The Zoo Of Neutron Stars

transcript

The Zoo The Zoo Of Of

Neutron StarsNeutron Stars

Sergei PopovSergei Popov

((SAI MSUSAI MSU))(www.bradcovington.com)

JINR, Dubna, August 30, 2006

Main reviewsMain reviews•NS basics: physics/0503245

•SGRs & AXPs: astro-ph/040613

•Magnetars:- Observations astro-ph/0505491 - Theory astro-ph/0504077

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

•The Magnificent Seven: astro-ph/0502457

•RRATs: astro-ph/0511587

•Cooling of NSs: astro-ph/0508056

http://xray.sai.msu.ru/~polar/sci_rev/ns.htmlТруды ГАИШ том 72 (2003)

PredictionPrediction ... ...

Neutron stars have been predicted in 30s:

L.D. Landau: Star-nuclei (1932) + anecdote

Baade and Zwicky: neutron stars and supernovae (1934)

(Landau)

(Baade)

(Zwicky)

Neutron starsNeutron stars

Radius: 10 kmMass: 1-2 solarDensity: about the nuclearStrong magnetic fields

Neutron starsNeutron stars - 2 - 2

Superdence matter and superstrong magnetic fields

The old zoo of neutron starsThe old zoo of neutron stars

In 60s the first X-ray sources have been discovered.

They were neutron stars in close binary systems, BUT ... .... they were «not recognized»....

Now we know hundredsof X-ray binaries with neutron stars in the Milky Way and in other galaxies.

Rocket experimentsRocket experimentsSco X-1Sco X-1

Giacconi, Gursky, Hendel

In 2002 R. Giacconi was awarded with theNobel prize.

UHURUUHURU

The satellite was launched on December 12, 1970.The program was ended inMarch 1973. The other name SAS-1

2-20 keV

The first full sky survey.339 sources.

Accretion in close binariesAccretion in close binaries

Accretion is the most powerfulsource of energyrealized in Nature,which can give a hugeenergy output.

When matter fall down onto the surface of a neutron star up to 10%of mc2 can be released.

Accretion discAccretion discThe theory ofaccretion discswas developed in 1972-73 byN.I. Shakura andR.A. Sunyaev.

Accretion is important not onlyin close binaries,but also in active galactic nuclei and manyother types ofastrophysical sources.

Close binary systemsClose binary systems

About ½ of massive starsAre members of close binarysystems.

Now we know many dozens of close binary systems withneutron stars.

•L=Mηc2

The accretion rate can be up to 1020 g/s;Accretion efficiency – up to 10%;Luminosity –thousands of hundreds of the solar.

DiscoveryDiscovery !!!! !!!!

1967: Jocelyn Bell. Radio pulsars.

Seredipitous discovery.

The pulsar in the Crab nebulaThe pulsar in the Crab nebula

Evolution of NSs. I.:Evolution of NSs. I.:temperaturetemperature

(Yakovlev et al. (1999) Physics Uspekhi)

more details will be described in the talk by Prof. H. Grigorian

Evolution of neutron stars. II.: Evolution of neutron stars. II.: rotation + magnetic fieldrotation + magnetic field

Ejector → Propeller → Accretor → Georotator

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

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

Magnetorotational evolution of Magnetorotational evolution of radio pulsarsradio pulsars

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

The 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..............

Compact central X-ray sources Compact central X-ray sources in supernova remnantsin supernova remnants

Cas A RCW 103New result: 6.7 hour period(de Luca et al. 2006)Problem: small emitting area

Puppis APuppis AOne of the most famouscentral compact X-ray sources in supernova remnants.

Age about 3700 years.

Probably the progenitor wasa very massive star(mass about 30 solar).

New results:Vkick=1500 km/s

Winkler, Petre 2006(astro-ph/0608205)

MagnetarsMagnetars

dE/dt > dEdE/dt > dErotrot/dt/dt By definition:By definition: The energy of the magnetic field is The energy of the magnetic field is

released released P-PdotP-Pdot Direct measurements of the field (Ibrahim et al.)Direct measurements of the field (Ibrahim et al.)

