Pulsarsand Collapsed Objects Pulsarsand ANDREA POSSENTI INAF – Osservatorio di Cagliari Medicina 1...

Pulsars Pulsars andand

Collapsed ObjectsCollapsed Objects

Pulsars Pulsars andand

Collapsed ObjectsCollapsed Objects

ANDREA POSSENTIANDREA POSSENTI INAF – Osservatorio di CagliariINAF – Osservatorio di Cagliari

Medicina Medicina

11stst MCCT-SKADS Training School MCCT-SKADS Training School 28 September 200728 September 2007

OutlineOutlineThe absolute beginnersThe absolute beginners - - Discovery of the first pulsarDiscovery of the first pulsar (1967)(1967)

Unveiling the misteryUnveiling the mistery - - Discovery of a pulsar associated with Discovery of a pulsar associated with the Crab Nebula the Crab Nebula (1968)(1968)Fun for twoFun for two - - Discovery of the binary pulsarDiscovery of the binary pulsar PSR PSR B1913+16B1913+16

(1974)(1974)Please put the pulsar in the recycle binPlease put the pulsar in the recycle bin - - Discovery of theDiscovery of the

millisecond pulsar PSR B1937+21millisecond pulsar PSR B1937+21 (1982)(1982)

Not only stellar matesNot only stellar mates - - Discovery of the first planet pulsarDiscovery of the first planet pulsar

PSR B1257+12PSR B1257+12 (1992)(1992)Fun from twoFun from two - - Discovery of the first double pulsar Discovery of the first double pulsar

PSR J0737-3039A/BPSR J0737-3039A/B (2003)(2003)

Spinning in the crowdsSpinning in the crowds - - Discovery of the first millisecond Discovery of the first millisecond pulsarpulsar PSR B1821+24A in a globular clusterPSR B1821+24A in a globular cluster (1987)(1987)

Fun for everyoneFun for everyone – – The present and future of radio The present and future of radio pulsarpulsar

sciencescience (from 2007 on…)(from 2007 on…)

Basic Basic ReferencesReferences

• Manchester & Taylor 1977 “Pulsars”Manchester & Taylor 1977 “Pulsars”• Lyne & Smith 2005 “Pulsar Astronomy”Lyne & Smith 2005 “Pulsar Astronomy”• Lorimer & Kramer 2005 “Handbook of Pulsar Astronomy”Lorimer & Kramer 2005 “Handbook of Pulsar Astronomy”

BooksBooks

Review Review ArticlesArticles• Rickett 1990, ARAA - ScintillationRickett 1990, ARAA - Scintillation• Science, April 2004 – Neutron Stars, Isolated Pulsars, Binary Science, April 2004 – Neutron Stars, Isolated Pulsars, Binary PulsarsPulsars• Living Reviews articles: Living Reviews articles: ((http://relativity.livingreviews.org/Articles)http://relativity.livingreviews.org/Articles)

• Stairs 2003: General Relativity and pulsar timingStairs 2003: General Relativity and pulsar timing• Lorimer 2005: Binary and millisecond pulsarsLorimer 2005: Binary and millisecond pulsars• Will, 2006: General Relativity theory and experimentWill, 2006: General Relativity theory and experiment

• SKA science: New Astron. Rev. 48 (2004)SKA science: New Astron. Rev. 48 (2004)• Cordes et al.: Pulsars as tools Cordes et al.: Pulsars as tools

• Kramer et al.: Strong-field tests of General Relativiy Kramer et al.: Strong-field tests of General Relativiy

Jocelyn BellJocelyn BellAnthony HewishAnthony Hewish

periodic periodic pulsespulses ! ! P = 1.33 secP = 1.33 sec

dt = 25 msdt = 25 ms

The absolute beginners The absolute beginners : : discovery ofdiscovery of

White Dwarfs oscillation ?White Dwarfs oscillation ?

White Dwarfs rotation ?White Dwarfs rotation ?

Neutron Star rotation ?Neutron Star rotation ?

pulsars pulsars (1967)(1967)

Unveiling the misteryUnveiling the mistery: : discovery of a pulsar discovery of a pulsar

associated with the Crab associated with the Crab Nebula Nebula (1968)(1968)

(Staelin & Reifenstein 1968)(Staelin & Reifenstein 1968)

A period of P = 33 ms, increasing by 36 A period of P = 33 ms, increasing by 36 ns/dayns/day

ESO-VLTESO-VLT

• Formed in Type II supernova explosion - core collapse of red giant when the mass exceeds “Chandrasekhar Mass”

• Diameter 20 - 30 km Mass ~ 1.4 Msun

(Lattimer & Prakash (Lattimer & Prakash 2004)2004)

Neutron stars do exist …Neutron stars do exist …

• Energy release ~ 3GM2/5R ~ 3 x 1053 erg ~ 0.1 Mc2

• En.Kinetic of SNR ~ 1051 erg; 99% of grav energy in ν and anti-ν

• Asymmetry in neutrino ejection gives kick to NS

• Measured pulsar proper motions: <V2D> = 211 km s-1

• <V3D> = 4<V2D>/ = 2<V1D> for isotropic velocities

(Hob

bs e

t al.

20

05

)

Guitar NebulaGuitar NebulaPSR B2224+65PSR B2224+65

(Cordes et al. 2003)

~ 30 young pulsars associated with a SNR

……and neutron stars/pulsars are and neutron stars/pulsars are bornborn

in supernova explosion !in supernova explosion !

