history i - issi · white dwarfs xte j0929-314 xte j1751-305 xte j1807-294 igr j00291+5934 sax...
TRANSCRIPT
Maurizio Falanga
Millisecond X-ray pulsars: 10 years of progress
History I
Radio Astronomy in the 30’s-60’s Radio Astronomy in the 30’s-60’s
Discovery (1961-63) Quasi-Stellar Radio Sources as the most energetic and distant members of a class of objects
3C273
Karl Jansky 1933
1967
Radio Signals from the Sky
Jocelyn Bell (1943-)
- They soon realized that the best clocks of the time were not accurate enough to time the object. It seemed very unnatural to receive such a perfectly regular signal from space!
Period of 1.337 s 1.3372866576 s
LGM-1 (Little Green Men)
- It could originate from extra terrestrial intelligence?
History II
M. Falanga
A massive star can collapse into something denser (1930). He was awarded the 1983 Nobel Prize in Physics for this fundamental prediction!
M. Falanga
In 1934, F. Zwicky and W. Baade and that a stellar collapse of a heavy star during a supernova event should lead to the formation of a dense core of neutrons (NS) at the center of the SN remnant.
S. Chandrasekhar (1910-1995)
Fritz Zwicky (1898 –1974)
In 1932, James Chadwick, then at the Cavendish Laboratory in Cambridge, England, discovers the neutron. He got the Nobel physics prize in 1935.
James Chadwick (1891-1974)
During the course of the next few months, J. Bell discovered 3 more pulsating radio sources (or pulsars). These pulsars were proposed to be rapidly rotating neutron stars.
PULSARS are NEUTRON STARS Anthony Hewish, won the Nobel Prize in Physics for the discovery in 1974.
R ~ 10 km ! ~1014g/cm3 M ~ 1.4 Msun -! Magnetic dipole -! Electromagnetic radiation -! Pulsar slowdown
Properties of neutron stars:
Core collapse of an evolved star •! Stellar core collapse => conservation of angular momentum => fast
spinning neutron star! •! Stellar core collapse => conservation of magnetic flux => highly
magnetized neutron star
•! Pacini (1967) proposed the existence of a highly magnetized, rapidly spinning neutron star as the power source of the nebula. This would radiate a very powerful EM wave with the rotational frequency of the star. This is below the plasma frequency of the nebula, therefore all this energy will be absorbed and re-radiated by the plasma of the nebula.
1968: The discovery of PSR B0531+21 (Crab Pulsar)
1968: The discovery of PSR B0531+21 (Crab Pulsar) PSR B0531+21 (Crab Pulsar) PSR B0531+21 (Crab Pulsar) These extremely short bursts (~33 ms) proved the
existence of a pulsar at the center of the Nebula. (This is the compact radio source detected by
Hewish and Okoye in 1964)
PSR 0531+21
Crab Nebula
1968: The discovery of 1968: The discovery of 1968: The discovery of In 1968, at the height of the “pulsar fever”, giant radio pulses originating in the Crab Nebula were detected.
1054
Observational confirmation that: !! Pulsars results from stellar collapse in Supernovae
"! W. Baade and F. Zwicky were right
!! The rotational Energy loss of the Crab Pulsar is Exactly the same as the emission of the Crab Nebula
"! Pacini was right, neutron stars are fast, have large magnetic fields, and one of them powers the Crab Nebula.
The basic model of pulsar emission becomes established Pulsars are the radio equivalent of lighthouses on a neutron star
Data from ATNF Pulsar Catalogue, V1.33
ms Pulsars
Pulsars as Clocks
Pspin ~ incredibly stable but not constant
R ~ 10 km ! ~1014g/cm3 M ~ 1.4 Msun
Pulsars lose energy and slow down
Pspin < µs/yr #
Rotation-Powered Pulsars
5.757451831072007 ± 0.000000000000008 ms
e.g., PSR J0437-4715 has a period of :
(www.atnf.csiro.au/research/pulsar/psrcat)
..
.
Stellar Evolution &
Predictions
Recycling model for MSPs
LMXB phase preceding the MSP stage; "! mass transfer stops; "!the radio MSP switches on
Most binary MSPs have short orbital periods and mass function identifying the companions as low mass evolved dwarfs
X-ray transients can be the missing link between LMXBs and MSPs!
