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Browsing by Author "Mattingly, A."

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    The 2005 November outburst in OJ 287 and the binary black hole model
    (IOP Publishing, 2006-05-20) Valtonen, M. J.; Nilsson, K.; Sillanpaa, A.; Takalo, L. O.; Lehto, H. J.; Keel, W. C.; Haque, S.; Cornwall, D.; Mattingly, A.; University of Turku; University West Indies Mona Jamaica; University West Indies Saint Augustine; University of Alabama Tuscaloosa
    We report observations of the largest optical outburst in 20 years in the quasar OJ 287. In some ways it was expected, due to the well-known quasi-periodic 12 yr outburst cycle of OJ 287. In other ways the timing of the outburst was surprising, since calculations based on the periodicity were predicting such an outburst in late 2006. Here we point out that, in the precessing binary black hole model, first proposed by Sillanpaa et al., and later refined by Lehto & Valtonen and Sundelius et al., the precession shifts the first outburst of each outburst season progressively to earlier times relative to the mean period. Thus, in this model, the timing of the outburst is quite acceptable, even if it was not predicted. The next test of the model comes in 2007 September when the second brightness peak is due. It may then be possible to detect the shortening of the binary period due to emission of gravitational waves from the system.
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    Variability and stability in blazar jets on time-scales of years: optical polarization monitoring of OJ 287 in 2005-2009
    (Oxford University Press, 2010) Villforth, C.; Nilsson, K.; Heidt, J.; Takalo, L. O.; Pursimo, T.; Berdyugin, A.; Lindfors, E.; Pasanen, M.; Winiarski, M.; Drozdz, M.; Ogloza, W.; Kurpinska-Winiarska, M.; Siwak, M.; Koziel-Wierzbowska, D.; Porowski, C.; Kuzmicz, A.; Krzesinski, J.; Kundera, T.; Wu, J. -H.; Zhou, X.; Efimov, Y.; Sadakane, K.; Kamada, M.; Ohlert, J.; Hentunen, V. -P.; Nissinen, M.; Dietrich, M.; Assef, R. J.; Atlee, D. W.; Bird, J.; DePoy, D. L.; Eastman, J.; Peeples, M. S.; Prieto, J.; Watson, L.; Yee, J. C.; Liakos, A.; Niarchos, P.; Gazeas, K.; Dogru, S.; Donmez, A.; Marchev, D.; Coggins-Hill, S. A.; Mattingly, A.; Keel, W. C.; Haque, S.; Aungwerojwit, A.; Bergvall, N.; University of Turku; Ruprecht Karls University Heidelberg; Pedagogical University of Cracow; Jagiellonian University; University of Toronto; Chinese Academy of Sciences; National Astronomical Observatory, CAS; Russian Academy of Sciences; Crimean Astrophysical Observatory; Osaka University of Education; University System of Ohio; Ohio State University; Texas A&M University System; Texas A&M University College Station; National & Kapodistrian University of Athens; Canakkale Onsekiz Mart University; University of Shumen; University of Alabama Tuscaloosa; University West Indies Mona Jamaica; University West Indies Saint Augustine; Naresuan University; University of Warwick; Uppsala University
    OJ 287 is a BL Lac object at redshift z = 0.306 that has shown double-peaked bursts at regular intervals of similar to 12 yr during the last similar to 40 yr. We analyse optical photopolarimetric monitoring data from 2005 to 2009, during which the latest double-peaked outburst occurred. The aim of this study is twofold: firstly, we aim to analyse variability patterns and statistical properties of the optical polarization light curve. We find a strong preferred position angle in optical polarization. The preferred position angle can be explained by separating the jet emission into two components: an optical polarization core and chaotic jet emission. The optical polarization core is stable on time-scales of years and can be explained as emission from an underlying quiescent jet component. The chaotic jet emission sometimes exhibits a circular movement in the Stokes plane. We find six such events, all on the time-scales of 10-20 d. We interpret these events as a shock front moving forwards and backwards in the jet, swiping through a helical magnetic field. Secondly, we use our data to assess different binary black hole models proposed to explain the regularly appearing double-peaked bursts in OJ 287. We compose a list of requirements a model has to fulfil to explain the mysterious behaviour observed in OJ 287. The list includes not only characteristics of the light curve but also other properties of OJ 287, such as the black hole mass and restrictions on accretion flow properties. We rate all existing models using this list and conclude that none of the models is able to explain all observations. We discuss possible new explanations and propose a new approach to understanding OJ 287. We suggest that both the double-peaked bursts and the evolution of the optical polarization position angle could be explained as a sign of resonant accretion of magnetic field lines, a 'magnetic breathing' of the disc.