Radiopulsars are rapidly Radiopulsars are rapidly rotatingrotating

and highly magnetized neutron and highly magnetized neutron stars anisotropically emitting stars anisotropically emitting

radiowaves radiowaves

Light-house effect Light-house effect

Radio emission mechanism is poorly Radio emission mechanism is poorly known yet, but certainly a known yet, but certainly a coherentcoherent

process process !!• Source power is very large, but source area is very small• Specific intensity is very large• Pulse timescale gives limit on source size ~ ct

(Manchester & Taylor 77)(Manchester & Taylor 77)

The rotational energy pays the energy billThe rotational energy pays the energy billSpin-down Luminosity:

Radio Luminosity:

Assuming magneto-dipole braking in vacuum :Ldipole ~ B2

surf Ω4

and by equating Ldipole = Lsd one can

get

(Manchester & Taylor 77)(Manchester & Taylor 77)

Per

iod

Time

Observed P andObserved P and

c = 1 P

2

Magnetic dipole energy lossMagnetic dipole energy loss

……pulsar Ages and Magnetic pulsar Ages and Magnetic fieldsfields

.Bsurf (P P)1/2

.. PP

. P

The The observed P observed P

and P and P translates in translates in

the the fundamental fundamental

PvsP PvsP diagramdiagram

Galactic disk pulsarsATNF Pulsar Catalogue

(www.atnf.csiro.au/research/pulsar/psrcat)

.. ..

..

PSR PSR 0329+540329+54

P = 714 msP = 714 ms

PSR 0833-PSR 0833-4545

P = 89 msP = 89 ms

… … since 1967 until 27 september 2007 … since 1967 until 27 september 2007 … 1765 1765 PULSARsPULSARs ! !

An immediate use of so many pulsars…An immediate use of so many pulsars…

……investigating the interstellar mediuminvestigating the interstellar medium

Dispersion in InterStellar Dispersion in InterStellar Medium Medium

ne

Free electrons

in ISM

t2t1 (2-2 1

-2) DM

DM = nedl

L

L

0

tDM =

1.2 104

3

DM @ 430 MHz 100 s for DM=1 pc/cm3 δν=1 MHz

@ 1400 MHz 3 s for DM=1 pc/cm3 δν=1 MHz

Dispersion smearingDispersion smearing

F

req

ue

ncy

F

req

ue

ncy

F

req

ue

ncy

time

time

time

Dispersion & Pulsar Distances Dispersion & Pulsar Distances

• For pulsars with independent distances

(parallax, SNR assoc, HI absorption) one can

detemine mean ne along path. Typical values ~ 0.03

cm-3

• From many such measurements can develop

model for Galactic ne distribution, e.g. NE2001

model [ Cordes & Lazio 2002]

• Can then use the model to determine distances to other

pulsars

A model for DM A model for DM in the Galaxy in the Galaxy

[ Taylor & Cordes 1993 ][ Taylor & Cordes 1993 ]

Smearing due to multi-path scatteringSmearing due to multi-path scattering

tscatt 14

A model for A model for ttscattscatt in the in the Galaxy Galaxy at 1.0 GHzat 1.0 GHz

[ Taylor & Cordes 1993 ][ Taylor & Cordes 1993 ]

ISM Fluctuation ISM Fluctuation SpectrumSpectrum

(Armstrong et al. 1995)(Armstrong et al. 1995)

• Spectrum of interstellar electron density fluctuations

• Follows Kolmogorov power-law spectrum

over 12 orders of magnitude in scale size (from 10-4 AU to 100 pc)

• Mostly based on pulsar observations

Faraday Rotation & Galactic Magnetic FieldFaraday Rotation & Galactic Magnetic Field

Faraday Rotation & Galactic Magnetic FieldFaraday Rotation & Galactic Magnetic Field

(Han et al. 2005)(Han et al. 2005)

Fun for twoFun for two - The discovery of the - The discovery of the binary pulsarbinary pulsar B1913+16 B1913+16 (1974)(1974)

P = 59 ms but P = 59 ms but not a steady not a steady slow downslow down

time

time

time

Tim

e re

sidu

alHow one can measure with high How one can measure with high

precision the pulse period…precision the pulse period…

Pulsar Timing: which other parameters can be Pulsar Timing: which other parameters can be determined…determined…

• Spin parameters: • Astrometric parameters: position, proper motion, parallax

,,,

Pulsar Timing: Binary Pulsar Timing: Binary pulsarspulsars

• 5 Keplerian-parameters:5 Keplerian-parameters:

PPorborb, a, app, e, , e, , T, T00

2

3

2

32 sinsin4),(

cp

c

orb

pcp

mm

im

P

ia

Gmmf

• Estimate of companion mass if inclination knownEstimate of companion mass if inclination known• Minimum companion mass for i=90 degMinimum companion mass for i=90 deg

• Mass function:Mass function:

First possibility of studying First possibility of studying relativistic effects on relativistic effects on the orbital evolution !the orbital evolution !

