RoboPol: connection between optical polarization plane rotations and gamma-ray flares in blazars

Blinov, D.; Pavlidou, V.; Papadakis, I. E.; Kiehlmann, S.; Liodakis, Ioannis; Panopoulou, G. V.; Angelakis, E.; Baloković, Mislav; Hovatta, T.; King, O. G.; Kus, A. J.; Kylafis, N. D.; Mahabal, A.; Maharana, S.; Myserlis, I.; Paleologou, E. V.; Papamastorakis, I.; Pazderski, E.; Pearson, T. J.; Ramaprakash, A. N.; Readhead, A. C. S.; Reig, P.; Tassis, Konstantinos; Zensus, J. A.

doi:10.1093/mnras/stx2786

Cited by 93 publications

(88 citation statements)

References 43 publications

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“…For rotation-dominated epochs with the helical B fields we can instead associate dx ch with the timescale of a typical observed optical rotation, roughly 360 • per month (Blinov et al 2018), so we take dx ch ≈ 1dc/β. For many typical blazar parameters these stochastic and he-lical characteristic length scales are of similar size.…”

Section: Light Travel Effectsmentioning

confidence: 99%

The Polarization Behavior of Relativistic Synchrotron Self-Compton Jets

Peirson

Romani

2019

ApJ

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We describe a geometric model for synchrotron and synchrotron self-Compton (SSC) radiation from blazar jets, involving multiple emission zones with turbulent magnetic fields and fully self-consistent seed photon mixing for SSC. Including the effects of jet divergence, particle cooling and the Relativistic PA rotation (RPAR) to the observer frame, we find that the multi-zone model recovers simple predictions for SSC polarization, but describes new dependencies on jet viewing geometry and zone multiplicity. Increasing the zone number decreases both synchrotron and SSC polarization, but with different scaling. A rise in synchrotron polarization fraction Π Sync at high energies is guaranteed by basic relativity considerations, and strengthened by jet non-uniformity. Finite light travel time effects can suppress the synchrotron polarization at energies well below the ν Sync peak. In general Π Sync and Π SSC are correlated with Π SSC /Π Sync ≈ 0.3, but individual realizations can lie far from this trend. This study lets us estimate Π across the SED, leading to predictions in the X-ray band helpful for planning observations with IXPE and other upcoming X-ray polarization missions.

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Section: Light Travel Effectsmentioning

confidence: 99%

The Polarization Behavior of Relativistic Synchrotron Self-Compton Jets

Peirson

Romani

2019

ApJ

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“…At this time, the variability behavior of the radio emission may only be related to the local variation of downstream extended radio emission region. Recent studies have found that in some blazars, their γ-ray emission is associated with their optical polarization degree and the rotation of PA (see, e.g., Itoh et al 2016;Blinov et al 2018). Since the ambiguity of the PA can not be completely eliminated (see Section 3.1 above), here we only analyze the cross-correlation between the po-larization degree and the γ-ray emission.…”

Section: Multiwavelength Correlationsmentioning

confidence: 99%

Exploring the Origin of Multiwavelength Activities of High-redshift Flat-spectrum Radio Quasar PKS 1502+106 during 2014–2018

Ding

Geng

et al. 2019

ApJ

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The origin of the multi-band activities (outbursts/flares) of blazars is still a heavily debated topic. Shock and magnetic reconnection have long been considered as possible triggers for the multi-band activities. In this paper, we present an exploration of the origin of multi-band activities for a high-redshift (z =1.8385) FSRQ PKS 1502+106. Utilizing multi-band data from radio to γ-ray and optical polarization observations, we investigate two dramatic activities in detail: a γ-ray dominated outburst in 2015 and an optical dominated outburst in 2017. Our main results are as follows. (I) A fast γ-ray flare with a flux-doubling time-scale as short as 1-hr in 2015 is discovered. Based on the variability time-scale, the physical parameters of the flaring region (e.g, minimum Doppler factor, emission region size, etc.) are constrained. At the peak of the flare, the γ-ray spectrum hardens to Γ γ = 1.82 ± 0.04 and exhibits an obvious curvature/break characteristic that is caused by the typical "cooling break". Modelings of multi-band SEDs reveal a very hard electronic energy spectrum with the electronic spectral index of 1.07 ± 0.53. This result suggests that this fast γ-ray flare may be triggered by magnetic reconnection. (II) During the outburst in 2017, the optical polarization degree and optical fluxes show a very tight correlation. By analyzing Stokes parameters of polarization observations, our results show that this outburst could be triggered by a transverse shock with a compression ratio of η > 2.2, and the magnetic field intensity of the shock emission region is about 0.032 G.

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“…Large EVPA rotations have been observed that are sometimes correlated with flares detected at γ-rays (e.g. Blinov et al 2018). The picture appears quite complex, as changes in the jet viewing angle can mimic a stochastic process even when the variations in flux and P , and EVPA rotations, are produced by a deterministic process (Lyutikov & Kravchenko 2017).…”

Section: Polarimetric Observationsmentioning

confidence: 99%

The beamed jet and quasar core of the distant blazar 4C 71.07

Raiteri

Villata

Carnerero

et al. 2019

Monthly Notices of the Royal Astronomical Society

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The object 4C 71.07 is a high-redshift blazar whose spectral energy distribution shows a prominent big blue bump and a strong Compton dominance. We present the results of a two-year multiwavelength campaign led by the Whole Earth Blazar Telescope (WEBT) to study both the quasar core and the beamed jet of this source. The WEBT data are complemented by ultraviolet and X-ray data from Swift, and by γ-ray data by Fermi. The big blue bump is modelled by using optical and near-infrared mean spectra obtained during the campaign, together with optical and ultraviolet quasar templates. We give prescriptions to correct the source photometry in the various bands for the thermal contribution, in order to derive the non-thermal jet flux. The role of the intergalactic medium absorption is analysed in both the ultraviolet and X-ray bands. We provide opacity values to deabsorb ultraviolet data, and derive a best-guess value for the hydrogen column density of N best H = 6.3 × 10 20 cm −2 through the analysis of Xray spectra. We estimate the disc and jet bolometric luminosities, accretion rate, and black hole mass. Light curves do not show persistent correlations among flux changes at different frequencies. We study the polarimetric behaviour and find no correlation between polarisation degree and flux, even when correcting for the dilution effect of the big blue bump. Similarly, wide rotations of the electric vector polarisation angle do not seem to be connected with the source activity.

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RoboPol: connection between optical polarization plane rotations and gamma-ray flares in blazars

Cited by 93 publications

References 43 publications

The Polarization Behavior of Relativistic Synchrotron Self-Compton Jets

The Polarization Behavior of Relativistic Synchrotron Self-Compton Jets

Exploring the Origin of Multiwavelength Activities of High-redshift Flat-spectrum Radio Quasar PKS 1502+106 during 2014–2018

The beamed jet and quasar core of the distant blazar 4C 71.07

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