciari et al 2020). In X-rays, Mrk 421 shows very complex flux and spectral variability (see for review Gupta 2020). MW observations of this source are used for fitting different emission models involving, e.g., the combination of SSC and IC processes, and occasionally lepto-hadronic models are applied (see for review Gupta 2020).…”

Section: Introductionmentioning

confidence: 99%

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X-ray intraday variability of the TeV blazar Mrk 421 with {\it XMM-Newton}

Noel¹,

Gaur²,

Gupta³

et al. 2022

Preprint

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Highly variable Markarian 421 is a bright high synchrotron energy peaked blazar showing wide featureless non-thermal spectrum making it a good candidate for our study of intraday flux and spectral variations over time. We analyse its X-ray observations of over 17 years taken with the EPIC-PN instrument to probe into the intraday variability properties. The photon energy band of 0.3 -10.0 keV, and its sub-bands, soft 0.3-2.0 keV and hard 2.0-10.0 keV. To examine flux variability, fractional variability amplitude and the minimum variability timescale have been calculated. We also probed into the spectral variability by studying hardness ratio for each observation and the correlation between the two energy bands using discrete correlation function and inspecting the normalized light curves. The parameters obtained from these methods have been studied for any correlation or non-random trends. From this work, we speculate on the constraints for possible particle acceleration and emission processes in the jet, for better understanding of the processes involving a turbulent behaviour except of shocks. A positive discrete correlation function between the two sub-bands indicates the role of the same electron population in the emission of photons in the two bands. The correlation between the parameters of flux variability and parameters of spectral variation and lags in sub-energy bands provide the constraints to be considered for any modelling of emission processes.

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Section: Introductionmentioning

confidence: 99%

“…In X-rays, Mrk 421 shows very complex flux and spectral variability (see for review Gupta 2020). MW observations of this source are used for fitting different emission models involving, e.g., the combination of SSC and IC processes, and occasionally lepto-hadronic models are applied (see for review Gupta 2020).…”

Section: Introductionmentioning

confidence: 99%

X-ray intraday variability of the TeV blazar Mrk 421 with {\it XMM-Newton}

Noel¹,

Gaur²,

Gupta³

et al. 2022

Preprint

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“…Multi-wavelength SEDs of PKS 2155−304 at various epochs of observations have been fit with with standard models, such as the synchrotron/Compton models, with possible contributions from accretion disks model and gravitational lensing etc. (for a review see Gupta 2020). Because the synchrotron peak of this HBL is in the UV-EUV region, its X-ray emission, at least out to 10 keV, is dominated by the falling part of the synchrotron hump (e.g.…”

Section: Introductionmentioning

confidence: 99%

X-ray Intraday Variability of the TeV Blazar PKS 2155-304 with Suzaku During 2005-2014

Zhang,

Gupta,

Gaur

et al. 2021

Preprint

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We have examined 13 pointed observations of the TeV emitting high synchrotron peak blazar PKS 2155−304, taken by the Suzaku satellite throughout its operational period. We found that the blazar showed large-amplitude intraday variabilities in the soft (0.8 -1.5 keV) and the hard (1.5 -8.0 keV) bands in the light curves. Spectral variability on intraday timescales is estimated using the hardness ratio. The blazar usually becomes harder when brighter and vice versa, following the typical behavior of high synchrotron peak blazars. The power spectral density (PSD) analyses of 11 out of 13 light curves in the total energy (0.8 -8.0 keV) are found to be red-noise dominated, with power-law spectral indices that span a large range, from −2.81 to −0.88. Discrete correlation function analyses of all the 13 light curves between the soft and the hard bands show that they are well correlated and peak at, or very close to, zero lag. This indicates that the emissions in soft and hard bands are probably cospatial and emitted from the same population of leptons. Considering fluxes versus variability timescales, we found no correlation on intraday timescales, implying that X-ray emission from PKS 2155−304 is not dominated by simple changes in the Doppler factor. We briefly discuss the most likely emission mechanisms responsible for the observed flux and spectral variabilities and place constraints on magnetic field strength and Lorentz factors of the electrons emitting the X-rays in the most likely scenario.

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X-Ray Intraday Variability of the TeV Blazar PKS 2155–304 with Suzaku during 2005–2014

Zhang

Gupta

Gaur

et al. 2021

ApJ

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We have examined 13 pointed observations of the TeV-emitting high synchrotron peak blazar PKS 2155−304, taken by the Suzaku satellite throughout its operational period. We found that the blazar showed large-amplitude intraday variabilities in the soft (0.8–1.5 keV) and the hard (1.5–8.0 keV) bands in the light curves. Spectral variability on intraday timescales is estimated using the hardness ratio. The blazar usually becomes harder when brighter and vice versa, following the typical behavior of high synchrotron peak blazars. The power spectral density analyses of 11 out of 13 light curves in the total energy (0.8–8.0 keV) are found to be dominated by red noise, with power-law spectral indices that span a large range, from −2.81 to −0.88. Discrete correlation function analyses of all the 13 light curves between the soft and the hard bands show that they are well correlated and peak at, or very close to, zero lag. This indicates that the emissions in soft and hard bands are probably cospatial and emitted from the same population of leptons. Considering fluxes versus variability timescales, we found no correlation on intraday timescales, implying that X-ray emission from PKS 2155−304 is not dominated by simple changes in the Doppler factor. We briefly discuss the most likely emission mechanisms responsible for the observed flux and spectral variabilities and place constraints on magnetic field strength and Lorentz factors of the electrons emitting the X-rays in the most likely scenario.

show abstract

X-ray Flux and Spectral Variability of the TeV Blazars Mrk 421 and PKS 2155-304

Cited by 6 publications

References 106 publications

X-ray intraday variability of the TeV blazar Mrk 421 with {\it XMM-Newton}

X-ray intraday variability of the TeV blazar Mrk 421 with {\it XMM-Newton}

X-ray Intraday Variability of the TeV Blazar PKS 2155-304 with Suzaku During 2005-2014

X-Ray Intraday Variability of the TeV Blazar PKS 2155–304 with Suzaku during 2005–2014

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