New adventures of UncatchablesNew adventures of Uncatchables

Sergei PopovSAI MSU

(astro-ph/0609275 and work in progress)

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Plan of the talkPlan of the talk

Intro. Pop. synthesis Some old results Two tests New improvements1. Initial distribution2. Mass spectrum and abundances3. ISM distribution Maps Age and distance distributions Where to search? Final conclusions

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Good old classicsGood old classicsGood old classicsGood old classics

The pulsar in the Crab nebulaThe pulsar in the Crab nebula A binary systemA binary system

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The new zoo of neutron starsThe new zoo of neutron starsThe new zoo of neutron starsThe new zoo of neutron starsDuring last 10 years it became clear that neutron stars can be born very different.In particular, absolutely non-similar to the Crab pulsar.

o Compact central X-ray sources in supernova remnants.

o Anomalous X-ray pulsars

o Soft gamma repeaters

o The Magnificent Seven

o Unidentified EGRET sources

o Transient radio sources (RRATs) ….

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Main reviewsMain reviewsMain reviewsMain reviews•NS basics: physics/0503245

•SGRs & AXPs: astro-ph/0406133

•Magnetars:-Observations AXPs astro-ph/0610304 SGR astro-ph/0608364- Theory astro-ph/0504077

•Central compact X-ray sources in supernova remnants: astro-ph/0311526

•The Magnificent Seven: astro-ph/0609066

•RRATs: astro-ph/0608311

•Cooling of NSs: astro-ph/0508056 Труды ГАИШ том 72 (2003)

http://xray.sai.msu.ru/~polar/sci_rev/ns.html

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Isolated neutron stars population: Isolated neutron stars population:

in the Galaxy and at the backyard in the Galaxy and at the backyard

Isolated neutron stars population: Isolated neutron stars population:

in the Galaxy and at the backyard in the Galaxy and at the backyard INSs appear in many flavours

Radio pulsarsAXPsSGRsCCOsRINSsRRATs

Local population of young NSs is different (selection)

Radio pulsarsGeminga+RINSs

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Evolution of NSs. I.:temperatureEvolution of NSs. I.:temperature

[Yakovlev et al. (1999) Physics Uspekhi]

First papers on the thermalevolution appeared already in early 60s, i.e. before the discovery of radio pulsars.

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Evolution of neutron stars. II.:

rotation + magnetic field

Evolution of neutron stars. II.:

rotation + magnetic fieldEjector → Propeller → Accretor → Georotator

See the book by Lipunov (1987, 1992)astro-ph/0101031

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

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Magnetorotational evolution of radio Magnetorotational evolution of radio pulsarspulsarsMagnetorotational evolution of radio Magnetorotational evolution of radio pulsarspulsars

Spin-down.Rotational energy is released.The exact mechanism is still unknown.

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Close-by radioquiet NSsClose-by radioquiet NSsClose-by radioquiet NSsClose-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 SevenMagnificent Seven

Name Period, sRX 1856 7.05RX 0720 8.39RBS 1223 10.31 RBS 1556 6.88?RX 0806 11.37RX 0420 3.45RBS 1774 9.44

Radioquiet (?)Close-byThermal emissionAbsorption featuresLong periods

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Population of close-by young NSsPopulation 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.

Where are the rest?UNCATCHABLES

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Population synthesis: ingredientsPopulation synthesis: ingredients

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

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

To build an artificial model

of a population of some astrophysical sources and

to compare the results ofcalculations with observations.

Task:

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Gould Belt : 20 NS Myr-1

Gal. Disk (3kpc) : 250 NS Myr-1

Arzoumanian et al. 2002

ROSAT

• Cooling curves by• Blaschke et al. • Mass spectrum

18°Gould BeltGould Belt

Population synthesis – I. Population synthesis – I.

© Bettina Posselt

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Solar vicinitySolar 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 BeltThe 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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Initial spatial distributionInitial spatial distribution

A very simple model for PS-I: The Gould Belt as a flat inclined disc pluscontribution from the galactic disc up to 3 kpc.