Magnetic fields 1014–1015 G

Known magnetarsKnown magnetarsSGRsSGRs 0526-660526-66 1627-411627-41 1806-201806-20 1900+141900+14 +candidates+candidates

AXPsAXPs CXO 010043.1-72CXO 010043.1-72 4U 0142+614U 0142+61 1E 1048.1-59371E 1048.1-5937 1 RXS J170849-401 RXS J170849-40 XTE J1810-197XTE J1810-197 1E 1841-0451E 1841-045 AX J1844-0258AX J1844-0258 1E 2259+5861E 2259+586

(СТВ 109)

Magnetars on the GalaxyMagnetars on the Galaxy

4 SGRs, 9 AXPs, plus candidates, plus 4 SGRs, 9 AXPs, plus candidates, plus radio pulsars with high magnetic fields…radio pulsars with high magnetic fields…

Young objects (about 10Young objects (about 1044 year). year). Probably about 10% of all NSs.Probably about 10% of all NSs.

Historical notesHistorical notes 05 March 1979. The ”Konus” experiment & Co. 05 March 1979. The ”Konus” experiment & Co.

Venera-11,12 (Mazets et alVenera-11,12 (Mazets et al.., Vedrenne et al.), Vedrenne et al.) Events in the LMC. SGR 0520-66.Events in the LMC. SGR 0520-66. Fluence: about 10Fluence: about 10-3-3 erg/cm erg/cm22

Mazets et al. 1979

N49 – supernovaremnant in theLarge Magellaniccloud(e.g. G. Vedrenne et al. 1979)

Main types of activity of SGRsMain types of activity of SGRs

Weak bursts. L<10Weak bursts. L<104141 erg/s erg/s Intermediate.Intermediate. L=10L=104141–10–104343 erg/s erg/s Giant. L<10Giant. L<104545 erg/s erg/s Hyperflares. L>10Hyperflares. L>104646 erg/s erg/s

See the review inWoods, Thompsonastro-ph/0406133

Power distribution is similarto the distribution of earthquakes

in magnitude

NormalNormal ( (weakweak) ) bursts of bursts of SGRsSGRs and AXPsand AXPs

Typical bursts of Typical bursts of SGR 1806-29, SGR 1806-29,

SGR 1900+14SGR 1900+14 And of AXP 1E And of AXP 1E

2259+586 2259+586 detected bydetected by RXTE RXTE (from(from the review by the review by Woods, Thompson, Woods, Thompson, 2004, 2004, astro-ph/0406133)astro-ph/0406133)

(from Woods, Thompson 2004)

Intermediate SGR bursts Intermediate SGR bursts

Examples of Examples of intermediate bursts.intermediate bursts.

The forth (bottom The forth (bottom right) is sometimes right) is sometimes defined as a giant defined as a giant burst (for example burst (for example by Mazets et al.). by Mazets et al.).

(from Woods, Thompson 2004)

Giant flare of the SGR 1900+14 Giant flare of the SGR 1900+14 (27 August 1998)(27 August 1998)

Ulysses observations Ulysses observations (figure(figure from Hurley from Hurley et al. 1999)et al. 1999)

Initial spike 0.35 sInitial spike 0.35 s P=5.16 sP=5.16 s L>3 10L>3 104444 erg/s erg/s EETOTALTOTAL>10>1044 44 ergerg

Hurley et al. 1999

SGRs: periods and giant flares SGRs: periods and giant flares

0526-660526-66 1627-411627-41 1806-201806-20 1900+141900+14

P, s Giant flares

5 March 1979

27 Aug 1998

24 Dec 2004

18 June 1998 (?)

See the review inWoods, Thompsonastro-ph/0406133

New result:oscillationsin the “tail”.“Trembling”of the crust(Israel et al. 2005,Watts and Strohmayer 2005).

