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

Sergei Popov

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

(astro-ph/0411618)

2

Plan of the talk

Abstract Close-by NSs Population synthesis Log N – Log S Test of cooling curves Final conclusions

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Abstract of the talk

We propose a new test ofcooling curves.

It is based onthe Log N – Log Sdistribution.

It should be usedtogether with thestandard testtemperature vs. age

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Isolated neutron stars population: in the Galaxy and at the backyard

INSs appear in many flavours Radio pulsars AXPs SGRs CCOs RINSs

Local population of young NSs is different (selection)

Radio pulsarsGeminga+RINSs

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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-byThermal emissionLong periods

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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

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Population synthesis: ingredients

Birth rate Initial spatial distribution Spatial velocity (kick) Mass spectrum Thermal evolution Emission properties Interstellar absorption Detector properties

A brief review on populationsynthesis in astrophysics canbe found in astro-ph/0411792

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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

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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

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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 for illustrative purposeswe use a set of cooling curves calculated by Blaschke, Grigorian and Voskresenski (2004)in the frame of the Nuclear medium cooling model

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Standard test: temperature vs. age

Kaminker et al. (2001)

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Log N – Log S

Log of flux (or number counts)

Lo

g o

f th

e n

um

ber

of

sou

rces

bri

gh

ter

than

th

e g

iven

flu

x

-3/2 sphere: number ~ r3

flux ~ r-2

-1 disc: number ~ r2

flux ~ r-2

calculations

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Log N – Log S: 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 Rbelt=500 pc

astro-ph/0304141

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Log N – Log S as an additional test

Standard test: Age – Temperature Sensitive to ages <105 years Uncertain age and temperature Non-uniform sample

Log N – Log S Sensitive to ages >105 years (when applied to close-by NSs) 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)

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 Ts-Tin

Pions Crust Gaps

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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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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!!!!

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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 !!!

(H. Grigorian 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 (>104-5 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 I (YCA) Model II (NDB) Model III (YCB) Model IV (NCB) Model V (YDB) Model VI (NEB)Model VII(YCB’) Model VIII (YCB’’) Model IX (NCA)

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Resume

Log N – Log S for close-by NSs can serve as a test for cooling curves

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.

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THAT’S ALL. THANK YOU!

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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)

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Evolution of NS: spin + magnetic field

Ejector → Propeller → Accretor → Georotator

Lipunov (1992) astro-ph/0101031

1 – spin-down2 – passage through a molecular cloud3 – magnetic field decay

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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

(back)

35

Model IX

No Pions Gaps from Takatsuka &

Tamagaki (2004) Ts-Tin from Blaschke,

Grigorian, Voskresenky (2004)

Can reproduce observed Log N – Log S

(back)

36

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

(back)

37

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

(back)

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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

(back)

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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

(back)

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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

(back)

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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

(back)

42

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

(back)