Marion Cadolle Bel

ESAC Research Fellow (Post-doc) since 2006 November 1st.

Main team: INTEGRAL (but also XMM-Newton I hope !)

I started my PhD in October 2003 at SAp (Service d'Astrophysique)
of CEA-Saclay (France) under the supervision of A. Goldwurm.  My
research work has been dedicated to the study of various X-ray
binary systems harboring accreting stellar mass black holes (or
candidates) associated in X-ray binary systems, mainly through the
spectral and time variability properties of the high energy 3 keV-1
MeV emission thanks to the XMM-Newton, Rossi-XTE and INTEGRAL data.
This work was sometimes completed by observations  performed in
other wavelength (radio, near-infrared and optical). 

Firstly, my work included understanding the standard data reduction
analysis based on coded-masked techniques in addition  to the
developpement of specific tools for my own analysis and for the
improvement of the usual software for a larger scientific 
community. My original main scientific interests are the study of
black hole X-ray binary systems like the persistent black hole
source Cygnus X-1, which  surprised us by an excess detected at
high energies;  two new transient sources, XTE J1720-318 located in
the galactic bulge and SWIFT J1753.5-0127, probably situated in the
halo. These two latter sources provided interesting  information,
the first one about spectral transitions and the second one which
did not seem to follow the usual radio/X-ray luminosity
correlation. I have also worked on other microquasars like H
1743-322 or the three (almost) persistent sources with superluminal
jets, 1E 1740.7-2942, GRS 1758-258 and GRS 1915+105.  I have
studied and  analyzed for each source spectral parameter evolutions
and their links with each other during state transitions to discuss
the presence and location/geometry of two different  X/gamma-ray
emitting media. I have discussed and compared my results in the
framework of theoretical models to explain the observations and I
have derived some caveats to the general (well understood) physical
processes which occur in X-ray binary systems. 

As a second more theoretical topic, while establishing an order
-which seems to be cyclic- for the different variability classes of
GRS 1915+105 observed during ten years with mostly Rossi-XTE, 
I have proposed an interpretation for such behavior which is 
compatible with the theoretical predictions of the
Accretion-Ejection Instability model of Tagger et al. (1999). This
work is still preliminary but it has lead to promising results. 
I am involved in several multi-wavelength programs (to study the
connection between disc, hot medium and jets) and the PI of 
Rossi-XTE and INTEGRAL observations of new X-ray novae. Also, 
specific proposals in which I collaborate are dedicated to the
study of GRS 1915+105 to continue the theoretical work  started
during my Thesis to understand what could drive, in addition to the
accretion rate, the spectral state changes.  A recent flare  (1
month ago) of Cygnus X-1 is under study  as well as a new  X-ray
source (paper recently submitted here).

My plans at ESAC are to extend this systematic analysis done to
neutron stars and AGN to take advantage of the specialists working
here, as well as to develop timing analysis above 30 keV which is
necessary, coupled to the spectral behaviors, to really understand
the physics of these systems. On the one side, Erik Kuulkers
monitors about ~100 sources every INTEGRAL orbit (~3 days) for 3.5
hours so there are a lot of things to be done with these beautiful
data. Also there are lots of data to be analyzed in the XMM-Newton
archive and the search for (relativistic or not) Fe lines is a very
interesting subject I would like to develop more, so I look foward
to join and to work with ESAC specialists on those topics ! Besides
I would be happy to be involved in any other areas this audience
may propose, but the time is too short to develop this here...