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8 results on '"OJ-287"'

1. Suzaku and multi-wavelength observations of OJ 287 during the periodic optical outburst in 2007

Author

Antoranz Canales, Pedro, Barrio Uña, Juan Abel, Contreras González, José Luis, Fonseca González, Mª Victoria, Miranda Pantoja, José Miguel, Nieto, Daniel, Antoranz Canales, Pedro, Barrio Uña, Juan Abel, Contreras González, José Luis, Fonseca González, Mª Victoria, Miranda Pantoja, José Miguel, and Nieto, Daniel

Abstract

Supported by INFN Padova., Suzaku observations of the blazar OJ 287 were performed in 2007 April 10-13 and November 7-9. They correspond to a quiescent and a flaring state, respectively. The X-ray spectra of the source can be well-described with single power-law models in both exposures. The derived X-ray photon index and the flux density at 1 keV were found to be Gamma = 1.65 +/- 0.02 and S(1) (keV) = 215 +/- 5 nJy in the quiescent state. In the flaring state, the source exhibited a harder X-ray spectrum (Gamma = 1.50 +/- 0.01) with a nearly doubled X-ray flux density of S(1 keV) = 404(-5)(+6) nJy Moreover, significant hard X-ray signals were detected up to similar to 27 keV. In cooperation with Suzaku, simultaneous radio, optical, and very-high-energy gamma-ray observations of OJ 287 were performed with the Nobeyama Millimeter Array, the KANATA telescope, and the MAGIC telescope, respectively. The radio and optical fluxes in the flaring state (3.04 +/- 0.46 Jy and 8.93 +/- 0.05 mJy at 86.75 Hz and in the V-band, respectively) were found to be higher by a factor of 2-3 than those in the quiescent state (1.73 +/- 0.26 Jy and 3.03 +/- 0.01 mJy at 86.75 Hz and in the V-band, respectively). No notable gamma-ray events were detected in either observation. The spectral energy distribution of OJ 287 indicated that the X-ray spectrum was dominated by inverse Compton radiation in both observations, while synchrotron radiation exhibited a spectral cutoff at around the optical frequency. Furthermore, no significant difference in the synchrotron cutoff frequency was found between the quiescent and flaring states. According to a simple synchrotron self-Compton model, the change of the spectral energy distribution is due to an increase in the energy density of electrons with small changes of both the magnetic field strength and the maximum Lorentz factor of electrons., INFN Padova, Depto. de Estructura de la Materia, Física Térmica y Electrónica, Fac. de Ciencias Físicas, TRUE, pub

Published
2023

2. Accretion Disk Parameters Determined from the Great 2015 Flare of OJ 287

Author

Helen Jermak, René Hudec, Stefano Ciprini, Mark R. Kidger, Kari Nilsson, Pauli Pihajoki, Vilppu Piirola, Tapio Pursimo, M. Zejmo, Marek Drozdz, Lankeswar Dey, Alok C. Gupta, Staszek Zola, Andrei Berdyugin, S. Enestam, Seppo Laine, Mauri Valtonen, Waldemar Ogloza, Harry Lehto, Achamveedu Gopakumar, Particle Physics and Astrophysics, Department of Physics, University of Turku, Jagiellonian University, University of Helsinki, Metsähovi Radio Observatory, Tata Institute of Fundamental Research, Pedagogical University of Cracow, University of Zielona Gora, Aryabhatta Research Institute of Observational Sciences, Nordic Optical Telescope, ASI Science Data Center, European Space Agency - ESA, Liverpool John Moores University, Czech Technical University in Prague, California Institute of Technology, Aalto-yliopisto, and Aalto University

Subjects
ACTIVE GALACTIC NUCLEI, Active galactic nucleus, 010504 meteorology & atmospheric sciences, Astrophysics::High Energy Astrophysical Phenomena, black hole physics, OJ-287, FOS: Physical sciences, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, 01 natural sciences, law.invention, Binary black hole, accretion, law, 0103 physical sciences, Astrophysics::Solar and Stellar Astrophysics, individual (OJ 287) [BL Lacertae objects], 010303 astronomy & astrophysics, Astrophysics::Galaxy Astrophysics, 0105 earth and related environmental sciences, Physics, High Energy Astrophysical Phenomena (astro-ph.HE), accretion disks, Bremsstrahlung, Astronomy and Astrophysics, Quasar, Light curve, 115 Astronomy, Space science, Astrophysics - Astrophysics of Galaxies, Accretion (astrophysics), BL Lacertae objects: individual (OJ 287), VARIABILITY, QUASARS, Space and Planetary Science, Astrophysics of Galaxies (astro-ph.GA), Astrophysics::Earth and Planetary Astrophysics, Astrophysics - High Energy Astrophysical Phenomena, VISCOSITY, Superflare, Flare
Abstract