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Mass spectrum of NSsMass 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(masses of secondary objects in NS+NS)

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Woosley et al. 2002

Progenitor mass vs. NS massProgenitor mass vs. NS massProgenitor mass vs. NS massProgenitor mass vs. NS mass

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Log N – Log S 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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Some results of PS-I:Log N – Log S and spatial distribution

Some results of PS-I:Log N – Log S and spatial distribution

(Popov et al. 2005 Ap&SS 299, 117)

More than ½ are in+/- 12 degrees from the galactic plane.19% outside +/- 30o

12% outside +/- 40o

Log N – Log S for close-by ROSAT NSs can be explained by standard cooling curves taking into account the Gould Belt.

Log N – Log S can be used as an additional

test of cooling curves

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Two testsTwo tests

Age – Temperature

&

Log N – Log S

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Standard test: temperature vs. Standard test: temperature vs. ageageStandard test: temperature vs. Standard test: temperature vs. ageage

Kaminker et al. (2001)

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Uncertainties in temperatureUncertainties in temperatureUncertainties in temperatureUncertainties in temperature

(Pons et al. astro-ph/0107404)

• Atmospheres (composition)• Magnetic field• Non-thermal contributions to the spectrum• Distance• Interstellar absorption• Temperature distribution

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Luminosity and age uncertaintiesLuminosity and age uncertaintiesLuminosity and age uncertaintiesLuminosity and age uncertainties

Page, Geppertastro-ph/0508056

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Log N – Log S as an additional testLog N – Log S as an additional testLog N – Log S as an additional testLog N – Log S as an additional test

Standard test: Age – TemperatureSensitive to ages <105 yearsUncertain age and temperatureNon-uniform sample

Log N – Log SSensitive 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)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 IModel I Pions. Gaps from Takatsuka & Tamagaki

(2004) Ts-Tin from Blaschke, Grigorian,

Voskresenky (2004)

Can reproduce observed Log N – Log S

(astro-ph/0411618)

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Model IIModel 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 IIIModel 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 IVModel 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 VModel 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 VIModel 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 VIIModel 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 VIIIModel 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 IXModel 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 constraintBrightness constraintBrightness constraintBrightness 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 SSensitivity of Log N – Log SSensitivity of Log N – Log SSensitivity 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

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Mass constraintMass constraintMass constraintMass constraint• Mass spectrum has to be taken into account when discussing data on cooling• Rare masses should not be used to explain the cooling data• Most of data points on T-t plot should be explained by masses <1.4 Msun

In particular:• Vela and Geminga should not be very massive

Phys. Rev .C (2006)nucl-th/0512098(published as a JINR preprint)

Cooling curves fromKaminker et al.

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Another attempt to test a set of Another attempt to test a set of models. models. Hybrid stars. Astronomy meets Hybrid stars. Astronomy meets QCDQCD

Another attempt to test a set of Another attempt to test a set of models. models. Hybrid stars. Astronomy meets Hybrid stars. Astronomy meets QCDQCD

We studied several models for hybrid stars applying all possible tests: - T-t- Log N – Log S- Brightness constraint- Mass constraint

nucl-th/0512098

We also tried to present examples when a model successfully passesthe Log N – Log S test, but fails to pass the standard T-t test or fails tofulfill the mass constraint.

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Model IModel I

Brightness - OKT-t - OKLog N – Log S - poorMass - NO

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Model IIModel II

Brightness - OK

T-t - No

Log N – Log S - OK

Mass - NO

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Model IIIModel III

Brightness - OK

T-t - poor

Log N – Log S - OK

Mass - NO

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Model IVModel IV

Brightness - OK

T-t - OK

Log N – Log S - OK

Mass - OK

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Resume for HySsResume for HySsResume for HySsResume for HySs

One model among four was able to pass all tests.

