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The Zoo Of Neutron Stars

The Zoo Of Neutron Stars. Sergei Popov ( SAI MSU ). ( www.bradcovington.com). JINR, Dubna, August 30, 2006. Main reviews. NS basics : physics/0503245 SGRs & AXPs: astro-ph/040613 Magnetars : - Observations astro-ph/0505491 - Theory astro-ph/0504077 Central compact X-ray

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The Zoo Of Neutron Stars

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  1. The Zoo Of Neutron Stars Sergei Popov (SAI MSU) (www.bradcovington.com) JINR, Dubna, August 30, 2006

  2. Main reviews • NS basics: physics/0503245 • SGRs & AXPs: astro-ph/040613 • Magnetars: • - Observationsastro-ph/0505491 • - Theoryastro-ph/0504077 • Central compact X-ray • sources in supernova • remnants: astro-ph/0311526 • The Magnificent Seven:astro-ph/0502457 • RRATs: astro-ph/0511587 • Cooling of NSs:astro-ph/0508056 • http://xray.sai.msu.ru/~polar/sci_rev/ns.html Труды ГАИШ том 72 (2003)

  3. Prediction ... Neutron stars have been predicted in 30s: L.D. Landau: Star-nuclei (1932) + anecdote Baade and Zwicky: neutron stars and supernovae (1934) (Landau) (Zwicky) (Baade)

  4. Neutron stars Radius: 10 km Mass: 1-2 solar Density: about the nuclear Strong magnetic fields

  5. Neutron stars - 2 Superdence matter and superstrong magnetic fields

  6. The old zoo of neutron stars In 60s the first X-ray sources have been discovered. They were neutron stars in close binary systems, BUT ... .... theywere «notrecognized».... Now we know hundreds of X-ray binaries with neutron stars in the Milky Way and in other galaxies.

  7. Rocket experimentsSco X-1 Giacconi, Gursky, Hendel 1962 In 2002 R.Giacconi was awarded with the Nobel prize.

  8. UHURU The satellite was launched on December 12, 1970. The program was ended in March 1973. The other nameSAS-1 2-20keV The first full sky survey. 339 sources.

  9. Accretion in close binaries Accretion is the most powerful source of energy realized in Nature, which can give a huge energy output. When matter fall down onto the surface of a neutron star up to 10% of mc2 can be released.

  10. Accretion disc The theory of accretion discs was developed in 1972-73 by N.I. Shakura and R.A. Sunyaev. Accretion is important not only in close binaries, but also in active galactic nuclei and many other types of astrophysical sources.

  11. Close binary systems About ½ of massive stars Are members of close binary systems. Now we know many dozens of close binary systems with neutron stars. • L=Mηc2 The accretion rate can be up to 1020g/s; Accretion efficiency – up to 10%; Luminosity –thousands of hundreds of the solar.

  12. Discovery !!!! 1967: JocelynBell. Radio pulsars. Seredipitous discovery.

  13. The pulsar in the Crab nebula

  14. Evolution of NSs. I.:temperature (Yakovlev et al. (1999) Physics Uspekhi) more details will be described in the talk by Prof. H. Grigorian

  15. Evolution of neutron stars. II.: rotation + magnetic field Ejector → Propeller → Accretor → Georotator 1 – spin down 2 – passage through a molecular cloud 3 – magnetic field decay astro-ph/0101031 See the book by Lipunov (1987, 1992)

  16. Magnetorotational evolution of radio pulsars Spin-down. Rotational energy is released. The exact mechanism is still unknown.

  17. The new zoo of neutron stars • During last 10 years • it became clear that neutron stars • can be born very different. • In particular, absolutely • non-similar to the Crab pulsar. • Compact central X-ray sources • in supernova remnants. • Anomalous X-ray pulsars • Soft gamma repeaters • The Magnificent Seven • Unidentified EGRET sources • Transient radio sources..............

