pulsars - ira.inaf.it · [sigurdsson 2003] [colpi, mapelli, possenti 2004] a double black-hole of...

Pulsarsand

Collapsed Objects

PulsarsPulsarsandand

CollapsedCollapsed ObjectsObjects

ANDREA POSSENTIANDREA POSSENTIINAF INAF –– Osservatorio di CagliariOsservatorio di Cagliari

Medicina Medicina 11stst MCCTMCCT--SKADS Training SchoolSKADS Training School

28 28 SeptemberSeptember 20072007

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

Unveiling the Unveiling the misterymistery -- Discovery of a pulsar associated with Discovery of a pulsar associated with

the Crab Nebulathe Crab Nebula (1968)(1968)

FunFun forfor twotwo -- Discovery of the binary pulsarDiscovery of the binary pulsar PSR PSR B1913+16B1913+16 (1974)(1974)

PleasePlease putput the pulsar in the the pulsar in the recyclerecycle binbin -- Discovery of theDiscovery of the

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

NotNot onlyonly stellar stellar matesmates -- Discovery of the first planet pulsarDiscovery of the first planet pulsar

PSR B1257+12PSR B1257+12 (1992)(1992)FunFun fromfrom twotwo -- Discovery of the first double pulsar Discovery of the first double pulsar

PSR J0737PSR J0737--3039A/B3039A/B (2003)(2003)

SpinningSpinning in the in the crowdscrowds -- Discovery of the first millisecond pulsarDiscovery of the first millisecond pulsar

PSR B1821+24A in a globular clusterPSR B1821+24A in a globular cluster (1987)(1987)

FunFun forfor everyoneeveryone –– The present and future of radio pulsarThe present and future of radio pulsar

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

Basic ReferencesBasic References

•• Manchester & Taylor 1977 Manchester & Taylor 1977 ““PulsarsPulsars””

•• LyneLyne & Smith 2005 & Smith 2005 ““Pulsar AstronomyPulsar Astronomy””

•• LorimerLorimer & Kramer 2005& Kramer 2005 ““Handbook of Pulsar AstronomyHandbook of Pulsar Astronomy””

BooksBooks

Review ArticlesReview Articles•• RickettRickett 1990, ARAA 1990, ARAA -- ScintillationScintillation

•• Science, April 2004 Science, April 2004 –– Neutron Stars, Isolated Pulsars, Binary PulsarsNeutron Stars, Isolated Pulsars, Binary Pulsars

•• 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

•• LorimerLorimer 2005: Binary and millisecond pulsars2005: 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)

•• CordesCordes et al.: Pulsars as tools et al.: Pulsars as tools

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

Jocelyn Jocelyn BellBellAnthony HewishAnthony Hewish

periodic pulsesperiodic pulses !!P = 1.33 secP = 1.33 sec

dt = 25 dt = 25 msms

The absolute beginners The absolute beginners : discovery : discovery ofof

White Dwarfs oscillation ?White Dwarfs oscillation ?

White Dwarfs rotation ?White Dwarfs rotation ?

Neutron Star rotation ?Neutron Star rotation ?

pulsars pulsars (1967)(1967)

Unveiling the Unveiling the misterymistery: discovery of : discovery of a pulsar associated with the Crab a pulsar associated with the Crab

Nebula Nebula (1968)(1968)

((StaelinStaelin & & ReifensteinReifenstein 1968)1968)

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

ESOESO--VLTVLT

• 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

((LattimerLattimer & & PrakashPrakash 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>/ππππ = 2<V1D> for isotropic velocities

(Hobbs et al. 2005)

Guitar NebulaGuitar NebulaPSR B2224+65PSR B2224+65

(Cordes et al. 2003)

~ 30 young pulsars associated with a SNR

……and neutron stars/pulsars are bornand neutron stars/pulsars are bornin supernova explosion !in supernova explosion !

