2. Neutron Stars 2: Phenomenology Andreas Reisenegger Depto. de Astronomía y Astrofísica Pontificia Universidad Católica de Chile Chandra x-ray images of the PWNs surrounding the (A) Crab and (B) Vela pulsars. [Credit: NASA/CXC/Smithsonian Astrophysical Observatory, NASA/Pennsylvania State University, and G. Pavlov]

3. Outline “Radio” pulsars: –Classical pulsars –Millisecond pulsars –Binary radio pulsars & General Relativity X-ray binaries: high & low mass Evolution, connections of pulsars & XRBs Magnetars Thermal emitters: isolated & in SNRs RRATs

4. Bibliography Radio pulsars: Lyne & Graham-Smith, Pulsar Astronomy, 2nd ed., Cambridge Univ. Press (1998) Lorimer & Kramer, Handbook of Pulsar Astronomy, Cambridge Univ. Press (2005) Manchester, Observational Properties of Pulsars, Science, 304, 542 (2004) Binary systems: Stairs, Pulsars in Binary Systems: Probing Binary Stellar Evolution & General Relativity, Science, 304, 547 (2004) Lorimer, Binary & Millisecond Pulsars, Living Reviews in Relativity, 8, 7 (2005) Others: See below.

5. NS Phenomenology The structure of a NS is almost entirely determined by its mass. The observable phenomenology, however, depends much more on several kinds of “hair”: –Rotation (  ) –Magnetic field (B) –Accretion ( )

6. “Radio” pulsars Very wide range of photon energies Mostly non- thermal Thermal X-ray bump  cooling UV/soft X-ray “hole” from interstellar absorption D. J. Thompson, astro-ph/0312272

7. Spin-down (magnetic dipole model) Spin-down time (age?): Lyne 2000, http://online.kitp.ucsb.edu/online/neustars_c00/lyne/oh/03.html Magnetic field :

8. Spin-down time vs. age The spin-down time generally agrees (roughly) with independent ages from: historic SNe (Crab) expansion of SNRs travel time from Galactic disk cooling of white-dwarf companions

9. Problem: “Braking index” K involves the dipole moment (strength & orientation) & the moment of inertia of the star. can only be measured in cases when is large & rapidly changing: young pulsars When measured, n  2.0 - 2.8 (< 3): –The dipole spin-down model is wrong, or –the dipole moment is increasing with time.

10. Kaspi et al. 1999 “Magnetars” Classical pulsars Millisecond pulsars

11. Magnetic field strengths From R. Duncan’s “magnetar” web page, http://solomon.as.utexas.edu/~duncan/magnetar.html

12. Manchester et al. 2002 “Magnetars” Classical pulsars Millisecond pulsars circled: binary systems

13. 2 populations of radio pulsars “Classical” P ~ 8 s – 16 ms t s  P/(2P’) ~ 10 3-8 yr B  (PP’) 1/2 ~ 10 11-13 G Very few binaries. Many of the youngest are associated with supernova remnants (SNRs). Galactic disk.  “Population I” Millisecond P ~ 20 ms – 1.4 ms t s  P/(2P’) ~ 10 8-10 yr B  (PP’) 1/2 ~ 10 8-9 G Most in binaries, esp. with cool white dwarfs. No associations with SNRs. Many in globular clusters.  “Population II” “The Sounds of Pulsars”: Jodrell Bank obs. Web page: http://www.jb.man.ac.uk/~pulsar/Education/Sounds/sounds.html http://www.jb.man.ac.uk/~pulsar/Education/Sounds/sounds.html

14. X-ray binaries High-mass companion (HMXB): Young X-ray pulsars: magnetic chanelling of accretion flow Cyclotron resonance features  B=(1-4)10 12 G Low-mass companion (LMXB): Likely old (low-mass companions, globular cluster environment) Mostly non-pulsating (but QPOs, ms pulsations): weak magnetic field http://wwwastro.msfc.nasa.gov/xray/openhouse/ns/

15. Origin & evolution of pulsars: the standard paradigm “Classical” radio pulsars born in core- collapse supernovae evolve to longer P, with B  const. eventually turn off (“death line”) Millisecond pulsars descend from low-mass X-ray binaries. Mass transfer in LMXBs produces spin-up magnetic field decay? Classical pulsars Millisecond pulsars

16. The binary pulsar & GR Kramer et al. 2006, Science, 314, 97

17. Magnetars: Brief history- 1 Strongest magnetic field that could possibly be contained in a NS: Woltjer (1964): Flux conservation from progenitor star could lead to NSs with B~10 14-15 G. Mazets & Golenetskii (1981): Multiple soft gamma-ray bursts from a single source (SGR 1806-20) detected by Venera spacecraft since Jan 1979. Mazets et al. (1979): “March 5 event”: Giant flare (highly super- Eddington) from SGR 0526-66 in LMC (possibly associated w. SNR N49). Fahlman & Gregory (1981): First “Anomalous X-ray Pulsar” (AXP): soft spectrum, at center of SNR, no optical counterpart. Koyama et al. (1987): AXP is spinning down, but X-ray luminosity much too high to attribute to rotational energy loss of a NS.

18. Bursting magnetar in supernova remnant N49 From R. Duncan’s “Magnetar” web site, http://solomon.as.utexas.edu/~ duncan/magnetar.html http://solomon.as.utexas.edu/~ duncan/magnetar.html

19. Magnetars: Brief history- 2 Thompson & Duncan (TD 1993): Dynamo action just after formation of a rapidly spinning NS can lead to B~10 16 G. DT (1992), Paczynski (1992), TD (1995, 1996): Strong, decaying field could explain super-Eddington bursts and persistent emission of SGRs & AXPs. TD 1996 predict slow pulsations and fast spin-down. Kouveliotou et al. (1998) measure P=7.5 s & B~10 15 G in SGR 1806-20. Gavriil et al. (2002); Kaspi et al. (2003): Several bursts detected from 2 different AXPs. SGRs & AXPs share –fairly long periods ~5-12 s, –persistent X-ray luminosities ~10 35-36 erg/s (BB T ~ 0.4-0.7 keV + high- energy tail), too high to be explained from rotation, –strong spin-down (inferred B~ 10 14-15 G).

20. Woods & Thompson, astro-ph/0406133

21. Woods & Thompson, astro-ph/0406133

22. Woods & Thompson, astro-ph/0406133

23. Isolated, dim, thermal X-ray emitters Burwitz et al. 2003, A&A, 399, 1109

24. Nebula around isolated NS van Kerkwijk & Kulkarni 2001, A&A, 380, 221

25. Compact Central Objects (CCOs) Near center of SNRs No radio or gamma-ray emission No pulsar wind nebula Thermal X-ray spectrum: temperature & luminosity intermediate between magnetars and dim isolated neutron stars Cas A - Hwang et al. 2004

26. “Rotating RAdio Transients” (RRATs; McLaughlin et al. 2006, Nature, 439, 817) emit occasional, bright radio bursts of 2-30 ms duration Intervals 4 min – 3 hr are multiples of a period P ~ 0.4 - 7 s, like slow radio pulsars or magnetars Hard to detect (visible ~ 1 s/day): True number should be much larger than for radio pulsars. McLaughlin et al. 2006; Nature, 439, 817

27. RRATs vs. pulsars & magnetars pulsars (dots) magnetars (squares) the 1 radio-quiet isolated neutron star with a measured period and period derivative (diamond) the 3 RRATs having measured periods and period derivatives (stars) vertical lines at the top of the plot mark the periods of the other 7 RRATs McLaughlin et al. 2006; Nature, 439, 817