Radio to gamma-ray variability study of blazar S5 0716+714

Rani, Bindu; Krichbaum, T. P.; Fuhrmann, L.; Boettcher, Markus; Lott, B.; Aller, H. D.; Aller, M. F.; Angelakis, E.; Bach, U.; Bastieri, D.; Falcone, A.; Fukazawa, Yasushi; Gabányi, K. É.; Gupta, Alok C.; Gurwell, M. A.; Itoh, R.; Kawabata, Koji S.; Krips, M.; Lähteenmäki, A.; Liu, X.; Marchili, N.; Max-Moerbeck, W.; Nestoras, I.; Nieppola, E.; Quintana-Lacaci, G.; Readhead, A. C. S.; Richards, J. L.; Sasada, Mahito; Sievers, A.; Sokolovsky, K. V.; Stroh, M. C.; Tammi, J.; Tornikoski, M.; Uemura, Makoto; Ungerechts, H.; Urano, T.; Zensus, J. A.

doi:10.1051/0004-6361/201321058

Cited by 109 publications

(89 citation statements)

References 72 publications

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“…We note that one of the jet components with the fastest angular speed in our sample, ID = 16 in the BL Lac object 0716+714, is a distinct outlier in Figure 12, with recent constraints on its redshift by Danforth et al (2013) implying an apparent speed of up to 43.6c ± 1.3c. This AGN is highly variable at all wavelengths (e.g., Wagner et al 1996;Larionov et al 2013) and has a Doppler factor of at least 20 (Rani et al 2013), making it a strong candidate for a masquerading BL Lac object.…”

Section: Speed Versus Distance Down the Jetmentioning

confidence: 99%

Mojave. X. Parsec-Scale Jet Orientation Variations and Superluminal Motion in Active Galactic Nuclei

Lister

Aller

et al. 2013

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We describe the parsec-scale kinematics of 200 active galactic nucleus (AGN) jets based on 15 GHz Very Long Baseline Array (VLBA) data obtained between 1994 August 31 and 2011 May 1. We present new VLBA 15 GHz images of these and 59 additional AGNs from the MOJAVE and 2 cm Survey programs. Nearly all of the 60 most heavily observed jets show significant changes in their innermost position angle over a 12-16 yr interval, ranging from 10• to 150• on the sky, corresponding to intrinsic variations of ∼0.• 5 to ∼2• . The BL Lac jets show smaller variations than quasars. Roughly half of the heavily observed jets show systematic position angle trends with time, and 20 show indications of oscillatory behavior. The time spans of the data sets are too short compared to the fitted periods (5-12 yr), however, to reliably establish periodicity. The rapid changes and large jumps in position angle seen in many cases suggest that the superluminal AGN jet features occupy only a portion of the entire jet cross section and may be energized portions of thin instability structures within the jet. We have derived vector proper motions for 887 moving features in 200 jets having at least five VLBA epochs. For 557 well-sampled features, there are sufficient data to additionally study possible accelerations. We find that the moving features are generally non-ballistic, with 70% of the well-sampled features showing either significant accelerations or non-radial motions. Inward motions are rare (2% of all features), are slow (<0.1 mas yr −1 ), are more prevalent in BL Lac jets, and are typically found within 1 mas of the unresolved core feature. There is a general trend of increasing apparent speed with distance down the jet for both radio galaxies and BL Lac objects. In most jets, the speeds of the features cluster around a characteristic value, yet there is a considerable dispersion in the distribution. Orientation variations within the jet cannot fully account for the dispersion, implying that the features have a range of Lorentz factor and/or pattern speed. Very slow pattern speed features are rare, comprising only 4% of the sample, and are more prevalent in radio galaxy and BL Lac jets. We confirm a previously reported upper envelope to the distribution of speed versus beamed luminosity for moving jet features. Below 10 26 W Hz −1 there is a fall-off in maximum speed with decreasing 15 GHz radio luminosity. The general shape of the envelope implies that the most intrinsically powerful AGN jets have a wide range of Lorentz factors up to ∼40, while intrinsically weak jets are only mildly relativistic.

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Section: Speed Versus Distance Down the Jetmentioning

confidence: 99%

Mojave. X. Parsec-Scale Jet Orientation Variations and Superluminal Motion in Active Galactic Nuclei

Lister

Aller

et al. 2013

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418

530

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“…This provides a physical explanation of the puzzling 'orphan flare' phenomenon which has been of much interest recently: short flares visible only at either high energy γ-ray or X-ray wavelengths with no corresponding increase in luminosity at other frequencies (e.g. Krawczynski et al 2004 andRani et al 2013 At t=0, a flaring front at x flare starts accelerating non-thermal electrons in the plasma passing through the front. Colour is used to show the peak emission frequency of the plasma and has been chosen for convenience to correspond approximately to the visible spectrum (grey represents highly magnetised, dimly emitting plasma).…”

