THE VIOLENT HARD X-RAY VARIABILITY OF MRK 421 OBSERVED BY<i>NuSTAR</i>IN 2013 APRIL

Paliya, Vaidehi S.; Böttcher, M.; Diltz, C.; Stalin, C. S.; Sahayanathan, S.; Ravikumar, C.

doi:10.1088/0004-637x/811/2/143

Cited by 60 publications

(71 citation statements)

References 35 publications

(37 reference statements)

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“…An estimate of B ≤ 0.1 G was the typical value for Mrk 421 obtained using SED modeling (Paliya et al 2015). Similar values of B were also obtained for Mrk 421 using NuStar and Chandra observations (Pandey et al 2017;Aggrawal et al 2018).…”

Section: Discussionsupporting

confidence: 78%

X-Ray Intraday Variability of the TeV Blazar Mrk 421 with Suzaku

Zhang

Gupta

Gaur

et al. 2019

ApJ

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We present X-ray flux and spectral analyses of the three pointed Suzaku observations of the TeV high synchrotron peak blazar Mrk 421 taken throughout its complete operational duration. The observation taken on 5 May 2008 is, at 364.6 kiloseconds (i.e., 101.3 hours), the longest and most evenly sampled continuous observation of this source, or any blazar, in the X-ray energy 0.8 -60 keV until now. We found large amplitude intra-day variability in all soft and hard bands in all the light curves. The discrete correction function analysis of the light curves in soft and hard bands peaks on zero lag, showing that the emission in hard and soft bands are cospatial and emitted from the same population of leptons. The hardness ratio plots imply that the source is more variable in the harder bands compared to the softer bands. The source is harder-when-brighter, following the general behavior of high synchrotron peak blazars. Power spectral densities of all three light curves are red noise dominated, with a range of power spectra slopes. If one assumes that the emission originates very close to the central super massive black hole, a crude estimate for its mass, of ∼ 4 × 10 8 M ⊙ , can be made; but if the variability is due to perturbations arising there that are advected into the jet and are thus Doppler boosted, substantially higher masses are consistent with the quickest seen variations. We briefly discuss the possible physical mechanisms most likely responsible for the observed flux and spectral variability.

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Section: Discussionsupporting

confidence: 78%

X-Ray Intraday Variability of the TeV Blazar Mrk 421 with Suzaku

Zhang

Gupta

Gaur

et al. 2019

ApJ

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“…The most dramatic flare in the GeV band occurred during in 2012 (MJD ∼ 56 140−56 180; calendar dates 2012-08-01 to 2012-09-10), which is reflected in the radio band after a gap of one and half months (MJD ∼ 56 193, Calendar date 2012-09-23). In contrast, the largest X-ray/optical flare happened during April 2013, which has been studied in detail by various authors (Sinha et al 2015;Pian et al 2014;Paliya et al 2015). In this section, we study the flux correlations between the various frequencies and quantify the nature of the variability.…”

Section: Multiwavelength Temporal Studymentioning

confidence: 99%

“…This blazar is a HBL with the synchrotron spectrum peaking in the X-ray regime. It is highly variable on all timescales and across all wavelengths from radio to TeVs, and has been studied comprehensively during its various flaring episodes by several authors (Aleksić et al 2012(Aleksić et al , 2010Acciari et al 2009;Shukla et al 2012;Isobe et al 2010;Krawczynski et al 2001;Ushio et al 2009;Tramacere et al 2009;Horan et al 2009;Lichti et al 2008;Fossati et al 2008;Albert et al 2007;Brinkmann et al 2003;Sinha et al 2015;Paliya et al 2015;Donnarumma et al 2009). Abdo et al (2011) studied the quiescent state emission from this source with the best-sampled SED to date.…”