In the binary black hole model of OJ 287 the secondary black hole orbits a much more massive primary, and impacts on the primary accretion disk at predictable times. We update the parameters of the disk, the viscosity $\alpha$ and the mass accretion rate $\dot m$. We find $\alpha=0.26 \pm 0.1$ and $\dot m = 0.08 \pm 0.04$ in Eddington units. The former value is consistent with Coroniti (1981) and the latter with Marscher and Jorstad (2011). Predictions are made for the 2019 July 30 superflare in OJ 287. We expect that it will take place simultaneously at the Spitzer infrared channels as well as in the optical and that therefore the timing of the flare in optical can be accurately determined from Spitzer observations. We also discuss in detail the light curve of the 2015 flare and find that the radiating volume has regions where bremsstrahlung dominates as well as regions that radiate primarily in synchrotron radiation. The former region produces the unpolarised first flare while the latter region gives rise to a highly polarized second flare., Comment: 12 pages, 4 figures, to appear in ApJ

Published
2019

3. The Unique Blazar OJ 287 and Its Massive Binary Black Hole Central Engine

Author

Dey, Lankeswar, Gopakumar, Achamveedu, Valtonen, Mauri, Zola, Stanislaw, Susobhanan, Abhimanyu, Hudec, Rene, Pihajoki, Pauli, Pursimo, Tapio, Berdyugin, Andrei, Piirola, Vilppu, Ciprini, Stefano, Nilsson, Kari, Jermak, Helen, Kidger, Mark, Komossa, Stefanie, Particle Physics and Astrophysics, and Department of Physics

Subjects
MODEL, GALACTIC NUCLEI, DISK, Astrophysics::High Energy Astrophysical Phenomena, OJ-287, TESTS, general relativity, blazar: OJ 287, NO-HAIR THEOREM, GENERAL-RELATIVITY, 115 Astronomy, Space science, black holes
Abstract

The bright blazar OJ 287 is the best-known candidate for hosting a nanohertz gravitational wave (GW) emitting supermassive binary black hole (SMBBH) in the present observable universe. The binary black hole (BBH) central engine model, proposed by Lehto and Valtonen in 1996, was influenced by the two distinct periodicities inferred from the optical light curve of OJ 287. The current improved model employs an accurate general relativistic description to track the trajectory of the secondary black hole (BH) which is crucial to predict the inherent impact flares of OJ 287. The successful observations of three predicted impact flares open up the possibility of using this BBH system to test general relativity in a hitherto unexplored strong field regime. Additionally, we briefly describe an ongoing effort to interpret observations of OJ 287 in a Bayesian framework.

Published
2019

4. Optical EVPA rotations in blazars

Author

Kiehlmann, S., Blinov, D., Pearson, T. J., Liodakis, I., Metsähovi Radio Observatory, St. Petersburg State University, California Institute of Technology, Stanford University, Department of Radio Science and Engineering, Aalto-yliopisto, and Aalto University

Subjects
polarization, GAMMA-RAY-LOUD, active [galaxies], OJ-287, jets [galaxies], nuclei [galaxies], COMPACT RADIO-SOURCES, SWINGS, POLARIZATION-PLANE, INNER JET, REGIONS, ANGLE
Abstract

We identify rotations of the polarization angle in a sample of blazars observed for three seasons with the RoboPol instrument. A simplistic stochastic variability model is tested against this sample of rotation events. The model is capable of producing samples of rotations with parameters similar to the observed ones, but fails to reproduce the polarization fraction at the same time. Even though we can neither accept nor conclusively reject the model, we point out various aspects of the observations that are fully consistent with a random walk process.

