how compact are blazar cores agn studied with micro- arcsecond/sub-pc scale resolution...
DESCRIPTION
What does VLBI at short millimeter wavelengths offer ? Study compact galactic and extragalactic radio sources with an angular resolution of a few ten micro-arcseconds (size, structure, kinematics, polarization) Image regions which are (self-) absorbed and therefore not observable at longer wavelength (spectrum, radiation/ energy transport, outburst – ejection relations). For nearby super-massive Black Holes a chance to study their immediate environment (Sgr A*, M87, etc.) with a spatial resolution of ~ gravitational radii (accretion, jet formation and collimation, GR-effects).TRANSCRIPT
How Compact are Blazar Cores – How Compact are Blazar Cores – AGN studied with micro-AGN studied with micro-
arcsecond/sub-pc scale resolutionarcsecond/sub-pc scale resolution
T.P.Krichbaum T.P.Krichbaum
with contributions from with contributions from U. Bach, S. Lee, U. Bach, S. Lee,
M. Gurwell and A. MarscherM. Gurwell and A. Marscher
Max-Planck-Institut für Radioastronomie, Max-Planck-Institut für Radioastronomie, Bonn, GermanyBonn, Germany
involved scientists:
IRAM: M. Bremer, P. Cox, S. Sanchez, C. Thum, H. Ungerechts, H. Wiesemeyer, et al.
MPIfR: I. Agudo, W. Alef, U. Bach, D. Graham, T. Krichbaum, S.S. Lee, A. Lobanov, R. Porcas, A. Witzel, A. Zensus, et al.
Onsala/Sest: R. Booth, J. Conway, M. Lindquist, et al.
Metsähovi: A. Mujunen, M. Tornikoski, E. Valtaoja, K. Wiik, et al.
NRAO-VLBA: V. Dhawan, J. Ulvestad, C. Walker, et al.
and for VLBI at 1 & 2mm:
ARO (HHT/KP): A. Apponi, H. Fagg, R. Freund, P. Strittmatter, L. Ziurys, et al.
MIT-Haystack: S. Doeleman, A. Rogers, A. Whitney, et al.
special thanks for providing data, partly prior to publication:
A. Marscher & S. Jorstad (Boston)
J.L. Gomez (IAA Spain)
M. Gurvell (SMA)
M. & H. Aller (UMRAO)
T. Savolainen (Tuorla, now MPIfR)
What does VLBI at short millimeter wavelengths offer ?
• Study compact galactic and extragalactic radio sources with an angular resolution of a few ten micro-arcseconds (size,
structure, kinematics, polarization)
• Image regions which are (self-) absorbed and therefore not observable at longer wavelength (spectrum, radiation/ energy transport, outburst – ejection relations).
• For nearby super-massive Black Holes a chance to study their immediate environment (Sgr A*, M87, etc.) with a spatial resolution of ~10 - 100 gravitational radii (accretion, jet formation and collimation, GR-effects).
Spectral variability of
3C454.3 after May
2005 Flare:
Effelsberg:
1.4 – 32 GHz
Pico Veleta:
90 – 230 GHz
SMA:
230, 350 GHz
combined data:
Krichbaum, Ungerechts, Wiesemeyer, Gurwell et al.
SMA data: M. Gurwell et al.
quasi periodicity during peak !
11days or 1.2as or 95 Rs
T. Krichbaum, et al. 2007
monthly 2004 - 2007
• Europe: Effelsberg (100m), Pico Veleta (30m), Plateau de Bure (35m), Onsala (20m), Metsähovi (14m)
• USA: 8 x VLBA (25m)
The Global Millimeter VLBI Array – VLBI Imaging The Global Millimeter VLBI Array – VLBI Imaging at 86 GHz with ~40 at 86 GHz with ~40 as resolutionas resolution
http://www.mpifr-bonn.mpg.de/div/vlbi/globalmm
Proposal deadlines: February 1st, October 1st
Baseline Sensitivity
in Europe:
50 – 350 mJy50 – 350 mJy
in US:
250 – 350 mJy250 – 350 mJy
transatlantic:
80 – 350 mJy80 – 350 mJy
Array:
2 – 4 mJy / hr2 – 4 mJy / hr
(assume 7, 100sec, 512 Mbps)
common beam 0.25 x 0.1 mas
43 GHz, Oct. 6
86 GHz, Oct. 17
Quasi-simultaneous mm-VLBI observations
of 3C454.3 after outburst
43 GHz: no emission near core
known jet emission at 0.3 -1.4 mas
86 GHz: emission near core clearly visible
jet components at 0.6 & 1.1mas
compare well to 43 GHz image
conclusion:
strong absorption in the 0.1-0.3 mas region,
i.e. on the 1-2 pc scale
spectral index : +1.1 .... + 2.6 (range of uncertainty)
43/86 GHz: - 0.4 (core), - 0.3 (jet)
8.5Jy 0.23 Jy
6.7Jy 0.14Jy 0.18Jy
data: Marscher et al.