From the determination of From the determination of the mass function of PSR the mass function of PSR B1913+16, it appeared B1913+16, it appeared

probable that the radiopulsar probable that the radiopulsar was in a binary system with a was in a binary system with a

second neutron starsecond neutron star as a as a companioncompanion

The modification in the shape of the orbitThe modification in the shape of the orbitperiastron precessionperiastron precession

Pulsar Timing: relativistic Pulsar Timing: relativistic pulsarspulsars

The modifications in the Time Of Arrival (TOA) The modifications in the Time Of Arrival (TOA) of the pulsesof the pulses

Shapiro DelayShapiro Delay

Gravitational redshift & time dilationGravitational redshift & time dilation

The modifications in the Time Of Arrival The modifications in the Time Of Arrival (TOA) (TOA)

of the pulsesof the pulses

The modification of the shape of the orbitsThe modification of the shape of the orbits

Orbital decayOrbital decay

What do we learn observing What do we learn observing these relativistic effects (PK parameters) ?these relativistic effects (PK parameters) ?

Periastron precession

Time dilation & gravitational redshift

Shapiro delay (amplitude)

Shapiro delay (shape)

Orbital period decay

……where…where…

• e e orbital eccentricityorbital eccentricity (observed!)(observed!)

• PPbb orbital periodorbital period (observed!)(observed!)

• x x projected semimajor axisprojected semimajor axis (observed!) (observed!)

• mmpp pulsar masspulsar mass

• mmcc companion star masscompanion star mass

• MM = = mmpp + + mmcc total system lagrangian masstotal system lagrangian mass

ObservingObserving the values ofthe values of only only 2 PK parameters2 PK parameters

One can measure the pulsar and companion star masses with unrivalled precision

Once more than 2 relativistic PK parametersOnce more than 2 relativistic PK parametersare known, one derives the masses ofare known, one derives the masses ofthe 2 bodies and hence predicts the further the 2 bodies and hence predicts the further PK par on the basis of a given Gravity TheoryPK par on the basis of a given Gravity Theory

A test for Gravity TheoriesA test for Gravity Theories

PSR B1913+16PSR B1913+16Pulsar Pulsar

+ Neutron Star+ Neutron Star( 2 PK par ( 2 PK par masses ) masses )

Radiative prediction Radiative prediction of the General of the General

Relativity matches Relativity matches the results of the results of 30 yrs30 yrs of observations at of observations at

0.2% level 0.2% level

NOBEL PrizeNOBEL Prize19931993

Taylor & HulseTaylor & Hulse

The measurements done by The measurements done by Russell Hulse & Joe Taylor…Russell Hulse & Joe Taylor…The prediction of theThe prediction of theGeneral Relativity for PGeneral Relativity for Pbb……

..

PSR B1534+12PSR B1534+12

after a dozen yrs after a dozen yrs of observationsof observations

non-radiative predictions of GR verified at 0.05% level

P = 1.557 P = 1.557 msms V = 0.13 V = 0.13

cc !! !! Extreme physical Extreme physical conditions occur in conditions occur in millisecond pulsarsmillisecond pulsars

tangential velocity

Please,put the pulsar in the Please,put the pulsar in the recycle binrecycle bin Discovery of the Discovery of the millisecond pulsar B1937+21 millisecond pulsar B1937+21

(1982)(1982)[Backer et al. 1982][Backer et al. 1982]

First promise of putting First promise of putting constraints to the constraints to the Equation of Equation of State for nuclear matter !State for nuclear matter !

ATNF Pulsar Catalogue(www.atnf.csiro.au/research/pulsar/psrcat)

..

How to explain How to explain this new group this new group

of pulsars ?of pulsars ?

A newly born pulsar

A newly born pulsar has high magnetic field and A newly born pulsar has high magnetic field and relatively short spin periodrelatively short spin period

1000 yr

deat

h lin

e

Hubble time

Medium age pulsars

A young pulsar evolves relatively fast and slows A young pulsar evolves relatively fast and slows down down

The magnetic field of an old pulsar might The magnetic field of an old pulsar might eventually decayeventually decay

1000 yr

deat

h lin

e

Hubble time

Died pulsars

Slow pulsars with low magnetic fields are not Slow pulsars with low magnetic fields are not observable as radio sources any moreobservable as radio sources any more

1000 yr

deat

h lin

e

Hubble time

A died pulsar could be spun up and A died pulsar could be spun up and rejuvenated by an evolving binary rejuvenated by an evolving binary companioncompanion

1000 yr

deat

h lin

e

Hubble time

A newly born fast spinning pulsar

1000 yr

Hubble time

deat

h lin

e

A recycled pulsarA recycled pulsar

Many Millisecond Pulsars are extremely good clocksMany Millisecond Pulsars are extremely good clocks

The spin period of the original millisecond pulsar The spin period of the original millisecond pulsar

PSR B1937+21:PSR B1937+21:

P = 0.0015578064924327 P = 0.0015578064924327 0.0000000000000004 sec0.0000000000000004 sec

In this pulsar, after few years of pulse timing, we can In this pulsar, after few years of pulse timing, we can

predict the time of arrival of pulses within predict the time of arrival of pulses within 1 1 s s

over 1 yearover 1 year ! !

A clock A clock stability stability comparablecomparable to to

the best time the best time standardsstandards!!!!!!

