Hydrodynamics of Small- Scale Jets: Observational aspects Esko Valtaoja Tuorla Observatory, University of Turku, Finland Metsähovi Radio Observatory, Helsinki University of Technology TUORLA-METSÄHOVI AGN GROUP: Talvikki Hovatta, Elina Lindfors, Anne Lähteenmäki, Elina Nieppola, Pia-Maria Saloranta, Tuomas Savolainen, Ilona Torniainen, Merja Tornikoski, Kaj Wiik

Meg Urry 2007: ”Luckily, nobody remembers what we said 25 years ago, and the old acetates have decayed.”

NEED: basic GLOBAL and LOCAL parameters from observations as inputs to theory / simulations which, in turn, should give predictions which observers can test GLOBAL: e.g., BH mass vs. jet speed? LOCAL: e.g., magnetic field strength along the jet?

Aloy et al. 2003Gómez et al Qualitative agreement -but need also quantitative: global and local parameters vs. simulated parameters

VLBA with all frequencies and polarization... (Savolainen et al., 2006, 2007) LOCAL data!

...gives us local information along and transverse to the jet (which you cannot get from single and/or low frequency VLBI) magnetic field vs. distance electron energy density vs. distance + jet/mf structures, instabilities, nonrelativistic plasma, speeds, IC fluxes... SAVE VLBA BY USING ITS FULL POWER!

Marscher & Gear shock-in-jet model (1985) (picture courtesy of Marc Türler)

Ten years of 3C 279 cm-to-optical variations modelled as ”M & G” shocks in a jet (Lindfors et al., 2006, original code developed by Marc Türler)

LOCAL data! Lindfors et al. 2005, 2006: shock and jet component spectra (+ SSC spectra) from mf continuum monitoring and 3-D fit simultaneously to all data VLBI: Savolainen et al. 2007

Exponential, sharp flares (Valtaoja et al. 1999) Theory and simulations: quite different flare shapes (Gomez et al. 1997)... are we missing something crucial?

- VLBI components correspond to TFD flares = shocks in the jet - strong gamma flares from the same shocks far from BH/BLR - T 0 (mm) < T 0 (VLBI) - T 0 (mm), T 0 (VLBI) < T 0 (gamma) need more accurate timings for each: physics of the radio core! Savolainen et al 2002 Jorstad et al Lähteenmäki & Valtaoja 2003

radio gamma Average delay from TFD/VLBI zero epoch to strong gamma flares ~ 2 months = parsecs, so External Compton fails......but the only alternative, synchrotron-self-Compton also fails (Lindfors et al. 2005, 2006) (Heh.) EC photons are here! radio core

Blazar sequence? (Ghisellini et al. 1998) One-parameter (total power) family: Most powerful sources have lowest synchrotron peak frequencies

...but fuller samples destroy the sequence! Nieppola et al. 2006: 381 Northern Veron- Cetty&Veron BL Lacs, a ”complete” sample (also Giommi et al. 2005; Padovani others)

Wu et al 2007: D(var) = [T B (var)/T B (lim)] 1/3 (Lähteenmäki & Valtaoja 1999)

Correcting the luminosities for Doppler boosting totally destroys the last traces of the ”blazar sequence” (Saloranta, Nieppola, in preparation) (quasars) (BL Lacs)

BH MASS as the fundamental parameter? (work in progress, Tuorla & Metsähovi): BH MASS 2 main observables: L (peak) DOPPLER- (peak) CORRECTED! 2 main jet parameters:  jet speed)  viewing angle) from SEDs from continuum and VLBI monitoring: D +  app   +  (Lähteenmäki and Valtaoja 1999) from spectroscopy and imaging

Arshakian et al 2005

Big BH mass  fast jet

Big BH mass  high absolute luminosity (quasars)

Peak frequency depends also on other parameters than just black hole mass

Fast jets have low peak frequencies

Jet speed does not depend on jet luminosity (quasars)

BH MASS correlates with: jet speed jet luminosity peak frequency Need more parameters! cross-correlations (or not):

LUMINOSITY and PEAK FREQUENCY depend on accretion rate (Wang et al. 2002) PEAK FREQUENCY depends on viewing angle (Saloranta, Nieppola, unpubl.) Wu et al. 2007

BH mass jet speed jet luminosity viewing angle accretion rate