Transcript Document

The Zoo
Of
Neutron Stars
Sergei Popov
(SAI MSU)
(www.bradcovington.com)
Main reviews
Труды ГАИШ том 72 (2003)
•NS basics:
physics/0503245
•SGRs & AXPs:
astro-ph/0406133
•Magnetars:
-Observations
AXPs
- Theory
astro-ph/0610304
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
2
http://xray.sai.msu.ru/~polar/sci_rev/ns.html
Prediction ...
Neutron stars have been predicted in 30s:
L.D. Landau:
Star-nuclei (1932) + anecdote
Baade and Zwicky:
neutron stars and supernovae (1934)
(Landau)
(Zwicky)
(Baade)
3
Neutron stars
Radius: 10 km
Mass: 1-2 solar
Density: about the nuclear
Strong magnetic fields
4
Neutron stars - 2
Superdence matter and superstrong magnetic fields
5
The 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 hundreds
of X-ray binaries with
neutron stars in the
Milky Way and in other
galaxies.
6
Rocket experiments
Sco X-1
Giacconi, Gursky, Hendel
1962
In 2002 R. Giacconi
was awarded with the
Nobel prize.
7
UHURU
The satellite was launched on
December 12, 1970.
The program was ended in
March 1973.
The other name SAS-1
2-20 keV
The first full sky survey.
339 sources.
8
Accretion in close binaries
Accretion is the most powerful
source of energy
realized in Nature,
which can give a huge
energy output.
When matter fall down
onto the surface of a
neutron star up to 10%
of mc2 can be released.
9
Accretion disc
The theory of
accretion discs
was developed
in 1972-73 by
N.I. Shakura and
R.A. Sunyaev.
Accretion is
important not only
in close binaries,
but also in
active galactic
nuclei and many
other types of
astrophysical
sources.
10
Close binary systems
About ½ of massive stars
Are members of close binary
systems.
Now we know many dozens
of close binary systems with
neutron 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.
11
Discovery !!!!
1967: Jocelyn Bell. Radio pulsars.
Seredipitous discovery.
12
The pulsar in the Crab nebula
13
Evolution of NSs. I.:
temperature
(Yakovlev et al. (1999)
Physics Uspekhi)
more details will be described in the
talk by Prof. H. Grigorian
14
Evolution of neutron stars. II.:
rotation + magnetic field
Ejector → Propeller → Accretor → Georotator
1 – spin down
2 – passage through a molecular cloud
3 – magnetic field decay
astro-ph/0101031
See the book by Lipunov (1987, 1992)
15
Magnetorotational evolution of
radio pulsars
Spin-down.
Rotational energy is released.
The exact mechanism is
still unknown.
16
The new zoo of neutron stars
During 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..............
17
Compact central X-ray sources
in supernova remnants
Cas A
Problem: small emitting area
RCW 103
New result: 6.7 hour period
(de Luca et al. 2006)
18
Puppis A
One of the most famous
central compact X-ray
sources in supernova
remnants.
Age about 3700 years.
Probably the progenitor was
a very massive star
(mass about 30 solar).
New results:
Vkick=1500 km/s
Winkler, Petre 2006
(astro-ph/0608205)
19
Magnetars




dE/dt > dErot/dt
By definition: The energy of the magnetic field is
released
P-Pdot
Direct measurements of the field (Ibrahim et al.)
Magnetic fields 1014–1015 G
20
Known magnetars
AXPs
 CXO 010043.1-72
 4U 0142+61
 1E 1048.1-5937
 CXOU J164710.3 1 RXS J170849-40
 XTE J1810-197
 1E 1841-045
 AX J1844-0258
 1E 2259+586
SGRs
 0526-66
 1627-41
 1806-20
 1900+14
 +candidates
(СТВ 109)
21
Magnetars on the Galaxy
4 SGRs, 9 AXPs, plus candidates, plus
radio pulsars with high magnetic fields…
 Young objects (about 104 year).
 Probably about 10% of all NSs.

22
Historical notes



05 March 1979. The ”Konus” experiment & Co.
Venera-11,12 (Mazets et al., Vedrenne et al.)
Events in the LMC. SGR 0520-66.
Fluence: about 10-3 erg/cm2
Mazets et al. 1979
23
N49 – supernova
remnant in the
Large Magellanic
cloud
(e.g. G. Vedrenne
et al. 1979)
24
Main types of activity of SGRs
 Weak
bursts. L<1041 erg/s
 Intermediate. L=1041–1043 erg/s
 Giant. L<1045 erg/s
 Hyperflares. L>1046 erg/s
Power distribution is similar
to the distribution of earthquakes
in magnitude
See the review in
Woods, Thompson
astro-ph/0406133
25
Normal (weak) bursts of
SGRs and AXPs

Typical bursts of
SGR 1806-29,
SGR 1900+14
And of AXP 1E
2259+586
detected by RXTE
(from the review
by Woods,
Thompson, 2004,
astro-ph/0406133)
(from Woods, Thompson 2004)
26
Intermediate SGR bursts
Examples of
intermediate bursts.
The forth (bottom
right) is sometimes
defined as a giant
burst (for example
by Mazets et al.).
(from Woods, Thompson 2004)
27
Giant flare of the SGR 1900+14
(27 August 1998)
Ulysses observations
(figure from
Hurley et al. 1999)
 Initial spike 0.35 s
 P=5.16 s
 L>3 1044 erg/s
 ETOTAL>1044 erg

