OJ 287 as a Rotating Helix

Cohen, M. H.

doi:10.3390/galaxies5010012

Cited by 30 publications

(42 citation statements)

References 16 publications

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“…This study supports the earlier suggestion by Cohen [41] that the jet of OJ 287 carries a helical B field, based on the evolution of the jet ridge lines, which are twisted and can be interpreted as sections of a rotating helix, as in the model of [39,40].…”

Section: Double Polarization Angle Rotationssupporting

confidence: 91%

Evidence for Helical Magnetic Fields Associated with AGN Jets and the Action of a Cosmic Battery

Gabuzda

2018

Galaxies

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Theoretical models for the electromagnetic launching of astrophysical jets have long indicated that this process should generate helical magnetic fields, which should then propagate outward with the jet plasma. Polarization observations of jets are key for testing this idea, since they provide direct information about the magnetic field structures in the synchrotron-emitting radio jets. Together with Faraday rotation measurements, it is possible in some cases to reconstruct the three-dimensional magnetic-field structure. There is now plentiful evidence for the presence of helical magnetic fields associated with the jets of active galactic nuclei, most directly the detection of transverse Faraday-rotation gradients indicating a systematic change in the line-of-sight magnetic field component across the jets. A variety of models involving helical jet magnetic fields have also been used to explain a great diversity of phenomena, including not only the linear polarization and Faraday rotation structures, but also circular polarization, anomalous wavelength dependences of the linear polarization, variability of jet ridge lines, variability of the Faraday rotation sign and polarization angle rotations. A joint consideration of Faraday rotation measurements on parsec and kiloparsec scales indicates a magnetic-field and current structure similar to that of a co-axial cable, suggesting the action of some kind of battery mechanism, such as the Poynting–Robertson cosmic battery.

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Section: Double Polarization Angle Rotationssupporting

confidence: 91%

Evidence for Helical Magnetic Fields Associated with AGN Jets and the Action of a Cosmic Battery

Gabuzda

2018

Galaxies

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“…Based on structural changes Agudo et al [65] have instead argued for an erratic wobbling of the jet along with superluminal motions in non-radial directions. Cohen [85] and Britzen et al [47] study of VLBA observations at 15 GHz, on the contrary, argue for a precessing jet with a period of ∼ 30-yr and ∼ 22-yr respectively. From the analysis of the ridgeline of contours, the former has argued the jet to be a rotating helix.…”

Section: Imagingmentioning

confidence: 96%

A Multi-Wavelength View of OJ 287 Activity in 2015–2017: Implications of Spectral Changes on Central-Engine Models and MeV-GeV Emission Mechanism

Kushwaha

2020

Galaxies

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A diverse range of observational results and peculiar properties across the domains of observation have made OJ 287 one of the best-explored BL Lac objects on the issues of relativistic jets and accretion physics as well as the strong theory of gravity. We here present a brief compilation of observational results from the literature and inferences/insights from the extensive studies but focus on the interpretation of its ∼ 12-yr quasi-periodic optical outbursts (QPOOs) and high energy emission mechanisms. The QPOOs in one model are attributed to the disk-impact related to dynamics of the binary SMBHs while alternative models attribute it to the geometrical effect related to the precession of a single jet or double jets. We discuss implications of the new spectral features reported during the 2015-2017 multi-wavelength high activity of the source -a break in the NIR-optical spectrum and hardening of the MeV-GeV emission accompanied by a shift in the location of its peak, in the context of the two. The reported NIR-optical break nicely fits the description of a standard accretion disk emission from an SMBH of mass ∼ 10 10 M while the time of its first appearance in end-May 2013 (MJD 56439) is in close coincidence with the time of impact predicted by the disk-impact binary SMBH model. This spectral and temporal coincidence with the model parameters of the disk-impact binary SMBH model provides independent evidence in favor of the model over the geometrical models which argue a total central-engine mass in the range of 10 7−9 M . On the other hand, the MeV-GeV spectral change is naturally reproduced by the inverse Compton scattering of photons from the broad-line region and is consistent with the detection of broad emission lines during the previous cycles of quasi-periodic outbursts. Combining this with previous SED studies suggests that in OJ 287, MeV-GeV emission results from external Comptonization. 2 of 21 minutes and even less to decades 1 [∼ 6-7 orders of magnitude; e.g. 2]. Their radio and optical emission is highly polarized and have been observed to vary often with the source flux, all the way from 0 to > 50%. Imaging in radio, infra-red (IR), optical, and X-ray, on the other hand, show an extremely well collimated jet extending up to Mpc scales [∼ 9-13 orders of magnitude; e.g. 3,4] with frequent sighting of superluminal features in high-resolution imaging of the core. Taken together with the observational and theoretical understanding of other astrophysical objects combined with their high and rarely repeating observational behavior indicates that they are the site of complex, multi-level, multi-scale physics and thus, are normally called extreme sources among non-catastrophic events.Though studies in different energy bands finally culminated into a unified scheme for radio-loud AGNs [5], it also revealed that AGNs need well-coordinated multi-wavelength (MW) observations to go beyond the limits associated with individual bands. The launch of the gamma-ray survey observatory Fermi-LAT (Large Area Telescope...

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“…During the period 1992 to 1996, three strong flares having flux of ∼3.9 × 10 −10 Jy (∼9.4 10 −11 erg cm −2 s −1 ) were detected at energies > The blazars are known to show aperiodic variability. Also claims of periodicity in radio band have been reported for several blazars, for example, A0 0235+16 (Raiteri et al 2001;Liu et al 2006a), PKS 1510-089 (Xie et al 2008), NRAO 530 , OJ 287 (Sillanpaa et al 1988;Valtaoja et al 2000;Cohen 2017) and PKS 0219-164 (Bhatta 2017). Ton 599 was regularly monitored by University of Michigan Radio Astronomy Observatory (UMRAO, Aller et al 1985).…”

mentioning

confidence: 99%

Temporal Variability and Estimation of Jet Parameters for Ton 599

Patel

Chitnis

Shukla

et al. 2018

ApJ

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The TeV blazar Ton 599 has exhibited a peculiar flare in 2017 November. The temporal variation of the source is studied using simultaneous γ-ray data from Fermi Large Area Telescope and radio data from Owens Valley Radio Observatory's 40 m telescope, over the period of nine years. Four major flaring periods are observed in the γ-ray energy band of 0.1-300 GeV. These periods are studied on a shorter timescale and modeled with a time-dependent function containing exponential rising and decaying components. The physical parameters of the jet are estimated numerically and compared with those reported in the literature. During the fourth flare a bunch of high energy photons (> 10 GeV) were detected. The two highest energy photons having an

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OJ 287 as a Rotating Helix

Cited by 30 publications

References 16 publications

Evidence for Helical Magnetic Fields Associated with AGN Jets and the Action of a Cosmic Battery

Evidence for Helical Magnetic Fields Associated with AGN Jets and the Action of a Cosmic Battery

A Multi-Wavelength View of OJ 287 Activity in 2015–2017: Implications of Spectral Changes on Central-Engine Models and MeV-GeV Emission Mechanism

Temporal Variability and Estimation of Jet Parameters for Ton 599

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