Research activities of the GAPHE and status of the AHEAD project

1. Research activities of the GAPHE and status of the AHEAD project Gregor Rauw on behalf of the Groupe d’Astrophysique des Hautes Energies (GAPHE)

2. High-energy astrophysics... • Study of the X-ray and γ-ray emission of astrophysical sources. • These radiations are produced by violent processes involving either very high temperatures or relativistic particles and liberating huge amounts of energy. • Sometimes these processes cannot be studied at other wavelengths. • This offers a complementary view of the Universe.

3. The high-energy astrophysics team • GAPHE: Groupe d’AstroPhysique des Hautes Energies • In alphabetic order: Michaël De Becker, Yassine Damerdji (until 11/2008, now AEOS), Eric Gosset, Anthony Hervé, Jean-Christophe Leyder, Natacha Linder (until 12/2008), Laurent Mahy, Jean Manfroid, Thierry Morel, Yaël Nazé, Gregor Rauw, Jean-Pierre Swings, Jean-Marie Vreux • Research topics mainly deal with multi-λ studies of massive stars (O, B and Wolf-Rayet). • Massive stars are rare objects but, due to their extreme properties, they are the engines of many processes in the Universe.

4. Massive stars: some general properties • Spectral types O and Wolf-Rayet (WR) • Massive, hot and luminous objects : • They have short lifetimes and are the progenitors of core-collapse supernovae.

5. Massive stars: some general properties • Powerful stellar winds driven by momentum transfer through scattering in UV resonance lines • huge mass-loss rates: • and large wind velocities:

6. Massive stars: some general properties • Massive stars usually do not form in isolation. They appear in open clusters or OB associations. NGC6231 Pismis 24

7. The research topics • Studies of binary systems: determination of their fundamental properties, studies of wind interactions in binary systems (including the acceleration of relativistic particles, see Michaël De Becker’s talk)...

8. The research topics • Studies of the surroundings of massive stars (circumstellar nebulae, low-mass PMS stars in young open clusters...)

9. The research topics • Studies of the variability of single O, B and Wolf-Rayet stars • Preparation of the GAIA mission (software for the data processing + preparatory observations). • Soon: studies of WR and LBV circumstellar nebulae with Herschel in the far-IR.

10. The tools... • Multi-λ studies require a broad expertise and access to a number of space-borne and ground-based facilities. • Observations in X-rays (XMM-Newton, Chandra...) and soft γ-rays (INTEGRAL): ARC-related activities (AHEAD, Simbol-X, Anthony Hervé’s thesis work,...)

11. The tools... • Complementary observations in the optical (spectroscopy, photometry, interferometry) and radio domain (the latter in collaboration with other teams): ARC related activities (interferometry of massive stars, see Michaël De Becker’s talk)

12. The AHEAD project • AHEAD = Integrated Activities for the High-Energy Astrophysics Domain • Initial goal: foster collaboration among European institutes/groups working in the field of high-energy astrophysics. • Preparation of a proposal for funding under the FP7 “integrated activities” programme under the leadership of the ISDC (Geneva). • G. Rauw appointed as a member of the AHEAD steering committee in January 2008. • Coordinated Belgian proposal involving the CSL, Hololab, GAPHE and ASPECT (UMH) teams submitted in August 2008.

13. The AHEAD project • Joint Research Activities with a proposed participation of the Belgian team: • JRA1 (detectors): further development of the surface plasmon resonance technology for the design of X-ray detectors. • JRA2 (optics): development of ion-beam polishing + metrology tools. • JRA3 (laboratory astrophysics): computation of atomic data for K-shell transitions (ASPECT team) • JRA4 (data software and analysis): development of codes for the modelling of X-ray spectra (see Anthony Hervé’s talk)

14. The AHEAD project • Networking Activities with a proposed participation of the Belgian team: • NA4 (coordination of ground-based observations): take advantage of our multi-wavelength expertise. • NA6 (meetings and conferences): organise scientific meetings related to high-energy astrophysics themes in the tradition of the Liège astrophysical colloquia. • NA7 (outreach activities): take part in the EPO activities to promote the work done within the project.

15. The AHEAD project • Outcome of the Rome meeting (9 & 10 February 2009): • Due to a change in EU policy, it is not granted that the AHEAD FP7 proposal can actually be submitted in 2009. • The contribution from the ASPECT team to JRA3 was selected. • The coordinators of JRA1 and JRA2 identified priorities that do not include the projects proposed by Liège. • JRA4 and NA4 were more or less dropped. • NA6 no longer includes scientific meetings, but will focus on meetings related to activities of the different JRAs. • We are still welcome (but not very enthusiastic) to take care of the outreach activities. • Is it worth remaining in the project????

16. 39th Liège International Astrophysical Colloquium: The multi-wavelength view of Hot, Massive Stars(July 2010 – Liège, Belgium) With the advent of new, high-performance, ground-based and space-borne facilities, the multi-wavelength investigation of massive stars has been boosted over the last decade. It is nowadays possible to study these objects from the radio domain up to the soft gamma-ray energies. The aim of this 4-days meeting, which will be organized in the well-known series of Liège astrophysical colloquia, is to bring astrophysicists from different wavelength ranges together to discuss how this multi-wavelength approach has revolutionized our view of massive stars and their surroundings in our Galaxy and beyond. Contacts: Michaël De Becker, Eric Gosset, Yaël Nazé & Gregor Rauw, liac2010@misc.ulg.ac.be