Hurley et al. 1999
28
SGRs: periods and giant flares
P, s
Giant flares
 0526-66
8.0
5 March 1979
 1627-41
6.4
 1806-20
7.5
27 Dec 2004
 1900+14
5.2
27 Aug 1998
New result:
oscillations
in the “tail”.
“Trembling”
of the crust
(Israel et al. 2005,
Watts and Strohmayer 2005).
18 June 1998 (?)
See the review in
Woods, Thompson
astro-ph/0406133
29
Anomalous 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
30
Known AXPs
Sources
Periods, s
CXO 010043.1-72 8.0
4U 0142+61
8.7
1E 1048.1-5937
6.4
CXOU J164710.2-
10.6
1RXS J170849-40 11.0
XTE J1810-197
5.5
1E 1841-045
11.8
AX J1845-0258
7.0
1E 2259+586
7.0
31
Pulse profiles
of SGRs and AXPs
32
Are SGRs and AXPs brothers?
Bursts of AXPs
 Spectral properties
 Quiescent periods
of SGRs (0525-66
since 1983)

Gavriil et al. 200233
Theory of magnetars
Thompson, Duncan
ApJ 408, 194 (1993)
 Convection in a protoNS
results in generation of
strong magnetic field
 Reconfiguration of the
magnetic field structure

(Figures from the web-page of Duncan)
34
Generation 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 a
protoNS is the critical parameter.
35
Strong field via flux
conservation
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
36
Alternative theory








Remnant fallback disc
Mereghetti, Stella 1995
Van Paradijs et al.1995
Alpar 2001
Marsden et al. 2001
Problems …..
How to generate strong
bursts?
Discovery of a passive
disc in one of AXPs
(Wang et al. 2006).
New burst of interest
to this model.
37
Magnetic field estimates
Direct
measurements of
magnetic field
(cyclotron lines)
 Spin down
 Long spin periods

Ibrahim et al. 2002
38
Hyperflare of SGR 1806-20
27 December 2004
A giant flare from
SGR 1806-20 was
detected by many
satellites: Swift,
RHESSI, KonusWind, Coronas-F,
Integral, HEND, …
 100 times brighter
than any other!

Palmer et al.
astro-ph/0503030
39
C
O
R
O
N
A
S
F
Integral
RHESSI
40
27 Dec 2004
Giant flare
SGR 1806-20
Spike 0.2 s
 Fluence 1 erg/cm2
 E(spike)=3.5 1046 erg
 L(spike)=1.8 1047 erg/s
 Long «tail» (400 s)
 P=7.65 s
 E(tail) 1.6 1044 erg
 Distance 15 kpc

41
Konus observations.
SGR 1806-20 27 Dec 2004
Mazets et al. 2005
42
The myth about Medusa
43
What is special about
magnetars?
Link with massive stars
There are reasons to suspect
that magnetars are connected
to massive stars.
Link to binary stars
There is a hypothesis that
magnetars are formed in close
binary systems
(astro-ph/0505406).
Westerlund 1
The question is still on the list.
44
ROSAT
ROentgen SATellite
German satellite
(with participation of US and UK).
Launched 01 June 1990.
The program was successfully ended
on 12 Feb 1999.
45
Close-by radio quiet NSs
Discovery:
Walter et al.
(1996)
 Proper motion and
parallax:
RX J1856.5-3754
Kaplan et al.
 No pulsations
 Thermal spectrum
 Later on:
six brothers

46
Relatives of magnetars?
Source
Period, s
RX 1856
-
RX 0720
8.39
RBS 1223
10.31
RBS 1556
-
RX 0806
The Magnificent seven
11.37
RX 0420
3.45
RBS 1774
9.44
Radio quiet
Close
Young
Thermal emission
Long periods
XDINS? RINS? ICoNS? PuTINS?
47
Radio detection of the
Magnificent Seven
Malofeev et al. (2005) reported
detection of
1RXS J1308.6+212708
(RBS 1223)
in the low-frequency band (60110 MHz)
with the radio telescope in
Pushchino.
Malofeev et al, Atel #798, 2006
1RXS J2143.7+065419 (RBS 1774)
48
Unidentified EGRET sources
Grenier (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)
49
Discovery of
radio 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.
50
P-Pdot diagram for RRATs
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 the
Magnificent seven?
(astro-ph/0603258)
51
Conclusion
There are several types
of sources: CCOs, M7,
SGRs, AXPs, RRATs ...
 Magnetars (?)
 Significant fraction of all
newborn NSs
 Unsolved problems:
1. Are there links?
2. Reasons for diversity

52
Dorothea Rockburne
53
That’s all, folks!
54
Main reviews
Труды ГАИШ том 72 (2003)
•NS basics:
physics/0503245
•SGRs & AXPs:
astro-ph/0406133
•Magnetars:
-Observations
AXPs
- Theory
astro-ph/0610304
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
55
http://xray.sai.msu.ru/~polar/sci_rev/ns.html