Close-by young isolated NSs: A new test for cooling curves Sergei Popov (Sternberg Astronomical Institute) Co-authors: H.Grigorian, R. Turolla, D. Blaschke

Plan of the talk NS: introduction Close-by NSs Population synthesis Test of cooling curves Final conclusions

Neutron stars: introduction Progenitors – massive stars Born in SN explosions R=10 km  >10 14 g/cm 3 (nuclear density) Appear in many flavours Radio pulsars X-ray binaries AXPs SGRs CCOs RINSs

Evolution of NS: spin + magnetic field Ejector → Propeller → Accretor → Georotator Lipunov (1992) astro-ph/ – spin-down 2 – passage through a molecular cloud 3 – magnetic field decay

Evolution of NSs: temperature Yakovlev et al. (1999) Physics Uspekhi

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

Magnificent Seven NamePeriod, s RX RX RBS RBS RX RX RBS Radioquiet Close-by Thermal emission Long periods

Population of close-by young NSs Magnificent seven Geminga and 3EG J Four radio pulsars with thermal emission (B ; B ; B ; B ) Seven older radio pulsars, without detected thermal emission. We need population synthesis studies of this population

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/

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

The Gould Belt Poppel (1997) R=300 – 500 pc Age 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

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/

Cooling of NSs Direct URCA Modified URCA Neutrino bremstrahlung Superfluidity Exotic matter (pions, quarks, hyperons, etc.) Kaminker et al. (2001) In our study we use curves by Blaschke, Grigorian and Voskresenski (2004)

Log N – Log S (and early results) 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/

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 Definite N (number) and S (flux) Uniform sample Two test are perfect together!!! astro-ph/

List of models (Blaschke et al. 2004) Model I. Pions. Model II. No pions. Model III. Pions. Model IV. No pions. Model V. Pions. Model VI. No pions. Model VII. Pions. Model VIII.Pions. Model IX. Pions. 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

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

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

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

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

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

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

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

Model VIII Pions Gaps from Yakovlev et al. (2004), 3 P 2 neutron gap suppressed by 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

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

Resume Magnificent Seven and other close-by NSs are genetically connected with the Gould Belt Log N – Log S for close-by NSs can serve as a test for cooling curves Two tests (LogN–LogS and Age-Temperature) are perfect together.