1. Observations and physics of accreting neutron star ISSI, Bern, Switzerland December 3-7, 2007

2. Participants Juri Poutanen (University of Oulu, Finland; Team Leader) Andrei Beloborodov (Columbia University, USA) Chris Done (University of Durham, UK) Maurizio Falanga (CEA-Saclay, Service d' Astrophysique, France) Marat Gilfanov (Max Planck Institute f\"ur Astrophysik, Garching, Germany) Tatiana Larchenkova (Astro Space Center, Moscow, Russia) Alexander Lutovinov (Space Research Institute, Moscow, Russia) Sergei Molkov (Space Research Institute, Moscow, Russia) Mike Revnivtsev (MPA, Garching, Germany) Valery Suleimanov (University of Tubingen, Germany) Andrzej Zdziarski (N. Copernicus Astronomical Center, Warsaw, Poland) Young scientists Marja Annala (University of Oulu, Finland) Kris Beckwith (Univ. of Virginia, USA) Askar Ibragimov (University of Oulu, Finland) Sergey Tsygankov (Space Research Institute, Moscow, Russia)

3. Program for the meeting Juri Poutanen: Introduction Alexander Lutovinov: About a possibility to observe the effect Shapiro for pulsars in globular clusters Sergey Tsygankov: Observational features of X-ray pulsars emission revealed with INTEGRAL and RXTE observatories Marja Annala: X-ray pulsars Maurizio Falanga: X-ray accreting millisecond pulsars in outbursts Valery Suleimanov: Importance of Compton scattering on radiation spectra of accretion columns in millisecond pulsars and intermediate polars Askar Ibragimov: SAX J1808 in 2002

4. Topics to be covered X-ray bursts & nuclear-powered millisecond pulsars (NMSPs) Accreting millisecond pulsars (AMSPs) X-ray pulsars Theory of accretion columns on a weakly magnetized neutron stars Theory of boundary layers on neutron stars © Michael Kramer

5. Nuclear-powered millisecond pulsars

6. SourceOrbital period [h] spin [Hz] 4U 1728-34?363 4U 1636-53?581 KS 1731-260?524 at Gal. center?589 Aql X-119.0549 4U 1702-429?330 MXB 1658-2987.1567 4U 1916-0530.83270 4U 1608-52?619 SAX J1750.8-2980?601 A 1744-3611.5530 IGR J1719.1-2821?294 SAX J1808.4-36582.0401 XTE J1814-3384.275314 XTE J1739-285?1122 ? EXO 0748-6763.8245 Nuclear-powered millisecond pulsars

7. Time (s) 4U 1728-34 Strohmayer et al (1996) ; Strohmayer, Markwardt (1999) Time (s) Millisecond oscillations during X-ray bursts

8. Time (s) simulations by A. Spitkovsky Millisecond oscillations during X-ray bursts

9. Piro & Bildsten 2006 Observed A(E) is consistent with the black body Pulse fraction in X-ray bursts

10. RMS in X-ray bursts from AMSP XTE J1814-338

11. Theory of the accretion column for X-ray bursters

12. Accretion-powered millisecond pulsars Romanova et al. (2004)

13. Power density spectrum. From Wijnands & van der Klis (1998). April 1998 outburst. From Gilfanov et al. (1998). SAX J1808.4-3658: the first accreting millisecond pulsar

14. SAX J1808.4-3658 XTE J1751-305 XTE J1807-294 Outbursts profiles

15. 1. Wijnands & van der Klis 1998, Chakrabarty & Morgan 1998; 2. Markwardt et al. 2002 3. Remillard et al. 2002; Galloway et al. 2002; 4. Markwardt et al. 2003 5. Markwardt et al. 2003; 6. Markwardt, Swank, Strohmayer, Dec 3, 2004 7. Morgan, Kaaret, Vanderspek, June 17, 2005; Kaaret et al. 2005; 8. Markwardt et al. June 14, 2007 Source P orb min n spin Hz f X / M Sun M c,min / M Sun 1. SAX J1808.4-3658 1204013.779 x 10 -5 0.05 2. XTE J1751-305424351.278 x 10 -6 0.013 3. XTE J0929-314441852.9 x 10 -7 0.01 4. XTE J1807-294401901.49 x 10 -7 0.007 5. XTE J1814-3382573142.016 x 10 -3 0.16 6. IGR J00291+59341485992.813 x 10 -5 0.038 7. HETE J1900.1-2455833772.00 x 10 -6 0.016 8. SWIFT J1756.9-2508551821.66 x 10 -7 0.007 Accretion-powered millisecond pulsars

16. XTE J1751-305 IGR J00291+5934 XTE J1807-294 disc spot kT bb =0.66keV kT e = 60 keV t T = 0.9 Spectral energy distribution

17. kT disc =0.43 keV kT seed = 0.75 keV A seed = 26 km 2 kT e = 37 keV t T = 1.7 disc Solid – persistent emission; histogram - X-ray bursts. Strohmayer et al. (2003). Kirsch et al. (2003) XTE J1751-305 XTE J1814-338XTE J1807-294 Gierlinski & Poutanen 2003 Pulse profiles

18. Pulsar geometry

19. In ms pulsars, rotational velocities are high (b =v/c ~0.1), the Doppler effect plays an important role Doppler effect

20. Phase slow pulsar (dashes) fast pulsar, =401 Hz F sc,E (fast) ~ d 3+ G F sc,E (slow) F bb (fast) = F bb (slow) x d 5 Poutanen & Gierliński (2003) Doppler boosting I obs =d 4 I em Aberration cos a obs =  d cos a e Light curves of MSP d =1/ g (1 - b cos q ) – Doppler factor g =1/  1-b 2 – Lorentz factor

21. Mass/ M  Poutanen & Gierlinski (2003) Radius, km Constraints on the equation of state Complications: Shape of the star Shape of the spot Influence of the accretion disk

22. Count rate Phase Pulses from SAX J1808

23. Bildsten et al. (1997) X-ray pulsars Obtaining neutron star parameters from the X-ray pulse profiles A0535+262

24. Boundary layers and quasi- periodic oscillations Sco X-1

25. 4U 1608-52

26. From Gilfanov, Revnivtsev and Molkov (2003). Frequency-resolved spectra of QPOs and the boundary layer

27. Matter has a significant latitude velocity component, spreading above the neutron star surface and decelerating due to friction with the neutron star surface (as the wind above the sea). From Inogamov and Sunyaev (1999) BL as a spreading layer

28. SL model Atoll & Z sources GX 340+0 Spectra of neutron star BL

29. Constraints on EOS of NS From Suleimanov and Poutanen (2006) How QPOs are produced ?

30. Analysis and theoretical modeling of the data on X-ray pulsars (Lutovinov, Tsygankov, Annala, Ibragimov) Modeling the accretion column (Suleimanov, Poutanen) Theoretical modeling the light curves from millisecond pulsars (Poutanen, Larchenkova, Falanga) Impact of the accretion disk on the light curves (Ibragimov, Annala, Poutanen) 2D and optically thin boundary layer models (Poutanen, Suleimanov) Proposed projects