Section: Introductionmentioning

confidence: 99%

Long-term study of Mkn 421 with the HAGAR Array of Telescopes

Sinha

Shukla

Saha

et al. 2016

A&A

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Context. The HAGAR Telescope Array at Hanle, Ladakh has been regularly monitoring the nearby blazar Mkn 421 for the past seven years. Aims. Blazars show flux variability in all timescales across the electromagnetic spectrum. While there is abundant literature characterizing the short-term flares from different blazars, comparatively little work has been carried out to study the long-term variability. We aim to study the long-term temporal and spectral variability in the radiation from Mkn 421 during 2009−2015. Methods. We quantify the variability and lognormality from the radio to very high-energy (VHE) bands, and compute the correlations between various wavebands using the z-transformed discrete correlation function. We construct the spectral energy distribution (SED) contemporaneous with HAGAR observation seasons and fit this SED with a one-zone synchrotron self-Compton model to study the spectral variability. Results. The flux is found to be highly variable across all timescales. The variability is energy dependant and is maximum in the X-ray and VHE bands. A strong correlation is found between the Fermi-LAT (gamma) and radio bands and between Fermi-LAT and optical, but no correlation is found between Fermi-LAT and X-ray. Lognormality in the flux distribution is clearly detected. This is the third blazar, following BL Lac and PKS 2155+304 to show this behaviour. The SED can be well fit by a one-zone SSC model, and variations in the flux states can be attributed mainly to changes in the particle distribution. A strong correlation is seen between the break energy γ b of the particle spectrum and the total bolometric luminosity.

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“…Due to the peculiar orientation of the jet that enhances the radiation because of the relativistic boosting , blazars are known to emit over entire electromagnetic spectrum, from low energy radio waves to very high energy γ-rays. In addition to that, another defining characteristic feature displayed by blazars is the rapid and high amplitude flux variations observed at all the accessible wavelengths (see, e.g., Stalin et al 2002;Sagar et al 2004;Jorstad et al 2010;Aleksić et al 2011;Bachev et al 2012;Paliya et al 2015a;Marchesini et al 2016). Based on the equivalent width (EW) of the optical emission lines, blazars are classified as flat spectrum radio quasars (FSRQs) and BL Lac objects with FSRQs exhibit broad emission lines (EW>5Å).…”

Section: Introductionmentioning

confidence: 99%

Intra-night Optical Variability Monitoring of Fermi Blazars: First Results from 1.3 m J. C. Bhattacharya Telescope

Paliya

Stalin

Ajello

et al. 2017

ApJ

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We report the first results obtained from our campaign to characterize the intranight-optical variability (INOV) properties of Fermi detected blazars, using the observations from the recently commissioned 1.3 m J C Bhattacharya telescope (JCBT). During the first run, we were able to observe 17 blazars in the Bessel R filter for ∼137 hrs. Using C and scaled F -statistics, we quantify the extent of INOV and derive the duty cycle (DC) which is the fraction of time during which a source exhibits a substantial flux variability. We find a high DC of 40% for BL Lac objects and the flat spectrum radio quasars are relatively less variable (DC ∼ 15%). However, when estimated for blazars sub-classes, a high DC of ∼59% is found in low synchrotron peaked (LSP) blazars, whereas, intermediate and high synchrotron peaked objects have a low DC of ∼11% and 13%, respectively. We find evidences about the association of the high amplitude INOV with the γ-ray flaring state. We also notice a high polarization during the elevated INOV states (for the sources that have polarimetric data available), thus supporting the jet based origin of the observed variability. We plan to enlarge the sample and utilize the time availability from the small telescopes, such as 1.3 m JCBT, to strengthen/verify the results obtained in this work and those existed in the literature.

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THE VIOLENT HARD X-RAY VARIABILITY OF MRK 421 OBSERVED BYNuSTARIN 2013 APRIL

Cited by 60 publications

References 35 publications

X-Ray Intraday Variability of the TeV Blazar Mrk 421 with Suzaku

X-Ray Intraday Variability of the TeV Blazar Mrk 421 with Suzaku

Long-term study of Mkn 421 with the HAGAR Array of Telescopes

Intra-night Optical Variability Monitoring of Fermi Blazars: First Results from 1.3 m J. C. Bhattacharya Telescope

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