J/A+A/623/A27 NGC1052 twin-jet VLBI images (Baczko+, 2019)
Asymmetric jet production in the active galactic nucleus of NGC 1052.
Baczko A.-K., Schulz R., Kadler M., Ros E., Perucho M., Fromm C.M., Wilms J.
<Astron. Astrophys. 623, A27 (2019)>
=2019A&A...623A..27B 2019A&A...623A..27B (SIMBAD/NED BibCode)
ADC_Keywords: Active gal. nuclei ; VLBI
Keywords: galaxies: active - galaxies: jets - methods: observational -
galaxies: kinematics and dynamics - galaxies: nuclei
Abstract:
Few active galactic nuclei (AGN) reveal double-sided jet systems.
However, these systems are crucial to understand basic physical
properties of extragalactic jets.
We address the questions whether jets in AGN are symmetric in nature,
how well they are collimated on small scales, and how they evolve with
time.
We monitored the sub-parsec scale morphology of NGC 1052 with the Very
Long Baseline Array at 43GHz from 2005 to 2009.
A detailed study of 29 epochs show a remarkable asymmetry between both
jets. A kinematic analysis of the outflows reveals higher apparent
velocities for the eastern (approaching) jet as compared to the
western (receding) jet, i.e., βej=0.529±0.038 and
βwj=0.343±0.037, respectively. Contradictory to previous
studies, we find higher flux densities for the western jet as compared
to the eastern. The distribution of brightness temperature and jet
width features well-collimated jets up to 1 mas distance to the
dynamic center and a nearly conical outflow further outward. By
combining flux density ratios and velocities of the jet flows, we were
unable to find a combination of intrinsic velocities and inclination
angles of the jets that is consistent for all four years of
observation; this contradicts findings for symmetrically evolving
jets. Spectral index maps between quasi-simultaneous 22GHz and 43GHz
observations support the existence of an optically thick absorber
covering the innermost ~=1.6mas around the 43GHz central feature
and an optically thin jet emission with a spectral index of ≤-1.
Our results fit into a picture in which we expect larger internal
energy and/or magnetic flux in the western jet and higher kinetic
energy in the eastern jet. Previous observations at lower frequencies
have found slower velocities of the moving jet features as compared to
this work. Considering the different velocities in different areas, we
suggest a spine-sheath structure with a faster inner layer and slower
outer layer.
Description:
Clean images of 29 observations of NGC1052 with the Very Long Baseline
Array at 43GHz from 2005 to 2009 are presented. Calibration was
performed in AIPS, followed by hybrid mapping in DIFMAP.
Objects:
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RA (2000) DE Designation(s)
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02 41 04.80 -08 15 20.8 NGC 1052 = LEDA 10175
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
list.dat 99 29 List of FITS images
fits/* . 29 Individual VLBI FITS images of NGC1052
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See also:
J/A+A/593/A47 : Pinpointing the SMBH in NGC1052 (Baczko+, 2016)
Byte-by-byte Description of file: list.dat
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Bytes Format Units Label Explanations
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1- 8 F8.5 deg RAdeg Right Ascension of center (J2000)
10- 17 F8.5 deg DEdeg Declination of center (J2000)
19- 21 I3 --- Nx Number of pixels along X-axis
23- 25 I3 --- Ny Number of pixels along Y-axis
27- 36 A10 "date" Obs.date Observation date
38- 44 F7.4 GHz Freq Observed frequency
46- 48 I3 Kibyte size Size of FITS file
50- 67 A18 --- FileName Name of FITS file, in subdirectory fits
69- 99 A31 --- Title Title of the FITS file
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Acknowledgements:
Anne-Kathrin Baczko, baczko(at)mpifr-bonn.mpg.de
(End) Anne-Kathrin Baczko [MPIfR], Patricia Vannier [CDS] 11-Jan-2019