Research output: Contribution to journal › Article › peer-review
Probing the Innermost Regions of AGN Jets and Their Magnetic Fields with RadioAstron. V. Space and Ground Millimeter-VLBI Imaging of OJ 287. / Gómez, José L.; Traianou, Efthalia; Krichbaum, Thomas P.; Lobanov, Andrei P.; Fuentes, Antonio; Lico, Rocco; Zhao, Guang Yao; Bruni, Gabriele; Kovalev, Yuri Y.; Lahteenmaki, Anne; Voitsik, Petr A.; Lisakov, Mikhail M.; Angelakis, Emmanouil; Bach, Uwe; Casadio, Carolina; Cho, Ilje; Dey, Lankeswar; Gopakumar, Achamveedu; Gurvits, Leonid I.; Jorstad, Svetlana; Kovalev, Yuri A.; Lister, Matthew L.; Marscher, Alan P.; Myserlis, Ioannis; Pushkarev, Alexander B.; Ros, Eduardo; Savolainen, Tuomas; Tornikoski, Merja; Valtonen, Mauri J.; Zensus, Anton.
In: Astrophysical Journal, Vol. 924, No. 2, 122, 10.01.2022.Research output: Contribution to journal › Article › peer-review
}
TY - JOUR
T1 - Probing the Innermost Regions of AGN Jets and Their Magnetic Fields with RadioAstron. V. Space and Ground Millimeter-VLBI Imaging of OJ 287
AU - Gómez, José L.
AU - Traianou, Efthalia
AU - Krichbaum, Thomas P.
AU - Lobanov, Andrei P.
AU - Fuentes, Antonio
AU - Lico, Rocco
AU - Zhao, Guang Yao
AU - Bruni, Gabriele
AU - Kovalev, Yuri Y.
AU - Lahteenmaki, Anne
AU - Voitsik, Petr A.
AU - Lisakov, Mikhail M.
AU - Angelakis, Emmanouil
AU - Bach, Uwe
AU - Casadio, Carolina
AU - Cho, Ilje
AU - Dey, Lankeswar
AU - Gopakumar, Achamveedu
AU - Gurvits, Leonid I.
AU - Jorstad, Svetlana
AU - Kovalev, Yuri A.
AU - Lister, Matthew L.
AU - Marscher, Alan P.
AU - Myserlis, Ioannis
AU - Pushkarev, Alexander B.
AU - Ros, Eduardo
AU - Savolainen, Tuomas
AU - Tornikoski, Merja
AU - Valtonen, Mauri J.
AU - Zensus, Anton
N1 - Publisher Copyright: © 2022. The Author(s). Published by the American Astronomical Society.
PY - 2022/1/10
Y1 - 2022/1/10
N2 - We present the first polarimetric space very long baseline interferometry (VLBI) observations of OJ 287, observed with RadioAstron at 22 GHz during a perigee session on 2014 April 4 and five near-in-time snapshots, together with contemporaneous ground VLBI observations at 15, 43, and 86 GHz. Ground-space fringes were obtained up to a projected baseline of 3.9 Earth diameters during the perigee session, and at a record 15.1 Earth diameters during the snapshot sessions, allowing us to image the innermost jet at an angular resolution of ∼50μ as, the highest ever achieved at 22 GHz for OJ 287. Comparison with ground-based VLBI observations reveals a progressive jet bending with increasing angular resolution that agrees with predictions from a supermassive binary black hole model, although other models cannot be ruled out. Spectral analyses suggest that the VLBI core is dominated by the internal energy of the emitting particles during the onset of a multiwavelength flare, while the parsec-scale jet is consistent with being in equipartition between the particles and magnetic field. Estimated minimum brightness temperatures from the visibility amplitudes show a continued rising trend with projected baseline length up to 1013 K, reconciled with the inverse-Compton limit through Doppler boosting for a jet closely oriented to the line of sight. The observed electric vector position angle suggests that the innermost jet has a predominantly toroidal magnetic field, which, together with marginal evidence of a gradient in rotation measure across the jet width, indicates that the VLBI core is threaded by a helical magnetic field, in agreement with jet formation models.
AB - We present the first polarimetric space very long baseline interferometry (VLBI) observations of OJ 287, observed with RadioAstron at 22 GHz during a perigee session on 2014 April 4 and five near-in-time snapshots, together with contemporaneous ground VLBI observations at 15, 43, and 86 GHz. Ground-space fringes were obtained up to a projected baseline of 3.9 Earth diameters during the perigee session, and at a record 15.1 Earth diameters during the snapshot sessions, allowing us to image the innermost jet at an angular resolution of ∼50μ as, the highest ever achieved at 22 GHz for OJ 287. Comparison with ground-based VLBI observations reveals a progressive jet bending with increasing angular resolution that agrees with predictions from a supermassive binary black hole model, although other models cannot be ruled out. Spectral analyses suggest that the VLBI core is dominated by the internal energy of the emitting particles during the onset of a multiwavelength flare, while the parsec-scale jet is consistent with being in equipartition between the particles and magnetic field. Estimated minimum brightness temperatures from the visibility amplitudes show a continued rising trend with projected baseline length up to 1013 K, reconciled with the inverse-Compton limit through Doppler boosting for a jet closely oriented to the line of sight. The observed electric vector position angle suggests that the innermost jet has a predominantly toroidal magnetic field, which, together with marginal evidence of a gradient in rotation measure across the jet width, indicates that the VLBI core is threaded by a helical magnetic field, in agreement with jet formation models.
UR - http://www.scopus.com/inward/record.url?scp=85123898055&partnerID=8YFLogxK
UR - http://arxiv.org/abs/2111.11200
UR - https://www.mendeley.com/catalogue/84835494-5f5e-33eb-b582-e69c1bccf8ab/
U2 - 10.3847/1538-4357/ac3bcc
DO - 10.3847/1538-4357/ac3bcc
M3 - Article
AN - SCOPUS:85123898055
VL - 924
JO - Astrophysical Journal
JF - Astrophysical Journal
SN - 0004-637X
IS - 2
M1 - 122
ER -
ID: 99847931