Published
2017

5. Stochastic modeling of multiwavelength variability of the classical BL Lac object OJ 287 on timescales ranging from decades to hours

Author

A. Goyal, Ł. Stawarz, S. Zola, V. Marchenko, M. Soida, K. Nilsson, S. Ciprini, A. Baran, M. Ostrowski, P. J. Wiita, null Gopal-Krishna, A. Siemiginowska, M. Sobolewska, S. Jorstad, A. Marscher, M. F. Aller, H. D. Aller, T. Hovatta, D. B. Caton, D. Reichart, K. Matsumoto, K. Sadakane, K. Gazeas, M. Kidger, V. Piirola, H. Jermak, F. Alicavus, K. S. Baliyan, A. Baransky, A. Berdyugin, P. Blay, P. Boumis, D. Boyd, Y. Bufan, M. Campas Torrent, F. Campos, J. Carrillo Gómez, J. Dalessio, B. Debski, D. Dimitrov, M. Drozdz, H. Er, A. Erdem, A. Escartin Pérez, V. Fallah Ramazani, A. V. Filippenko, E. Gafton, F. Garcia, V. Godunova, F. Gómez Pinilla, M. Gopinathan, J. B. Haislip, S. Haque, J. Harmanen, R. Hudec, G. Hurst, K. M. Ivarsen, A. Joshi, M. Kagitani, N. Karaman, R. Karjalainen, N. Kaur, D. Kozieł-Wierzbowska, E. Kuligowska, T. Kundera, S. Kurowski, A. Kvammen, A. P. LaCluyze, B. C. Lee, A. Liakos, J. Lozano de Haro, J. P. Moore, M. Mugrauer, R. Naves Nogues, A. W. Neely, W. Ogloza, S. Okano, U. Pajdosz, J. C. Pandey, M. Perri, G. Poyner, J. Provencal, T. Pursimo, A. Raj, B. Rajkumar, R. Reinthal, T. Reynolds, J. Saario, S. Sadegi, T. Sakanoi, J. L. Salto González, null Sameer, A. O. Simon, M. Siwak, T. Schweyer, F. C. Soldán Alfaro, E. Sonbas, J. Strobl, L. O. Takalo, L. Tremosa Espasa, J. R. Valdes, V. V. Vasylenko, F. Verrecchia, J. R. Webb, M. Yoneda, M. Zejmo, W. Zheng, P. Zielinski, J. Janik, V. Chavushyan, I. Mohammed, C. C. Cheung, and M. Giroletti

Subjects
ACTIVE GALACTIC NUCLEI, Astrophysics::High Energy Astrophysical Phenomena, OJ-287, FOS: Physical sciences, Astrophysics, individual: OJ 287 [BL Lacertae objects], Type (model theory), Astronomy & Astrophysics, magnetic fields, 01 natural sciences, LARGE-AREA TELESCOPE, Radio telescope, PERIODICITIES, 0103 physical sciences, individual (OJ 287) [BL Lacertae objects], Blazar, 010303 astronomy & astrophysics, LACERTAE OBJECTS, acceleration of particles, MISSION, Physics, High Energy Astrophysical Phenomena (astro-ph.HE), Science & Technology, 010308 nuclear & particles physics, OPTICAL POLARIZATION, Spectral density, Astronomy and Astrophysics, Light curve, non-thermal [radiation mechanisms], BLAZARS, 13. Climate action, Space and Planetary Science, Colors of noise, Physical Sciences, active [galaxies], UNEQUALLY-SPACED DATA, Astrophysics - High Energy Astrophysical Phenomena, OJ 287, Noise (radio), BL Lac object
Abstract

We present the results of our power spectral density analysis for the BL Lac object OJ\,287, utilizing the {\it Fermi}-LAT survey at high-energy $\gamma$-rays, {\it Swift}-XRT in X-rays, several ground-based telescopes and the {\it Kepler} satellite in the optical, and radio telescopes at GHz frequencies. The light curves are modeled in terms of continuous-time auto-regressive moving average (CARMA) processes. Owing to the inclusion of the {\it Kepler} data, we were able to construct \emph{for the first time} the optical variability power spectrum of a blazar without any gaps across $\sim6$ dex in temporal frequencies. Our analysis reveals that the radio power spectra are of a colored-noise type on timescales ranging from tens of years down to months, with no evidence for breaks or other spectral features. The overall optical power spectrum is also consistent with a colored noise on the variability timescales ranging from 117 years down to hours, with no hints of any quasi-periodic oscillations. The X-ray power spectrum resembles the radio and optical power spectra on the analogous timescales ranging from tens of years down to months. Finally, the $\gamma$-ray power spectrum is noticeably different from the radio, optical, and X-ray power spectra of the source: we have detected a characteristic relaxation timescale in the {\it Fermi}-LAT data, corresponding to $\sim 150$\,days, such that on timescales longer than this, the power spectrum is consistent with uncorrelated (white) noise, while on shorter variability timescales there is correlated (colored) noise., Comment: ApJ accepted

