| Autor: |
Carnerero, M. I., Raiteri, C. M., Villata, M., Acosta-Pulido, J. A., D'Ammando, F., Smith, P. S., Larionov, V. M., Agudo, I., Arévalo, M. J., Arkharov, A. A., Bach, U., Bachev, R., BenÃ-tez, E., Blinov, D. A., Bozhilov, V., Buemi, C. S., Bueno, A. Bueno, Carosati, D., Casadio, C., Chen, W. P. |
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| Zdroj: |
Monthly Notices of the Royal Astronomical Society; 7/1/2015, Vol. 450 Issue 3, p2677-2691, 15p |
| Abstrakt: |
We present an analysis of the multiwavelength behaviour of the blazar OJ 248 at z = 0.939 in the period 2006-2013. We use low-energy data (optical, near-infrared, and radio) obtained by 21 observatories participating in the Gamma-Ray Large Area Space Telescope (GLAST)-AGILE Support Program of the Whole Earth Blazar Telescope, as well as data from the Swift (optical-UV and X-rays) and Fermi (y-rays) satellites, to study flux and spectral variability and correlations among emissions in different bands. We take into account the effect of absorption by the Damped Lyman a intervening system at z = 0.525. Two major outbursts were observed in 2006-2007 and in 2012-2013 at optical and near-IR wavelengths, while in the high-frequency radio light curves prominent radio outbursts are visible peaking at the end of 2010 and beginning of 2013, revealing a complex radio-optical correlation. Cross-correlation analysis suggests a delay of the optical variations after the γ-ray ones of about a month, which is a peculiar behaviour in blazars. We also analyse optical polarimetric and spectroscopic data. The average polarization percentage P is less than 3 per cent, but it reaches ~ 19 per cent during the early stage of the 2012-2013 outburst. A vague correlation of P with brightness is observed. There is no preferred electric vector polarization angle and during the outburst the linear polarization vector shows wide rotations in both directions, suggesting a complex behaviour/structure of the jet and possible turbulence. The analysis of 140 optical spectra acquired at the Steward Observatory reveals a strong Mg ii broad emission line with an essentially stable flux of 6.2 x 10-15 erg cm-2 s-1 and a full width at half-maximum of 2053 km s-1. [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
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