LOCATION OF {gamma}-RAY FLARE EMISSION IN THE JET OF THE BL LACERTAE OBJECT OJ287 MORE THAN 14 pc FROM THE CENTRAL ENGINE

Journal Article · Sat Jan 01 00:00:00 EST 2011 · Astrophysical Journal Letters

DOI:https://doi.org/10.1088/2041-8205/726/1/L13· OSTI ID:21560583

Agudo, Ivan; Jorstad, Svetlana G; Marscher, Alan P; D'Arcangelo, Francesca D; Taylor, Brian ^[1]; Larionov, Valeri M; Blinov, Dmitriy A; Hagen-Thorn, Vladimir A; Morozova, Daria A ^[2]; Gomez, Jose L; Roca-Sogorb, Mar ^[3]; Laehteenmaeki, Anne; Nieppola, Elina; Tornikoski, Merja ^[4]; Gurwell, Mark ^[5]; Smith, Paul S ^[6]; Wiesemeyer, Helmut ^[7]; Thum, Clemens ^[8]; Heidt, Jochen ^[9]

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1. Institute for Astrophysical Research, Boston University, 725 Commonwealth Avenue, Boston, MA 02215 (United States)
2. Astronomical Institute, St. Petersburg State University, Universitetskij Pr. 28, Petrodvorets, 198504 St. Petersburg (Russian Federation)
3. Instituto de Astrofisica de Andalucia, CSIC, Apartado 3004, 18080, Granada (Spain)
4. Aalto University Metsaehovi Radio Observatory, Metsaehovintie 114, FIN-02540 Kylmaelae (Finland)
5. Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States)
6. Steward Observatory, University of Arizona, Tucson, AZ 85721-0065 (United States)
7. Instituto de Radio Astronomia Milimetrica, Avenida Divina Pastora, 7, Local 20, E-18012 Granada (Spain)
8. Institut de Radio Astronomie Millimetrique, 300 Rue de la Piscine, 38406 St. Martin d'Heres (France)
9. ZAH, Landessternwarte Heidelberg, Koenigstuhl, 69117 Heidelberg (Germany)

We combine time-dependent multi-waveband flux and linear polarization observations with submilliarcsecond-scale polarimetric images at {lambda} = 7 mm of the BL Lacertae type blazar OJ287 to locate the {gamma}-ray emission in prominent flares in the jet of the source >14 pc from the central engine. We demonstrate a highly significant correlation between the strongest {gamma}-ray and millimeter-wave flares through Monte Carlo simulations. The two reported {gamma}-ray peaks occurred near the beginning of two major millimeter-wave outbursts, each of which is associated with a linear polarization maximum at millimeter wavelengths. Our very long baseline array observations indicate that the two millimeter-wave flares originated in the second of two features in the jet that are separated by >14 pc. The simultaneity of the peak of the higher-amplitude {gamma}-ray flare and the maximum in polarization of the second jet feature implies that the {gamma}-ray and millimeter-wave flares are cospatial and occur >14 pc from the central engine. We also associate two optical flares, accompanied by sharp polarization peaks, with the two {gamma}-ray events. The multi-waveband behavior is most easily explained if the {gamma}-rays arise from synchrotron self-Compton scattering of optical photons from the flares. We propose that flares are triggered by interaction of moving plasma blobs with a standing shock. The {gamma}-ray and optical emission is quenched by inverse Compton losses as synchrotron photons from the newly shocked plasma cross the emission region. The millimeter-wave polarization is high at the onset of a flare, but decreases as the electrons emitting at these wavelengths penetrate less polarized regions.

• OSTI ID: 21560583
• Journal Information: Astrophysical Journal Letters, Vol. 726, Issue 1; Other Information: DOI: 10.1088/2041-8205/726/1/L13; ISSN 2041-8205
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTROPHYSICS
COSMOLOGY AND ASTRONOMY
BL LACERTAE OBJECTS
COMPUTERIZED SIMULATION
CORRELATIONS
COSMIC GAMMA BURSTS
EMISSION
GALAXIES
GAMMA RADIATION
JETS
MONTE CARLO METHOD
POLARIZATION
CALCULATION METHODS
COSMIC RADIATION
COSMIC RADIO SOURCES
ELECTROMAGNETIC RADIATION
IONIZING RADIATIONS
PRIMARY COSMIC RADIATION
RADIATIONS
SIMULATION