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

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
http://xray.sai.msu.ru/~polar/html/kniga.html
Neutron stars: introduction
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Progenitors – massive stars
Born in SN explosions
R=10 km
>1014 g/cm3 (nuclear density)
Appear in many flavours
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Radio pulsars
X-ray binaries
AXPs
SGRs
CCOs
RINSs
Evolution of NS:
spin + magnetic field
Ejector → Propeller → Accretor → Georotator
1 – spin-down
2 – passage through a molecular cloud
3 – magnetic field decay
Lipunov (1992)
astro-ph/0101031
Evolution of NSs:
temperature
Yakovlev et al. (1999)
Physics Uspekhi
Close-by radioquiet NSs
 Discovery:
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RX J1856.5-3754
Walter et al. (1996)
Proper motion and
distance: Kaplan et al.
No pulsations
Thermal spectrum
Later on: six brothers
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
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
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
Solar vicinity
 Solar neighborhood is not a
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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
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
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
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)
Log N – Log S
(and early results)
 Task: to understand the
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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
Log N – Log S as an additional test
 Standard test: Age – Temperature
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Sensitive to ages <105 years
Uncertain age and temperature
Non-uniform sample
 Log N – Log S
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Sensitive to ages >105 years
Definite N (number) and S (flux)
Uniform sample
 Two test are perfect together!!!
astro-ph/0411618
List of models (Blaschke et al. 2004)
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 Ts-Tin
 Model I.
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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.
Model I
 Pions.
 Gaps from Takatsuka & Tamagaki
(2004)
 Ts-Tin from Blaschke, Grigorian,
Voskresenky (2004)
Can reproduce observed Log N – Log S
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
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
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
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
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
Model VII
 Pions
 Gaps from Yakovlev et
al. (2004), 3P2 neutron
gap suppressed by 0.1.
1P proton gap
0
suppressed by 0.5
 Ts-Tin from Blaschke,
Grigorian, Voskresenky
(2004)
Cannot reproduce observed Log N – Log S
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
Model IX
 No Pions
 Gaps from Takatsuka &
Tamagaki (2004)
 Ts-Tin 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.