Published
2017
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6. Optical EVPA rotations in blazars: testing a stochastic variability model with RoboPol data

Author

Sebastian Kiehlmann, T. J. Pearson, Dmitry A. Blinov, and Ioannis Liodakis

Subjects
Polarization plane, galaxies: active, OJ-287, FOS: Physical sciences, 01 natural sciences, symbols.namesake, GAMMA-RAY-LOUD, 0103 physical sciences, Statistical physics, COMPACT RADIO-SOURCES, SWINGS, Blazar, POLARIZATION-PLANE, 010303 astronomy & astrophysics, Physics, High Energy Astrophysical Phenomena (astro-ph.HE), polarization, Brewster's angle, ta115, 010308 nuclear & particles physics, Astronomy and Astrophysics, galaxies: jets, Polarization (waves), Random walk, INNER JET, REGIONS, ANGLE, Classical mechanics, Space and Planetary Science, symbols, galaxies: nuclei, Astrophysics - High Energy Astrophysical Phenomena
Abstract

We identify rotations of the polarization angle in a sample of blazars observed for three seasons with the RoboPol instrument. A simplistic stochastic variability model is tested against this sample of rotation events. The model is capable of producing samples of rotations with parameters similar to the observed ones, but fails to reproduce the polarization fraction at the same time. Even though we can neither accept nor conclusively reject the model, we point out various aspects of the observations that are fully consistent with a random walk process., Comment: 17 pages, 18 figures, 4 tables. Accepted 2017 August 17 for publication in MNRAS

Published
2017
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7. Authenticating the Presence of a Relativistic Massive Black Hole Binary in OJ 287 Using Its General Relativity Centenary Flare: Improved Orbital Parameters

Author

Lankeswar Dey, M. J. Valtonen, A. Gopakumar, S. Zola, R. Hudec, P. Pihajoki, S. Ciprini, K. Matsumoto, K. Sadakane, M. Kidger, K. Nilsson, S. Mikkola, A. Sillanpää, L. O. Takalo, H. J. Lehto, A. Berdyugin, V. Piirola, H. Jermak, K. S. Baliyan, T. Pursimo, D. B. Caton, F. Alicavus, A. Baransky, P. Blay, P. Boumis, D. Boyd, M. Campas Torrent, F. Campos, J. Carrillo Gómez, S. Chandra, V. Chavushyan, J. Dalessio, B. Debski, M. Drozdz, H. Er, A. Erdem, A. Escartin Pérez, V. Fallah Ramazani, A. V. Filippenko, E. Gafton, S. Ganesh, F. Garcia, K. Gazeas, V. Godunova, F. Gómez Pinilla, M. Gopinathan, J. B. Haislip, J. Harmanen, G. Hurst, J. Janík, M. Jelinek, A. Joshi, M. Kagitani, R. Karjalainen, N. Kaur, W. C. Keel, V. V. Kouprianov, T. Kundera, S. Kurowski, A. Kvammen, A. P. LaCluyze, B. C. Lee, A. Liakos, E. Lindfors, J. Lozano de Haro, M. Mugrauer, R. Naves Nogues, A. W. Neely, R. H. Nelson, W. Ogloza, S. Okano, U. Pajdosz-Śmierciak, J. C. Pandey, M. Perri, G. Poyner, J. Provencal, A. Raj, D. E. Reichart, R. Reinthal, T. Reynolds, J. Saario, S. Sadegi, T. Sakanoi, J.-L. Salto González, null Sameer, T. Schweyer, A. Simon, M. Siwak, F. C. Soldán Alfaro, E. Sonbas, I. Steele, J. T. Stocke, J. Strobl, T. Tomov, L. Tremosa Espasa, J. R. Valdes, J. Valero Pérez, F. Verrecchia, V. Vasylenko, J. R. Webb, M. Yoneda, M. Zejmo, W. Zheng, P. Zielinski, and Department of Physics