Anomalous X-ray pulsarsAnomalous X-ray pulsars

Identified as a separate group in 1995. (Mereghetti, Stella 1995 Van Paradijs et al.1995)

• Similar periods (5-10 sec)• Constant spin down• Absence of optical companions• Relatively weak luminosity• Constant luminosity

Known AXPsKnown AXPs

CXO 010043.1-72CXO 010043.1-72 8.08.0

4U 0142+614U 0142+61 8.78.7

1E 1048.1-59371E 1048.1-5937 6.46.4

1RXS J170749-401RXS J170749-40 11.011.0

XTE J1841-197XTE J1841-197 5.55.5

1E 1841-0451E 1841-045 11.811.8

AX J1844-0258AX J1844-0258 7.07.0

1E 2259+5861E 2259+586 7.07.0

Sources Periods, s

Pulse profilesof SGRs and AXPs

Are SGRs and AXPs brothers?Are SGRs and AXPs brothers?

Bursts of AXPsBursts of AXPs Spectral propertiesSpectral properties Quiescent periods Quiescent periods

of SGRs (0525-66 of SGRs (0525-66 sincesince 1983)1983)

Gavriil et al. 2002

Theory of magnetarsTheory of magnetars

Thompson, Duncan ApJ Thompson, Duncan ApJ 408, 194 (1993)408, 194 (1993)

Convection in a protoNS Convection in a protoNS results in generation of results in generation of strong magnetic fieldstrong magnetic field

Reconfiguration of the Reconfiguration of the magnetic field structuremagnetic field structure

(Figures from the web-page of Duncan)

Generation of the magnetic fieldGeneration of the magnetic field

The mechanism of the magnetic field generation is still unknown.

Turbulent dynamo

α-Ω dynamo (Duncan,Thompson) α2 dynamo (Bonanno et al.) or their combination

In any case, initial rotation of aprotoNS is the critical parameter.

Strong field via flux Strong field via flux conservationconservation

There are reasons to suspect that the magnetic fields of magnetars are not due to any kind of dynamo mechanism, but just due to flux conservation:

1. Study of SNRs with magnetars (Vink and Kuiper 2006). If there was a rapidly rotating magnetar then a huge energy release is inevitable. No traces of such energy injections are found.

2. There are few examples of massive stars with field strong enough to produce a magnetars due to flux conservation (Ferrario and Wickramasinghe 2006)

Still, these suggestions can be criticized

Alternative theoryAlternative theory Remnant fallback discRemnant fallback disc Mereghetti, Stella 1995Mereghetti, Stella 1995 Van Paradijs et al.1995Van Paradijs et al.1995 Alpar 2001Alpar 2001 Marsden et al. 2001Marsden et al. 2001 Problems …..Problems ….. How to generate strong How to generate strong

bursts?bursts? Discovery of a passiveDiscovery of a passive disc in one of AXPs disc in one of AXPs (Wang et al. 2006).(Wang et al. 2006). New burst of interestNew burst of interest to this model.to this model.

Magnetic field estimatesMagnetic field estimates

Direct Direct measurements of measurements of magnetic field magnetic field (cyclotron lines)(cyclotron lines)

Spin downSpin down Long spin periods Long spin periods

Ibrahim et al. 2002

Hyperflare of SGR 1806-20Hyperflare of SGR 1806-20

27 December27 December 2004 2004 A giant flare from A giant flare from SGR 1806-20 was SGR 1806-20 was detected by many detected by many satellites: Swift, satellites: Swift, RHESSI, Konus-RHESSI, Konus-Wind, Coronas-F, Wind, Coronas-F, Integral, HEND, …Integral, HEND, …

100 times brighter 100 times brighter than any other!than any other!

