kinematics of parsec-scale radio jet in 3c48 tao an 1, in collaboration with x.y.hong 1,...
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Kinematics of parsec-scale radio jet in 3C48
Tao An1,
In collaboration with X.Y.Hong1, M.J.Hardcastle2, T.Venturi3,
D.Worrall2,T.J.Pearson4,Z.-Q.Shen1, W.Zhao1, W.X.Feng5
1: Shanghai Astronomical Observatory, China2: Department of Physics, University of Bristol , UK3: INAF-Istituto di Radioastronomia, Italy4: California Institute of Technology, USA5: Liaocheng University, China
2009-03-19 An et al. @ 2009 EAVN 2
OUTLINE
1. Motivation
2. Observations and data reduction
3. Images (total intensity and polarization)
4. Kinematics of pc-scale radio jet
5. Helical jet
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1. Motivations
• CSSs are good candidates for studying dynamics and evolution of host galaxies, AGN feedback to host galaxies.
• 3C48, first found QSO, a typical CSS, ample gas in host galaxy, violent jet-ISM, (Wilkinson et al. 1991, Worrall et al. 2004, Feng etal. 2005, Gupta etal.2005,Stockton et al. 2007; et al.)
• We propose to study the dynamics of the radio jet and physical environment in the host galaxy
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2.1 OBSERVATIONS
Array VLBA+VLA(1) EVN MERLIN
R.A. 01 37 41.29943 01 37 41.29949 01 37 41.29675
Dec. 33 09 35.1330 33 09 35.1338 33 09 35.5117
Date 2004 June 25 2005 June 7 2005 June 7
Time (UT) 08:00—20:00 02:00—14:00 02:00—14:00
Freq (GHz) 1.5/4.8/8.3 1.65 1.65
Int.time(hour)
2.6/2.6/2.6 8 8
Baseline(km) 20—8600 130—8800 0.3—220
Calibrators DA193,3C138,3C345 DA193,3C138,3C286 DA193,3C138,3C286
BW(MHz) 32 32 15
Correlator Socorro (VLBA) JIVE(MkIV) Jodrell Bank
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2.2 Calibration of the data
• Standard data reduction procedure in AIPS• Hybrid selfcalibration and imaging in
AIPS/DIFMAP • Polarization calibration (ionospheric Faraday
rotation, D-term, absolute EVPA)• Final image multi-frequency synthesis
(bandwidth smearing)• Combination of EVN and MERLIN data
(alignment of flux scale and phase center)
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3.1 Total intensity images
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Total intenstiy images
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Figure parameters
LabelFreq
(GHz)
Restoring Beam
(mas,mas,degree)
Rms
(mJy/b)
Contours
(mJy/b)
MERLIN 1.65 [email protected] 1,5 6.0x(-2,1,2,…512)
VLBA 1.51 [email protected] 0.25 1.0x(1,2,4,…256)
EVN 1.65 5.0x [email protected] 0.30 1.0x(1,4,16,64,256)
VLBA 4.78 2,[email protected] 0.04 0.16x(1,4,16,64,256)
VLBA 8.31 [email protected] 0.06 0.24x(1,4,16,64,256)
EVN+ MERLIN
1.65 [email protected] 1.6 6.0x(1,4,16,32,64,128)
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MODEL FITTING of radio components
• 1996 January 20, 1.5GHz (Worrall et al. 2004)• 2004 June 25, 1.65GHz• 2005 June 7, 1.5 GHz• 1996 January 20, 5GHz (Worrall et al. 2004)• 2004 June 25, 5 GHz• 1996 January 20, 8.3 GHz (Worrall et al. 2004)• 2004 Juen 25, 8.3 GHz• 1996 January 20, 15GHz (Worrall et al. 2004)
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3.2 Polarized emission
Rotation of EVPA -- Faraday Rotation structure ?
m%~5%, uniform magnetic field direction in extended radio structure
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4. Kinematics of pc-scale jet – images
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Constraints to the viewing angle and jet speed
• Jet sideness parameter – jet-to-counterjet intensity ratio 2600>R>100
• Jet apparent velocity
Jet velocity>0.82c
Viewing angle<30O
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5.1 Helical jet model fit – sketch map• Assumptions of conservative quantities
– Ekin=const– Va=const– Opening angle=const
• Assumed parameters : – opening angle – viewing angle– Initial origin of K-H wave
• Measured parameters: – jet velocity, – position angle
• Fitted parameters– Wavelength– Initial amplitude and phase of K-H
wave– Changing rate of position angle
(Steffen et al. 1995 Case 2; Hardee 1987,1990s,2000s)
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5.2 Helical jet model fit – fitted curves
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5.3 Helical jet model fit -- fitted parameters
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6. conclusions
• MERLIN maps show two components – compact jet accounts for half of the total flux, surrounding by an envelope component
• Firstly distinct detection of inner 280pc jet• Proper motions in 3C48: inner jet component 3.7c to the
north; outer jet ~1.4c to the northeast• Kinematics analysis suggests the kpc-scale jet is as fast
as 0.8c, with viewing angle less than 30deg; the inner 280pc is even faster and/or closer to the line of sight.
• polarization images suggest an ordered magnetic field in extended component; while at some hot spots Faraday rotation structure is shown
• The general wavelike bending jet is fitted by a helical model; the model fitting suggest different K-H waves inside and outside 280pc (different physical condition)
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7. Prospect
• EAVN observations of Compact Steep Spectrum sources
• EAVN monitoring of proper motions of CSO/GPS
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We’ll see bright future in East Asia VLBI Network