Old Neutron stars spin up by accretion from a companion
Accreting NS in LMXBs are conventionally thought to be the progenitors of millisecond or „recycled“ radio pulsars (Alpar et al. 1982)
birth
Spin up by
accretion
Young Pulsars
1.! We have to discover the first Accreting Millisecond X-ray Pulsar (AMXP)
2. We have to discover an AMXP spinning-up 3. We have to prove that LMXB are the
progenitors of radio millisecond pulsar
1998 the first Accreting Millisecond X-ray Pulsar
&
The growing family of the X-ray millisecond pulsars
20
!! 14 MSP
!! Ps 180-600 Hz !! Porb 40 min. - few hrs. (e.g., Wijnands 2004)
L ~ 1031-1032 erg/s L ~ 1036-1038 erg/s Recurence time 2-5yr
Close X-ray binaries:
Companion: M << Msun
NS: B~108-9 G
20
21
Source Name PSpin POrbit MC,Min Discovered
SAX J1808.4-3658 (ms) (min) (M$)
2.5 120 Apr. 1998 0.043
XTE J1751-306 2.3 42 0.014 Apr. 2002
XTE J0929-314 Apr. 2002 5.4 44 0.083
XTE J1807-294
IGR J00291+5934
HETE J1900.1-2455
Swift J1756.9-2508
Swift J1749.4-2807
XTE J1814-338
Feb. 2003
Jun. 2003
Dec. 2004
Jun. 2005
Jun. 2007
Sep. 2009
Apr. 2010
IGR J17511-3057
40
258
150
84
54
208
530
0.0066
0.17 0.039
0.016
0.007
5.2
3.2
1.67
2.6
5.5
+ Two Intermittent Pulsars
4.1
1.9 0.13 0.6
21 21
IGR J18245-2452 660 Apr. 2013 3.9 0.204
IGR J00291+5934
SAX J1808.4-3658
2005 the first Accreting Millisecond X-ray Pulsar spinning-up
23
(NASA, D. Barry)
23
Pulsar spin-up Animation
Geometry of the emission region
XTE J1807-294
Thermal disk emission
Seed photons from the hotspot
B ~ 108-9 G
Rm
(Falanga et al. 2005, A&A)
"
Thermal Comptonization in plasma of Temperature ~ 40 keV
25 (Falanga, Kuiper, Poutanen et al. 2005)
PULSE PROFILE IGR J00291+5934
Porbit = 2.457 hr
Ps = 1.67 ms
Pdot = +8.4 x 10-13 Hz/s
Mag.
#
25
26
IGR J00291+5934
We measured for the first time a spin-up for an accreting X-ray millisecond Pulsar
$ = + 8.4 % 10-13 Hz s-1
$ = + 3.7 % 10-13 (L37/&-1I45) (Rm/Rco)1/2 (M/1.4Msun) ($spin/600)-1/3 Hz s-1 (Falanga et al. 2005, A&A)
26
27
« Star eats companion »
Cannibalism in Space: A Star Eats its Companion
2013 the first Accreting Millisecond X-ray Pulsar Swinging between rotation and accretion power in a binary millisecond pulsar
Accreting Millisecond X-ray Pulsar in General
Burst oscillations reflect the NS spin frequency
(D. Chakrabarty, Nature, 2003
Time
X-r
ay F
lux
Freq
uenc
y
Flux oscillations are observed in the tails of some bursts
4U 1728-34; 363 Hz ( 2.7 ms)
(Strohmayer et al, 1996 ApJ)
SAX J1808.4-3658
Mag.
#
X-ray bursts
(Falanga et al, 2007, A&A)
Standard Candle to determine the Source Distance: LEdd ' 3 % 1038 erg s-1 (e.g. Kuulkers 2004, ApJ)
Bursts with Photosphere Radius Expansion
(Falanga et al, 2011, A&A)
<F bol,pers >-1.1
!
"M = M•
(t)dt0
Trec
# $
M•
Trec $ cont%
Trec & M• '1
& F '1
36
OUTBURST PROFILE
(For a review Wijnands 2005, astro-ph/0403409)
Outburst are extended as a consequence of X-ray irradiation of the disk?
Distinct knee
(Falanga, Kuiper, Poutanen et al. 2005)
36
Outburst are extended as a consequence of X-ray irradiation of the disk
(Powell, Haswell & Falanga, 2007)
SAX J1808.4-3658
XTE J1751-305
Central object prevents the disk to cool down due to Irradiation, on a viscous time-scale, accounting for the exponential decay of the outburst on a timescale (~20–40 d.
Theory: dwarf novae, SXT
Rh < Rdisc
(King & Ritter 1998)
38
Thank You
Pulsed fraction and Time lag : IGR J00291+5934
If the spectrum has a sharp cutoff, the amplitude of the pulse at energies above the cutoff increases dramatically.
F(E) 'E-()-1) exp(-[E/Ec]*),Componization photon index )(E) = )0 + !(E/Ec)*
(Falanga, Kuiper, Poutanen et al. 2005)
40
Time/Phase Lag Model (Falanga & Titarchuk 2007)
+t(Cill,!ref,!hot,neref,ne
hot) =
upscattering lag + downscattering lag 40
Companion mass Mc/Msun
Com
pani
on ra
dius
Rc/
Rsu
n
Brown dwarfs 0.1 Gyr
5 Gyr 1 Gyr
White dwarfs
XTE J0929-314 XTE J1751-305 XTE J1807-294
IGR J00291+5934 SAX J1808..4-3658 XTE J1814-338
The companion star should fill ist Roche lobe to
allow sufficient accretion on the compact star
Companion Star
!!Brown dwarf models at different ages (Chabrier et al. 2000)
!!Cold low-mass white dwarfs with pure-helium composition
!! IGR J00291+5934 !! SAX J1808.4-3658 H-rich donor, brown dwarf !! XTE J1814-338
!! XTE J0292-314 !! XTE J1751-305 H-poor, highly evolved dwarf !! XTE J1807-294
M. Falanga
Sloa
n D
igita
l Sky
Sur
vey
!! 30 M$ Blue supergiant main-sequence star (optically bright, X-ray dim)
Optical Astronomy
!! Orbits, 5.6 days, an unseen optically (but bright X-ray) object
X-ray Binary System !! The companion has a mass between of ~ 10 M$
What is it?
Cygnus X-1
!! Can’t be a Neutron star because M > 3 M$
By elimination, we are left with a Black Hole
!! A red giant would be easily seen
!! A main-sequence star would be seen with a little effort
!! Can’t be a White Dwarf because M > 1.4 M$