A new and comprehensive 86 GHz VLBI Survey:
Comparison with previous surveys at 86 GHz
VLBI Surveys at 86 GHz
1. Beasley et al. (1996) (N=45, 16% detect)
2. Lonsdale et al. (1998) (N=79, 14% detect)
3. Rantakyro et al. (1998) (N=67, 24% detect)
4. Lobanov et al. (2000) (N=28, 93% detect)
5. Lee et al. (2006, 2007)
- 3~4 times better sensitivity (Scorr >0.3 Jy)
- larger sample (127sources)
taken from surveys at lower frequencies
- 121 (95%) sources were detected and
- 109 (86%) sources could be imaged This Survey
S.S. Lee et al. 2006
86 GHz VLBI Survey: Some preliminary statistics
distribution of core flux densities distribution of measured core sizes
BL Lacs are more compact and more core dominated than QSOs. QSOs are more compact and core dominated than Radio-Galaxies.
Lee, Lobanov, Krichbaum et al. 2006
Lee et al. 2007, in prep.
normalized visibilities vs. uv-distance
M87 with the VLBA at 43 GHz
Ly et al. 2004, & 2007
counter-jet or self-absorbed jet base ?
234 x 59 as = 25 x 6 light days = 82 x 21 Rs9
transverse width of jet at 1mas: ~250 – 300 Rs
assume size of VLBI core = size of jet base:
300 Rs
1 mas = 0.09 pc
April 2002
96 light days
The Mini – Spiral
VLA 2cm
Krichbaum et al. 1993
VLBI 86 GHz
19 Rs size
Krichbaum et al. 1998 & 2006
From VLBI at 1.3mm:
50 as < FWHM < 190 as
or
5 RS < size < 19 RS
(for a SMBH with 4 x106 M)
best estimate: 110 ± 60 as
or : 11 ± 6 RS
3mm VLBI of M87 with the participation of PdBure
Peak: approx. 1.5 Jy
One year later:completely different visbility functions →the source structure must vary !
Mode: 512-8-2-LU
Peak: approx 0.7 Jy
Variability in the inner jet of M87 detected : 0.2 mas/yr 18000 km/s (0.06c)
(but: 3 – 6 c seen further downstream)
53 light days
counter-jet or new jet component ?April 2002 April 2003
new global 3mm map of M87 observed with the GMVA in April 2004:
now with better sensitivity, data rate: 512 Mbit/s (MK5 hard disk recording)
The size of the jet base (uniform weighting):
197 x 54 as = 21 x 6 light days = 69 x 19 Rs
transverse width of jet at 0.5 mas: ~174 Rs
M87 at 86 GHz
Krichbaum et al. 2006
174 Rs
The diameter of the light-cylinder
determines the jet width:
Camenzind, 1990jet width Rs for Kerr
BH)
> 40 Rs
Casse & Keppens 2004
Bach et al. 2006 and in prep.
The two-sided Jets of Cygnus AThe two-sided Jets of Cygnus A
Jet-to-counter-jet ratio modified by free-free absorption
apparent jet speed
Magnetic acceleration
Vlahakis & Königl, 2003
intrinsic jet acceleration from 0.1c – 0.7c
Enhance 3mm VLBI sensitivity by including the 3 largest European mm-telescopes:
Effelsberg 100 m (MPIfR)
Pico Veleta 30 m (IRAM, Spain)
Plateau de Bure, 6 x 15 m (IRAM, France)
Baseline lengths (km):
PdB PVEB 658 1700Pdb 1146
fringe spacing: 0.4 – 1.1 mas,
sensitivity > 40 -70 mJy (7512 Mbps)
plus the GBT, asap :
SEFD[Jy]
150GBT
590Plateau de Bure
710Pico Veleta
950 Effelsberg
Global mm-VLBI at 150 - 230 GHzGlobal mm-VLBI at 150 - 230 GHzKitt Peak, 12m
HHT, 10m
Metsähovi, 14m
Pico Veleta, 30mAPEX, 10m
angular resolutions: for 230 GHz
Plateau de Bure, 6x15m
near future
ALMA 50x12m
20 as
60 a
s
first detection of 2 first detection of 2 QSOs with VLBI QSOs with VLBI at 230 GHz !at 230 GHz !
Model of Sgr A*image distorted by gravitational light bending
Reconstructed Clean Image
Simulation of future 230 GHz VLBI of Sgr A* with IRAM (Pico Veleta, Plateau de Bure), HHT, CSO/SMA, CARMA, APEX
weighted mean: 3mm =0.18 ± 0.02 mas, range: 0.10 – 0.36 mas
weighted mean: 7mm =0.55 ± 0.03 mas, range: 0.43 – 0.70 mas
Does the observed 3mm size of Sgr A* vary ?