Subjects
General relativity, Astrophysics::High Energy Astrophysical Phenomena, black hole physics, OJ-287, FOS: Physical sciences, GRAVITATIONAL-RADIATION REACTION, General Relativity and Quantum Cosmology (gr-qc), Astrophysics, individual: OJ 287 [quasars], OUTBURSTS, 01 natural sciences, General Relativity and Quantum Cosmology, law.invention, VDP::Matematikk og Naturvitenskap: 400::Fysikk: 430::Astrofysikk, astronomi: 438, Binary black hole, MOMENTS, law, quasars: general, 0103 physical sciences, Blazar, 010303 astronomy & astrophysics, QC, QB, High Energy Astrophysical Phenomena (astro-ph.HE), Orbital elements, Physics, general [quasars], COMPACT BINARIES, OJ287, 010308 nuclear & particles physics, Gravitational wave, quasars: individual (OJ 287), SYSTEMS NONSPINNING BODIES, Astronomy and Astrophysics, 115 Astronomy, Space science, Orbital period, Astrophysics - Astrophysics of Galaxies, VDP::Mathematics and natural science: 400::Physics: 430::Astrophysics, astronomy: 438, MODEL, Black hole, SPIN, gravitation, Space and Planetary Science, Astrophysics of Galaxies (astro-ph.GA), Astrophysics - High Energy Astrophysical Phenomena, WAVE-FORM, Flare
Abstract

Results from regular monitoring of relativistic compact binaries like PSR 1913+16 are consistent with the dominant (quadrupole) order emission of gravitational waves (GWs). We show that observations associated with the binary black hole central engine of blazar OJ 287 demand the inclusion of gravitational radiation reaction effects beyond the quadrupolar order. It turns out that even the effects of certain hereditary contributions to GW emission are required to predict impact flare timings of OJ 287. We develop an approach that incorporates this effect into the binary black hole model for OJ~287. This allows us to demonstrate an excellent agreement between the observed impact flare timings and those predicted from ten orbital cycles of the binary black hole central engine model. The deduced rate of orbital period decay is nine orders of magnitude higher than the observed rate in PSR 1913+16, demonstrating again the relativistic nature of OJ 287's central engine. Finally, we argue that precise timing of the predicted 2019 impact flare should allow a test of the celebrated black hole "no-hair theorem" at the 10% level., 24 pages, 11 figures, 3 tables, accepted for publication in ApJ

Published
2018
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8. Suzaku and Multi-Wavelength Observations of OJ 287 during the Periodic Optical Outburst in 2007

