Close-by young isolated NSs: A new test for cooling curves

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Close-by young isolated NSs A new test for
cooling curves

• Sergei Popov
• (Sternberg Astronomical Institute)
• Co-authors H.Grigorian, R. Turolla, D. Blaschke

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Plan of the talk

• NS introduction
• Close-by NSs
• Population synthesis
• Test of cooling curves
• Final conclusions

http//xray.sai.msu.ru/polar/html/kniga.html
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Neutron stars introduction

• Progenitors massive stars
• Born in SN explosions
• R10 km
• ?gt1014 g/cm3 (nuclear density)
• Appear in many flavours
• Radio pulsars
• X-ray binaries
• AXPs
• SGRs
• CCOs
• RINSs

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Evolution of NS spin magnetic field
Ejector ? Propeller ? Accretor ? Georotator
1 spin-down 2 passage through a molecular
cloud 3 magnetic field decay
astro-ph/0101031
Lipunov (1992)
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Evolution of NSstemperature
Yakovlev et al. (1999) Physics Uspekhi
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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 J1856.5-3754
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Magnificent Seven
Name Period, 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
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Population of close-by young NSs

• Magnificent seven
• Geminga and 3EG J18535918
• Four radio pulsars with thermal emission
  (B0833-45 B065614 B1055-52 B192910)
• Seven older radio pulsars, without detected
  thermal emission.

We need population synthesis
studies of this population
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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
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Solar vicinity

• Solar neighborhood is not a typical region of our
  Galaxy
• Gould Belt
• R300-500 pc
• Age 30-50 Myrs
• 20-30 SN per Myr (Grenier 2000)
• The Local Bubble
• Up to six SN in a few Myrs

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The Gould Belt

• Poppel (1997)
• R300 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

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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
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Cooling of NSs

• Direct URCA
• Modified URCA
• Neutrino bremstrahlung
• Superfluidity
• Exotic matter (pions, quarks, hyperons, etc.)

In our study we use curves by Blaschke,
Grigorian and Voskresenski (2004)
Kaminker et al. (2001)
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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
• Rbelt500 pc

astro-ph/0304141
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Log N Log S as an additional test

• Standard test Age Temperature
• Sensitive to ages lt105 years
• Uncertain age and temperature
• Non-uniform sample
• Log N Log S
• Sensitive to ages gt105 years
• Definite N (number) and S (flux)
• Uniform sample
• Two test are perfect together!!!

astro-ph/0411618
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List of models (Blaschke et al. 2004)

• Blaschke et al. used 16 sets of cooling curves.
• They were different in three main respects
• Absence or presence of pion condensate
• Different gaps for superfluid protons and
  neutrons
• Different Ts-Tin

• 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.

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Model I

• Pions.
• Gaps from Takatsuka Tamagaki (2004)
• Ts-Tin from Blaschke, Grigorian, Voskresenky
  (2004)

Can reproduce observed Log N Log S
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Model II

• No Pions
• Gaps from Yakovlev et al. (2004), 3P2 neutron gap
  suppressed by 0.1
• Ts-Tin from Tsuruta (1979)

Cannot reproduce observed Log N Log S
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Model III

• Pions
• Gaps from Yakovlev et al. (2004), 3P2 neutron gap
  suppressed by 0.1
• Ts-Tin from Blaschke, Grigorian, Voskresenky
  (2004)

Cannot reproduce observed Log N Log S
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Model IV

• No Pions
• Gaps from Yakovlev et al. (2004), 3P2 neutron gap
  suppressed by 0.1
• Ts-Tin from Blaschke, Grigorian, Voskresenky
  (2004)

Cannot reproduce observed Log N Log S
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Model V

• Pions
• Gaps from Yakovlev et al. (2004), 3P2 neutron gap
  suppressed by 0.1
• Ts-Tin from Tsuruta (1979)

Cannot reproduce observed Log N Log S
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Model VI

• No Pions
• Gaps from Yakovlev et al. (2004), 3P2 neutron gap
  suppressed by 0.1
• Ts-Tin from Yakovlev et al. (2004)

Cannot reproduce observed Log N Log S
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Model VII

• Pions
• Gaps from Yakovlev et al. (2004), 3P2 neutron gap
  suppressed by 0.1.
• 1P0 proton gap suppressed by 0.5
• Ts-Tin from Blaschke, Grigorian, Voskresenky
  (2004)

Cannot reproduce observed Log N Log S
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Model VIII

• Pions
• Gaps from Yakovlev et al. (2004), 3P2 neutron gap
  suppressed by 0.1. 1P0 proton gap suppressed by
  0.2 and 1P0 neutron gap suppressed by 0.5.
• Ts-Tin from Blaschke, Grigorian, Voskresenky
  (2004)

Can reproduce observed Log N Log S
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Model IX

• No Pions
• Gaps from Takatsuka Tamagaki (2004)
• Ts-Tin from Blaschke, Grigorian, Voskresenky
  (2004)

Can reproduce observed Log N Log S
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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
  !!!

astro-ph/0507052
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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 (gt105 yrs).
• Log N Log S is not very sensitive to presence
  or absence of pions

We conclude that the two test complement each
other
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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 (LogNLogS and Age-Temperature) are
  perfect together.

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Radio detection
Malofeev et al. (2005) reported detection of
1RXS J1308.6212708 (RBS 1223) in the
low-frequency band (60-110 MHz) with the radio
telescope in Pushchino.
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