1. Michael Kramer Chiang Mai- 28 June 2005 Title High precision radio pulsar timing with the EPTA Gemma Janssen, UvA

2. High precision radio pulsar timing with the EPTA Outline: radio pulsars high precision radio pulsar timing the European Pulsar Timing Array high precision radio pulsar timing with the EPTA

3. Radio pulsars Radio pulsar: highly magnetized,rapidly rotating neutron star Beam of radiation detectable as pulses P: 1.4ms - 12s ~1800 known Pulsar science: Surveys Single pulses Emission mechanism Interior/equation of state Timing

4. High precision radio pulsar timing Radio pulsar timing Measure arrival times of pulses very precisely As accurate as best clocks on Earth ~ ns accuracy Compare with model to study - pulsar parameters - binary parameters - ISM Pulsars as tools: - testing theories of gravity (relativistic binaries) - detecting nHz-gravitational waves (pulsar timing array)

5. Pulsar timing arrays Pulsar timing array: use pulsars as endpoints of a huge GW detector Times of arrival of pulses of different pulsars will be correlated! Needed: 20 pulsars, 100 ns ToAs, 5 years of timing David Champion Pulsar timing array: -sensitive to GWs with nHz frequencies -complementaty to other detectors like LIGO(100Hz) or LISA(mHz) -3 groups: PPTA, EPTA, NanoGRAV Rick Jenet, George Hobbs

6. Michael Kramer Chiang Mai- 28 June 2005 EPTA partners The EPTA: partners University of Manchester, JBO, UK ASTRON, NL Max-Planck Insitut fur Radioastronomie, GER INAF Osservatorio Astonomico di Cagliari, IT Nancay Observatory, FR

7. The EPTA: people Jodrell Bank/University of Manchester, UK Michael Kramer, Ben Stappers, Andrew Lyne, Tim Ikin, Christine Jordan, Mark Purver, Ralph Eatough Astron/University of Amsterdam/University of Leiden, NL Gemma Janssen, Ramesh Karuppusamy, Yuri Levin, Rutger van Haasteren Effelsberg/MPIfR, GER Axel Jessner, Kosmas Lazarides Nancay/Orleans, FR Ismael Cognard, Gilles Theureau, Gregory Desvignes, Alessandro Corongiu, Rob Ferdman Sardinia, IT Andrea Possenti, Marta Burgay Regular meetings (2/yr) and teleconferences (1/month)

8. The EPTA: aims & goals Pulsar Timing Array: Detection of nano-Hz gravitational waves Stochastic GW background Needed: 20 pulsars, 100 ns, 5 years Multi-Telescope Timing Advantages: more data, more frequencies, consistency checks between observatories Coordinated source lists and observing sessions Common data handling - software & hardware Share data for other projects Each observatory has students to make optimal use of all data available - more science, more output

9. The EPTA: observatories Optimal use of observing facilities: in addition to regular timing, planning to have simultaneous sessions at the same and different frequencies.

10. Example of completed project: J1518+4904 Green Bank WSRT Nancay Jodrell Bank Effelsberg Janssen et al. (submitted to A&A) PSR J1518+4904: 40.6 ms pulsar in an 8.6 day orbit around another NS relativistic effects needed to describe the orbit! EPTA collaboration: using all available data -> limits on the masses of the system -> constraints on evolution All combined

11. High precision radio pulsar timing with the EPTA Conclusions: EPTA is now making full use of its possibilities Advantages of collaboration already visible: publications Software and hardware for PTA purposes developed and tested in near future Hopefully the first to directly detect GWs! -Stay Tuned!

12. High precision radio pulsar timing with the EPTA

13. Example of completed project: J1518+4904 Shapiro constraint Xdot constraint Total mass = 2.7183(7) M sun Janssen et al. (submitted to A&A)