[SEMINARI] Jet Precesion in the AGN of M81. Physical Parameters and Evidence of a Binary Black Hole

Enric Marco Enric.Marco en uv.es
Lun Jul 16 17:11:16 CEST 2012


Title: Jet Precesion in the AGN of M81. Physical Parameters and
Evidence of a Binary Black Hole

Speaker:Ivan Marti-Vidal

from: Onsala Space Observatory (Chalmers University), Onsala, Suècia

Seminari del departament d'Astronomia i Astrofísica

Dimecres 18 juliol 2012

12:00

http://celeste.uv.es/daa/seminari.php.UTF8?id=1060

Resum

We report on a full campaign of multi-frequency global-VLBI
observations of M81, phase-referenced to the closeby supernova
SN1993J. From these observations, we find a systematic drift in the
intensity peak of M81 among the different frequencies (possibly due to
opacity effects in the radio jet). From these results, we can estimate
the mass of the central black hole and the strength of the magnetic
field at the jet base. The former is compatible with previous
estimates using independent approaches; the latter is about 4 orders
of magnitude higher than previous estimates. Furthermore, from the
astrometry to SN1993J, we also detect an evolution in the jet position
angle that is correlated to changes in the total flux density of M81
and to changes in the orientation of the jet cores at all frequencies.
These results can be interpreted as due to jet precesion, with a
period of a few decades. Indeed, from the modelling of the core
orientation vs. time, we also detect strong evidence of two different
period contributions to the jet precesion (binary black hole in
M81?!). Further results on the astrometry monitoring of M81, now
phase-referenced to a new closeby supernova, are also being analyzed.
We are also analyzing radio light curves of M81 (with the VLA,
covering almost 12 years at frequencies ranging from 300MHz to 22GHz),
to help us better constrain the physical parameters and evolution of
the jet in M81.
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/------------------------------------\
Dr. Enric Marco
Departament d'Astronomia i Astrofísica
Facultat de Física
Universitat de València
C/  Dr. Moliner, 50
46100 Burjassot, Spain
Phone: (34)-96-354-3069
Fax:(34)-96-354-3084
enric.marco en uv.es
www.uv.es/marco
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