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CHaracterizing Accretion-ejection in Outbursting compact binary Systems – CHAOS

CHaracterizing Accretion-ejection in Outbursting compact binary Systems

Unveiling the physical conditions around black holes is one of the major astrophysical challenges of the 21st century. Indeed we are still at the dawn of black hole astrophysics and very little about these objects is understood: improving our knowledge of the physical processes occuring in black hole environment is at the heart of this CHAOS project.

Challenges and objectives

The proposed CHAOS project is a collaboration of leading competences with state- of-the-art skills on accretion-ejection processes, radiative transfer numerical simulations and multi-wavelength observations, in order to lead a decisive advance in our understanding of accretion-ejection processes in compact objects. Building on the rich expertise we developed in our past ANR project Astro2flow (2006-2009), we propose to carry on developing our global holistic theoretical framework with now the additional ambition of a direct comparison with the most up-to- date multi-wavelength observations.

Our aim is to develop new numerical tools able to produce, within the dynamically consistent accretion-ejection framework proposed by the IPAG group, broadband SEDs directly comparable to real data. New tools, developed with the IRAP group, will be used to produce realistic SEDs and constrain the required changes in the model parameter to reproduce the observed HID. We will be in a position to investigate the predictions of different coronal geometry (like ADAF or JED) and parameters. We will also be able to make robust predictions regarding the polarization of the X-ray emission of BHBs

Most of the developments proposed in this project require essential inputs that can only be provided from observations: spectral shapes, timing properties, multi-wavelength behavior etc... The AIM group will thus construct the most generic diagram of black holes properties along the course of their outbursts. It will characterize the evolution of the accretion-ejection coupling with time in order to provide the most important set of constraints for models to date. These are informations of crucial importance as they will allow falsifying the theoretical framework and are unaccessible for non-observer experts.

The project started officially on January 1, 2013. The kick-off meeting took place the 1st of February 2013 in Grenoble. A first important step for the project, which has been decided during this meeting, was the research of postdoc candidates (one for each node of the project, i.e. three in total) and the development of a website.

The postdoc offer was advertized via mailing lists, on the project website, but also on the site of the American Astronomical Society. Forty-one candidates have answered before its closure in late April. The postdoc selection is now finished and 3 postdocs should begin in fall of 2013 in each of the institutes.

The next meeting of the consortium should also take place in fall in Toulouse.

This first period of six months has already led to the startup of collaborative work IPAG-IRAP. The different members of the project have also participated in various conferences to show first new results.

Works initiated by the postdocs become fruitful with submission / publication of articles of high quality on hot topics largely discussed in the literature (wind and jets in XrB).

The project is progressing very positively and open new windows that will become more and more important withthe future launch of Astro-H and the development of Radio telescopes like LOFAR or SKA

Only multipartner publications and communications are listed below

1. Drappeau et al., 2015a, MNRAS, 447, 3832
2. Rozanska et al., 2015, A&A, 580, 77
3. Susmita et al. 2015, A&A, soumis
4. Drappeau et al. 2015b, A&A, en pre´paration
5. Clavel et al. 2015, A&A en pre´paration
6. Petrucci, Cabanac, Corbel et al., 2014, A&A, 564, A37
7. Corbel et al., 2013, MNRAS Letters, 431, L107

1. Chakravorty et al., “Magneto-centrifugal winds from accretion discs around black hole binaries”. Confe´rence “The Extremes of Black Hole Accretion », Juin 2015, Madrid, Espagne
2. Clavel et al., « « Broad-band analysis of the spectral evolution of GX 339-4”. Confe´rence “The Extremes of Black Hole Accretion », Juin 2015, Madrid, Espagne
3. Petrucci et al., « Magneto-centrifugal outflows from accretion discs in black hole X-ray binaries”. Confe´rence «From the Dolomites to the event horizon: sledging down the black hole potential well», Juillet 2015, Sesto, Italie
4. Drappeau, « Does accretion flow variability drives internal shocks in the compact jet of the black hole binary GX 339-4? », 40th COSPAR, Moscou, Russie, 2014
5. Petrucci, Cabanac, Corbel et al., «Suzaku Observations of GX 339-4 during its soft-to-hard state transition». Confe´rence « From the Dolomites to the event horizon: sledging down the black hole potential well», Juillet 2013, Sesto, Italie
6. Petrucci, Cabanac, Corbel et al «Suzaku monitoring of the return back to the hard state of GX 339-4», Confe´rence « Spectral/timing properties of accreting objects: from X-ray binaries to AGN », April 2013, ESAC, Madrid, Espagne

Unveiling the physical conditions around black holes is one of the major astrophysical challenges of the 21st century. Indeed we are still at the dawn of black hole astrophysics and very little about these objects is understood: what are the geometry, dynamics and energetics of the accretion flow onto the black hole? How can accretion of material onto the hole be simultaneously intimately related to violent relativistic ejecta and/or powerful self-confined persistent jets? What are the processes at the origin of the fascinating hysteresis cycles observed in some X ray binaries? These unsolved and puzzling issues are at the heart of this ANR2012-CHAOS proposal. It is focused on Black-Hole X-ray Binaries (hereafter BHB ) as they are actually the best candidates for such studies, their complex multi-wavelength behaviour occurring on timescales that can be handled very well (i.e. minutes to months).
This project is the natural development of a precedent theoretical and numerical ANR “Jeunes Chercheurs” with now the additional ambition of getting closer to observations, in spite of the major criticism made upon our ANR 2011 submission. Indeed, collaborating with experts in multi-wavelength observations is crucial for the present project for two reasons. First, a precise knowledge of the global observational characteristics of microquasars is needed to drive the theoretical and numerical developments. Such knowledge is unaccessible for non-experts. Second, a direct comparison with observations is essential to validate/invalidate our theoretical framework.
Within the present project, each field of expertise (dynamics, radiation, observation) will first improve existing tools and/or develop new ones: (i) time dependent accretion disc models, where ejection is consistently taken into account, will be designed; (ii) multi-zones, radiative and kinetic simulation codes will be developed and (iii) the most up-to-date broad band (from radio to gamma-rays) database of BHB properties will be set-up, coupled with opening of new observing windows.
Then, these tools will be brought together in an unprecedented effort within the community. Thus, besides the development of new simulation tools that can be applied to many different astrophysical problems, we will be able to produce synthetic Spectral Energy Distribution for these sources, analyse and predict their timing evolution, and directly compare with the most complete and stringent set of multi-wavelength data that we will produce.
By gathering together well-known experts in observation, radiation processes and theory of accretion-ejection processes around compact objects, this project aims at strengthening the French BHB community. It will not only strengthen our leadership in the field but will also significantly enhance our knowledge on the accretion-ejection processes in BHB and, more generally, in all types of compact accretors.

Project coordination

Pierre-Olivier PETRUCCI (Institut de Planetologie et d'Astrophysique de Grenoble) –

The author of this summary is the project coordinator, who is responsible for the content of this summary. The ANR declines any responsibility as for its contents.


IPAG Institut de Planetologie et d'Astrophysique de Grenoble
CEA/Irfu (AIM) Commissariat à l’Energie atomique et aux énergies alternatives
IRAP Institut de Recherche en Astrophysique et Planetologie

Help of the ANR 487,187 euros
Beginning and duration of the scientific project: December 2012 - 48 Months

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