Core shift effect in blazars

Agarwal, Aditi; Mohan, Prashanth; Gupta, Alok C.; Mangalam, A.; Volvach, A. E.; Aller, M. F.; Aller, H. D.; Gu, Minfeng; Lähteenmäki, A.; Tornikoski, M.; Volvach, L. N.

doi:10.1093/mnras/stx847

Cited by 26 publications

(23 citation statements)

References 82 publications

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“…It has also been categorized as an optically violent variable (OVV) revealing large and rapid polarized outbursts in optical bands on various timescales (days to years). Multifrequency radio light curves (4.8 have been used to study the core shift effect and to estimate the equipartition field strength and the spin of its black hole (Agarwal et al 2017). Based on the measurements of its spectral lines (luminosity and line width) the mass of its central black hole has been estimated to be 10 8.9±0.5 M (Nilsson et al 2009;Gu et al 2001;Woo & Urry 2002).…”

Section: Introductionmentioning

confidence: 99%

Possible evidence of a supermassive black hole binary with two radio jets in blazar 3C279

Qian

Britzen

Krichbaum

et al. 2018

A&A

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Context. Studies of periodic and quasi-periodic phenomena in optical and radio bands are important for understanding the physical processes in quasars. Investigation of periodic/quasi-periodic behavior of the relativistic jets in blazars is particularly significant because it can provide unique information about the formation, collimation, and acceleration of the jets and the properties of the central engines (black hole/accretion disk systems) in blazars. Aims. We investigate the parsec-scale kinematics of the 31 superluminal components observed in blazar 3C279 and attempt to search for evidence of its jet precession and double-jet structure. Methods. The previously suggested precessing jet nozzle model is applied to model-fit the kinematics of its superluminal components observed during the 1981–2015 period. It is shown that the parsec-scale kinematics of the entire source can be interpreted in terms of a double-jet scenario. Results. The superluminal components observed in 3C279 can be divided into two groups that are ejected from two relativistic jets. The two jets have different orientations in space and jet-cone shapes, but both jets precess with the same precession period of 25 yr (16.3 yr in the source frame). The kinematic features of all the superluminal knots (trajectory, core separation, and apparent velocity) can be consistently explained. Their innermost trajectories follow the respective precessing common parabolic patterns with trajectory curvatures that occurred in the outer jet regions at different core separations. The bulk Lorentz factor, Doppler factor, and viewing angle of their motion are derived. The unusual jet-direction change of ∼100° observed in 2010–2011 can be naturally explained. Conclusions. We propose a double-jet structure scenario for 3C279 and suggest that there may be a supermassive black hole binary in the center of 3C279 ejecting two precessing relativistic jets, resulting in its very complex structure and kinematics on parsec scales, and with extremely variable emission across the electromagnetic spectrum. Because the two jets have the same precession period, the precession of the double jet may have originated from the modulation of their jet orientation by the change in their orbital velocity direction relative to the observer. In this case the mass ratio m/M of the binary is approximately equal to the ratio of the jet cone widths, being on the order of ∼0.5.

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Section: Introductionmentioning

confidence: 99%

Possible evidence of a supermassive black hole binary with two radio jets in blazar 3C279

Qian

Britzen

Krichbaum

et al. 2018

A&A

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“…The magnetic field strength in the γ-ray emitting region is more or less similar to that in the pc-scale jet as estimated from the core-shift effect (e.g., Fromm et al 2013;Zamaninasab et al 2014;Agarwal et al 2017). In the jet core-shift studies, it was found that µ~-B R 1 within the region of radio cores (e.g., O'Sullivan & Gabuzda 2009;Sokolovsky et al 2011;Fromm et al 2013;Agarwal et al 2017). Assuming the magnetic field strength in the γ-ray emitting region, as constrained from the blazar SED fitting, roughly follows the magnetic field distribution as derived from the core-shift effect, using = -B B R 1 1 (B 1 is the magnetic field strength at 1 pc), we calculate position of the γ-ray emitting region g R for each source in our sample.…”

Section: Resultsmentioning

confidence: 54%

“…Due to the rough agreement of the magnetic field strength in the γ-ray emitting region and that of the radio core at the pc scale (e.g., Fromm et al 2013;Zamaninasab et al 2014;Agarwal et al 2017), we calculate the location of the γ-ray emitting region for these blazars by assuming that the magnetic field strength derived in the SED fitting follows the magnetic field strength distribution as derived from the radio core-shift measurements. The main results are summarized as follows.…”

