Hydrodynamics of Small- Scale Jets: Observational aspects

Hydrodynamics of Small-Scale Jets: Observational

aspectsEsko Valtaoja

Tuorla Observatory, University of Turku, FinlandMetsähovi Radio Observatory, Helsinki University of Technology

TUORLA-METSÄHOVI AGN GROUP: Talvikki Hovatta, ElinaLindfors, Anne Lähteenmäki, Elina Nieppola, Pia-Maria Saloranta,Tuomas Savolainen, Ilona Torniainen, Merja Tornikoski, Kaj Wiik

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

NEED: basic GLOBAL and LOCALparameters from observations asinputs to theory / simulations...... which, in turn, should givepredictions which observers can test

GLOBAL: e.g., BH mass vs. jet speed?LOCAL: e.g., magnetic field strength along the jet?

Aloy et al. 2003 Gómez et al. 2001

Qualitativeagreement-but need alsoquantitative:global andlocal parametersvs. simulatedparameters

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

LOCALdata!

...gives us local information along and transverse to the jet(which you cannot get from single and/or low frequency VLBI)

magnetic fieldvs. distance

electron energy densityvs. distance

+ jet/mf structures,instabilities, nonrelativisticplasma, speeds, IC fluxes...

SAVE VLBA BY USING ITS FULL POWER!

Mar

sch

er &

Gea

r sh

ock

-in

-jet

mod

el (

1985

)

(picturecourtesy ofMarc Türler)

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

LOCALdata!

Lindfors et al. 2005, 2006: shock and jet component spectra(+ SSC spectra) from mf continuum monitoring and 3-D fitsimultaneously 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- T0(mm) < T0(VLBI)- T0(mm), T0(VLBI) < T0(gamma)

need more accurate timings foreach: physics of the radio core!

Savolainen et al 2002

Jorstad et al.2001

Lähteenmäki & Valtaoja 2003

radiogamma

Average delay from TFD/VLBI zero epoch to strong gammaflares ~ 2 months = parsecs, so External Compton fails...

...but the only alternative,synchrotron-self-Comptonalso fails (Lindfors et al.2005, 2006)

(Heh.)

EC photonsare here!

radiocore

Blazar sequence?(Ghisellini et al. 1998)

One-parameter(total power) family:

Most powerful sourceshave lowest synchrotronpeak 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 2007 + others)

Doppler boosting vs. peak frequency(PMS + Nieppola, QSOs and BLOs)

Nu peak (z, D -corrected)

11 12 13 14 15 16

D(v

ar)

0

5

10

15

20

25

30

Wu et al 2007:

D(var) = [TB(var)/TB(lim)]1/3 (Lähteenmäki & Valtaoja 1999)

Correcting the luminositiesfor Doppler boosting totallydestroys the last traces ofthe ”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 VLBImonitoring: D + app + (Lähteenmäki and Valtaoja 1999)

from spectroscopyand 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

MA

SS

corr

elat

es w

ith

:

jet speed

jet luminosity

peak frequency

Nee

d m

ore

para

met

ers!

cros

s-co

rrel

atio

ns

(or

not

):

LUMINOSITY and PEAK FREQUENCYdepend on accretion rate (Wang et al. 2002)

PEAK FREQUENCYdepends on viewing angle(Saloranta, Nieppola, unpubl.)

Wu et al. 2007

BH mass

jet speed

jet luminosity viewing angle

accretionrate