2. X-ray Observations of Solitary Neutron Stars an adventure to understand the structure and evolution of neutron stars 國立清華大學物理系與天文所 張祥光

3. * The concept of neutron stars * The many faces of neutron stars * An evolution story? * Looking closer to a neutron star * Coming next…

4. (Baym & Pethick 1979, ARA&A 17, 415)

5. (Scientific American, Feb. 2003)

6. The many faces of neutron stars * radio pulsars. X-ray and  –ray emission from pulsars.. * Anomalous X-ray Pulsars (AXPs).. * Soft Gamma Repeaters (SGRs).. * other radio-quiet neutron stars. some with possible  –ray emission (unidentified EGRET sources) some associated with SNRs some truly solitary

7. o o o o o o o o o o o o o o o o O  -ray pulsar O other RQNS o

8. * For radio-quiet neutron stars, to find periodicity and its time derivatives in X-ray data is a crucial issue in understanding their various properties. * There are different methods to perform periodicity search, e.g., FFT, epoch folding, Z m 2 -test, H-test, etc. * The many faces of neutron stars may represent different evolution stages of a neutron star. The scenario is made more complicated by initial conditions and geometrical factors.

9. Radio image of CTA 1 with ROSAT/PSPC contours (Slane et al., 2004, ApJ 601, 1045) Using ASCA and XMM data, a probable period of RX J0007.0+7302 at 127.5 ms was found. (Lin & Chang, 2004, Ap&SS, in press)

10. (Chang, Lin, Chiu & Liang, 2004, Ap&SS, submitted) X-ray pulsations from a compact clump in RCW 89 ROSAT/HRI image of RCW 89 (Brazier & Becker, 1997, MNRAS 284, 335)

11. (Possenti et al., 1996, A&A 313, 565) (Finley et al., 1992, ApJ 394, L21) Looking closer to a neutron star… For X-ray thermal emission from neutron stars, the blackbody approximation is not good enough.

12. high-energy excess and limb darkening (Wu 2003, master thesis, NTHU) BeppoSAX spectrum of 1RXS J170849.0-400910 (Chang, 2004, CJP 42, 135)

13. Spectral analysis of surface thermal emission from neutron stars may help to determine various properties at the surface, such as temperature, magnetic field strength, composition, mass-to-radius ratio, viewing geometry, etc. Looking closer to a neutron star…

14. The Vela pulsar’s Chandra spectrum (Pavlov et al., 2001, ApJ 552, L129)

15. XMM spectrum of 1E1207.4-5209 PN (top) & MOS (bottom) spectra fitted with two blackbodies (kT = 0.211 keV, 0.40 keV) (Bignami et al., 2003, Nature 423, 725)

16. Modelling the spectrum of surface thermal emission from neutron stars 2 Part I: the emergent spectrum from a local spot at the surface

17. the thermal bremsstrahlung cross section in a magnetized plasma

18. Modelling the spectrum of surface thermal emission from neutron stars Part II: the composite spectrum from the whole stellar surface * photon path bending * temperature distribution over the surface * features may be smeared out We are constructing a set of codes, which in particular allows arbitrary magnetic field directions, contribution of thermal conduction, and a more proper treatment of line-broadening and polarization propagation.

19. * Modelling realistic spectra Coming next… Thank You! * Measuring the polarization * Are ‘neutron stars’ really neutron stars? * More observations: temporal and spectral analysis * Understanding emission mechanisms in neutron star magnetospheres and possible evolutionary scenarios * Measuring neutron star oscillations (!!!)

23. (Thompson et al. 1999, ApJ 516, 297) return

24. AXPs Properties of AXPs spin periods in a narrow range (~ 6 – 12 s) relatively low X-ray luminosity (10 34 – 10 36 erg s -1 ), but higher than their spin-down luminosity no signature of a binary system very soft X-ray spectra some of them are associated with supernova remnants

25. Anomalous X-ray Pulsars AXPs P (s) log L sd SNR associations CX J0110-7211 5.44 33.57 (in SMC) 1E 1048.1-5937 6.45 33.75 (AX J1845-0300) 6.97 -- G29.6+0.1 1E 2259+586 6.98 31.75 G109.1-0.1 4U 0142+61 8.69 32.07 RX J1708-4009 11.0 31.16 1E 1841-045 11.8 33.00 Kes 73 AXPs return

27. Soft Gamma Repeaters SGRs 0526-66 1806-20 1900+14 1627-41 (1801-23) SNR N49 (in LMC) G10.0-0.3 G42.8+0.6 G337.0-0.1 -- Distance 55 kpc 17 kpc 5 kpc 11 kpc -- (in bursts) L 10 42 erg s -1 10 41 erg s -1 10 41 erg s -1 10 43 erg s -1 -- P 8 sec -- 5.16 sec -- -- (giant flare) (1979.03.05) (1998.08.27) L 10 45 erg s -1 -- 10 43 erg s -1 -- -- (in quiescence) L 10 36-37 erg s -1 10 35.3 erg s -1 10 34.5 erg s -1 10 35 erg s -1 -- P -- 7.47 sec 5.16 sec (6.4 sec) -- L s-d -- 10 33.4 erg s -1 10 34.2 erg s -1 -- -- SGRs (The associations with SNRs are not secure: Gaensler et al. 2001, ApJ 559, 963) return