Author

Aaron Dominguez, Giacomo Bonnoli, Felicitas Pauss, Dorota Sobczyńska, Abelardo Moralejo, Elsa De Cea DelPozo, M. Tluczykont, A. Saggion, Adrian Biland, Mario Meucci, Michael Backes, Elisa Prandini, Thomas Schweizer, T. Jogler, Markus Gaug, M. Meyer, Victor Zabalza, Maria Victoria Fonseca, Hristofor Vankov, Elina Lindfors, Antonio Stamerra, Carlos Delgado Mendez, Antonio La Barbera, Konstancja Satalecka, Daniel Mazin, Kari Nilsson, Michele Doro, Daniela Ferenc, Tomoka Tosaki, Hiroko Miyamoto, R. G. Pegna, Marc Ribó, Mariano Moles, Ma Teresa Costado Dios, Louis Antonelli, R. Firpo, Agnieszka Sierpowska-Bartosik, Debanjan Bose, A. Laille, L. Peruzzo, Silvia Balestra, M. Rissi, Yuichi Yaji, Ilia Britvitch, R. J. García-López, Ignasi Reichardt, Enrique Fernández, Alessandro DeAngelis, C. C. Hsu, Francesco Longo, W. Wittek, Masaaki Hayashida, Nicola Galante, Naoki Isobe, Stefano Covino, N. Otte, Jordi Zapatero, Jose Luis Contreras, Mahito Sasada, Dominik Elsaesser, Valentin Curtef, Luisa Sabrina Stark Schneebeli, G. Maneva, Juan Cortina, Javier Rico, Massimo Persic, Donatella López, Artemio Herrero, A. Robert, Francisco Prada, Hiromi Seta, Igor Oya, Makoto Uemura, H. Anderhub, Lluis Font, R. Mirzoyan, D. Tescaro, Nicola Turini, Fabrizio Tavecchio, Riccardo Paoletti, Denis Bastieri, Roberta Zanin, Laura Maraschi, Daniel Kranich, Daniel Nieto, K. Berger, Josep M. Paredes, Takayuki Y. Saito, Raquel DelosReyes, Yoshito Shimajiri, Michela DeMaria, M. I. Martínez, Fabio Zandanel, V. Scalzotto, Karl Mannheim, Nuria Sidro, E. Carmona, Wodzimierz Bednarek, D. Pascoli, S. Rügamer, Juan Abel Barrio, Valentí Bosch-Ramon, Felix Spanier, R. K. Bock, Miguel A. Pérez-Torres, Josefa González, Markus Garczarczyk, Makoto Tashiro, Leo O. Takalo, C. Baixeras, Javier Moldon, Akira Arai, V. Scapin, Neus Puchades, Elvira Leonardo, Daniela Borla Tridon, Julian Sitarek, J. Hose, Pol Bordas, Dorothee Hildebrand, P. Antoranz, Isabel Braun, P. Majumdar, Julia Becker, S. Commichau, Jelena Ninkovic, Diego F. Torres, M. Pasanen, Daniela Dorner, Daniel Höhne-Mönch, Daniela Hadasch, Robert Wagner, Francesco Dazzi, Jose Miguel Miranda, Miguel A. Sánchez-Conde, Mosè Mariotti, Barbara DeLotto, Saverio Lombardi, Masayuki Fukuhara, Manel Errando, M. Shayduk, Nijil Mankuzhiyil, Kotaro Kohno, Masahiro Teshima, M. Salvati, Thomas Bretz, Miguel Camara, A. Sillanpää, S. N. Shore, Kouichiro Nakanishi, Wolfgang Rhode, Francesco DeSabata, Florian Goebel, E. Lorenz, Petar Temnikov, Elisa Bernardini, Universitat de Barcelona, H., Seta, N., Isobe, M. S., Tashiro, Y., Yaji, A., Arai, M., Fukuhara, K., Kohno, K., Nakanishi, M., Sasada, Y., Shimajiri, T., Tosaki, M., Uemura, H., Anderhub, L. A., Antonelli, P., Antoranz, M., Backe, C., Baixera, S., Balestra, J. A., Barrio, D., Bastieri, J. B., Gonzalez, J. K., Becker, W., Bednarek, K., Berger, E., Bernardini, A., Biland, R. K., Bock, G., Bonnoli, P., Borda, D. B., Tridon, V., Bosch Ramon, D., Bose, I., Braun, T., Bretz, I., Britvitch, M., Camara, E., Carmona, S., Commichau, J. L., Contrera, J., Cortina, M. T. C., Dio, S., Covino, V., Curtef, F., Dazzi, A. D., Angeli, E. D., del Pozo, R. d., los Reye, B. D., Lotto, M. D., Maria, F. D., Sabata, C. D., Mendez, A., Dominguez, D., Dorner, M., Doro, D., Elsaesser, M., Errando, D., Ferenc, E., Fernandez, R., Firpo, M. V., Fonseca, L., Font, N., Galante, R. J. G., Lopez, M., Garczarczyk, M., Gaug, F., Goebel, D., Hadasch, M., Hayashida, A., Herrero, D., Hildebrand, D., Hohne Monch, J., Hose, C. C., Hsu, T., Jogler, D., Kranich, A. L., Barbera, A., Laille, E., Leonardo, E., Lindfor, S., Lombardi, Longo, Francesco, D., Lopez, E., Lorenz, P., Majumdar, G., Maneva, N., Mankuzhiyil, K., Mannheim, L., Maraschi, M., Mariotti, M., Martinez, D., Mazin, M., Meucci, M., Meyer, J. M., Miranda, R., Mirzoyan, H., Miyamoto, J., Moldon, M., Mole, A., Moralejo, D., Nieto, K., Nilsson, J., Ninkovic, N., Otte, I., Oya, R., Paoletti, J. M., Parede, M., Pasanen, D., Pascoli, F., Pau, R. G., Pegna, M. A., Perez Torre, M., Persic, L., Peruzzo, F., Prada, E., Prandini, N., Puchade, I., Reichardt, W., Rhode, M., Ribo, J., Rico, M., Rissi, A., Robert, S., Rugamer, A., Saggion, T. Y., Saito, M., Salvati, M., Sanchez Conde, K., Satalecka, V., Scalzotto, V., Scapin, T., Schweizer, M., Shayduk, S. N., Shore, N., Sidro, A., Sierpowska Bartosik, A., Sillanpaa, J., Sitarek, D., Sobczynska, F., Spanier, A., Stamerra, L. S. S., Schneebeli, L., Takalo, F., Tavecchio, P., Temnikov, D., Tescaro, M., Teshima, M., Tluczykont, D. F., Torre, N., Turini, H., Vankov, R. M., Wagner, W., Wittek, V., Zabalza, F., Zandanel, R., Zanin, and J., Zapatero