  18. Compact central X-ray sources in supernova remnants RCW 103 Cas A New result: 6.7 hour period (de Luca et al. 2006) Problem: small emitting area

  19. Puppis A One of the most famous central compact X-ray sources in supernova remnants. Age about 3700 years. Probably the progenitor was a very massive star (mass about 30 solar). • New results: • Vkick=1500 km/s • Winkler, Petre 2006 • (astro-ph/0608205)

  20. Magnetars • dE/dt > dErot/dt • By definition:The energy of the magnetic field is released • P-Pdot • Direct measurements of the field (Ibrahim et al.) Magnetic fields 1014–1015G

  21. SGRs 0526-66 1627-41 1806-20 1900+14 +candidates AXPs CXO 010043.1-72 4U 0142+61 1E 1048.1-5937 1 RXS J170849-40 XTE J1810-197 1E 1841-045 AX J1844-0258 1E 2259+586 Known magnetars (СТВ 109)

  22. Magnetars on the Galaxy • 4 SGRs, 9 AXPs, plus candidates, plus radio pulsars with high magnetic fields… • Young objects (about 104 year). • Probably about 10% of all NSs.

  23. Historical notes • 05 March 1979. The ”Konus” experiment & Co. Venera-11,12 (Mazets et al., Vedrenne et al.) • Events in the LMC. SGR 0520-66. • Fluence: about 10-3 erg/cm2 Mazets et al. 1979

  24. N49 – supernova remnant in the Large Magellanic cloud (e.g. G. Vedrenne et al. 1979)

  25. Main types of activity of SGRs • Weak bursts. L<1041 erg/s • Intermediate.L=1041–1043 erg/s • Giant. L<1045 erg/s • Hyperflares. L>1046 erg/s Power distribution is similar to the distribution of earthquakes in magnitude See the review in Woods, Thompson astro-ph/0406133

  26. Normal (weak) bursts of SGRsand AXPs • Typical bursts of SGR 1806-29, SGR 1900+14 And of AXP 1E 2259+586 detected byRXTE (fromthe review by Woods, Thompson, 2004, astro-ph/0406133) (fromWoods, Thompson 2004)

  27. Intermediate SGR bursts Examples of intermediate bursts. The forth (bottom right) is sometimes defined as a giant burst (for example by Mazets et al.). (from Woods, Thompson 2004)

  28. Giant flare of the SGR 1900+14 (27 August 1998) • Ulysses observations (figurefrom Hurley et al. 1999) • Initial spike 0.35 s • P=5.16 s • L>3 1044 erg/s • ETOTAL>1044 erg Hurley et al. 1999

  29. SGRs: periods and giant flares Giant flares P, s • 0526-66 • 1627-41 • 1806-20 • 1900+14 8.0 5 March 1979 (?) 18 June 1998 6.4 24 Dec 2004 7.5 5.2 27 Aug 1998 New result: oscillations in the “tail”. “Trembling” of the crust (Israel et al. 2005, Watts and Strohmayer 2005). See the review in Woods, Thompson astro-ph/0406133

  30. Anomalous X-ray pulsars Identified as a separate group in 1995. (Mereghetti, Stella 1995Van Paradijs et al.1995) • Similar periods (5-10 sec) • Constant spin down • Absence of optical companions • Relatively weak luminosity • Constant luminosity

  31. Known AXPs Sources Periods, s

  32. Pulse profiles of SGRs and AXPs

  33. Are SGRs and AXPs brothers? • Bursts of AXPs • Spectral properties • Quiescent periods of SGRs (0525-66 since1983) Gavriil et al. 2002

  34. Theory of magnetars • Thompson, Duncan ApJ 408, 194 (1993) • Convection in a protoNS results in generation of strong magnetic field • Reconfiguration of the magnetic field structure (Figures from the web-page of Duncan)

  35. Generation of the magnetic field The mechanism of the magnetic field generation is still unknown. Turbulent dynamo α-Ω dynamo (Duncan,Thompson) α2 dynamo (Bonanno et al.) or their combination In any case, initial rotation of a protoNS is the critical parameter.