Palmer et al.astro-ph/0503030

Integral

RHESSI

CORONAS-F

27 Dec 200427 Dec 2004Giant flareGiant flare

SGR 1806-20 SGR 1806-20 Spike 0.2 sSpike 0.2 s FluenceFluence 1 erg/cm1 erg/cm22

E(spike)E(spike)==3.5 103.5 1046 46 ergerg L(spike)L(spike)==1.8 101.8 1047 47 erg/serg/s LongLong « «tailtail»» (400 s) (400 s) P=7.65 sP=7.65 s E(tail) 1.6 10E(tail) 1.6 104444 erg erg Distance 15 kpcDistance 15 kpc

Konus observations.Konus observations.SGR 1806-20 27 Dec 2004 SGR 1806-20 27 Dec 2004

Mazets et al. 2005

The myth about MedusaThe myth about Medusa

What is special about What is special about magnetarsmagnetars??

Westerlund 1

Link withLink with massive starsmassive starsThere are reasons to suspect that magnetars are connected to massive stars.

Link to binary starsThere is a hypothesis that magnetars are formed in close binary systems (astro-ph/0505406).

The question is still on the list.

ROSATROSATROentgen SATellite

Launched 01 June 1990. The program was successfully endedon 12 Feb 1999.

German satellite(with participation of US and UK).

Close-by radio quiet NSsClose-by radio quiet NSs Discovery: Discovery:

Walter et al. (1996)Walter et al. (1996) Proper motion and Proper motion and

parallax: parallax: Kaplan et al.Kaplan et al. No pulsationsNo pulsations Thermal spectrumThermal spectrum Later on: Later on: six brotherssix brothers

RX J1856.5-3754

Relatives of magnetars?Relatives of magnetars?

SourceSource Period, sPeriod, s

RX 1856RX 1856 --

RX 0720RX 0720 8.398.39

RBS 1223RBS 1223 10.31 10.31

RBS 1556RBS 1556 --

RX 0806RX 0806 11.3711.37

RX 0420RX 0420 3.453.45

RBS 1774RBS 1774 9.449.44

Radio quietCloseYoungThermal emissionLong periods

The Magnificent seven

XDINS? RINS? ICoNS? PuTINS?

Radio detection of the Radio detection of the Magnificent SevenMagnificent Seven

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.

Malofeev et al, Atel #798, 2006Malofeev et al, Atel #798, 20061RXS J2143.7+065419 (RBS 1774)1RXS J2143.7+065419 (RBS 1774)

Unidentified EGRET sourcesUnidentified EGRET sourcesGrenier (2000), Gehrels et al. (2000) Unidentified sources are divided into several groups.One of them has sky distribution similar to the Gould Belt objects.

It is suggested that GLAST (and, probably, AGILE)Can help to solve this problem.

Actively studied subject (see for example papers by Harding, Gonthier)

New results: no radio pulsars in 56 EGRET error boxes (Crawford et al. 2006)

Discovery of Discovery of radio transientsradio transients

McLaughlin et al. (2006) discovered a new type of sources– RRATs (Rotating Radio Transients).

For most of the sources periods about few seconds were discovered.The result was obtained during the Parkes survey of the Galactic plane.

These sources can be related to The Magnificent seven.

Thermal X-rays were observed from one of the RRATs(Reynolds et al. 2006). This one seems to me the youngest.

P-Pdot diagram forP-Pdot diagram for RRATsRRATs

McLaughlin et al. 2006 Nature

Estimates show that there should be about 400 000

Sources of this type in the Galaxy.

Young or old???

Relatives of theMagnificent seven?(astro-ph/0603258)

ConclusionConclusion There are several types of There are several types of

sourcessources: : CCOs, M7CCOs, M7, ,

SGRs, AXPs, RRATsSGRs, AXPs, RRATs ... ... Magnetars (?)Magnetars (?) Significant fraction of all Significant fraction of all

newborn NSsnewborn NSs Unsolved problemsUnsolved problems::

1. 1. Are there linksAre there links??

2. 2. Reasons for diversity Reasons for diversity

Dorothea Rockburne

That’s all, folksThat’s all, folks!!