RadiopulsarsRadiopulsars are rapidly rotatingare rapidly rotatingand highly magnetized neutron stars and highly magnetized neutron stars anisotropicallyanisotropically emitting emitting radiowavesradiowaves

LightLight--house effect house effect

Radio emission mechanism is poorly known Radio emission mechanism is poorly known yet, but certainly a 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 ~ c∆t

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

The rotational energy pays the energy billThe rotational energy pays the energy bill

Spin-down Luminosity:

Radio Luminosity:

Assuming magneto-dipole braking in vacuum :Ldipole ~ B2surf Ω4

and by equating Ldipole = Lsd one can get

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

Per i

od

Time

Observed P andObserved P and

τc = 1 P

2

Magnetic dipole energy lossMagnetic dipole energy loss

……pulsar Ages and Magnetic fieldspulsar Ages and Magnetic fields

.Bsurf ∝ (P P)1/2

..PP

.P

The observed The observed P and P P and P

translates in translates in the the

fundamental fundamental PvsPPvsP diagramdiagram

Galactic disk pulsarsATNF Pulsar Catalogue

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

.. ..

..

PSR 0329+54PSR 0329+54

P = 714 P = 714 msms

PSR 0833PSR 0833--4545

P = 89 P = 89 msms

…… sincesince 1967 1967 untiluntil 27 27 septemberseptember 2007 2007 …… 1765 1765 PULSARsPULSARs !!

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

……investigating the interstellar mediuminvestigating the interstellar medium

Dispersion in Dispersion in InterStellarInterStellar Medium Medium

ne

Free electrons

in ISM

t2−t1 ∝ (ν2-2 −ν1

-2) DM

DM = nedl∫

L

L

0

δδδδtDM =1.2 10−−−−4

δνδνδνδννννν3

DM @ 430 MHz →→→→ 100 µµµµs for DM=1 pc/cm 3 δν=1 MHz

@ 1400 MHz →→→→ 3 µµµµs for DM=1 pc/cm 3 δν=1 MHz

Dispersion smearingDispersion smearing

Fre

quen

cy

F

requ

ency

Fre

quen

cy

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 nedistribution, 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 & [ Taylor & CordesCordes 1993 ]1993 ]

Smearing due to multiSmearing due to multi--path scatteringpath scattering

δδδδtscatt ∼∼∼∼ 1νννν4

A model for A model for ttscattscatt

in the Galaxy in the Galaxy at 1.0 GHzat 1.0 GHz

[ Taylor & [ Taylor & CordesCordes 1993 ]1993 ]

ISM Fluctuation ISM Fluctuation SpectrumSpectrum

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

• Spectrum of interstellar electron density

fluctuations

• Follows Kolmogorovpower-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)

FunFun forfor twotwo -- The discovery of the The discovery of the binary pulsarbinary pulsar B1913+16 B1913+16 (1974)(1974)

P = 59 P = 59 msms butbutnotnot a steady a steady slow downslow down

time

time

time

Tim

e re

sidu

al

How one can measure with high precision the How one can measure with high precision the pulse periodpulse period……

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

• Spin parameters:

• Astrometric parameters: position, proper motion, parallaxK&&&&&& νννν ,,,

Pulsar Timing: Binary pulsarsPulsar Timing: Binary pulsars

•• 5 5 KeplerianKeplerian--parameters:parameters:

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

( ) ( )( )2

3

2

32 sinsin4),(

cp

c

orb

pcp

mm

im

P

ia

Gmmf

+=π=

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

radiopulsarradiopulsar was in a binary system was in a binary system with a 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 orbitperiastronperiastron precessionprecession

Pulsar Timing: relativistic pulsarsPulsar Timing: relativistic pulsars

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 Gravitational redshiftredshift & time dilation& time dilation

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

……wherewhere……

•• e e orbitalorbital eccentricityeccentricity ((observedobserved!)!)

