Evolution of isolated neutron stars: magnetic field decay rules

1. Evolution of isolated neutronstars: magnetic field decay rules Sergei Popov (SAI MSU) Collaborators: J.A. Pons (Univ. Alicante) P.A. Boldin (Space Res. Inst. and SAI) B. Posselt (PennState) J.A. Miralles (Univ. Alicante) N. Tetzlaff (Obs. Jena)

2. Outline • Intro. Isolated neutron stars in the sky (1111.1158) • Population synthesis approach • Magnetic field decay framework • Extensive population synthesis of isolated neutron stars • “Public outreach”: a web-tool for population synthesis and test of cooling curves • P-Pdot diagram, “one second problem” and fine tuning

3. Good old classics For years two main types of NSs have been discussed:radio pulsars and accreting NSs in close binary systems Pulsar in the Crab nebula A binary system

4. Diversity of young neutron stars • Young isolated neutron starscan appear in many flavors: • Radio pulsars • Compact central X-ray sources • in supernova remnants. • Anomalous X-ray pulsars • Soft gamma repeaters • The Magnificent Seven & Co. • Transient radio sources (RRATs) • …………………… “GRAND UNIFICATION” is welcomed! (Kaspi 2010)

5. Compact central X-ray sources in supernova remnants Cas A RCW 103 Rapid cooling (Heinke et al. 1007.4719) 6.7 hour period (de Luca et al. 2006)

6. CCOs For two sources there are strong indications for large (>~100 msec) initial spin periods and low magnetic fields:1E 1207.4-5209 in PKS 1209-51/52 andPSR J1852+0040 in Kesteven 79 [see Halpern et al. arxiv:0705.0978] Puppis A Recent list in: 0911.0093

7. Anti-magnetars Star marks the CCO from 0911.0093

8. Magnetars • dE/dt > dErot/dt • By definition:The energy of the magnetic field is released Magnetic fields 1014–1015G

9. SGRs 0526-66 1627-41 1806-20 1900+14 0501+4516 0418+5729 1833-0832 1801-23 (?) 2013+34 (?) AXPs CXO 010043.1-72 4U 0142+61 1E 1048.1-5937 CXO J1647-45 1 RXS J170849-40 XTE J1810-197 1E 1841-045 AX J1845-0258 1E 2259+586 1E 1547.0-5408 PSR J1622-4950 CXO J171405-381031 Known magnetars (СТВ 109) Catalogue: http://www.physics.mcgill.ca/~pulsar/magnetar/main.html

10. Soft Gamma Repeaters: main properties Saturationof detectors • Energetic “Giant Flares” (GFs, L ≈ 1045-1047 erg/s) detected from 3 (4?) sources • No evidence for a binary companion, association with a SNR at least in one case • Persistent X-ray emitters, L ≈ 1035 - 1036 erg/s • Pulsations discovered both in GFs tails and persistent emission, P ≈ 5 -10 s • Huge spindown rates, Ṗ/P ≈ 10-10 s-1

11. 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

12. 27 Dec 2004: Giant flare of the 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 – see the latestdata in arXiv: 1103.0006

13. Magnetic field estimates • Spin down • Long spin periods • Energy to support bursts • Field to confine a fireball (tails) • Duration of spikes (alfven waves) • Direct measurements of magnetic field (cyclotron lines) Ibrahim et al. 2002

14. 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

15. Transient radio emission from AXP ROSAT and XMM imagesan X-ray outburst happened in 2003. AXP has spin period 5.54 s Radio emission was detected from XTE J1810-197during its active state. Clear pulsations have been detected. Large radio luminosity. Strong polarization. Precise Pdot measurement.Important to constrain models, for better distanceand coordinates determinations, etc. (Camilo et al. astro-ph/0605429)

16. Are SGRs and AXPs brothers? • Bursts of AXPs (from 7 now) • Spectral properties • Quiescent periods of SGRs (0525-66 since1983) Gavriil et al. 2002

17. Twisted Magnetospheres – I • The magnetic field inside a magnetar is “wound up” • The presence of a toroidal component induces a rotation of the surface layers • The crust tensile strength resists • A gradual (quasi-plastic ?) deformation of the crust • The external field twists up (Thompson, Lyutikov & Kulkarni 2002) Thompson & Duncan 2001