  36. Strong field via flux conservation There are reasons to suspect that the magnetic fields of magnetars are not due to any kind of dynamo mechanism, but just due to flux conservation: • Study of SNRs with magnetars (Vink and Kuiper 2006). • If there was a rapidly rotating magnetar then a huge • energy release is inevitable. No traces of such energy • injections are found. • There are few examples of massive stars with field • strong enough to produce a magnetars due to flux • conservation (Ferrario and Wickramasinghe 2006) Still, these suggestions can be criticized

  37. Alternative theory • Remnant fallback disc • Mereghetti, Stella 1995 • Van Paradijs et al.1995 • Alpar 2001 • Marsden et al. 2001 • Problems ….. • How to generate strong bursts? • Discovery of a passive disc in one of AXPs (Wang et al. 2006). New burst of interest to this model.

  38. Magnetic field estimates • Direct measurements of magnetic field (cyclotron lines) • Spin down • Long spin periods Ibrahim et al. 2002

  39. Hyperflare of SGR 1806-20 • 27 December2004 A giant flare from SGR 1806-20 was detected by many satellites: Swift, RHESSI, Konus-Wind, Coronas-F, Integral, HEND, … • 100 times brighter than any other! Palmer et al. astro-ph/0503030

  40. C O R O N A S - F Integral RHESSI

  41. 27 Dec 2004Giant flare SGR 1806-20 • Spike 0.2 s • Fluence1 erg/cm2 • E(spike)=3.5 1046 erg • L(spike)=1.8 1047 erg/s • Long «tail» (400 s) • P=7.65 s • E(tail) 1.6 1044 erg • Distance 15 kpc

  42. Konus observations.SGR 1806-20 27 Dec 2004 Mazets et al. 2005

  43. The myth about Medusa

  44. What is special about magnetars? Link withmassive stars There are reasons to suspect that magnetars are connected to massive stars. Link to binary stars There is a hypothesis that magnetars are formed in close binary systems (astro-ph/0505406). Westerlund 1 The question is still on the list.

  45. ROSAT ROentgen SATellite German satellite (with participation of US and UK). Launched 01June 1990. The program was successfully ended on 12 Feb 1999.

  46. Close-by radio quiet NSs • Discovery: Walter et al. (1996) • Proper motion and parallax: Kaplan et al. • No pulsations • Thermal spectrum • Later on: six brothers RX J1856.5-3754

  47. Relatives of magnetars? The Magnificent seven Radio quiet Close Young Thermal emission Long periods XDINS? RINS? ICoNS? PuTINS?

  48. Radio detection of the Magnificent Seven Malofeev et al, Atel #798, 2006 1RXS J2143.7+065419 (RBS 1774) Malofeev et al. (2005) reported detection of 1RXS J1308.6+212708 (RBS 1223) in the low-frequency band (60-110 MHz) with the radio telescope in Pushchino.

  49. Unidentified EGRET sources Grenier (2000), Gehrels et al. (2000) Unidentified sources are divided into several groups. One of them has sky distribution similar to the Gould Belt objects. It is suggested that GLAST (and, probably, AGILE) Can help to solve this problem. Actively studied subject (see for example papers byHarding, Gonthier) New results: no radio pulsars in 56 EGRET error boxes (Crawford et al. 2006)

  50. Discovery of radio transients McLaughlin et al. (2006) discovered a new type of sources– RRATs (Rotating Radio Transients). For most of the sources periodsabout few seconds were discovered. The result was obtained during the Parkes survey of the Galactic plane. These sources can be related to The Magnificent seven. Thermal X-rays were observed from one of the RRATs (Reynolds et al. 2006). This one seems to me the youngest.

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