Close-by young isolated NSs: A new test for cooling curves Sergei Popov (Sternberg Astronomical...

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

3

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

4

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

5

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

6

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

7

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

8

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

9

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

10

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

11

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

12

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

13

Standard test: temperature vs. age

Kaminker et al. (2001)

14

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

15

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

16

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

17

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

18

Model I

Pions. Gaps from Takatsuka & Tamagaki

(2004) Ts-Tin from Blaschke, Grigorian,

Voskresenky (2004)

Can reproduce observed Log N – Log S

19

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

20

Model III

Pions Gaps from Yakovlev et al.


Ts-Tin from Blaschke, Grigorian, Voskresenky (2004)


21

Model IV





22

Model V





23

Model VI



Ts-Tin from Yakovlev et al. (2004)


24

Model VII

Pions Gaps from Yakovlev et

al. (2004), 3P2 neutron gap suppressed by 0.1.

1P0 proton gap suppressed by 0.5



25

Model VIII


(2004), 3P2 neutron gap suppressed by 0.1. 1P0

proton gap suppressed by 0.2 and 1P0 neutron gap suppressed by 0.5.



26

Model IX

No Pions Gaps from Takatsuka &

Tamagaki (2004) Ts-Tin from Blaschke,

Grigorian, Voskresenky (2004)


27

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!!!!

28

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)

29

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)

30

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.

31

THAT’S ALL. THANK YOU!

32

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)

33

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

34

Model I

Pions. Gaps from Takatsuka & Tamagaki

(2004) Ts-Tin from Blaschke, Grigorian,

Voskresenky (2004)


(back)

35

Model IX

No Pions Gaps from Takatsuka &

Tamagaki (2004) Ts-Tin from Blaschke,

Grigorian, Voskresenky (2004)


(back)

36

Model III





(back)

37

Model II





(back)

38

Model IV





(back)

39

Model V





(back)

40

Model VI



Ts-Tin from Yakovlev et al. (2004)


(back)

41

Model VII

Pions Gaps from Yakovlev et

al. (2004), 3P2 neutron gap suppressed by 0.1.

1P0 proton gap suppressed by 0.5



(back)

42

Model VIII


(2004), 3P2 neutron gap suppressed by 0.1. 1P0

proton gap suppressed by 0.2 and 1P0 neutron gap suppressed by 0.5.



(back)

Close-by young isolated NSs: A new test for cooling curves Sergei Popov (Sternberg Astronomical...

Documents

Transcript of Close-by young isolated NSs: A new test for cooling curves Sergei Popov (Sternberg Astronomical...