Spinning in the crowdsSpinning in the crowds - Discovery - Discovery of the first millisecond pulsar PSR of the first millisecond pulsar PSR B1821+24A in a globular cluster B1821+24A in a globular cluster

(1987)(1987) [Lyne et al. 1987][Lyne et al. 1987]

M 28 (NGC 6626 in Sagittarius )

… … animation of 22 pulsars in 47 Tucanaeanimation of 22 pulsars in 47 Tucanae

©

© K

ram

er

at

Kra

mer

at

JBO

JBO

Pulsars in Pulsars in Globular ClustersGlobular Clusters

Ionized gas in 47 Ionized gas in 47 TucanaeTucanae

• Correlation of DM and P

• P due to acceleration in cluster potential

• Pulsars on far side of cluster have higher DM

• Gas density ~ 0.07 cm-

3, about 100 times local density

• Total mass of gas in cluster ~ 0.1 Msun

.

(Freire et al. 2001)(Freire et al. 2001)

.

First detection of intra-cluster gas in a globular cluster!

Millisecond pulsars in other Millisecond pulsars in other clustersclusters NGC 6266 NGC 6397 NGC6544 NGC 6752

PSR J1701-30 PSR J1740-53 PSR J1807-24 PSR J1910-59

P 5.24 ms 3.65 ms 3.06 ms 3.27 ms

Pb 3.81 d 1.35 d (eclipse) 0.071 d (1.7 h) 0.86 d

Mc >0.19 Msun >0.18 Msun >0.009 Msun (10 MJup) >0.19 Msun

d 6.7 kpc 2.2 kpc 2.5 kpc 3.9 kpc[ D’Amico et al. [ D’Amico et al. 2001 ]2001 ]

Probing the central M/L in NGC 6752Probing the central M/L in NGC 67525 pulsars discovered and timed @ Parkes [D’Amico et al 2000] [D’Amico [D’Amico et al 2000] [D’Amico et al 2002]et al 2002]

the negative (dP/dt)/P of two MSPlocated in the central regions is

dominated by the cluster potential well

a unusually high M/L>6-7 in the central regions of the

cluster

~ 3400 Msun of low-luminosity matter in the

inner 0.076 pc

[D’Amico et al 2002 ] [Ferraro et al 2003 ] [D’Amico et al 2002 ] [Ferraro et al 2003 ]

An energetic encounter for PSR-A in NGC 6752An energetic encounter for PSR-A in NGC 6752

PSR-A is the most offset pulsar ever detected in a globular cluster and PSR-C the second most offset [D’Amico et al 2000] [D’Amico [D’Amico et al 2000] [D’Amico

et al 2002]et al 2002]

[Sigurdsson 2003] [Colpi, Mapelli, Possenti [Sigurdsson 2003] [Colpi, Mapelli, Possenti 2004]2004]

a double black-hole of mass [10-50 Msun] appears the most probable center of scattering

both pulsars probably ejected in the halo by a dynamical encounter in the cluster core occurred less than ~ 0.7 Gyr ago [Colpi, Possenti & Gualandris 2002] [Colpi, Possenti & Gualandris 2002]

tint = 54 h!

(Hessels et al. 2006)(Hessels et al. 2006)

(Ransom et al. 2005)

GBT Search of Globular Cluster Terzan 5GBT Search of Globular Cluster Terzan 5• 5.9h obs with 82 s sampling

• Smin ~ 15 Jy• 600 MHz bandwidth at 2 GHz

• 32 pulsars discovered!! 34 total in cluster (www.naic.edu/~pfreire/GCpsr.html)

• Two eccentric relativistic binaries; N-star ~ 1.7 M?

• PSR J1748-2446ad - fastest known pulsar!

• P = 1.3959 ms, f0 = 716.3 Hz, S2000 ~ 80 Jy

• Binary, circular orbit, Pb = 1.09 d

• Eclipsed for ~40% of orbit

• mc > 0.14 M

PSR J1748-2446ad

Interpulse

Not only stellar matesNot only stellar mates - Discovery - Discovery of the first planet pulsar of the first planet pulsar

PSR B1257+12 PSR B1257+12 (1992)(1992)

[Wolcszczan & Frail 1992][Wolcszczan & Frail 1992]

A: 3.4 Earth masses,

66.5-day orbit

B: 2.8 Earth masses,

98.2-day orbit

C: ~ 1 Moon mass, 25.3-

day orbit

High-mass MS companion:P medium-long, Pb large, highly eccentric orbit, youngish pulsar4 known, e.g. B1259-63

Double neutron-star systems:P medium-short, Pb ~ 1 day, highly eccentric orbit, pulsar old8 + 2? known, e.g. B1913+16

Young pulsar with massive WD companion:P medium-long, Pb ~ 1 day, eccentric orbit, youngish pulsar2 known, e.g. J1141-6545

Pulsars with planets:MSP, planet orbits from months to years, circular2 known, e.g. B1257+12

Intermediate-Mass systems:P medium-short, Pb ~days, circular orbit, massive WD

companion, old pulsar 12 + 2? known, e.g. B0655+64 Low-mass systems:

MSP, Pb hours to years, circular orbit, low-mass WD, very old pulsar

~105 known, ~55 in globular clusters, e.g. J0437-4715, 47Tuc J

Binary Pulsars Binary Pulsars ZoologyZoology

[ Stairs 2004 ] [ Stairs 2004 ]

An An intriguinintriguin

g zoo g zoo for for

stydying stydying stellar stellar

and and binary binary

EvolutioEvolutionn

[ Sta

irs

200

4 ]

[ Sta

irs

200

4 ]

Fun from Fun from twotwo

Discovery Discovery of the first of the first

double double pulsar pulsar

J0737-3039 J0737-3039 (2003)(2003)