ConclusionsConclusions• The Global 3mm VLBI Array (GMVA) provides up to 40 as resolution and 50 –
250 mJy baseline sensitivity. USE IT !
• misalignement of jets between 86 GHz and longer wavelengths indicates transverse jet stratification (3C120, 3C273, 3C454.3, ...).
• M87 and SgrA* can be imaged with nearly the same spatial resolution of a few 10 Schwarzschild radii (M87 has a jet, SgrA* not).
• The small diameter (~20 RS) and high brightness temperature of the M87 jet base points towards MHD driven jet formation (Kerr metric, BH rotation acc. jet?)
• SgrA* is smaller than 11±6 RS; need global 1mm VLBI (+ SMA, CARMA, HHT, APEX, ALMA,...) to image GR effects near a SMBH.
• Global VLBI at 2mm & 1.3mm is technical feasible. The further increase of bandwith (2-4 Gbit/s), will facilitate imaging of compact sources with a resolution of 10 - 20 micro-arcseconds at Restz) ! (e.g. for z=3 and 345 GHz, RestHz ).
• mm-VLBI monitoring is needed in support of GLAST, Herschel and Planck. The GMVA provides good sensitivity and the smallest observing beam in Astronomy.
Station CountryDiamete
r Zenith Tsys Gain App.Eff. SEFD [m] [K] [K/Jy] % [Jy]Effelsberg Germany 80 130 0.14 8 930Plateau de Bure France 35 120 0.21 60 570Pico Veleta Spain 30 120 0.14 55 715Onsala Sweden 20 300 0.049 43 6100Metsähovi Finland 14 400 0.017 30 23500VLBA(8) USA 25 100 0.036 20 2800 Hopefully soon: GBT Va, USA 100 150 1.0 35 150Noto Italy 32 150 0.05 20 3000Yebes Spain 40 150 0.22 50 680Nobeyama Japan 45 150 0.17 30 880 Future: CARMA Ca ,USA 35 150 0.14 50 1070LMT Mexico 50 150 0.43 60 350ALMA Chile 64x12 100 1.8 70 55
Global VLBI at 3mm: Existing and possible future antennas
• need more sensitivity
• need more stations to allow better self –calibration
• need southern antennas for low declinatioin sources
What does the GMVA offer ?
• a global 13 station VLBI array allowing high dynamic range imaging with angular resolution of up to 40 as at 86 GHz
• 3 – 4 times higher sensitivity than stand-alone VLBA (512 Mbps is standard, max. 7 baseline sensitivity is ~ 50 mJy)
• 2 epochs/year, each session ~ 3 – 5 days long (limitation by proposal pressure)
• open to cummunity by usual proposal procedures (deadlines Feb. 1st, Oct. 1st)
• AIPS ready FITS files after correlation
3C120 with the full GMVA at 86 GHz, Oct. 12, 2004
1.3 pc
east-west resolution: 54 light days
present sensitivity limit on long baselines ~ 0.2 – 0.3 Jy (512 Mbps)
quasi-simultaneous VLBI maps (within 16 days) allow spectral index determination of inner jet
3C120 at 43 GHz (data: A. Marscher et al.)
misalignement possibly due to transverse opacity effects orthogonal to jet axis jet stratification
1.3 pc
43 GHz
86 GHz
-1.0-0.7-0.3-0.443/86 :
3C120 : Structural differences at 43 and 86 GHz within 14 days
43 GHz, Oct. 28
A B C D
86 GHz, Oct. 12
A B C D
radial distances agree well, p.a.'s differ
spectral index near position A: -0.4; B: 0.0; C: -1.4 (error: +/- 0.3)
0.13 pc
mm-VLBI resolves jet transversely:
A double rail structure
in the jet of 3C273 –
decollimation at 3 pc ?
3.2 pc
3.
5 pc
z = 0.158
1 mas 2.7 pc
MHD simulation of a confining B-field anchored in a rotating disk
The central engine – a MHD dynamo ?
Source PdBI - PV HHT - PVNRAO150 10.73C120 8.20420-014 24.90736+017 7.10716+714 6.8 6.4 ?OJ287 10.41055+0183C273 8.23C279 9.6NRAO530SgrA*3C3451633+3821749+0962013+370BL Lac 9.02145+067CTA1023C454.3 7.3
Signal-to-Noise ratios for the
230 GHz detections in 2003
(PV –PdB – HHT baselines):
short baselines: SNR : 25long baseline: SNR : 6 – 7
Two sources detected at 6.4 G:
3C454.3 and 0716+714
for 3C454.3 (z = 0.859)
´ = 428 GHz , life time B 2 = 3.6 105 ,
16 as = 0.1 pc = 1050 RS9 ,
SSA: B 1 G 600