1

IAU symp. 238 (Aug. 2006)IAU symp. 238 (Aug. 2006)

Synchrotron Outbursts

in Galactic and Extra-galactic Jets,

Any Difference ?

Marc TürlerINTEGRAL Science Data Centre

Geneva Observatory

Elina LindforsTuorla Observatory, Finland

2

Model & MethodologyModel & Methodology

● Aim. Derive the properties of synchrotron outbursts in astrophysical jets

● Method. Fit a series of model outbursts to the lightcurves at different frequencies

● Outburst model. Generalization of the shock-in-jet model of Marscher & Gear (1985) with modifications of Björnsson & Aslaksen (2000)

3

From Spectra to LightcurvesFrom Spectra to Lightcurves

Evolution of the spectrum from high to low frequencies

Longer outbursts at lower frequencies

4

Simulated jet imagesSimulated jet images

● Outbursts differ from each other by their:● onset time● normalization of

the electron energy spectrum

● magnetic field strength

● Doppler factor of the shock

● Jet images can be simulated from model outbursts assuming a constant apparent speed

5

3C 273 3C 273 (1980-2000)(1980-2000)

Ref.: Türler et al. (1999, 2000)

6

3C 279 3C 279 (1990-2000)(1990-2000)

Ref.: Lindfors et al. (2005, 2006)

7

Cyg X-3 Cyg X-3 (Feb-Mar 1994)(Feb-Mar 1994)

Ref.: Lindfors et al. (in prep.)

8

GRS 1915+105 GRS 1915+105 (15 May 1997)(15 May 1997)

Ref.: Türler et al. (2004)

9

Derived jet propertiesDerived jet properties

● Similarities among all sources● Infrared outbursts are higher and last longer than

expected by the standard adiabatic shock model of Marscher & Gear (1985) [except for 3C 273 ?].

● True outbursts have also a slower rise and a faster decay than expected. These differences are reduced by the modifications to the Compton stage by Björnsson & Aslaksen (2000) and the choice of a shock viewed sideways for the 2 quasars.

● Differences between galactic & extra-galactic jets● The electron energy index s tends to be smaller for

the microquasars (1.7-1.8) than for the quasars 2.1 (3C 279) and 2.5 (3C 273). NB: Giant outbursts in GRS 1915+105 have s = 2.2 (spectral index = 0.6)

● The jet of the galactic sources are apparently widening with distance (like a trumpet), while quasars tend to have rather conical jets.

10

ConclusionConclusion

● We showed that infrared-to-radio variability of quasars and microquasars can be well reproduced by a shock-in-jet model, suggesting that:● the basic physics of relativistic jets are independent of

the mass of the black hole over height orders of magnitude

● outbursts in the lightcurves are associated to moving structures in the inner jet (e.g. the unresolved AU-scale “baby” jet of GRS 1915+105)

● these moving stuctures are likely propagating shock waves rather than ejected plasma clouds

● Future studies shall further constrain the physical properties of the jets by modelling also the associated Compton (SSC) emission in the X-rays