Neutron Stars 2: Phenomenolog y 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]
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Neutron Stars 2: Phenomenology
Andreas ReiseneggerDepto. 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]
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
Magnetars: Brief history- 2• Thompson & Duncan (TD 1993): Dynamo action just after formation of
a rapidly spinning NS can lead to B~1016G.
• 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~1015G 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 ~1035-36 erg/s (BB T ~ 0.4-0.7 keV + high-energy tail), too high to be explained from rotation,
– strong spin-down (inferred B~ 1014-15 G).
Woods & Thompson,astro-ph/0406133
Woods & Thompson,astro-ph/0406133
Woods & Thompson,astro-ph/0406133
Isolated, dim, thermal X-ray emitters
Burwitz et al. 2003, A&A, 399, 1109
Nebula around isolated NS
van Kerkwijk & Kulkarni 2001, A&A, 380, 221
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
• “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
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