B2 1144+35B, a giant low power radio galaxy with superluminal motion
Orientation and evidence for recurrent activity
1
Dipartimento di Astronomia, Universita' di Bologna, via Ranzani 1, 40127 Bologna, Italy e-mail: ggiovann@ira.inaf.it
2
Istituto di Radioastronomia – INAF, via Gobetti 101, 40129 Bologna, Italy
3
Department of Physics and Astronomy, University of New Mexico, Albuquerque, NM 87131, USA
Received:
11
June
2007
Accepted:
3
August
2007
Aims.The goal of this work is a detailed study of the nearby, low power radio galaxy B2 1144+35B.
Methods.For this purpose, we performed new Very Long Baseline Array (VLBA) and Very Large Array (VLA) observations.
Results.This source has several properties (bright, nearby, large range of
spatial structures, visible counterjet, etc.) that make it an
excellent astrophysical laboratory for the study of the evolution of
radio jets. Here we report the detection of motion in the counterjet
at 
c, which allows us to estimate the orientation of
the parsec-scale jet at 33
from the line of sight,
with an intrinsic velocity of
(0.94
)c. We also report on a brightening of the core at high
frequencies which we suggest could be the result of a new component
emerging from the core. High dynamic range VLBA observations at 5 GHz
reveal, for the first time, extended emission connecting the core with
the bright complex of emission that dominates the flux density of the
parsec scale structure at frequencies below 20 GHz. The evolution of
this bright complex is considered and its slow decline in flux density
is interpreted as the result of an interaction with the interstellar
medium of the host galaxy.
Key words: galaxies: active / galaxies: jets / galaxies: nuclei / galaxies: individual: B2 1144+35B
© ESO, 2007