Deconstructing blazars: A different scheme for jet kinematics in flat-spectrum AGN

Karouzos, Marios; Britzen, S.; Witzel, A.; Zensus, J. A.; Eckart, A.

doi:10.1051/0004-6361/201116886

Cited by 10 publications

(10 citation statements)

References 71 publications

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“…That no superluminal motion is observed in the jet of 1ES 2344+514 is in line with the previous findings that this source and a number of other TeV (Piner & Edwards 2004;Piner et al 2010) and non-TeV (Karouzos et al 2012) BL Lacs show much slower apparent jet speeds compared to those typically found in compact extragalactic radio sources (Lister et al 2009b). Note however, that Piner et al (2010) report the detection of significant component motion in 1ES 2344+514 with speeds inconsistent with the results presented above.…”

Section: Interferometric Observationssupporting

confidence: 90%

The simultaneous low state spectral energy distribution of 1ES 2344+514 from radio to very high energies

Aleksić¹,

Antonelli²,

Antoranz³

et al. 2013

A&A

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Context. BL Lacertae objects are variable at all energy bands on time scales down to minutes. To construct and interpret their spectral energy distribution (SED), simultaneous broad-band observations are mandatory. Up to now, the number of objects studied during such campaigns is very limited and biased towards high flux states. Aims. We present the results of a dedicated multi-wavelength study of the high-frequency peaked BL Lacertae (HBL) object and known TeV emitter 1ES 2344+514 by means of a pre-organised campaign. Methods. The observations were conducted during simultaneous visibility windows of MAGIC and AGILE in late 2008. The measurements were complemented by Metsähovi, RATAN-600, KVA+Tuorla, Swift and VLBA pointings. Additional coverage was provided by the ongoing long-term F-GAMMA and MOJAVE programs, the OVRO 40-m and CrAO telescopes as well as the Fermi satellite. The obtained SEDs are modelled using a one-zone as well as a self-consistent two-zone synchrotron self-Compton model. Results. 1ES 2344+514 was found at very low flux states in both X-rays and very high energy gamma rays. Variability was detected in the low frequency radio and X-ray bands only, where for the latter a small flare was observed. The X-ray flare was possibly caused by shock acceleration characterised by similar cooling and acceleration time scales. MOJAVE VLBA monitoring reveals a static jet whose components are stable over time scales of eleven years, contrary to previous findings. There appears to be no significant correlation between the 15 GHz and R-band monitoring light curves. The observations presented here constitute the first multi-wavelength campaign on 1ES 2344+514 from radio to VHE energies and one of the few simultaneous SEDs during low activity states. The quasi-simultaneous Fermi-LAT data poses some challenges for SED modelling, but in general the SEDs are described well by both applied models. The resulting parameters are typical for TeV emitting HBLs. Consequently it remains unclear whether a so-called quiescent state was found in this campaign.

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Section: Interferometric Observationssupporting

confidence: 90%

The simultaneous low state spectral energy distribution of 1ES 2344+514 from radio to very high energies

Aleksić¹,

Antonelli²,

Antoranz³

et al. 2013

A&A

Self Cite

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“…The similar phenomena of the apparent stationarity of jet components with time have also been reported in BL Lac objects S5 1803+784 and PKS 0735+178, by Britzen et al (2010aBritzen et al ( , 2010b. From CJF sample (Caltech-Jodrell Bank flatspectrum sample of radio loud active galaxies), Karouzos et al (2012) investigated the morphologies and pc-scale jet kinematics of more than 200 sources by using the so-called jet ridge-line method. They found that about a half of the sample show jet widths > 10 • , with BL Lac jet ridge lines showing significantly larger apparent widths than both quasars and radio galaxies, indicating that the BL Lacs have more significant position angle changes of jets in their evolution.…”

Section: Introductionsupporting

confidence: 64%

Correlations between the peak flux density and the position angle of inner-jet in three blazars

Liu

et al. 2012

Astrophys Space Sci

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Aims. We aim to investigate the relation between the long-term flux density and the position angle (PA) evolution of inner-jet in blazars. Methods. We have carried out the elliptic Gaussian model-fit to the 'core' of 50 blazars from 15 GHz VLBA data, and analyzed the variability properties of three blazars from the model-fit results. Results. Diverse correlations between the long-term peak flux density and the PA evolution of the major axis of the 'core' have been found in ∼ 20% of the 50 sources. Of them, three typical blazars have been analyzed, which also show quasi-periodic flux variations of a few years (T). The correlation between the peak flux density and the PA of inner-jet is positive for S5 0716+714, and negative for S4 1807+698. The two sources cannot be explained with the ballistic jet models, the non-ballistic models have been analyzed to explain the two sub-luminal blazars. A correlation between the peak flux density and the PA (with a T/4 time lag) of inner-jet is found in [HB89] 1823+568, this correlation can be explained with a ballistic precession jet model. All the explanations are based mainly on the geometric beaming effect; physical flux density variations from the jet base would be considered for more complicated situations in future, which could account for the no or less significance of the correlation between the peak flux density and the PA of inner-jet in the majority blazars of our sample. Conclusions.

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“…Pulsational accretion flow instabilities, approximating periodic behavior, are able to explain modulations in the energy outflow efficiency. Magnetically-arrested and magnetically-dominated accretion flows (MDAF) could be suitable regimes for radiatively inefficient BL Lacs (Fragile & Meier 2009), characterized by advection-dominated accretion flows and subluminal, turbulent and peculiar radio kinematics (Karouzos et al 2012;Piner & Edwards 2014). Such kinematics are sometimes explained as a precessing or helical jet (Conway & Murphy 1993).…”

Section: Discussionmentioning

confidence: 99%

Multiwavelength Evidence for Quasi-Periodic Modulation in the Gamma-Ray Blazar Pg 1553+113

Ackermann

Ajello

Albert

et al. 2015

ApJ

184

146

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We report for the first time a γ-ray and multiwavelength nearly-periodic oscillation in an active galactic nucleus. Using the Fermi Large Area Telescope (LAT) we have discovered an apparent quasi-periodicity in the γ-ray flux (E > 100 MeV) from the GeV/TeV BL Lac object PG 1553+113. The marginal significance of the 2.18 ± 0.08 year-period γ-ray cycle is strengthened by correlated oscillations observed in radio and optical fluxes, through data collected in the OVRO, Tuorla, KAIT, and CSS monitoring programs and Swift UVOT. The optical cycle appearing in ∼ 10 years of data has a similar period, while the 15 GHz oscillation is less regular than seen in the other bands. Further long-term multi-wavelength monitoring of this blazar may discriminate among the possible explanations for this quasi-periodicity.

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Deconstructing blazars: A different scheme for jet kinematics in flat-spectrum AGN

Cited by 10 publications

References 71 publications

The simultaneous low state spectral energy distribution of 1ES 2344+514 from radio to very high energies

The simultaneous low state spectral energy distribution of 1ES 2344+514 from radio to very high energies

Correlations between the peak flux density and the position angle of inner-jet in three blazars

Multiwavelength Evidence for Quasi-Periodic Modulation in the Gamma-Ray Blazar Pg 1553+113

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