[Burgay et al. 2003][Burgay et al. 2003]

[Lyne et al. 2004][Lyne et al. 2004]

©

© S

averi

o C

era

volo

Saveri

o C

era

volo

©

© S

averi

o C

era

volo

Saveri

o C

era

volo

The discovery of PSR J0737-3039A (April 2003)The discovery of PSR J0737-3039A (April 2003)

• Binary pulsar Binary pulsar

• P = 22.7 msP = 22.7 ms

• Orbital period = 2.4 hr Eccentricity = 0.08 Orbital period = 2.4 hr Eccentricity = 0.08

• Orbital parameters suggest that the system is Orbital parameters suggest that the system is relatively massive, probably consisting of two relatively massive, probably consisting of two NSsNSs

• Huge periastron advance (16.88 deg/yr)Huge periastron advance (16.88 deg/yr)

[ Burgay, D’Amico, Possenti et al. 2003][ Burgay, D’Amico, Possenti et al. 2003]

Pulsations from PSR J0737-3039B (Oct Pulsations from PSR J0737-3039B (Oct 2003) 2003)

The first double pulsar ever The first double pulsar ever known !known !

[ Lyne, Burgay, Kramer, Possenti et al. 2004][ Lyne, Burgay, Kramer, Possenti et al. 2004]

© H

ow

e –

ATN

F

© H

ow

e –

ATN

F

22.7 ms22.7 ms

1.7 x 101.7 x 10-18-18

210 Myr210 Myr

6 x 106 x 1099 G G

1,080 km1,080 km

5 x 105 x 1033 G G

6 x 106 x 103333 erg s erg s-1-1

301 km s301 km s-1-1

AA2.77 s2.77 s

0.88 x 100.88 x 10-15-15

50 Myr50 Myr

1.6 x 101.6 x 101212 G G

1.32 x 101.32 x 1055 km km

0.7 G0.7 G

1.6 x 101.6 x 103030 erg s erg s-1-1

323 km s323 km s-1-1

PP

PP

SpinDown SpinDown ageage

BBsurfsurf

RRLCLC

BBLCLC

EErotationalrotational

Mean Orbit Mean Orbit VelocityVelocity

BBBasic ParametersBasic Parameters

.

.

The basic parameters Period, SpinDown age The basic parameters Period, SpinDown age and Band Bsurfsurf fit with the evolutionary path to the fit with the evolutionary path to the double pulsar systems suggested since long double pulsar systems suggested since long agoago

The basic parameters Period, SpinDown age The basic parameters Period, SpinDown age and Band Bsurfsurf fit with the evolutionary path to the fit with the evolutionary path to the double pulsar systems suggested since long double pulsar systems suggested since long agoago

[van den Heuvel & deLoore 1975][van den Heuvel & deLoore 1975]

© H

ow

e –

ATN

F

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e –

ATN

F

Mass-mass diagram for J0737-Mass-mass diagram for J0737-3039A&B3039A&B

© K

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Mass function A


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O

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Mass function B


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Kepler’s 3Kepler’s 3rdrd law lawKepler’s 3Kepler’s 3rdrd law lawTo 1PN order, relative separation given by:To 1PN order, relative separation given by:

field) strong( 1,ˆ2,/,/2

2356

11

2

3/2

3

3/1

2

ABABtotBAb

totABtotABR

GGMmmPn

c

nMG

n

MGa

…so that for “any” theory of gravity to 1PN order:…so that for “any” theory of gravity to 1PN order:

B

A

A

B

m

m

x

xR Ratio is independent of

strong (self-)field effects!

Ratio is independent of strong (self-)field effects!

Different to other PK parameters, which all depend on strong-field modified “constants” like GAB which differs

from GNewton depending on strong-field effects in theory!

Different to other PK parameters, which all depend on strong-field modified “constants” like GAB which differs

from GNewton depending on strong-field effects in theory!

Mass ratio


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Periastron advance

GR!Theory

dependent!


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Grav. Redshift+ 2nd order Doppler

GR!Theory

dependent!


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Shapiro delay in PSR-A arrival Shapiro delay in PSR-A arrival timestimes

sinsin1

cos1ln

ie

cRt g

Shap

[ Lyne, Burgay, Kramer, Possenti et al. 2004][ Lyne, Burgay, Kramer, Possenti et al. 2004]

Shapiro s

GR!Theory

dependent!


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O

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Shapiro r GR!Theory

dependent!


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Mass-mass diagram for J0737-3039 @ Feb Mass-mass diagram for J0737-3039 @ Feb 20042004

at June 2007

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MB=1.249(1)M

MA=1.338(1)M

Observed shape of Shapiro delay in

agreement with GR at 0.05% level

4 independent tests of GR!

