Volume 586, February 2016
|Number of page(s)||22|
|Published online||26 January 2016|
PKS 1502+106: A high-redshift Fermi blazar at extreme angular resolution
Structural dynamics with VLBI imaging up to 86 GHz⋆
Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, 53121
2 Instituto de Radio Astronomía Milimétrica, Avenida Divina Pastora 7, Local 20, 18012 Granada, Spain
3 Agenzia Spaziale Italiana (ASI) Science Data Center, 00133 Roma, Italy
4 Istituto Nazionale di Astrofisica – Osservatorio Astronomico di Roma, 00040 Monte Porzio Catone ( Roma), Italy
5 Istituto Nazionale di Fisica Nucleare, Sezione di Perugia, 06123 Perugia, Italy
Received: 21 August 2015
Accepted: 29 October 2015
Context. Blazars are among the most energetic objects in the Universe. In 2008 August, Fermi/LAT detected the blazar PKS 1502+106, which showed a rapid and strong γ-ray outburst followed by high and variable flux over the next months. This activity at high energies triggered an intensive multi-wavelength campaign that also covered the radio, optical, UV, and X-ray bands, indicating that the flare was accompanied by a simultaneous outburst at optical/UV/X-rays and a delayed outburst at radio bands.
Aims. We explore the phenomenology and physical conditions within the ultra-relativistic jet of the γ-ray blazar PKS 1502+106. Additionally, we address the question of the spatial localization of the MeV/GeV-emitting region of the source.
Methods. We used ultra-high angular resolution mm-VLBI observations at 43 and 86 GHz complemented by VLBI observations at 15 GHz. We also employed single-dish radio data from the F-GAMMA program at frequencies matching the VLBI monitoring.
Results. PKS 1502+106 shows a compact core-jet morphology and fast superluminal motion with apparent speeds in the range 5–22 c. Estimating Doppler factors along the jet yields values of between ~7 up to ~50. This Doppler factor gradient implies an accelerating jet. The viewing angle towards the source differs between the inner and outer jet, with the former at θ ~ 3° and the latter at θ ~ 1°, after the jet bends towards the observer beyond 1 mas. The de-projected opening angle of the ultra-fast magnetically dominated jet is found to be (3.8 ± 0.5)°. A single jet component can be associated with the pronounced flare both at high energies and in radio bands. Finally, the γ-ray emission region is localized at ≤ 5.9 pc away from the jet base.
Key words: galaxies: active / galaxies: jets / quasars: individual: PKS 1502+106 / radiation mechanisms: non-thermal / radio continuum: galaxies / gamma rays: galaxies
Images as FITS files are only available at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (22.214.171.124) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/586/A60
© ESO, 2016
Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.
Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.
Initial download of the metrics may take a while.