Subjects
Photon, Radiation mechanisms: non-thermal, OJ-287, Synchrotron radiation, Astrophysics, 01 natural sciences, Spectral line, law.invention, law, 010303 astronomy & astrophysics, High Energy Astrophysical Phenomena (astro-ph.HE), Physics, Very High Energy Gamma-ray Astronomy, MAGIC telescope, Active Galactic Nuclei, Lorentz factor, Forats negres (Astronomia), ALL-SKY SURVEY, symbols, Spectral energy distribution, Galaxies: BL lacertae objects: individual (OJ 287), BLACK-HOLE MODEL, Raigs X, Astrophysics - High Energy Astrophysical Phenomena, Galaxies: BL lacertae objects: general, Astrophysics - Cosmology and Nongalactic Astrophysics, BOARD SUZAKU, Cosmology and Nongalactic Astrophysics (astro-ph.CO), Active galactic nucleus, TELESCOPE, Astrophysics::High Energy Astrophysical Phenomena, FOS: Physical sciences, Telescope, symbols.namesake, 0103 physical sciences, X-rays, Blazar, 010308 nuclear & particles physics, BL-LACERTAE OBJECTS, GAMMA-RAY EMISSION, BLAZARS, SYSTEM, PERFORMANCE, Astronomy and Astrophysics, Galaxies, Galàxies, X-rays: galaxies, Space and Planetary Science, Black holes (Astronomy)
Abstract

Suzaku observations of the blazar OJ 287 were performed in 2007 April 10--13 and November 7--9. They correspond to a quiescent and a flaring state, respectively. The X-ray spectra can be well described with single power-law models in both exposures. The derived X-ray photon index and the flux density at 1 keV were found to be Gamma = 1.65 +- 0.02 and S_{1 keV} = 215 +- 5 nJy, in the quiescent state. In the flaring state, the source exhibited a harder X-ray spectrum (Gamma = 1.50 +- 0.01) with a nearly doubled X-ray flux density S_{1 keV} = 404^{+6}_{-5} nJy. Moreover, significant hard X-ray signals were detected up to ~ 27 keV. In cooperation with the Suzaku, simultaneous radio, optical, and very-high-energy gamma-ray observations were performed with the Nobeyama Millimeter Array, the KANATA telescope, and the MAGIC telescope, respectively. The radio and optical fluxes in the flaring state (3.04 +- 0.46 Jy and 8.93 +- 0.05 mJy at 86.75 Hz and in the V-band, respectively) were found to be higher by a factor of 2--3 than those in the quiescent state (1.73 +- 0.26 Jy and 3.03 +- 0.01 mJy at 86.75 Hz and in the V-band, respectively). No notable gamma-ray events were detected in either observation. The spectral energy distribution indicated that the X-ray spectrum was dominated by inverse Compton radiation in both observations, while synchrotron radiation exhibited a spectral cutoff around the optical frequency. Furthermore, no significant difference in the synchrotron cutoff frequency was found between the quiescent and flaring states. According to a simple synchrotron self-Compton model, the change of the spectral energy distribution is due to an increase in the energy density of electrons with small changes of both the magnetic field strength and the maximum Lorentz factor of electrons., 22 pages, 8 figures; accepted for publication in PASJ

Published
2009

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