Mass-mass diagram for J0737-3039 @ Jun Mass-mass diagram for J0737-3039 @ Jun 20072007

What What will bewill be feasible to feasible to measure:measure:

Geodetic PrecessionGeodetic PrecessionPrecession periods only ~70 yearsPrecession periods only ~70 years

[ Burgay et al. 2003 ][ Burgay et al. 2003 ]

~ ~ 44 time shorter time shorterthan in any otherthan in any other

double neutron star:double neutron star:much easier tomuch easier to

be detected,be detected,thence imposing thence imposing

strongstrongconstraints toconstraints tothe geometrythe geometry

of the pulsar beamof the pulsar beam

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What What will bewill be feasible to feasible to measure: Aberrationmeasure: Aberration

What What will bewill be feasible to feasible to measure: Aberrationmeasure: Aberration

Aberration affects pulse profiles andAberration affects pulse profiles and

influences the Time of Arrivals of the pulses.influences the Time of Arrivals of the pulses.

cos)(cos

sin)(sin

euAB

euAA

e

eA

Unfortunately the related PK parameters ( Unfortunately the related PK parameters ( AA & & B B ) are usually absorbed in Roemer delays) are usually absorbed in Roemer delays

[ Damour & Deruelle 1986 ][ Damour & Deruelle 1986 ]

Measuring masses, orbital semi-major axes Measuring masses, orbital semi-major axes and eccentricities of two sources in the same and eccentricities of two sources in the same binary binary we should be able to disentangle the we should be able to disentangle the aberration contribution!aberration contribution!

What What could becould be feasible to feasible to measure: Neutron Star measure: Neutron Star

StructureStructureTotal periastron advance to 2PN level:Total periastron advance to 2PN level:

BS

BS

AS

AS

T

tot ggfe

k 00

200

20 1

1

3

1PN1PN 2PN2PN Spin ASpin A Spin BSpin B

Neutron star dependentNeutron star dependent

2

12

m

I

PG

c

pS

Equation-of-StateEquation-of-State

for the nuclear matter!!for the nuclear matter!!

[ Damour & Schaefer 1988 ][ Damour & Schaefer 1988 ]

[ Lattimer & Schutz 2004 ][ Lattimer & Schutz 2004 ][ Morrison et al. 2004][ Morrison et al. 2004]

A 10% accuracy on IA 10% accuracy on Iwould exclude most EoSwould exclude most EoS

The unique occurrence of strong interactions The unique occurrence of strong interactions between the energetic flux from A and the between the energetic flux from A and the

magnetosphere of B ( 1magnetosphere of B ( 1stst evidence ) evidence )


magnetosphere of B ( 1magnetosphere of B ( 1stst evidence ) evidence )

The signal of PSR A displays eclipses for ~20 s at superior conjunction…

… and the nature of the occulting medium is dependent on the rotational phase of B

The signal of PSR A displays eclipses for ~20 s at superior conjunction…

… and the nature of the occulting medium is dependent on the rotational phase of B

Superiorconjunction

Superiorconjunction

B phase 1.00B phase 1.00B phase 0.75B phase 0.75

B phase 0.25B phase 0.25

[Breton et al. 2007][Breton et al. 2007][Breton et al. 2007][Breton et al. 2007]


magnetosphere of B ( 2magnetosphere of B ( 2ndnd evidence ) evidence )


magnetosphere of B ( 2magnetosphere of B ( 2ndnd evidence ) evidence )The intensity and pulse profile of B

strongly vary along the orbit …… and during a portion of the phases

of high brightness, the radio emission from B matches the ~ 44 Hz electromagnetic pulses arriving from A

The intensity and pulse profile of B strongly vary along the orbit …

… and during a portion of the phases of high brightness, the radio emission from B matches the ~ 44 Hz electromagnetic pulses arriving from A

[McLaughlin et al. 2004][McLaughlin et al. 2004][McLaughlin et al. 2004][McLaughlin et al. 2004]

[Burgay, Possenti et al. 2005][Burgay, Possenti et al. 2005]

Nov0

4 J

ul0

4 A

pr0

4 J

an

04

S

ep

03

Ju

l03

Nov0

4 J

ul0

4 A

pr0

4 J

an

04

S

ep

03

Ju

l03

High brightess phases High brightess phases of B are changing !of B are changing !

Possibility of Possibility of removing degeneracy removing degeneracy

between different between different models checking their models checking their

predictions about predictions about evolution in a human-evolution in a human-

scale time !scale time !

Spin-Powered Pulsars: A Spin-Powered Pulsars: A CensusCensus

• Number of known pulsars: 1765

• Number of millisecond pulsars: 170

• Number of binary pulsars: 131

• Number of pulsars in globular clusters: 129

• Number of extragalactic pulsars: 20

Data from ATNF Pulsar Catalogue, V1.25 (www.atnf.csiro.au/research/pulsar/psrcat; Manchester et al. 2005)

[ @ Manchester – ATNF ][ @ Manchester – ATNF ]

Pulsars are excellent clocks, leading to many interesting experiments in astrophysics and fundamental physics: gravity theories, nuclear matter, plasma physics.

Pulsars are excellent probes of the interstellar medium and are widely distributed in the Galaxy.

A few especially interesting objects with unique properties will probably be found in a large-scale survey.

Leads to a better understanding of the Galactic distribution and birthrate of pulsars, of binary and stellar evolution, of their relationship to other objects such as supernova remnants, and of the emission physics.

Why searching more pulsars?Why searching more pulsars?

