A Multiwavelength View of the TeV Blazar Markarian 421: Correlated Variability, Flaring, and Spectral Evolution

Błażejowski, M.; Blaylock, G.; Bond, I. H.; Bradbury, S. M.; Buckley, J. H.; Carter‐Lewis, D. A.; Çelik, Ö.; Cogan, P.; Cui, Wei; Daniel, M. K.; Duke, C.; Falcone, A.; Fegan, D. J.; Fegan, S. J.; Finley, J. P.; Fortson, L.; Gammell, S.; Gibbs, K.; Gillanders, G. G.; Grube, J.; Gutierrez, K.; Hall, J.; Hanna, D.; Holder, J.; Horan, D.; Humensky, Brian; Kenny, G. E.; Kertzman, M.; Kieda, D. B.; Kildea, J.; Knapp, J.; Kosack, K.; Krawczynski, H.; Krennrich, F.; Lang, M. J.; LeBohec, S.; Linton, E.; Lloyd‐Evans, J.; Maier, G.; Mendoza, Daniel; Milovanovic, A.; Moriarty, P.; Nagai, T.; Ong, R. A.; Power-Mooney, B.; Quinn, J.; Quinn, M.; Ragan, K.; Reynolds, P. T.; Rebillot, P.; Rose, H. J.; Schroedter, M.; Sembroski, G. H.; Swordy, S. P.; Syson, A.; Valcarel, L.; Vassiliev, V. V.; Wakely, S. P.; Walker, G.; Weekes, T. C.; White, R.; Zweerink, J.; Mochejska, B. J.; Smith, B. R.; Aller, M. F.; Aller, H. D.; Teräsranta, H.; Boltwood, P.; Sadun, A. C.; Stanek, K. Z.; Adams, Elisabeth R.; Foster, Jonathan B.; Hartman, J. D.; Lai, Kamson; Böttcher, M.; Reimer, A.; Jung, I.

doi:10.1086/431925

Cited by 193 publications

(189 citation statements)

References 48 publications

(43 reference statements)

Supporting

Mentioning

174

Contrasting

Order By: Relevance

“…This was reported at least two times (e.g. Krawczynski et al 2004;Blazejowski et al 2005) and is know in the literature as an orphan flare phenomenon.…”

Section: The Observations Of Mrk 421 Made In March 2001mentioning

confidence: 82%

On the correlation between the X-ray and gamma-ray emission in TeV blazars

Walczewska¹

2010

A&A

View full text Add to dashboard Cite

Aims. The observations of TeV blazars published recently show an unexpected quadratic or even cubic correlation between the X-ray and gamma-ray emission. A standard model of the synchrotron self-Compton emission of a compact source inside a jet is not able to explain such a correlation. Therefore, we propose an alternative scenario where the emission of at least two independent compact components is observed at the same time. Methods. We compare two different models. The first model assumes the injection of relativistic particles into a downstream region of a shock wave inside a jet that creates the emitting source. The model precisely describes the evolution of the particle energy spectrum inside the source and takes into account a light-crossing time effect for the produced radiation. The second model assumes an intrinsically constant emission of a homogeneous source that travels inside the jet along a curved trajectory, where the activity is produced simply by different values of the source's Doppler factor. To verify the two models we use recently published observations of Mrk 421. Results. Our simulations show that simultaneous radiation of at least two independent sources, where the first source dominates the emission in the X-ray range and the second source radiates strongly in the gamma-ray range, can explain the observed correlations. However, the injection model provides inadequate results because it gives different values for the correlation of the rise and decay of a flare. This problem is negligible in the scenario that uses the Doppler boosting effect. Therefore, this approach yields much better results.

show abstract

“…This was reported at least two times (e.g. Krawczynski et al 2004;Blazejowski et al 2005) and is know in the literature as an orphan flare phenomenon.…”

Section: The Observations Of Mrk 421 Made In March 2001mentioning

confidence: 82%

On the correlation between the X-ray and gamma-ray emission in TeV blazars

Walczewska¹

2010

A&A

View full text Add to dashboard Cite

show abstract

“…often directly observable in the Swift-XRT band, as in other similar HBL sources (e.g., Tramacere et al 2007a;Furniss et al 2015). Its location in frequency space can be estimated from the UV/optical and X-ray data, using a reasonable smooth interpolation or extrapolation model (e.g., Massaro et al 2004;Błażejowski et al 2005;Tramacere et al 2009;Ushio et al 2010). For the analysis presented here, we use 30 pairs of Swift-XRT and NuSTAR spectra assembled from data taken simultaneously, together with UV data taken within the same Swift observation and R-band data taken within 24 hr.…”