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1. Spatial distribution of progenitor stars

a) Hipparcos stars up to 500 pc[Age: spectral type & cluster age (OB

ass)]b) 49 OB associations: birth rate ~

Nstar

c) Field stars in the disc up to 3 kpc

Population sythesis – II.recent improvementsPopulation sythesis – II.recent improvements

Solid – new initial XYZDashed – Rbelt = 500 pcDotted – Rbelt = 300 pc

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Population sythesis – II.recent improvementsPopulation sythesis – II.recent improvements

2. New cross sections & abundances and new mass spectrum

Solid – new abundances, old massDotted – old abundances, old massDashed – new abundances, new mass

Low mass stars are treated followingastro-ph/0409422

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3. Spatial distribution of ISM (NH)

instead of :

now :

Population synthesis – II.recent improvementsPopulation synthesis – II.recent improvements

Dot-dashed and dot-dot-dashed linesRepresent two new models of theISM distribution.

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b= +90°

b= -90°

Popov et al. 2005

Count rate > 0.05 cts/s

OriSco OB

Cep?Per?

PSRs+

Geminga+

M7

PSRs-

First results: new mapsFirst results: new maps

Clearly several richOB associations startto dominate in thespatial distribution

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INSs and local surroundingINSs and local surrounding

De Zeeuw et al. 1999 Motch et al. 2006

Massive star population in the Solar vicinity (up to 2 kpc) is dominated by OB associations. Inside 300-400 pc the Gould Belt is mostly important.

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50 000 tracks, new ISM model50 000 tracks, new ISM model

AguerosChieregato

Candidates:

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Age and distance distributionsAge and distance distributions

Age

1 < cts/s < 10 0.1 < cts/s < 1 0.01 < cts/s < 0.1

Distance

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Where to search for more cowboys?Where to search for more cowboys?

We do not expect to find much more candidates at fluxes >0.1 cts/s.

Most of new candidates should be at fluxes 0.01< f < 0.1 cts/s.So, they are expected to be young NSs (<few 100 Mys) just outside the Belt.I.e., they should be in nearby OB associations and clusters.

Most probable candidates are Cyg OB7, Cam OB1, Cep OB2 and Cep OB3.Orion region can also be promising.

Name           l-      l+      b-    b+      Dist., pc

Cyg OB7     84      96     -5     9       600-700

Cep OB2     96     108    -1   12       700

Cep OB3    108    113     1     7       700-900

Cam OB1   130    153    -3     8       800-900

0

10

-10

L=110 90130

(ads.gsfc.nasa.gov/mw/)

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Resume Resume

New more detailed population synthesis model for local population of isolated NS is made

New results provide a hint to search for new coolers. We predict that new objects can be identified at

0.01<cts/s<0.1 behind the Gould Belt in the directions of close-by rich OB associations, in particular Cep OB2.

These objects are expected to be younger and hotter than the Magnificent seven.

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The Magnificent Seven Vs. UncatchablesThe Magnificent Seven Vs. Uncatchables

Born in the Gould Belt.Bright. Middle-aged.Already observed.

Born behind the Belt.Dimmer. Younger.Wanted.

I thank all scientists with whom I collaborated during

different stages of work on INSs and had fruitful discussions:

D. Blaschke, M. Colpi, H. Grigorian, F. Haberl, V. Lipunov,

R. Neuhauser, B. Posselt, M. Prokhorov, A. Treves, J. Trumper, ….

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Main reviewsMain reviewsMain reviewsMain reviews•NS basics: physics/0503245

•SGRs & AXPs: astro-ph/0406133

•Magnetars:-Observations AXPs astro-ph/0610304 SGR astro-ph/0608364- Theory astro-ph/0504077

•Central compact X-ray sources in supernova remnants: astro-ph/0311526

•The Magnificent Seven: astro-ph/0609066

•RRATs: astro-ph/0608311

•Cooling of NSs: astro-ph/0508056 Труды ГАИШ том 72 (2003)

http://xray.sai.msu.ru/~polar/sci_rev/ns.html

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Radio detectionRadio 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.

In 2006 Malofeev et al. reported radio detectionof another one.

(back)

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NS+NS binariesNS+NS binaries

Pulsar Pulsar mass Companion mass

B1913+16 1.44 1.39B2127+11C 1.35 1.36B1534+12 1.33 1.35J0737-3039 1.34 1.25J1756-2251 1.40 1.18

(PSR+companion)/2

J1518+4904 1.35J1811-1736 1.30J1829+2456 1.25

(David Nice, talk at Vancouver 2005)

(Back)