The sensitivity formulaThe sensitivity formula

Smin Tsys + Tsky

G Np t

We

P We Tsys = system noise temperature

Tsky = sky temperature

G = antenna gain

Np = number of polarizations

= total bandwidth

t = total integration time

P = pulsar period

We = effective pulse width

WWee = W = W22 + + tt22 + + tt22DMDM + + tt22

scattscatt

t = sampling time t = sampling time

ttDMDM = dispersion = dispersion smearing smearing

ttscattscatt = scattering = scattering smearingsmearing

Smin Tsys + Tsky

G Np t

We

P We

tDM =

1.2 104

3

DM

tscatt 14

tsamp

Nch = /…but…

…but… S 1.7

…but… Nsamp = t/tsamp

We = W2 + t2samp + t2

DM + t2scatt

G large aperture

Tsky 2.7 (r.a. & dec) Spsr 1.7

0

You are here

Better use high

tDM 3

tscatt 4

Tsky 2.7

Narrow beam OkDeep surveys in the diskDeep surveys in the disk

In order to find many pulsars we have to search large In order to find many pulsars we have to search large volumesvolumes

You are here

Better use low

Large telescope beam !

Spsr 1.7

Away from the Galactic plane:

Low DM

Scattering negligible

Tsky 30 °KWide all-sky surveysWide all-sky surveys

In order to find many pulsars we have to search large In order to find many pulsars we have to search large volumesvolumes

Standard search Standard search techniquetechnique

time

time

Rad

io

fre

quen

cy

Power spectrum

Fluctuation frequency

DMk

FFT Pulse phase

Integrated pulse profile

Folding

time

Pulse phase


Folding

s/n

If the code If the code picked up the picked up the

correct apparent correct apparent pulse repetition pulse repetition

period P period P

time

Pulse phase


Folding

s/n

If the If the code code

picked picked up a up a

slighlty slighlty wrong wrong

apparenapparent pulse t pulse repetitirepetiti

on on period P period P

time

Pulse phase


Folding

s/n

If the If the apparent apparent

pulse pulse repetition repetition period P is period P is

not not changing changing

too too quickly quickly

along the along the observatioobservatio

n, the n, the code can code can

still pick P still pick P

Knowning Knowning exactly exactly how P how P

changes, changes, one can one can easily easily

recover recover the pulse the pulse

profileprofile

But if the Doppler acceleration is too high, But if the Doppler acceleration is too high, the signal is not picked up in the fluctuation the signal is not picked up in the fluctuation

spectrum !spectrum !

time

Power spectrum


FFT

time

Power spectrum


FFTNo pulsar

suspect !

But if the Doppler acceleration is too high, But if the Doppler acceleration is too high, the signal is not picked up in the fluctuation the signal is not picked up in the fluctuation

spectrum !spectrum !

One way to take into account Doppler is to One way to take into account Doppler is to resample the time series according to a trial resample the time series according to a trial

acceleration acceleration

time

Power spectrum


FFT

Nr of FFTs = NNr of FFTs = NDMDM x N x Naccacc

Coherent (linear) acceleration searchCoherent (linear) acceleration search

[ Camilo et al 2000 [ Camilo et al 2000 ]]

Segmented FFT procedure Segmented FFT procedure helpshelps

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Segmented vs standard Segmented vs standard searchsearch

[ Faulkner, PhD Thesis 2004 [ Faulkner, PhD Thesis 2004 ]]

9 ms pulsar

Dynamic spectrum searchDynamic spectrum search

[ Chandler, PhD Thesis 2004 [ Chandler, PhD Thesis 2004 ]]

Phase modulation searchPhase modulation search

[ Ransom et al 2001 [ Ransom et al 2001 ]]

Phase modulation VS segmented Phase modulation VS segmented searchsearch

[ Faulkner, PhD Thesis 2004 [ Faulkner, PhD Thesis 2004 ]]

9 ms pulsar

The choice of the observing The choice of the observing parameters of the survey (parameters of the survey (wide wide

or deepor deep) and the amount of ) and the amount of computational capabilities computational capabilities

result in a different sampling of result in a different sampling of evolutionary stage of pulsars evolutionary stage of pulsars and hence of the P-P diagramand hence of the P-P diagram

..

Parkes 64 m radiotelescopeParkes 64 m radiotelescope

Multibeam receiverMultibeam receiver

System parameters:System parameters:

• 13 beams

• Tsys ~ 25 °K

• 288 MHz @ 1.4GHz

• = 13 x 96 x 3 MHz

• = 512 x 0.5 MHz

The Parkes multibeam surveysThe Parkes multibeam surveys

PM Group:PM Group: Jodrell Bank, ATNF, Cagliari, Columbia, Jodrell Bank, ATNF, Cagliari, Columbia, McGill, …McGill, …

PH Group:PH Group: Cagliari, Jodrell Bank, ATNF, Columbia, …Cagliari, Jodrell Bank, ATNF, Columbia, …

Swin Group:Swin Group: Swinburne, CaltechSwinburne, Caltech

PM Survey (PM PM Survey (PM Group)Group)

PH Survey (PH PH Survey (PH Group)Group)

SW Survey (Swinburne SW Survey (Swinburne Group)Group)

[ M

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Parkes PM = 725Parkes PM = 725

Parkes Swin = Parkes Swin = 69+2569+25

Parkes PH = 18 Parkes PH = 18

Total = Total = 837837

Parkes GC search = 12Parkes GC search = 12

Parkes 47 Tuc search = Parkes 47 Tuc search = 2222

a real boom of pulsar a real boom of pulsar discoveries !discoveries !

