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 (gamma-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 alpha 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 gamma-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 similar to 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).

Multiwavelength behaviour of the blazar OJ 248 from radio to gamma-rays

D'AMMANDO, FILIPPO;
2015

Abstract

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 (gamma-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 alpha 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 gamma-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 similar to 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).
2015
Carnerero MI; Raiteri CM; Villata M; Acosta-Pulido JA; DAmmando F; Smith PS; Larionov VM; Agudo I; Arevalo MJ; Arkharov AA; Bach U; Bachev R; Benitez E; Blinov DA; Bozhilov V; Buemi CS; Bueno AB; Carosati D; Casadio C; Chen WP; Damljanovic G; Di Paola A; Efimova NV; Ehgamberdiev SA; Giroletti M; Gomez JL; Gonzalez-Morales PA; Grinon-Marin AB; Grishina TS; Gurwell MA; Hiriart D; Hsiao HY; Ibryamov S; Jorstad SG; Joshi M; Kopatskaya EN; Kurtanidze OM; Kurtanidze SO; Lahteenmaki A; Larionova EG; Larionova LV; Lazaro C; Leto P; Lin CS; Lin HC; Manilla-Robles AI; Marscher AP; McHardy IM; Metodieva Y; Mirzaqulov DO; Mokrushina AA; Molina SN; Morozova DA; Nikolashvili MG; Orienti M; Ovcharov E; Panwar N; Yabar AP; Gimenez IP; Ramakrishnan V; Richter GM; Rossini M; Sigua LA; Strigachev A; Taylor B; Tornikoski M; Trigilio C; Troitskaya YV; Troitsky IS; Umana G; Valcheva A; Velasco S; Vince O; Wehrle AE; Wiesemeyer H
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11585/595739
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