Download The energy distribution of electrons in radio jets

The energy distribution of electrons
in radio jets
Nick Kylafis
University of Crete
(with Alexandros Tsouros)
Ierapetra, 12 June 2017
Introduction

This conference is mainly on AGN. Thus, I feel that
an introduction on stellar-mass X-ray transients is
appropriate.

X-ray transients exhibit during an outburst a
characteristic “q”-shaped curve, sometimes called a
hysteresis curve (next slide).

I will use GX 339-4 as the prototype.
GX 339-4
Similar behavior for BH, NS, WD!!!
Kylafis & Belloni (2015)

We have offered a physical explanation of the
observed phenomenology of the q-curve.

The outburst of a black-hole X-ray transient lasts for
~ 1 year.

If you miss an outburst, no problem, you can catch
the next one in ~ a year.

The only parameter that we use is the accretion rate.

The appearance of the accretion flow at different
accretion rates is as follows:
In quiescence, we are at a point well
below point A in the diagram
We proceed to point B
We turn left at point B
Now we are at point C going to D
Counter-clock-wise traversal.
Criss-crossing of the jet line.
An unexpected result:
Tsouros & Kylafis (2017)

Let me ask a rhetoric question: what is the energy
distribution of the electrons in the jet?

Answer: power law, of course! We know this since 1979
(Blandford & Koenigl 1979; but see also Jones & Hardee 1979).

However, now we know that the jet originates in the hot inner
flow (ADAF-like).

Thus, at least at the bottom of the jet, and possibly higher up,
the electrons obey a thermal distribution.

Question: what radio spectrum does a thermal jet produce?

Answer: the same as for a power-law distribution of electrons!!!
Thermal and power-law distributions
Emissivity of the various distributions
at frequency 10^11 Hz
We have found that:

Both distributions give flat to slightly inverted radio spectra.

For a power-law distribution, 0 < alpha < 0.2.

For a thermal distribution, 0 < alpha < 0.5.

As the source MAXI J1836-194 (Russell T.D. et al. 2014)
traverses its q-shaped curve, the radio spectral index alpha flipflops between 0.2 and 0.5.

It is too early to draw any conclusion for the energy distribution
of the electrons, but it is intriguing.
Summary & conclusions

Work on jets with a thermal distribution of electrons (Falcke &
Markoff 2000, for Sgr A*; Pe’er & Casella 2009).

Largely, however, our community has ignored the possibility of a
thermal distribution of electrons in jets.

This must change! Now we know more than in 1979!!!

In addition, since most of the electrons in a jet have low gamma,
the gyro-synchrotron formalism must be used.

There is no reason in LMXBs to invoke an artificial “corona”. The
jet can be this corona. In LMXBs, the jet is not just fireworks.
It probably plays a central role in the observed phenomena. But
this is the subject of another talk (Ile de Porquerolles, 25 Sept.).
THANKS