Gravitational Waves & Related Studies (N6-WG3)

Transcription

1 Gravitational Waves & Related Studies (N6-WG3) Kostas Kokkotas Department of Physics Aristotle University of Thessaloniki Greece

2 Working Groups and financial Repartition: Overall annual budget ~100k Coordinator: Günter Sigl WG1: Neutrinoless Double Beta Decay and Related Studies: 30% Coordinator: Amand Fäßler. WG2: Dark Matter and Related Studies: 30% Coordinator: Leszek Roszkowski WG3: Gravitational Waves and Related Studies: 25% Coordinator: Kostas Kokkotas. Common Activities: 15% Of these roughly 1/3 for training sessions, 1/3 for working group activities/visitor programme, and 1/3 for conferences/annual meetings. These three points also represent roughly the different tasks.

3 WG3: Gravitational Waves and Related Studies Objectives: Coordinate current and new programs of analytical and numerical studies of potential sources of gravitational radiation, particularly those involving neutron stars and black holes. Work out theoretical templates to be used by experimental teams for better signal/noise separation in upcoming detectors of gravitational waves. Develop links with the teams involved in the related activity in ILIAS (N5). Support further integration of the theory groups involved in gravitational wave research with mother European centers of excellence.

4 Physics examples WG3 Gravitational Wave signatures of interesting events are usually deeply buried in noise. To extract them, one needs detailed theoretical predictions for the expected temporal structure of expected events, so-called TEMPLATES. These can then be extracted from data by computing overlap functions. Spectral Methods: Transforming non-linear Einstein equations using various base functions. WHISKY: Solving hydro on curved space time; was developed by EU network on sources of gravitational waves.

5 WG3: Gravitational Waves and Related Studies Meetings supported Tuebingen (Hydro-Workshop) (22-23/6/05) (travel support of 3 young scientists) Potsdam (Whisky Retreat) (8-10/6/05) (travel support of 6 young scientists) COSMO-05 (28/8-1/9/05) (travel support of 1-2 scientists) Einsteinwoche, International Conference on General Relativity, Jena (26-29/9/05) (support only to young European scientists) Meetings to be supported School on Spectral Methods: Application to General Relativity and Field Theory (14-18/11/2005),Centre International d'ateliers Scientifiques, Meudon Observatory,

6 WG3: Gravitational Waves and Related Studies Training sessions Training sessions should be planned in collaboration with the experimental networking activity N5 on gravitational waves, but not before The new generation of gravitational wave astronomers should have expertise on the theory of the sources, the data analysis techniques and the way that the various types of detectors operate. Experts meetings An annual experts meeting of theorists, experimentalists and key astrophysicists to create a white paper on the event rates, efficiency of the various GW sources and the designing of present and future gravitational wave detectors.

7 WG3: Gravitational Waves and Related Studies Short visits: Funding for about 10 short visits is foreseen. January-October 2005 Portsmouth -> Thessaloniki (M.Bruni, A.Passamonti) Munich -> Thessaloniki (H.Dimmelmeir) Athens -> Paris (Th. Apostolatos) SISSA -> AEI-Postdam (Enrico Barausso) PLANNED (November 2005 March 2006) Palma -> Jena Portsmouth -> Rome Alicante -> Rome Valencia -> Paris

8 GW sources in ground-based detectors BH and NS Binaries Supernovae, BH/NS formation Spinning neutron stars in X-ray binaries Instabilities of Young Neutron Stars

9 GW sources Binary systems Generation of the waveform part that is missing for BH/BH, BH/NS and NS/NS coalescence (Numerical Relativity). Event rates (Astrophysics) events/year LIGO- Virgo Advanced detectors NS/NS ~0.05 ~ BH/NS ~0.02 ~80 BH/BH ~0.8 ~2000 Total missing

10 GW sources Collapse & Instabilities The energy emitted in Gravitational Waves during: Core collapse Subsequent Oscillations And the onset of Dynamical and Secular Instabilities Critically depend on the rotation (uniform or differential) of the core! In normal massive stars, differential rotation in the core produces a toroidal magnetic fields through a dynamo effect. The magnetic torque slows down the core, by transferring away angular momentum. This leads to slowly rotating neutron stars at birth (~10-15ms). BUT: Stellar evolution proceeds much faster for higher masses - there is less time to slow down the core (e.g. 25M -> 6.3ms, 35M -> 3ms). Example: if a binary companion strips the outer envelope of a massive star before core collapse, a rapidly rotating NS forms.

11 GW sources - LMXBs LMXBs can be weak but long lasting sources of GWs ( Hz) R-mode instability Crust deformations The existence of this source critically depends on the details of the NS structure (crust, huperon or quark core etc).