Section: Conclusion and Discussionmentioning

confidence: 99%

“…More simultaneous or quasi-simultaneous observations will also further help to build better multi-wavelength SEDs for blazars, and, in particular, the infrared data and γ-ray data at around MeV that are absent or quite limited now, are expected in the near future. Sokolovsky et al 2011;Fromm et al 2013;Pushkarev & Kovalev 2015;Agarwal et al 2017). In case of a conical jet, the magnetic field strength and the electron number density are assumed to decrease with the increasing distance from the central engine following powerlaw dependencies, where B∝R −1 and µ -n R e 2 (Blandford & Königl 1979).…”

Section: Conclusion and Discussionmentioning

confidence: 99%

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Constraints on the Location of γ-Ray Sample of Blazars with Radio Core-shift Measurements

Yan

et al. 2018

ApJ

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We model simultaneous or quasi-simultaneous multi-band spectral energy distributions (SEDs) for a sample of 25 blazars that have radio core-shift measurements, where a one-zone leptonic model and Markov chain Monte Carlo technique are adopted. In the SED fitting for 23 low-synchrotron-peaked (LSP) blazars, the seed photons from the broad-line (BLR) and molecular torus are considered respectively in the external Compton process. We find that the SED fitting with the seed photons from the torus are better than those utilizing BLR photons, which suggest that the γ-ray emitting region may be located outside the BLR. Assuming the magnetic field strength in the γ-ray emitting region as constrained from the SED fitting follows the magnetic field distribution as derived from the radio core-shift measurements (i.e.,1 , where R is the distance from the central engine and B 1 pc is the magnetic field strength at 1 pc), we further calculate the location of the γ-ray emitting region, g R , for these blazars. We find that~ǵ  R R R 2 10 10 4 S B L R (R S is the Schwarzschild radius and R BLR is the BLR size), where R BLR is estimated from the broad-line luminosities using the empirical correlations obtained using the reverberation mapping methods.

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“…This indicates that the inferred variability here probes only the noise floor as opposed to intrinsic source based variability which often leads to indices in the range −1.5 − −2.5 (e.g. Mohan et al 2014, 2015, Agarwal et al 2017Goyal et al 2017 and references therein). The bending power law is the best fit model in the light curves of PKS 0235+164: 10-02-2002 and PKS 0528+134: 14-09-2009.…”

Section: Temporal Variabilitymentioning

confidence: 85%

Signature of inverse Compton emission from blazars

Gaur

Mohan

Wierzcholska

et al. 2017

Monthly Notices of the Royal Astronomical Society

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Blazars are classified into high, intermediate and low energy peaked sources based on the location of their synchrotron peak. This lies in infra-red/optical to ultra-violet bands for low and intermediate peaked blazars. The transition from synchrotron to inverse Compton emission falls in the X-ray bands for such sources. We present the spectral and timing analysis of 14 low and intermediate energy peaked blazars observed with XMMNewton spanning 31 epochs. Parametric fits to X-ray spectra helps constrain the possible location of transition from the high energy end of the synchrotron to the low energy end of the inverse Compton emission. In seven sources in our sample, we infer such a transition and constrain the break energy in the range 0.6 10 keV. The Lomb-Scargle periodogram is used to estimate the power spectral density (PSD) shape. It is well described by a power law in a majority of light curves, the index being flatter compared to general expectation from AGN, ranging here between 0.01 and 1.12, possibly due to short observation durations resulting in an absence of long term trends. A toy model involving synchrotron self-Compton (SSC) and external Compton (EC; disk, broad line region, torus) mechanisms are used to estimate magnetic field strength 0.03 -0.88 G in sources displaying the energy break and infer a prominent EC contribution. The timescale for variability being shorter than synchrotron cooling implies steeper PSD slopes which are inferred in these sources.

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Core shift effect in blazars

Cited by 26 publications

References 82 publications

Possible evidence of a supermassive black hole binary with two radio jets in blazar 3C279

Possible evidence of a supermassive black hole binary with two radio jets in blazar 3C279

Constraints on the Location of γ-Ray Sample of Blazars with Radio Core-shift Measurements

Signature of inverse Compton emission from blazars

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