The relentless variability of Mrk 421 from the TeV to the radio

Arbet-Engels, Axel; Baack, Dominik; Balbo, Matteo; Biland, A.; Blank, Michael; Bretz, T.; Bruegge, Kai; Bulinski, Michael; Buß, Jens; Doerr, Manuel; Dorner, D.; Elsäesser, D.; Hildebrand, D.; Mannheim, K.; Mueller, S.; Neise, Dominik; Noethe, Maximilian; Paravac, Aleksander; Rhode, W.; Schleicher, Bernd; Sedlaczek, Kevin; Shukla, Amit; Sliusar, Vitalii; Walter, R.; Willert, Elan von

doi:10.1051/0004-6361/201935557

Cited by 25 publications

(32 citation statements)

References 73 publications

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“…5,9]. The highest variability of Mrk 421 was found in the X-rays and TeVs [9] with compatible to zero lag between the two bands [9,10].…”

Section: Introductionmentioning

confidence: 91%

“…To characterize the SED and study Mrk 421 variavility in different bands, numerous multi-wavelength (MWL) campaigns were caried out to date, observing Mrk 421 from radio to TeV -rays [e.g. 5,9]. The highest variability of Mrk 421 was found in the X-rays and TeVs [9] with compatible to zero lag between the two bands [9,10].…”

Section: Introductionmentioning

confidence: 99%

“…In this paper we investigate the GeV-radio correlation using the same data set as was used in [9]. The analysis is limited to over 7 years of GeV and radio data, from November 2010 to April 2018.…”

Section: Introductionmentioning

confidence: 99%

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GeV-radio correlation in Markarian 421

Sliusar¹,

Walter²,

Balbo³

2021

Proceedings of 37th International Cosmic Ray Conference — PoS(ICRC2021)

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Markarian 421 (Mrk 421) is a high-synchrotron-peaked blazar showing relentless variability across the electromagnetic spectrum from radio to gamma-rays. We use over 7-years of radio and GeV observations to study the correlation and connected variability in radio and GeV bands. Radio data was obtained in a 15GHz band by the OVRO 40-m radio telescope, and GeV data is from Fermi Large Area Telescope. To determine the location of the gamma-ray emission regions in Mrk 421 we correlate GeV and radio light curves. We found that GeV light curve varies independently and accurately leads the variations observed in radio. Using a fast-rise-slow-decay profile derived for shock propagation within a conical jet, we manage to reproduce the radio light curve from GeV variations. The profile rise time is comparable with the Fermi-LAT binning the decay time is about 7.6 days. The best-fit value for the response profile also features a 44 days delay between the GeV and radio, which is compatible with the wide lag range obtained from the correlation. Such a delay corresponds to 10 17 cm/c, which is comparable with the apparent light crossing time of the Mrk 421 radio core. Generally, the observed variability matches the predictions of the leptonic models and suggests that the physical conditions vary in the jet. The emitting region moving downstream the jet, while the environment becomes first transparent to gamma rays and later to the radio.

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“…5,9]. The highest variability of Mrk 421 was found in the X-rays and TeVs [9] with compatible to zero lag between the two bands [9,10].…”

Section: Introductionmentioning

confidence: 91%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

GeV-radio correlation in Markarian 421

Sliusar¹,

Walter²,

Balbo³

2021

Proceedings of 37th International Cosmic Ray Conference — PoS(ICRC2021)

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“…A data quality selection based on the artificial trigger rate [7,8] was applied. More details on the analysis can be found in [9]. Since the observations are ground-based, there are seasonal gaps of ∼ 120 days each year.…”

Section: Fermi-latmentioning

confidence: 99%

Statistical properties of flux variations in blazar light curves at GeV and TeV energies

Wagner¹,

Burd²,

Dorner³

et al. 2021

Proceedings of 37th International Cosmic Ray Conference — PoS(ICRC2021)

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Despite numerous detections of individual flares, the physical origin of the rapid variability observed from blazars remains uncertain. Using Bayesian blocks and the Eisenstein-Hut HOP algorithm, we characterize flux variations of high significance in the -ray light curves of two samples of blazars. Daily binned long-term light curves of TeV-bright blazars observed with the First G-APD Cherenkov Telescope (FACT) are compared to those of GeV-bright blazars observed with the Large Area Telescope on board the Fermi Gamma-ray Space Telescope (Fermi-LAT). We find no evidence for systematic asymmetry of the flux variations based on the derived rise and decay time scales. Additionally, we show that the daily-binned blazar light curves can be described by an exponential stochastic Ornstein-Uhlenbeck process with parameters depending on energy. Our analysis suggests that the flux variability in both samples is a superposition of faster fluctuations. This is, for instance, challenging to explain by shock-acceleration but expected for magnetic reconnection.

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“…Numerous multi-wavelength (MWL) campaigns were performed to date observing Mrk 421 from radio to the TeVs [e.g. 4,7]. Mrk 421 shows the highest variability in the X-rays and TeVs [7].…”

Section: Introductionmentioning

confidence: 99%

Relentless multi-wavelength variability of Markarian 421 and Markarian 501

Sliusar¹,

Arbet-Engels²,

Baack³

et al. 2021

Proceedings of 37th International Cosmic Ray Conference — PoS(ICRC2021)

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Mrk 421 and Mrk 501 are two close bright and well-studied high-synchrotron-peaked blazars, which feature bright and persistent GeV and TeV emission. We use the longest and densest dataset of unbiased observations of these two sources, obtained at TeV and GeV energies during 5 years with the FACT telescope and Fermi-LAT. To characterize the variability and derive constraints on the emission mechanism, we augment the dataset with contemporaneous multi-wavelength observations from radio to X-rays. We correlate the light curves, identify individual flares in TeV and X-rays, and look for inter-band connections, which are expected from the shock propagations within the jet. For Mrk 421 we find that the X-rays and TeV are well correlated with close to zero lag, supporting the SSC emission scenario. The timing between the TeV, X-ray flares in Mrk 421 is consistent with periods expected in the case of Lense-Thirring precession of the accretion disc. Mrk 501 variability on long-term periods is also consistent with SSC, with a sub-day lag between X-rays and TeVs. Fractional variability for both blazars shows two bump structure with the highest variability in X-ray and TeV bands.

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The relentless variability of Mrk 421 from the TeV to the radio

Cited by 25 publications

References 73 publications

GeV-radio correlation in Markarian 421

GeV-radio correlation in Markarian 421

Statistical properties of flux variations in blazar light curves at GeV and TeV energies

Relentless multi-wavelength variability of Markarian 421 and Markarian 501

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