1. Cooling constraints for color superconductivity in hybrid stars Sergei Popov (Sternberg Astronomical Institute) Co-authors: D. Blaschke, H.Grigorian

2. 2 Plan of the talk Intro. Close-by NSs Cooling of compact stars Population synthesis of NSs Solar vicinity Some (old) results Two tests of cooling Brightness constraint Sensitivity of two tests Mass constraint Hybrid stars New prospects and results Final conclusions

3. 3 Isolated neutron stars population: in the Galaxy and at the backyard  INSs appear in many flavours Radio pulsars AXPs SGRs CCOs RINSs (ICoNS) RRATs  Local population of known young NSs is different (selection) Radio pulsars Geminga+ EGRET unidentified sources RINSs (ICoNS)

4. 4 Isolated neutron stars population: in the Galaxy and at the backyard  INSs appear in many flavours Radio pulsars AXPs SGRs CCOs RINSs RRATs RRATs  Local population of known young NSs is different (selection) Radio pulsars Geminga+ EGRET unidentified sources RINSs (ICoNS) Hot stuff!!! Published in Nature on 23 March 2006

5. 5 Compact central objects in SNRs Cas A RCW 103

6. 6 Known magnetars 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 (СТВ 109)

7. 7 SGRs: periods and bursts 0526-66 1627-41 1806-20 1900+14 +candidates P, sec Giant bursts 8.0 6.4 7.5 5.2 5 March 1979 27 Aug 1998 24 Dec 2004 18 June 1998 (?) See a review in Woods, Thompson astro-ph/0406133

8. 8 Known AXPs CXO 010043.1-728.0 4U 0142+618.7 1E 1048.1-59376.4 1RXS J170749-4011.0 XTE J1841-1975.5 1E 1841-04511.8 AX J1844-02587.0 1E 2259+5867.0 Source Period, sec

9. 9 P-Pdot for new transient sources: RRATs – Rapid RAdio Transients McLaughlin et al. 2006 Nature Estimates show that there should be about 400 000 sources of this type in the Galaxy High formation rate makes RRATs probable relatives of ICoNS, not of magnetars. (astro-ph/0603258)

10. 10 Close-by radioquiet NSs or ICoNS Discovery: Walter et al. (1996) Proper motion and distance: Kaplan et al. No pulsations Thermal spectrum Later on: six brothers RX J1856.5-3754

11. 11 Magnificent Seven NamePeriod, s RX 1856 - RX 0720 8.39 RBS 1223 10.31 RBS 1556 - RX 0806 11.37 RX 0420 3.45 RBS 1774 9.44 Radioquiet (?) Close-by Thermal emission Long periods

12. 12 Population of close-by young NSs Magnificent seven Geminga and 3EG J1853+5918 Four radio pulsars with thermal emission (B0833-45; B0656+14; B1055-52; B1929+10) Seven older radio pulsars, without detected thermal emission. We need population synthesis studies of this population

13. 13 Population synthesis: ingredients Birth rate Initial spatial distribution Spatial velocity (kick) Mass spectrum Thermal evolution Interstellar absorption Detector properties A brief review on population synthesis in astrophysics can be found in astro-ph/0411792

14. 14 Cooling of NSs Direct URCA Modified URCA Neutrino bremstrahlung Superfluidity Exotic matter (pions, quarks, hyperons, etc.) (see a recent review in astro-ph/0508056) Studies of cooling of NSs is one of few ways to obtain information about interiors of compact objects, and about physical processes under extreme conditions.

15. 15 Gould Belt : 20 NS Myr -1 Gal. Disk (3kpc) : 250 NS Myr -1 Arzoumanian et al. 2002 ROSAT Cooling curves by Blaschke et al. Mass spectrum 18° Gould Belt Population synthesis © Bettina Posselt

16. 16 Solar vicinity Solar neighborhood is not a typical region of our Galaxy Gould Belt R=300-500 pc Age: 30-50 Myrs 20-30 SN per Myr (Grenier 2000) The Local Bubble Up to six SN in a few Myrs

17. 17 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

18. 18 Log N – Log S Log of flux (or number counts) Log of the number of sources brighter than the given flux -3/2 sphere: number ~ r 3 flux ~ r -2 -1 disc: number ~ r 2 flux ~ r -2 calculations

19. 19 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 R belt =500 pc astro-ph/0304141

20. 20 Two tests Age – Temperature & Log N – Log S

21. 21 Standard test: temperature vs. age Kaminker et al. (2001)

22. 22 Log N – Log S Log of flux (or number counts) Log of the number of sources brighter than the given flux -3/2 sphere: number ~ r 3 flux ~ r -2 -1 disc: number ~ r 2 flux ~ r -2 calculations

23. 23 Log N – Log S as an additional test Standard test: Age – Temperature Sensitive to ages <10 5 years Uncertain age and temperature Non-uniform sample Log N – Log S Sensitive to ages >10 5 years (when applied to close-by NSs) Definite N (number) and S (flux) Uniform sample Two test are perfect together!!! astro-ph/0411618