18. Growing twist (images from Mereghetti arXiv: 0804.0250)

19. A Growing Twist in SGR 1806-20 ? • Evidence for spectral hardening AND enhanced spin-down • Γ-Pdot and Γ-L correlations • Growth of bursting activity • Possible presence of proton cyclotron line only during bursts All these features are consistent with an increasingly twisted magnetosphere

20. Mereghetti et al 2006 Hard X-ray Emission INTEGRAL revealed substantial emission in the 20 -100 keV band from SGRs and APXs Hard power law tails with Г ≈ 1-3 Hard emission pulse

21. Transient radiopulsar However,no radio emissiondetected. Due to beaming? PSR J1846-0258 P=0.326 sec B=5 1013 G Among all rotation poweredPSRs it has the largest Edot.Smallest spindown age (884 yrs). The pulsar increased its luminosity in X-rays. Increase of pulsed X-ray flux. Magnetar-like X-ray bursts (RXTE). Timing noise. See additional info about this pulsar at the web-site http://hera.ph1.uni-koeln.de/~heintzma/SNR/SNR1_IV.htm 0802.1242, 0802.1704

22. Bursts from the transient PSR Chandra: Oct 2000 June 2006 Gavriil et al. 0802.1704

23. Weak dipole field magnetar Spin period of a neutron star grows. The rate of deceleration is related to the dipole magnetic field. Measuring the spin-down rate we measure the field. The source is a soft gamma-rayrepeater: SGR0418+5729 P=9.1 s The straight line in the plotcorresponds to a constantspin periods: i.e. no spin-down 200 400 B<7.5 1012G arXiv: 1010.2781 However, spectral modeling (arXiv: 1103.3024) suggests that the surface field is~1014 G.This can indicate a strongly non-dipolar field.

24. Quiescent magnetar Normally magnetars are detected via theirstrong activity: gamma-ray bursts orenhanced X-ray luminosity. This one was detected in radio observations The field is estimated to be B~3 1014G It seems to be the first magnetar to be Detected in a quescent state. PSR J1622–4950 was detected in a radio survey As a pulsar with P=4.3 s. Noisy behavior in radio Chandra ATCA (see a review on high-B PSRs in 1010.4592 arXiv: 1007.1052

25. Magnetars bursting activity due to decay In the field decay model it is possible to study burst activity.Bursts occur due to crust cracking. The decaying fieldproduce stresses in the crust that are not compensated byplastic deformations. When the stress level reaches acritical value the crust cracks, and energy can be released.At the moment the model is very simple, but this justthe first step. 1101.1098

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

27. Close-by radioquiet NSs • Discovery: Walter et al. (1996) • Proper motion and distance: Kaplan et al. • No pulsations (at first) • Thermal spectrum • Later on: six more RX J1856.5-3754

28. Magnificent Seven Radioquiet Close-by Thermal emission Absorption features Long periods

29. Spin properties and other parameters Kaplan arXiv: 0801.1143 • Updates: • 1856. νdot=-6 10 -16 (| νdot|<1.3 10-14 ) van Kerkwijk & Kaplan arXiv: 0712.3212 • 2143. νdot=-4.6 10 -16 Kaplan & van Kerkwijk arXiv: 0901.4133 • 0806. |νdot|<4.3 10 -16 Kaplan and van Kerkwijk arXiv: 0909.5218

30. Radio observations Up to now the M7 are not detected for sure at radio wavelengths,however, there was a paper by Malofeev et al., in which the authorsclaim that they had detect two of the M7 at very low wavelength (<~100 MHz). At the moment the most strict limits are given by Kondratiev et al. Non-detection is still consistent with narrow beams. Kondratiev et al. arXiv: 0907.0054

31. M7 among other NSs Evolutionary links of M7with other NSs are not clear, yet. M7-like NSs can benumerous. They can be descendantsof magnetars. Can be related to RRATs. Or, can be a differentpopulation. Kaplan arXiv: 0801.1143

32. 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. Burst duration 2-30 ms, interval 4 min-3 hr Periods in the range 0.4-7 s Thermal X-rays were observed from one of the RRATs (Reynolds et al. 2006). This one seems to be the youngest.

