Close-by young isolated neutron stars (and black holes)

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Close-by young isolated neutron stars (and black
holes)

• Sergey Popov
• (Sternberg Astronomical Institute)

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Plan of the talk

• NS introduction
• Close-by NSs
• Population synthesis
• Test of cooling curves
• Close-by BHs
• 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
• ?1014 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/04011792
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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.)

Kaminker et al. (2001)
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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
• 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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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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Black holes

• Black holes are born from very massive
  progenitors
• It is very difficult to observe as isolated BH
• Microlensing
• Weak accretion
• .?
• It is important to try to estimate at least
  approximate positions

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Close-by BHs and runaway stars
Star Mass Velocity km/s Age, Myr
? Per 33 65 1
HD 64760 25-35 31 6
? Pup 67 62 2
? Cep 40-65 74 4.5

• 56 runaway stars inside 750 pc (Hoogerwerf et
  al. 2001)
• Four of them have M gt 30 Msolar

Prokhorov, Popov (2002)
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Supernova explosion in a binary
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? Pup

• Distance 404-519 pc
• Velocity 33-58 km/s
• Error box 12o x 12o
• NEGRET 1

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? Per

• Distance 537-611 pc
• Velocity 19-70 km/s
• Error box 7o x 7o
• NEGRET 1

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Resume

• Approximate positions of young close-by BHs can
  be estimated basing on data on massive runaway
  stars
• For two cases we obtained relatively small error
  boxes
• For HD 64760 and for ? Cep we obtained very
  large error boxes (40-50o)
• Several EGRET sources inside

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Final conclusions

• We live in the region of the Galaxy enriched with
  young NSs and BHs
• NSs appear as radio pulsars, gamma and X-ray
  sources
• Local population teaches us that radio pulsars do
  not represent all young NSs
• Log N Log S can be a good additional test for
  cooling curves of NSs
• Position of close-by isolated BHs can be roughly
  estimated for those originated from binary systems