24. 24 List of models (Blaschke et al. 2004) Model I. Yes C A Model II. No D B Model III. Yes C B Model IV. No C B Model V. Yes D B Model VI. No E B Model VII. Yes C B’ Model VIII.Yes C B’’ Model IX. No C A Blaschke et al. used 16 sets of cooling curves. They were different in three main respects: 1. Absence or presence of pion condensate 2. Different gaps for superfluid protons and neutrons 3. Different T s -T in Pions Crust Gaps

25. 25 Model I Pions. Gaps from Takatsuka & Tamagaki (2004) T s -T in from Blaschke, Grigorian, Voskresenky (2004) Can reproduce observed Log N – Log S

26. 26 Model II No Pions Gaps from Yakovlev et al. (2004), 3 P 2 neutron gap suppressed by 0.1 T s -T in from Tsuruta (1979) Cannot reproduce observed Log N – Log S

27. 27 Model III Pions Gaps from Yakovlev et al. (2004), 3 P 2 neutron gap suppressed by 0.1 T s -T in from Blaschke, Grigorian, Voskresenky (2004) Cannot reproduce observed Log N – Log S

28. 28 Model IV No Pions Gaps from Yakovlev et al. (2004), 3 P 2 neutron gap suppressed by 0.1 T s -T in from Blaschke, Grigorian, Voskresenky (2004) Cannot reproduce observed Log N – Log S

29. 29 Model V Pions Gaps from Yakovlev et al. (2004), 3 P 2 neutron gap suppressed by 0.1 T s -T in from Tsuruta (1979) Cannot reproduce observed Log N – Log S

30. 30 Model VI No Pions Gaps from Yakovlev et al. (2004), 3 P 2 neutron gap suppressed by 0.1 T s -T in from Yakovlev et al. (2004) Cannot reproduce observed Log N – Log S

31. 31 Model VII Pions Gaps from Yakovlev et al. (2004), 3 P 2 neutron gap suppressed by 0.1. 1 P 0 proton gap suppressed by 0.5 T s -T in from Blaschke, Grigorian, Voskresenky (2004) Cannot reproduce observed Log N – Log S

32. 32 Model VIII Pions Gaps from Yakovlev et al. (2004), 3 P 2 neutron gap suppressed by 0.1. 1 P 0 proton gap suppressed by 0.2 and 1 P 0 neutron gap suppressed by 0.5. T s -T in from Blaschke, Grigorian, Voskresenky (2004) Can reproduce observed Log N – Log S

33. 33 Model IX No Pions Gaps from Takatsuka & Tamagaki (2004) T s -T in from Blaschke, Grigorian, Voskresenky (2004) Can reproduce observed Log N – Log S

34. 34 HOORAY!!!! Log N – Log S can select models!!!!! Only three (or even one!) passed the second test! …….still………… is it possible just to update the temperature-age test??? May be Log N – Log S is not necessary? Let’s try!!!!

35. 35 Brightness constraint Effects of the crust (envelope) Fitting the crust it is possible to fulfill the T-t test … …but not the second test: Log N – Log S !!! (H. Grigorian astro-ph/0507052)

36. 36 Sensitivity of Log N – Log S Log N – Log S is very sensitive to gaps Log N – Log S is not sensitive to the crust if it is applied to relatively old objects (>10 4-5 yrs) Log N – Log S is not very sensitive to presence or absence of pions We conclude that the two test complement each other Model Model I (YCA) Model II (NDB) Model III (YCB)Model Model III (YCB) Model Model IV (NCB) Model V (YDB) Model VI (NEB)ModelModel VI Model Model VII(YCB’) Model VIII (YCB’’) Model IX (NCA)ModelModel IX

37. 37 Mass constraint Mass spectrum has to be taken into account when discussing data on cooling Rare masses should not be used to explain the cooling data Most of data points on T-t plot should be explained by masses <1.4 Msun In particular: Vela and Geminga should not be very massive Subm. to Phys. Rev.C nucl-th/0512098 (published as a JINR [Dubna] preprint)

38. 38 Hybrid stars We use models of HySs introduced by Grigorian et al. (2005) Phys. Rev. C 71, 045801 astro-ph/0511619 2SC phase μ c = 330 MeV

39. 39 Mass spectrum

40. 40 List of models

41. 41 Model I

42. 42 Model II

43. 43 Model III

44. 44 Model IV

45. 45 Resume for HySs One model among four was able to pass all tests.

