J/ApJ/747/63 7mm VLBA observations of BL Lac object OJ287 (Agudo+, 2012)
Erratic jet wobbling in the BL Lacertae object OJ287 revealed by sixteen years
of 7 mm VLBA observations.
Agudo I., Marscher A.P., Jorstad S.G., Gomez J.L., Perucho M., Piner B.G.,
Rioja M., Dodson R.
<Astrophys. J., 747, 63 (2012)>
=2012ApJ...747...63A 2012ApJ...747...63A
ADC_Keywords: BL Lac objects ; Millimetric/submm sources ; Radio continuum
Keywords: BL Lacertae objects: general - radio continuum: galaxies -
BL Lacertae objects: individual: (OJ287) -
galaxies: active - galaxies: jets - polarization
Abstract:
We present the results from an ultra-high-resolution 7 mm Very Long
Baseline Array study of the relativistic jet in the BL Lacertae object
OJ287 from 1995 to 2011 containing 136 total intensity images.
Analysis of the image sequence reveals a sharp jet-position-angle
swing by >100° during [2004,2006], as viewed in the plane of the
sky, which we interpret as the crossing of the jet from one side of
the line of sight to the other during a softer- and longer-term swing
of the inner jet. Modulating such long-term swing, our images also
show for the first time a prominent erratic wobbling behavior of the
innermost ∼0.4 mas of the jet with fluctuations in position angle of
up to ∼40° over timescales ∼2 yr. This is accompanied by highly
superluminal motions along non-radial trajectories, which reflect the
remarkable non-ballistic nature of the jet plasma on these scales. The
erratic nature and short timescales of the observed behavior rule out
scenarios such as binary black hole systems, accretion disk
precession, and interaction with the ambient medium as possible
origins of the phenomenon on the scales probed by our observations,
although such processes may cause longer-term modulation of the jet
direction. We propose that variable asymmetric injection of the jet
flow, perhaps related to turbulence in the accretion disk, coupled
with hydrodynamic instabilities leads to the non-ballistic dynamics
that causes the observed non-periodic changes in the direction of the
inner jet.
Description:
We present 136 total-intensity Verry Long Baseline Array (VLBA) images
of OJ287 at 7 mm obtained from 1995 January to 2011 June; see Table 1
and Figure 1 (and Figure 2).
Objects:
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RA (2000) DE Designation(s)
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08 54 48.87 +20 06 30.6 OJ287 = OHIO J 287
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 41 136 Observing log and image information
table2.dat 53 590 Model fit parameters
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See also:
J/MNRAS/421/1861 : OJ287 polarization and VLBI jet direction (Valtonen+, 2012)
J/ApJ/742/27 : 15GHz and jet properties of MOJAVE blazars (Lister+, 2011)
J/AJ/141/65 : BATC ceimo light curves of OJ 287 (Dai+, 2011)
J/ApJS/189/1 : A 3.5mm polarimetric survey of radio-loud AGNs (Agudo+, 2010)
J/MNRAS/402/2087 : OJ287 optical polarization in 2005-2009 (Villforth+, 2010)
J/ApJ/707/L56 : VLBI and bright Fermi/LAT sources (Kovalev, 2009)
J/ApJ/706/1253 : MOJAVE VII. Blazar jet acceleration (Homan+, 2009)
J/AJ/138/1874 : MOJAVE. VI. Kinematic analysis of blazar jets (Lister+, 2009)
J/AJ/137/3718 : 15GHz monitoring of AGN jets with VLBA (Lister+, 2009)
J/MNRAS/385/823 : UBVRI light curves of OJ 287 (Zheng+, 2008)
J/AJ/134/799 : Multiwaveband polarimetry of 15 AGN (Jorstad+, 2007)
J/AJ/133/2357 : Relativistic jets in the RRFID database (Piner+, 2007)
J/A+A/466/63 : VLBI observations of BL Lac objects (Wu+, 2007)
J/AJ/132/1256 : eim BATC photometry of OJ 287 (Wu+, 2006)
J/AJ/131/1262 : Circular polarization images of AGN jets (Homan+, 2006)
J/A+A/450/39 : BVRI photometry of 8 red blazars (Gu+, 2006)
J/AJ/130/1418 : AGN jet kinematics (Jorstad+, 2005)
J/AJ/130/1389 : Linear polarization of AGN jets at 15GHz (Lister+, 2005)
J/ApJ/522/846 : Optical monitoring of GeV loud blazars (Xie+, 1999)
J/A+AS/136/455 : BVRI photometry of 3 BL Lac objects (Bai+, 1999)
J/A+AS/132/83 : BVRI photometry of 7 BL Lac objects (Bai+ 1998)
J/A+AS/129/569 : BVRI photometry of OJ 287 (Jia Guibin+ 1998)
J/A+AS/122/271 : mm-monitoring of radio sources IV. (Reuter+ 1997)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 10 A10 "YYYY/MM/DD" Date Date of the observation
12- 14 I3 min Tint [12/110] Total integration time
16 I1 --- Bit [1/2] Bit sampling
18- 20 I3 MHz Dnu [32/128] Observing frequency bandwidth
22- 26 F5.2 Jy Sint [0.8/10.2] Integrated flux density (at 7mm)
28- 31 F4.2 Jy Speak [0.3/7.1] Peak flux density (in Jy/beam)
33- 35 F3.1 mJy Noise [0.5/4.4] Image noise level (in mJy/beam)
37- 41 A5 --- Ref References(s) (1)
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Note (1): References as follows:
1 = Jorstad et al. (2001ApJS..134..181J 2001ApJS..134..181J);
2 = Gomez et al. (2001ApJ...561L.161G 2001ApJ...561L.161G);
3 = Agudo et al. (2006A&A...453..477A 2006A&A...453..477A);
4 = Bach et al. (2006A&A...456..105B 2006A&A...456..105B);
5 = Gomez et al. (2008ApJ...681L..69G 2008ApJ...681L..69G);
6 = Gomez et al. (2011ApJ...733...11G 2011ApJ...733...11G);
7 = Piner et al. (2006ApJ...640..196P 2006ApJ...640..196P);
8 = data from VLBA archive;
9 = Agudo et al. (2007, Cat. J/A+A/476/L17);
10 = D'Arcangelo et al. (2009ApJ...697..985D 2009ApJ...697..985D);
11 = Agudo et al. (2010; Agudo, I., Jorstad, S. G., & Marscher, A. P. et al.
Fermi Meets Jansky -AGN in Radio and Gamma-Rays, ed. T. Savolainen
et al. (Bonn: Max-Planck-Institute fur Radioastronomie), 143);
12 = Agudo et al. (2011ApJ...726L..13A 2011ApJ...726L..13A);
13 = this paper.
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Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 10 A10 "YYYY/MM/DD" Date Date of the observation
12 A1 --- Comp [A-Wa-p] Jet feature (see Figure 1)
14- 17 I4 mJy S [3/8132] Flux density (at 7mm)
19- 21 I3 mJy e_S [0/548] Uncertainty in S
23- 26 F4.2 mas r [0/1.6] Distance to the core
28- 31 F4.2 mas e_r Uncertainty in r
33- 36 I4 deg theta [-148/174] Position angle θ
38- 41 I4 deg e_theta Uncertainty in theta
43- 47 F5.3 mas FWHM [0/0.9] Full-Width at Half-Maximum of
Gaussian
49- 53 F5.3 mas e_FWHM Uncertainty in FWHM
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History:
From electronic version of the journal
(End) Greg Schwarz [AAS], Emmanuelle Perret [CDS] 26-Sep-2013