A 15.7-min periodicity in OJ287

Valtaoja, E.; Lehto, H. J.; Teerikorpi, P.; Korhonen, T.; Valtonen, M. J.; Teräsranta, H.; Salonen, E.; Urpo, S.; Tiuri, M.; Piirola, V.; Saslaw, William C.

doi:10.1038/314148a0

Cited by 60 publications

(53 citation statements)

References 11 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…For four of our targets -0923+392, 3C 111, 3C 273, and 3C 345 -we find that the 1.3-mm and 3-mm lightcurves are simultaneous within 3σ confidence levels. This is in agreement with shock-models like the "generalized" model by Valtaoja et al (1992); given the measurement accuracies of tens of days however these constraints are fairly loose. For 3C 454.3 (in its "flare state(s)" after 2005.2) and 3C 84 we find spectral time delays of ≈55 days and ≈300 days, respectively, with the 1.3-mm emission leading.…”

Section: Discussionsupporting

confidence: 67%

“…Our results are consistent with those obtained by the time delay analyses of Tornikoski et al (1994) and Hovatta et al (2008) in the cm-radio range. Hovatta et al (2008) conclude that those limits on time delays, both in the cm-and mm-regimes, can be understood in the frame of the semi-empiric "generalized shock model" by Valtaoja et al (1992).…”

Section: Spectral Time Delaysmentioning

confidence: 99%

See 1 more Smart Citation

The long-term millimeter activity of active galactic nuclei

Trippe¹,

Krips²,

Piétu³

et al. 2011

A&A

View full text Add to dashboard Cite

We analyze the long-term evolution of the fluxes of six active galactic nuclei (AGN) -0923+392, 3C 111, 3C 273, 3C 345, 3C 454.3, and 3C 84 -in the frequency range 80−267 GHz using archival calibration data of the IRAM Plateau de Bure Interferometer. Our dataset spans a long timeline of ≈14 years with 974−3027 flux measurements per source. We find strong (factors ≈2−8) flux variability on timescales of years for all sources. The flux density distributions of five out of six sources show clear signatures of bi-or even multimodality. Our sources show mostly steep (α ≈ 0.5−1), variable spectral indices that indicate outflow dominated emission; the variability is most probably due to optical depth variations. The power spectra globally correspond to red-noise spectra with five sources being located between the cases of white and flicker noise and one source (3C 111) being closer to the case of random walk noise. For three sources the low-frequency ends of their power spectra appear to be upscaled in spectral power by factors ≈2−3 with respect to the overall powerlaws. In two sources, 3C 454.3 and 3C 84, the 1.3-mm emission preceeds the 3-mm emission by ≈55 and ≈300 days, respectively, probably due to (combinations of) optical depth and emission region geometry effects. We conclude that the source emission cannot be described by uniform stochastic emission processes; instead, a distinction of "quiescent" and (maybe multiple) "flare" states of the source emission appears to be necessary.

show abstract

Section: Discussionsupporting

confidence: 67%

Section: Spectral Time Delaysmentioning

confidence: 99%

The long-term millimeter activity of active galactic nuclei

Trippe¹,

Krips²,

Piétu³

et al. 2011

A&A

View full text Add to dashboard Cite

show abstract

“…On short time scale, for example, periodic flux variation is reported in OJ 287 in radio as well as in optical band. Valtaoja et al (1985) have reported 15.7 min periodicity at 37 GHz, Carrasco et al (1985) have reported 23 minute period in their observations in optical B passband and Carini et al (1992) have shown the optical periodicity of 32 min.…”

Section: Discussionmentioning

confidence: 99%

Multi-color optical variability of the TeV blazar Mrk 501 in the low-state

et al. 2008

View full text Add to dashboard Cite

“…Flare onsets and maxima appear first at higher frequencies and successively progress towards the lower end of the observed frequency range (e.g., Valtaoja et al 1992). This is usually connected to the motion of disturbances whose optical depth decreases, while moving downstream the jet (e.g., Marscher & Gear 1985) and expanding adiabatically (van der Laan 1966).…”

Section: Introductionmentioning

confidence: 99%

“…Among these are: shocks generated and propagating along the relativistic jet (e.g., Marscher & Gear 1985;Valtaoja et al 1992), colliding relativistic plasma shells (Spada et al 2001), precession of the jet (e.g., Lister et al 2003), helical motion in the jet (e.g., Camenzind & Krockenberger 1992), and Kelvin-Helmholtz instabilities developing in the outflow (e.g., Lobanov & Zensus 2001). Testing the validity of such models means quantitatively contrasting the observational signatures of the mechanisms they invoke with observations.…”

Section: Introductionmentioning

confidence: 99%

What can the 2008/10 broadband flare of PKS 1502+106 tell us?

Karamanavis

Fuhrmann

Angelakis

et al. 2016

A&A

View full text Add to dashboard Cite

Context. The origin of blazar variability, as seen from radio up to γ rays, is still a heavily debated matter, and broadband flares offer a unique testbed for developing a better understanding of these extreme objects. One of these energetic outbursts was detected by Fermi/LAT in 2008 from the blazar PKS 1502+106. The outburst was observed from γ rays down to radio frequencies. Aims. Through the delay between flare maxima at different radio frequencies, we study the frequency-dependent position of the unitopacity surface and infer its absolute position with respect to the jet base. This nuclear opacity profile enables the jet's magnetic field tomography. We also localize the γ-ray emission region and explore the flare production mechanism. Methods. The PKS 1502+106 radio flare is studied through single-dish flux density measurements at 12 frequencies in the range 2.64 to 226.5 GHz. To quantify the flare, we employ both a Gaussian process regression and a discrete cross-correlation function analysis. Results. We find that the light curve parameters (flare amplitude and cross-band delays) show a power-law dependence on frequency. Delays decrease with frequency, and the flare amplitudes increase up to about 43 GHz, and then decay. This behavior is consistent with the propagation of a shock downstream in the jet. The self-absorbed radio cores are located between approximately ten and four pc from the jet base, and their magnetic field strengths range between 14 and 176 mG, at the frequencies 2.64 to 86.24 GHz. Finally, the γ-ray active region is located at (1.9 ± 1.1) pc away from the jet base.

show abstract

A 15.7-min periodicity in OJ287

Cited by 60 publications

References 11 publications

The long-term millimeter activity of active galactic nuclei

The long-term millimeter activity of active galactic nuclei

Multi-color optical variability of the TeV blazar Mrk 501 in the low-state

What can the 2008/10 broadband flare of PKS 1502+106 tell us?

Contact Info

Product

Resources

About