Detection of significant cm to sub-mm band radio and  -ray correlated variability in Fermi bright blazars

Fuhrmann, L.; Larsson, Stefan; Chiang, J.; Angelakis, E.; Zensus, J. A.; Nestoras, I.; Krichbaum, T. P.; Ungerechts, H.; Sievers, A.; Pavlidou, V.; Readhead, A. C. S.; Max-Moerbeck, W.; Pearson, T. J.

doi:10.1093/mnras/stu540

Cited by 155 publications

(190 citation statements)

References 59 publications

(85 reference statements)

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“…In summary, on long timescales, we find that (1) variations at γ-ray energies (γ-ray light curve 1 in 2008 August 5-2013 October 31) are very well correlated with those at 1.3 mm, with the latter delayed by 143 ± 5 days and a secondary, but statistically significant, DCF peak at 87 ± 10 days delay (we note that Fuhrmann et al (2014) find a delay at 3 mm of 93 ± 16 days) ; (2) X-ray and 1.3 mm variations are correlated with a delay less than several days, but alternating which band varies first; and (3) variations at the UVM2 and optical V bands were simultaneous to within 0 ± 0.5 days. On medium timescales of 1-2 years, the optical and UV bands are correlated, with no delay, and variations at other bands are uncorrelated.…”

Section: Summary Of the Correlationssupporting

confidence: 52%

Erratic Flaring of Bl Lac in 2012–2013: Multiwavelength Observations

Wehrle

Grupe

Jorstad

et al. 2016

ApJ

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BL Lac, the eponymous blazar, flared to historically high levels at millimeter, infrared, X-ray, and gamma-ray wavelengths in 2012. We present observations made with Herschel, Swift, NuSTAR, Fermi, the Submillimeter Array, CARMA, and the VLBA in 2012-2013, including three months with nearly daily sampling at several wavebands. We have also conducted an intensive campaign of 30 hr with every-orbit observations by Swift and NuSTAR, accompanied by Herschel, and Fermi observations. The source was highly variable at all bands. Time lags, correlations between bands, and the changing shapes of the spectral energy distributions can be explained by synchrotron radiation and inverse Compton emission from nonthermal seed photons originating from within the jet. The passage of four new superluminal very long baseline interferometry knots through the core and two stationary knots about 4 pc downstream accompanied the high flaring in 2012-2013. The seed photons for inverse Compton scattering may arise from the stationary knots and from a Mach disk near the core where relatively slowmoving plasma generates intense nonthermal radiation. The 95 spectral energy distributions obtained on consecutive days form the most densely sampled, broad wavelength coverage for any blazar. The observed spectral energy distributions and multi-waveband light curves are similar to simulated spectral energy distributions and light curves generated with a model in which turbulent plasma crosses a conical shock with a Mach disk.

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Section: Summary Of the Correlationssupporting

confidence: 52%

Erratic Flaring of Bl Lac in 2012–2013: Multiwavelength Observations

Wehrle

Grupe

Jorstad

et al. 2016

ApJ

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“…Valtaoja & Teraesranta (1996); Jorstad et al (2001); Lähteenmäki & Valtaoja (2003); Kovalev et al (2009);Pushkarev et al (2010); León-Tavares et al (2011);Fuhrmann et al (2014); Ramakrishnan et al (2015) and Karamanavis et al (2016) reported significant correlations between these bands. While localizing the γ-ray emitting region authors agree that it originates in the relativistic jet of AGN, but dispute about more precise location of this emission within a jet.…”

Section: Introductionmentioning

confidence: 93%

Multiwavelength observations of the γ-ray flaring quasar S4 1030+61 in 2009–2014

Kravchenko

Kovalev

Hovatta

2016

Mon. Not. R. Astron. Soc.

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We present a study of the parsec-scale multi-frequency properties of the quasar S4 1030+61 during a prolonged radio and γ-ray activity. Observations were performed within Fermi γ-ray telescope, OVRO 40-m telescope and MOJAVE VLBA monitoring programs, covering five years from 2009. The data are supplemented by four-epoch VLBA observations at 5, 8, 15, 24, and 43 GHz, which were triggered by the bright γ-ray flare, registered in the quasar in 2010. The S4 1030+61 jet exhibits an apparent superluminal velocity of (6.4±0.4)c and does not show ejections of new components in the observed period, while decomposition of the radio light curve reveals nine prominent flares. The measured variability parameters of the source show values typical for Fermi-detected quasars. Combined analysis of radio and γ-ray emission implies a spatial separation between emitting regions at these bands of about 12 pc and locates the γ-ray emission within a parsec from the central engine. We detected changes in the value and direction of the linear polarization and the Faraday rotation measure. The value of the intrinsic brightness temperature of the core is above the equipartition state, while its value as a function of distance from the core is well approximated by the power-law. Altogether these results show that the radio flaring activity of the quasar is accompanied by injection of relativistic particles and energy losses at the jet base, while S4 1030+61 has a stable, straight jet well described by standard conical jet theories.

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“…The data were reduced using standard processing and calibration techniques described in detail in Richards et al (2011). Radio observations of Mrk 421 between 2.64 and 142GHz have been obtained within the framework of the F-GAMMA program (Fuhrmann et al 2007(Fuhrmann et al , 2014; Angelakis et al 2010), a γ-ray blazar monitoring program related to the Fermi Gamma-ray Space Telescope. Observations with the Effelsberg 100 m and Pico Veleta 30 m telescopes are performed roughly once per month.…”

Section: Radiomentioning

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

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111

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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.

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Detection of significant cm to sub-mm band radio and -ray correlated variability in Fermi bright blazars

Cited by 155 publications

References 59 publications

Erratic Flaring of Bl Lac in 2012–2013: Multiwavelength Observations

Erratic Flaring of Bl Lac in 2012–2013: Multiwavelength Observations

Multiwavelength observations of the γ-ray flaring quasar S4 1030+61 in 2009–2014

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

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