Section: The Peak Of the Synchrotron Sed Componentmentioning

confidence: 99%

MULTIWAVELENGTH STUDY OF QUIESCENT STATES OF Mrk 421 WITH UNPRECEDENTED HARD X-RAY COVERAGE PROVIDED BY NuSTAR IN 2013

Baloković¹,

Paneque²,

Madejski³

et al. 2016

ApJ

Self Cite

113

View full text Add to dashboard Cite

We present coordinated multiwavelength observations of the bright, nearby BL Lacertae object Mrk 421 taken in 2013 January-March, involving GASP-WEBT, Swift, NuSTAR, Fermi-LAT, MAGIC, VERITAS, and other collaborations and instruments, providing data from radio to very high energy(VHE) γ-ray bands. NuSTAR yielded previously unattainable sensitivity in the 3-79keV range, revealing that the spectrum softens when the source is dimmer until the X-ray spectral shape saturates into a steep 3 G » power law, with no evidence for an exponential cutoff or additional hard components up to ∼80keV. For the first time, we observed both the synchrotron and the inverse-Compton peaks of the spectral energy distribution (SED) simultaneously shifted to frequencies below the typical quiescent state by an order of magnitude. The fractional variability as a function of photon energy shows a double-bump structure that relates to the two bumps of the broadband SED. In each bump, the variability increases with energy, which, in the framework of the synchrotron self-Compton model, implies that the electrons with higher energies are more variable. The measured multi band variability, the significant X-ray-to-VHE correlation down to some of the lowest fluxes ever observed in both bands, the lack of correlation between optical/UV and X-ray flux, the low degree of polarization and its significant (random) variations, the short estimated electron cooling time, and the significantly longer variability timescale observed in the NuSTAR light curves point toward in situ electron acceleration and suggest that there are multiple compact regions contributing to the broadband emission of Mrk 421 during low-activity states.

show abstract

“…It is an HBL, with the synchrotron spectrum peaking in the X-ray regime. Moreover, the X-ray emission is known to be highly correlated with the TeV emission (Błażejowski et al 2005;Katarzynski et al 2005;Qian et al 1998), but like other HBLs, shows moderate correlation with the GeV emission (Li et al 2013). It is highly variable and has been well studied during its flaring episodes by several authors (Aleksić et al 2010(Aleksić et al , 2012Shukla et al 2012;Isobe et al 2010;Krawczynski et al 2001;Acciari et al 2009;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).…”

Section: Introductionmentioning

confidence: 99%

Underlying particle spectrum of Mkn 421 during the huge X-ray flare in April 2013

Sinha

Shukla

Misra

et al. 2015

A&A

View full text Add to dashboard Cite

Context. In April 2013, the nearby TeV blazar, Mkn 421, showed one of the largest flares in X-rays in the past decade. Aims. We study all multiwavelength data available during MJD 56 392 to 56 403, with special emphasis on X-ray data to understand the underlying particle energy distribution. Methods. We studied the correlations between the UV and gamma-ray bands with the X-ray band using the z-transformed discrete correlation function. We modelled the underlying particle energy spectrum with a single population of electrons emitting synchrotron radiation, and statistically fitted the simultaneous time-resolved data from Swift-XRT and NuSTAR. Results. The flux varied rapidly in the X-ray band, with a minimum doubling timescale of 1.69 ± 0.13 h. There were no corresponding flares in UV and gamma-ray bands. The variability in UV and gamma rays was relatively modest with ∼8% and ∼16%, respectively, and no significant correlation was found with the X-ray light curve. The observed X-ray spectrum shows a clear curvature that can be fit by a log parabolic spectral form. This is best explained as originating from a log parabolic electron spectrum. However, a broken power law or a power law with an exponentially falling electron distribution cannot be ruled out either. Moreover, the excellent broadband spectrum from 0.3-79 keV allows us to make predictions of the UV flux. We find that this prediction is compatible with the observed flux during the low state in X-rays. However, during the X-ray flares, depending on the adopted model, the predicted flux is a factor of 2-50 lower than the observed one. This suggests that the X-ray flares are probably caused by a separate population that does not contribute significantly to the radiation at lower energies. Alternatively, the underlying particle spectrum can be much more complex than those explored in this work.

show abstract

A Multiwavelength View of the TeV Blazar Markarian 421: Correlated Variability, Flaring, and Spectral Evolution

Cited by 193 publications

References 48 publications

On the correlation between the X-ray and gamma-ray emission in TeV blazars

On the correlation between the X-ray and gamma-ray emission in TeV blazars

MULTIWAVELENGTH STUDY OF QUIESCENT STATES OF Mrk 421 WITH UNPRECEDENTED HARD X-RAY COVERAGE PROVIDED BY NuSTAR IN 2013

Underlying particle spectrum of Mkn 421 during the huge X-ray flare in April 2013

Contact Info

Product

Resources

About