1. The Magnetic Field of an Isolated Neutron Star from X-ray Cyclotron Absorption Lines G.F.Bignami (1,2) P.A.Caraveo (3) A.De Luca (3,4) S.Mereghetti (3) (1) CESR, Toulouse, France (2) Università di Pavia, Pavia, Italy (3) CNR-IASF, Milano, Italy (4) Università di Milano Bicocca, Milano, Italy

2. INS results from Chandra PSR B0656+14 PSR B1055-52 Vela pulsar RX J0720.4-3125

3. INS results from XMM-Newton Puppis A PSR J0030+0451 PSR B1055-52 RX J0720.4-3125

4. Then came 1E1207.4-5209 Discovered by Einstein Close to the center of SNR G296.5+10.0 “High” galactic latitude: b≈10° SNR age: 7 kyears SNR distance: 2 kpc

5. A radio-quiet INS candidate Lack of optical counterpart No radio source BB-like X-ray spectrum Radio-quiet INS?

6. Finally recognized as an INS through its 424 msec periodicity

7. NS nature confirmed by Chandra P~424 ms (Zavlin et al.2000) Estimate of Pdot (0.7-3.1)x10 -14 s s -1 (Pavlov et al.2002) Age Problem: τ PSR >> τ SNR

8. This INS was the first to show features in its spectrum Chandra Sanwal et al, 2002 Same data Hailey & Mori 2002 XMM-Newton Mereghetti et al, 2002

9. The latest EPIC view: 260 ksec The deepest XMM-Newton galactic field

10. Phase-averaged spectroscopy pn data 208,000 photons MOS (1+2) data 151,300 photons

11. 0.7 keV 1.4 keV 2.1 keV 2.8 keV

12. Check for possible miscalibrations Red: 3C273Black: 1E1207.4-5209 0.7 1.4 2.1 (2.8) Au Si

13. Timing Analysis Pulsed fraction ~ 7%

14. Phase-resolved spectroscopy

15. Conclusions IF electron cyclotron: 8 10 10 IF proton 1.6 10 14 Problem with B as derived from timing parameters: Current pdot:(1.4  0.3) 10 -14 s/s implies B= 2-3 10 12 but also implies an age of 5 10 5 years in contrast with the SNR age ( about 10 4 ys)

17. 0.7 keV 1.4 keV 2.1 keV2.8 keV