Parkes Parkes discoveriesdiscoveries

Radio pulsars in the Catalog:Radio pulsars in the Catalog: 17651765

131131 Binaries Binaries

170170 Millisecond (P<25ms) Millisecond (P<25ms)

26 26 Vela-likeVela-like

8 8 Double Neutron star Double Neutron star binariesbinaries

1 1 Double pulsarDouble pulsar

129 129 in 24 Globular Clustersin 24 Globular Clusters

The total score:The total score:

Arecibo Alfa Survey at 1.4 GHzArecibo Alfa Survey at 1.4 GHz

300-500 discoveries in 3-5 yrs ?300-500 discoveries in 3-5 yrs ?

Parkes Perseus Arm Survey at 1.4 GHz Parkes Perseus Arm Survey at 1.4 GHz 15-30 discoveries ?15-30 discoveries ?

GBT Pilot Surveys at 350 MHz GBT Pilot Surveys at 350 MHz 30-50 30-50

discoveriesdiscoveries

GBT Drift Scan Survey at 350 MHz > GBT Drift Scan Survey at 350 MHz > > 100 > 100 discoveries ?discoveries ?

GMRT Survey at 610 MHz GMRT Survey at 610 MHz 5-10 discoveries ? 5-10 discoveries ?

GBT Surveys of Globular Clusters at 2.1 GBT Surveys of Globular Clusters at 2.1 GHz GHz > 100 discoveries ?> 100 discoveries ?

Parkes Galactic MSP Survey at 1.4 GHzParkes Galactic MSP Survey at 1.4 GHz 50-100 MSP discoveries ?50-100 MSP discoveries ?

Fun for everyoneFun for everyone: Pulsar : Pulsar Astrophysics with the SKA Astrophysics with the SKA (from (from

200x )200x )General science case covers lots of topics

• Galactic probesGalactic probes• Extragalactic pulsarsExtragalactic pulsars• Relativistic plasma physicsRelativistic plasma physics• Extreme Dense Matter PhysicsExtreme Dense Matter Physics• Multi-wavelength studiesMulti-wavelength studies• Exotic systemsExotic systems• Gravitational physics (SKA KSP)Gravitational physics (SKA KSP)

[ Cordes et al. 2004 [ Cordes et al. 2004 ]]

Strong-field testsStrong-field tests of gravity using pulsar & black holes

identified as one of five SKA Key Science one of five SKA Key Science ProjectsProjects

Galactic Census with the SKAGalactic Census with the SKA

• Discovery of almost every pulsars Discovery of almost every pulsars inin Galaxy: in total Galaxy: in total 10000-20000 10000-20000 pulsarspulsars

• ~ 1000 millisecond pulsars~ 1000 millisecond pulsars

• more and more Double-Pulsar more and more Double-Pulsar SystemsSystems

[ Kramer et al. 2004 [ Kramer et al. 2004 ]]

Galactic Census with the SKAGalactic Census with the SKA

Timing of discovered binary and millisecond pulsars to very high precision:

• “ “Find them!”Find them!”• “ “Time them!”Time them!”• “ “VLBI them!”VLBI them!”

Not just a continuation of what has been done beforeNot just a continuation of what has been done before Complete new quality of science possible! Complete new quality of science possible!


[ K

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20

04

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Cosmological Gravitational Wave BackgroundCosmological Gravitational Wave Background

• Pulsars discovered in Galactic Census alsoPulsars discovered in Galactic Census also provide network of arms of a hugeprovide network of arms of a huge cosmic gravitational wave detectorcosmic gravitational wave detector

• Perturbation inPerturbation in space-time can bespace-time can be detected in timingdetected in timing residualsresiduals

• Sensitivity: dimensionless strainSensitivity: dimensionless strain

Tfh TOA

c

~)(

PulsarPulsar TimingTiming ArrayArray

PTA:PTA:

Cosmological Gravitational Wave Background


With such an array of pulsars, Pulsar timing can detect aWith such an array of pulsars, Pulsar timing can detect a stochastic gravitational wave backgroundstochastic gravitational wave background

and also:and also: merging massive BH binaries merging massive BH binaries in early galaxy evolutionin early galaxy evolution

Sources:Sources:

• InflationInflation• String cosmologyString cosmology• Cosmic stringsCosmic strings• phase transitionsphase transitions

.~)(20 constfh GW

3/220 )( ffh GW




LISAPulsarsAdvanced

LIGO

Spectral range: Spectral range: nHznHzonly accessible with only accessible with SKA!SKA!

Further by correlation:

PSRN/1

PTA limit:422

0 ~)( ffh TOAGW

Improvement: 10Improvement: 104 4 !!

CMB

complementary tocomplementary toLISALISA, , LIGOLIGO & & CMBCMB


• Astrophysical black holes are expected to rotate• BH have spin and quadrupole moment• Both can be measured by high precision pulsar timing via relativistic and classical spin-orbit coupling

• Not easy! It is not possible today!• Requires SKA sensitivity!

[ Wex & Kopeikin 1999 ][ Wex & Kopeikin 1999 ]

Test Cosmic Censorship Conjecture & No-Hair Theorem!Test Cosmic Censorship Conjecture & No-Hair Theorem![ Kramer et al. 2004 [ Kramer et al. 2004 ]]

The last not prohibited dreamThe last not prohibited dream: : a pulsar orbiting a Black Holea pulsar orbiting a Black Hole

(200?)(200?)

Happy hunting,

Happy hunting,

folks !!!

folks !!!Happy huntin

g,

Happy hunting,

folks !!!

folks !!!

Pulsarsand Collapsed Objects Pulsarsand ANDREA POSSENTI INAF – Osservatorio di Cagliari Medicina 1...

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