J/A+A/684/A211 Gaussian model fit components for 3C345 (Roder+, 2024)
Up around the bend: A multiwavelength view of the quasar 3C 345.
Roder J., Ros E., Schinzel F.K., Lobanov A.P.
<Astron. Astrophys. 684, A211 (2024)>
=2024A&A...684A.211R 2024A&A...684A.211R (SIMBAD/NED BibCode)
ADC_Keywords: VLBI ; Active gal. nuclei ; Galaxies, radio
Keywords: black hole physics - relativistic processes -
instrumentation: interferometers - galaxies: jets -
quasars: general - quasars: individual: 3C 345
Abstract:
The flat-spectrum radio quasar 3C 345 has been showing gamma-ray
activity since the mid-2000s along with activity across the
electromagnetic spectrum. A gamma-ray burst in 2009 was successfully
linked to relativistic outflow in 43GHz very long baseline
interferometry (VLBI) observations and has since been analyzed also
using single dish measurements. A multi-wavelength followup VLBI
observation to the 2009 flare in conjunction with 43GHz catalogue
data from the VLBA-BU-BLAZAR and BEAM-ME programs are analyzed in this
study in the context of the long-term evolution of the source.
We aim to probe the innermost few milli-arcseconds of the ultracompact
3C 345 jet. In the process, we analyze the long-term kinematics of the
inner jet and discuss the magnetic field morphology at different
scales, as well as the origin of the gamma-ray emission.
New observations at 23, 43, and 86GHz took place on ten epochs between
2017 and 2019. We calibrate the 30 data sets using the rPicard
pipeline, image them in Difmap and carry out polarization calibration
using the GPCAL pipeline. We complement our VLBI data by 43GHz
observations carried out in the framework of the BEAM-ME and
VLBA-BU-BLAZAR monitoring programs.
We find multiple distinct component paths in the inner jet, forming a
helical geometry. The helix is anchored at a stationary feature some
0.16mas from the 43GHz VLBI core and has a timescale of about 8
years. The characteristic bends in the jet morphology are caused by
variations in the component ejection angle. We confirm the result of
previous studies that the gamma-ray emission is produced (or caused)
by relativistic outflow and violent interactions within the jet.
Description:
We present multifrequency VLBI observations at 23, 43, and 86GHz from
a two-year time period between 2017 and 2019, complemented with
archival 43GHz data taken from the VLBA-BU-BLAZAR and BEAM-ME
programs from 2019 onwards. Ejections of new moving features into the
relativistic jet in 3C345, as well as violent interactions within the
jet, can be linked to spikes in the Fermi/LAT gamma-ray light curve.
This confirms results of previous works: relativistic outflow drives
the gamma-ray emission in AGN.
Circular Gaussian model fit components for 10 VLBI maps at 23 and
86GHz each, as well as 50 maps at 43GHz are presented for the quasar
3C345. For each epoch and component, the flux density, on-sky
position, FWHM size and frequency are given.
Objects:
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RA (2000) DE Designation(s)
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16 42 58.80 +39 48 36.9 3C 345 = QSO J1642+3948
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
tablea1.dat 44 1769 Gaussian model fit components for 3C 345
at three frequencies (23, 43, 86GHz)
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See also:
J/AZh/72/447 : Optical Monitoring of Quasar 3C345 (Babadzhanyants+, 1995)
J/PAZh/25/893 : Optical outbursts of the blazar 3C 345 (Belokon+, 1999)
J/A+A/648/A82 : Quasar 3C 345 at 18 cm with RadioAstron (Poetzl+, 2021)
Byte-by-byte Description of file: tablea1.dat
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Bytes Format Units Label Explanations
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1- 8 F8.3 yr Epoch Observation date
10- 11 I2 --- ID [0/99] Component identifier
13- 17 F5.3 Jy Flux ?=- Flux density of Gaussian fit
19- 24 F6.3 mas Xpos ?=- On-sky X position
26- 31 F6.3 mas Ypos ?=- On-sky Y position
33- 40 E8.3 mas Size ?=- Gaussian FWHM size
43- 44 I2 GHz Freq Observing frequency (23, 43 or 86)
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Acknowledgements:
Jan Roder, jroeder.astro(at)gmail.com
(End) Jan Roder [MPIfR, Germany], Patricia Vannier [CDS] 01-Mar-2024