46. 46 1. Spatial distribution of progenitor stars a) Hipparcos stars up to 400 pc [Age: spectral type & cluster age (OB ass)] b) Star associations: birth rate ~ N star c) Field stars in the disc up to 3 kpc Population synthesis – recent improvements

47. 47 Further improvements: Mass spectrum fainter XMM EPIC PN count rates cooling curves (Grigorian et al. 2000, Popov et al. 2006) 2. Spatial distribution of ISM (N H ) instead of :now : + new cross sections & abundances 1kpc Population synthesis – recent improvements (by Bettina Posselt)

48. 48 l=90°l=180°l=270° b= +90° b= -90° First results The new initial distribution of progenitor stars: For comparison: ROSAT, old ISM distribution, masses etc. as before Cep + Cyg Ass ? Col 121 +Ori OB ? Sco OB2 ? GB 300 pc GB 500 pc New Popov et al. 2005 Outlook Different log N - log S curve for distinct sky regions Population synthesis for fainter (XMM) sources Count rate > 0.05 cts/s

49. 49 Resume We live in a very interesting region of the Milky Way! Log N – Log S test can include NSs with unknown ages, so additional sources (like the Magnificent Seven) can be used to test cooling curves Two tests (LogN–LogS and Age-Temperature) are perfect together. Mass constraint can be an important limitation. Some models for HySs successfully passed all test. We are looking forward to have a more detailed model.

50. 50 THAT’S ALL. THANK YOU! Collaborators on pop. synthesis of isolated NSs: D. Blaschke, M. Colpi, H. Grigorian, V. Lipunov, B. Posselt, M. Prokhorov, A.Treves, R. Turolla Also thanks to: F. Haberl, J. Trumper, D. Voskresenski

51. 51 Radio detection 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. (back) Malofeev et al, Atel #798, 2006 1RXS J2143.7+065419 (RBS 1774)

52. 52 Model I Pions. Gaps from Takatsuka & Tamagaki (2004) T s -T in from Blaschke, Grigorian, Voskresenky (2004) Can reproduce observed Log N – Log S (back)

53. 53 Model IX No Pions Gaps from Takatsuka & Tamagaki (2004) T s -T in from Blaschke, Grigorian, Voskresenky (2004) Can reproduce observed Log N – Log S (back)

54. 54 Model III Pions Gaps from Yakovlev et al. (2004), 3 P 2 neutron gap suppressed by 0.1 T s -T in from Blaschke, Grigorian, Voskresenky (2004) Cannot reproduce observed Log N – Log S (back)

55. 55 Model II No Pions Gaps from Yakovlev et al. (2004), 3 P 2 neutron gap suppressed by 0.1 T s -T in from Tsuruta (1979) Cannot reproduce observed Log N – Log S (back)

56. 56 Model IV No Pions Gaps from Yakovlev et al. (2004), 3 P 2 neutron gap suppressed by 0.1 T s -T in from Blaschke, Grigorian, Voskresenky (2004) Cannot reproduce observed Log N – Log S (back)

57. 57 Model V Pions Gaps from Yakovlev et al. (2004), 3 P 2 neutron gap suppressed by 0.1 T s -T in from Tsuruta (1979) Cannot reproduce observed Log N – Log S (back)

58. 58 Model VI No Pions Gaps from Yakovlev et al. (2004), 3 P 2 neutron gap suppressed by 0.1 T s -T in from Yakovlev et al. (2004) Cannot reproduce observed Log N – Log S (back)

59. 59 Model VII Pions Gaps from Yakovlev et al. (2004), 3 P 2 neutron gap suppressed by 0.1. 1 P 0 proton gap suppressed by 0.5 T s -T in from Blaschke, Grigorian, Voskresenky (2004) Cannot reproduce observed Log N – Log S (back)

60. 60 Model VIII Pions Gaps from Yakovlev et al. (2004), 3 P 2 neutron gap suppressed by 0.1. 1 P 0 proton gap suppressed by 0.2 and 1 P 0 neutron gap suppressed by 0.5. T s -T in from Blaschke, Grigorian, Voskresenky (2004) Can reproduce observed Log N – Log S (back)

61. 61 NS+NS binaries Pulsar Pulsar mass Companion mass B1913+16 1.44 1.39 B2127+11C 1.35 1.36 B1534+12 1.33 1.35 J0737-3039 1.34 1.25 J1756-2251 1.40 1.18 (PSR+companion)/2 J1518+4904 1.35 J1811-1736 1.30 J1829+2456 1.25 (David Nice, talk at Vancouver) (Back)Back

62. 62 P-Pdot for new transient sources: RRATs McLaughlin et al. 2006 Nature (back) Estimates show that there should be about 400 000 sources of this type in the Galaxy High formation rate makes RRATs probable relatives of Mag.7, not of magnetars. (astro-ph/060; MNRAS)

63. 63 Mass spectrum of NSs Mass spectrum of local young NSs can be different from the general one (in the Galaxy) Hipparcos data on near-by massive stars Progenitor vs NS mass: Timmes et al. (1996); Woosley et al. (2002) astro-ph/0305599 (masses of secondary objects in NS+NS)

64. 64 Woosley et al. 2002 Progenitor mass vs. NS mass