1. Compact radio jets and nuclear regions in galaxies
Andrei Lobanov Max-Planck-Institut für Radioastronomie
8th European VLBI Network Symposium Torun, September 2006

2. Compact radio jets and nuclear region in galaxies
Outline
A. Lobanov
Observational studies of extragalactic relativistic jets
Anatomy of extragalactic jets: – VLBI “cores” – collimation and acceleration scales (~103 RS) – regions dominated by strong shocks (~10 pc) – dissipation of shocks and development of instabilities (~100 pc) – kiloparsec-scale jets
Relation between the jets and the nuclear environment in active galaxies: – jets from supermassive binary black hole systems – probing absorbing material in the nucleus – connection to accretion disks and broad-line emission
Compact radio jets and nuclear region in galaxies

3. Compact radio jets and nuclear region in galaxies
Jets and AGN
A. Lobanov
Mbh = 5*108 M
Event horizon: Rg pc
Ergosphere: 1-2 Rg pc
Corona: – 102 Rg – 10-3 pc
Accretion disk: 101 – 103 Rg – 10-2 pc
Broad line region: 102 – 105 Rg – 1 pc
Molecular torus: > 105 Rg > 1 pc
Narrow line region: > 106 Rg > 10 pc
Jet formation: ~ 102 Rg ~ 10-3 pc
Jet visible in the radio: > 103 Rg > 10-2 pc.
Compact radio jets and nuclear region in galaxies

4. Compact radio jets and nuclear region in galaxies
Anatomy of Jets
Compact radio jets and nuclear region in galaxies

5. Compact radio jets and nuclear region in galaxies
“Cores” of jets
A. Lobanov
Location at which jets become visible in radio is most likely determined solely by t=1 condition for synchrotron emission (Königl 1981).
Lobanov & Zensus 1999
Zensus et al. 1995, Lobanov 1996, Klare et al. 2005
Compact radio jets and nuclear region in galaxies

6. Collimation and acceleration
A. Lobanov
VLBI observations of compact jets in nearby AGN provide strong evidence for collimation on linear scales of ~103 RG and strong accelerations on sub-parscec scales
230 Rs
Krichbaum et al. 2005
M 87
Bach et al. 2003
Cyg A
Magnetically driven acceleration is a viable explanation for the observed speeds (Vlahakis & Königl 2004)
Compact radio jets and nuclear region in galaxies

7. Compact radio jets and nuclear region in galaxies
Shocks on pc scales
A. Lobanov
Strong shocks are clearly present in jets on small scales (several decaparsecs) – from polarization and distribution of the synchrotron turnover frequency.
3C 273
Core J1 J2 J1
Core J2
Carrara et al. 1997
Compact radio jets and nuclear region in galaxies

8. Compact radio jets and nuclear region in galaxies
Shocks on pc scales
A. Lobanov
Shock dissipate rapidly while approaching hectoparsec scales: shock models can no longer explain kinematic and spectral evolution observed in jets on these scales
Lobanov & Zensus 1999
Compact radio jets and nuclear region in galaxies

9. Instabilities on pc scales
A. Lobanov
Linear regime of K-H instability
lHs=18.0, lEs=12.0, lEb1=4.0, lEb2=1.9
Gj=2.1, Mj=3.5, h=0.02, aj=0.53, vw=0.21
Lobanov & Zensus 2001, Perucho, Lobanov, Martí 2006
Compact radio jets and nuclear region in galaxies

10. Instabilities on kpc-scales
A. Lobanov
On kiloparsec scales, jets are well represented by MHD models; e.g., models for 3C31 (Laing & Bridle 2002,2004), and M87 (Lobanov, Hardee & Eilek 2003, 2006)
M87 C
HST D E G I A B
Compact radio jets and nuclear region in galaxies

11. Jet disruption on kpc scales
A. Lobanov
Lobanov et al. 2006
Perucho, Lobanov, Martí 2007
Compact radio jets and nuclear region in galaxies

12. Jets and Nuclear Regions
Compact radio jets and nuclear region in galaxies

13. Compact radio jets and nuclear region in galaxies
Jets from binary SMBH
A. Lobanov
Sol, Pelletier, Asséo (1989), Lobanov & Roland (2005)
Magnetically confined outflow from a binary SMBH Jet components are produced by perturbations in the beam
Explains both evolution of a feature in the jet and optical variability
Jet contains information about the dynamic state of the binary
Compact radio jets and nuclear region in galaxies

14. Compact radio jets and nuclear region in galaxies
Properties of BBH in 3C345
A. Lobanov
(Lobanov & Roland 2005)
Compact radio jets and nuclear region in galaxies

15. Disk variability and flares
A. Lobanov
Flares and ejections of new jet components in 3C345 may be related to the characterstic instability timescales in the disk at Rg
Lobanov & Roland 2005
Compact radio jets and nuclear region in galaxies

16. Compact radio jets and nuclear region in galaxies
Nuclear absorption
A. Lobanov
Absorption due to several species, most notably HI, CO, OH, HCO+
HI absorption toward compact jets is an excellent tool to probe nuclear regions on parsec scales.
Good indicator of physical conditions of the neutral gas(Pedlar 2004)
NGC 4151
0.6pc
Mundell et al. 2003
Compact radio jets and nuclear region in galaxies

17. Compact radio jets and nuclear region in galaxies
Nuclear absorption
A. Lobanov
: Absorption probed on scales of ~100pc; broad (200km/s) and narrow (50km/s) – likely from a gas in a rotating toroidal structure.
Peck & Taylor 2001
Compact radio jets and nuclear region in galaxies

18. Nuclear opacity: Core shift
A. Lobanov
Position offset of the optically thick „core“ of a VLBI jet can be used to estimate physical conditions in the nuclear region of AGN
Core location:
(Königl 1981)
Core offset measure:
Derived magnetic field and distance from the central engine to the core:
Lobanov 1998
Compact radio jets and nuclear region in galaxies

19. Physics from the core shift
A. Lobanov
Pressure and density profile in the broad-line regions; magnetic field distributions in compact jets
3C345
Lobanov 1998
Compact radio jets and nuclear region in galaxies

20. Disk-Jet Connection: 3C120
A. Lobanov
(Marscher et al. 2002)
Compact radio jets and nuclear region in galaxies

21. Compact radio jets and nuclear region in galaxies
Jet-BLR connection
A. Lobanov
BLRG 3C390.3: jet can produce a large fraction of non-thermal continuum
Optical maxima correlate with the passages of relativistic plasma through S1
An X-ray minimum is found close to the ejection epochs of C5 and C6
Arshakian et al. 2006
Compact radio jets and nuclear region in galaxies

22. Compact radio jets and nuclear region in galaxies
Jet-BLR connection
A. Lobanov
The jet in 3C390.3 may power a BLR associated with a subrelativistic outflow from the nucleus.
Corona
BLR 1 (disk)
Subrelativistic outflow
VLBI “core”
BLR 2 (outflow)
Relativistic jet
Compact radio jets and nuclear region in galaxies

23. Compact radio jets and nuclear region in galaxies
Summary
A. Lobanov
Jets are an excellent laboratory for AGN studies
Small scale jets are dominated by shocks
At larger scales, shocks dissipate, and Kelvin-Helmholtz instability determines the structure and dynamics of the flow
Elliptical and helical modes of K-H instability are most prominent, leading to eventual disruption of the flow
Magnetically confined outflows may preserve information about the dynamic evolution of the nucleus
Jets can be used as probes of nuclear regions in AGN
Jet-BLR connection may exist and should be investigated in detail.
Compact radio jets and nuclear region in galaxies