Section: A Physical Explanation For Orphan Flaresmentioning

confidence: 94%

“…In a one-zone model all the observed emission comes from the flaring region and so all frequencies will be observed to rise in luminosity during a flaring event. It is no surprise therefore, that it is difficult to understand orphan flares in the context of one-zone models (Błażejowski et al 2005 andRani et al 2013). In our model the emission from the flare has to be sufficiently luminous to be observed above the quiescent emission.…”

Section: A Physical Explanation For Orphan Flaresmentioning

confidence: 99%

Modelling blazar flaring using a time-dependent fluid jet emission model – an explanation for orphan flares and radio lags

Potter¹

2017

Monthly Notices of the Royal Astronomical Society

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Blazar jets are renowned for their rapid violent variability and multiwavelength flares, however, the physical processes responsible for these flares are not well understood. In this paper we develop a time-dependent inhomogeneous fluid jet emission model for blazars. We model optically thick radio flares for the first time and show that they are delayed with respect to the prompt optically thin emission by ∼ months to decades, with a lag that increases with the jet power and observed wavelength. This lag is caused by a combination of the travel time of the flaring plasma to the optically thin radio emitting sections of the jet and the slow rise time of the radio flare. We predict two types of flares: symmetric flares -with the same rise and decay time, which occur for flares whose duration is shorter than both the radiative lifetime and the geometric path-length delay timescale; extended flares -whose luminosity tracks the power of particle acceleration in the flare, which occur for flares with a duration longer than both the radiative lifetime and geometric delay. Our model naturally produces orphan X-ray and γ-ray flares. These are caused by flares which are only observable above the quiescent jet emission in a narrow band of frequencies. Our model is able to successfully fit to the observed multiwavelength flaring spectra and lightcurves of PKS1502+106 across all wavelengths, using a transient flaring front located within the broad-line region.

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“…To determine height and location of a DCF peak, we fit a Gaussian function defined as DCF(t) = a × exp −(t − c) 2 /2w 2 to the DCF durve, with a being the amplitude, c being the time-lag, and w being the width of the Gaussian profile. The statistical significance of the correlation is calculated following Rani et al (2013a), by calculating the Pearson correlation coefficient for the ALMA data and LAT data and its uncertainty after applying the time shift derived from the Gaussian fit to the DCF curve.…”

Section: Correlation Between the Radio And γ-Ray Light Curvesmentioning

confidence: 99%

Investigating the connection between γ-ray activity and the relativistic jet in 3C 273 during 2015−2019

Kim

Trippe

Kravchenko

2020

A&A

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Context. Due to its powerful radiation over the entire electromagnetic spectrum and its radio jet activity, the blazar 3C 273 offers the opportunity to study the physics of γ-ray emission from active galactic nuclei. Since a historically strong outburst in 2009, 3C 273 showed relatively weak emission in the γ-ray band over multiple years. However, recent Fermi-Large Area Telescope observations indicate elevated activity during 2015-2019. Aims. We aim at constraining the origin of the γ-ray outbursts towards 3C 273 and investigate their connection to the parsec-scale jet. Methods. We generate Fermi-LAT γ-ray light curves with multiple binning intervals and study the spectral properties of the γ-ray emission. Using a 3 mm ALMA light curve, we study the correlation between radio and γ-ray emission. Relevant activity in the parsec-scale jet of 3C 273 is investigated with 7 mm VLBA observations obtained close in time to notable γ-ray outbursts. Results. We find two prominent γ-ray outbursts in 2016 (MJD 57382) and 2017 (MJD 57883) accompanied by mm-wavelength flaring activity. The γ-ray photon index time series show a weak hump-like feature around the γ-ray outbursts. The monthly γ-ray flux-index plot indicates a transition from softer-when-brighter to harder-when-brighter at 1.03 × 10 −7 ph cm −2 s −1 . A significant correlation between the γ-ray and mm-wavelength emission is found, with the radio lagging the γ-rays by about 105-112 days. The 43 GHz jet images reveal the known stationary features (i.e., the core, S 1, and S 2) in a region upstream of the jet. We find indication for a propagating disturbance and a polarized knot between the stationary components around the times of both γ-ray outbursts. Conclusions. Our results support a parsec-scale origin for the observed γ-ray elevated activity, suggesting association with standing shocks in the jet.

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Radio to gamma-ray variability study of blazar S5 0716+714

Cited by 109 publications

References 72 publications

Mojave. X. Parsec-Scale Jet Orientation Variations and Superluminal Motion in Active Galactic Nuclei

Mojave. X. Parsec-Scale Jet Orientation Variations and Superluminal Motion in Active Galactic Nuclei

Modelling blazar flaring using a time-dependent fluid jet emission model – an explanation for orphan flares and radio lags

Investigating the connection between γ-ray activity and the relativistic jet in 3C 273 during 2015−2019

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