33. RRATs. X-ray + radio data X-ray pulses overlaped onradio data of RRAT J1819-1458. (arXiv: 0710.2056)

34. New data: McLaughlin et al. et al. arXiv: 0908.3813; Deneva et al. arXiv: 0811.2532 and Keane et al. arXiv: 1104.2727. A review: Keane arXiv: 1008.3693 P-Pdot diagram forRRATs Estimates show that there should be about 400 000 Sources of this type in the Galaxy. Relatives of the Magnificent seven? (astro-ph/0603258)

35. Some reviews on isolated neutron stars • NS basics: physics/0503245 • astro-ph/0405262 • X-rays from INS arXiv:1008.2891 • SGRs & AXPs: arXiv:0804.0250arXiv: 1101.4472 • CCOs: astro-ph/0311526arxiv:0712.2209 • Quark stars: arxiv:0809.4228 • The Magnificent Seven:astro-ph/0609066 • arxiv:0801.1143 • RRATs: arXiv:1008.3693 • Cooling of NSs:arXiv: 0906.1621 • astro-ph/0402143 • NS structure arXiv:0705.2708 • EoS arXiv:1001.3294 • arXiv: 1001.1272 • NS atmospheres astro-ph/0206025 • NS magnetic fields arxiv:0711.3650arxiv:0802.2227 • Different types arXiv:1005.0876 OVERVIEW in the book by Haensel, Yakovlev, Potekhin

36. NS birth rate [Keane, Kramer 2008, arXiv: 0810.1512]

37. Population synthesis «Artifitialobserved universe» Modeling ofobservations «Artificial universe» Ingredients:- initial conditions- evolutionary laws

38. Population synthesis: ingredients • Birth rate of NSs • Initial spatial distribution • Spatial velocity (kick) • Mass spectrum • Thermal evolution • Interstellar absorption • Detector properties Task: To build an artificial model of a population of some astrophysical sources and to compare the results of calculations with observations. A brief review on population synthesis in astrophysics can be found in astro-ph/0411792 and in Physics-Uspekhi (2007).

39. calculations -3/2 sphere: number ~ r3 flux ~ r-2 -1 disc: number ~ r2 flux ~ r-2 Log N – Log S Log of the number of sources brighter than the given flux Log of flux (or number counts)

40. Cooling curves by • Blaschke et al. • Mass spectrum Gould Belt : 20 NS Myr-1 Gal. Disk (3kpc) : 250 NS Myr-1 ROSAT 18° Gould Belt Arzoumanian et al. 2002 Population synthesis – I.

41. Thermal evolution Photon luminosity Neutrino luminosity “Minimal” Cooling Curves Page, Geppert & Weber (2006) astro-ph/0508056

42. Results – 2003: Log N – Log S • Task: to understand the Gould Belt contribution • Calculate separately disc (without the Belt) and both together • Cooling curves from Kaminker et al. (2001) • Flat mass spectrum • Single maxwellian kick • Rbelt=500 pc astro-ph/0304141

43. The Gould Belt • Poppel (1997) • R=300 – 500 pc • Age 30-50 Myrs • Center at 150 pc from the Sun • Inclined respect to the galactic plane at 20 degrees • 2/3 massive stars in 600 pc belong to the Belt

44. Spatial distribution We use the same normalization for NS formation rate inside 3 kpc: 270 per Myr. Most of NSs are born inOB associations. For stars <500 pc we eventry to take into accountif they belong to OB assoc.with known age. a) Hipparcos stars up to 500 pc [Age: spectral type & cluster age (OB ass)] b) 49 OB associations: birth rate ~ Nstar c) Field stars in the disc up to 3 kpc

45. Mass distribution • Mass spectrum of local young NSs can be different from the general one (in the Galaxy) • Hipparcos data onnear-by massive stars • Progenitor vs NS mass: Timmes et al. (1996); Woosley et al. (2002) Low mass progenitors for thedotted mass spectrum are treated following astro-ph/0409422.

46. Spatial distribution of ISM instead of : NH inside 1 kpc (see astro-ph/0609275 for details) now : Modification of the old one Hakkila

47. Results for the new model Known – from the Gould Belt Weaker – behind the Belt A&A 2008, 2010

48. Sky distributions Weak sources Bright sources

49. INSs and local surrounding Massive star population in the Solar vicinity (up to 2 kpc) is dominated by OB associations. Inside 300-400 pc the Gould Belt is mostly important. Motch et al. 2006 De Zeeuw et al. 1999

50. Magnetic field decay A model based on the initial field-dependent decay can provide an evolutionary link between different populations (Pons et al.). arXiv: 0710.4914 (Aguilera et al.)