•• PPbb orbitalorbital periodperiod ((observedobserved!)!)

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

•• mmpp pulsar masspulsar mass

•• mmcc companioncompanion star massstar mass

•• MM = = mmpp + + mmcc total system total system lagrangianlagrangian massmass

ObservingObserving the the valuesvalues ofof onlyonly 2 PK 2 PK parametersparameters

One can measure the pulsar and companion star masses withunrivalled precision

Once more Once more thanthan 2 2 relativisticrelativistic PK PK parametersparametersare 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 PK par on the basis of a given Gravity TheoryTheory

A test A test forfor GravityGravity TheoriesTheories

PSR B1913+16PSR B1913+16Pulsar Pulsar

+ + NeutronNeutron StarStar( 2 PK par ( 2 PK par massesmasses ))

RadiativeRadiative predictionprediction of of the the GeneralGeneral RelativityRelativitymatchesmatches the the resultsresults of of 30 30 yrsyrs of of observationsobservations

at 0.2% at 0.2% levellevel

NOBEL NOBEL PrizePrize19931993

TaylorTaylor & & HulseHulse

The The measurementsmeasurements donedone bybyRussellRussell HulseHulse & & JoeJoe TaylorTaylor……The The predictionprediction of theof theGeneralGeneral RelativityRelativity forfor PPbb……

..

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 conditions Extreme physical conditions occur in millisecond pulsarsoccur in millisecond pulsars

tangential velocity

PleasePlease,,putput the pulsar in the the pulsar in the recyclerecycle binbinDiscovery of the millisecond pulsar Discovery of the millisecond pulsar

B1937+21 B1937+21 (1982)(1982)

[Backer et al. 1982][Backer et al. 1982]

First promise of putting First promise of putting constraints to the Equation of constraints to the 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 of this new group of

pulsars ?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

hlin

e

Hubble time

Medium age pulsars

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

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

1000 yr

deat

hlin

e

Hubble time

Died pulsars

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

1000 yr

deat

hlin

e

Hubble time

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

1000 yr

deat

hlin

e

Hubble time

A newly born fast spinning pulsar

1000 yr

Hubble time

deat

hlin

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 In thisthis pulsar, after few pulsar, after few yearsyears of of pulsepulse timing, timing, wewe can can predictpredict

the time of the time of arrivalarrival of of pulsespulses withinwithin ∼∼∼∼∼∼∼∼ 1 1 µµµµµµµµs over 1 s over 1 yearyear !!

A clock A clock stability comparablestability comparable toto

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

SpinningSpinning in the in the crowdscrowds -- Discovery of Discovery of the first millisecond pulsar PSR the first millisecond pulsar PSR

B1821+24A in a globular cluster B1821+24A in a globular cluster (1987)(1987)[[LyneLyne et al. 1987]et al. 1987]

M 28 (NGC 6626 in Sagittarius )

…… animationanimation of 22 of 22 pulsarspulsars in 47 in 47 TucanaeTucanae

©©K

ram

erK

ram

erat

JB

Oat

JB

O

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

.

((FreireFreire et al. 2001)et al. 2001)

.

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

Millisecond pulsars in other clustersMillisecond pulsars in other clustersNGC 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 dMc >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[ D’’Amico et al. 2001 ]Amico et al. 2001 ]

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

the negative (dP/dt)/P of two MSPlocated in the central regions isdominated 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[D’’Amico et al 2002 ] [Ferraro et al 2003 ] Amico et al 2002 ] [Ferraro et al 2003 ]

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

PSR-A is the most offset pulsar ever detected in a globular cluster and PSR-C the second most offset [D[D’’Amico et al 2000] [DAmico et al 2000] [D’’Amico et al 2002]Amico et al 2002]

[Sigurdsson 2003] [[Sigurdsson 2003] [ColpiColpi, , MapelliMapelli, , PossentiPossenti 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 [[ColpiColpi, , PossentiPossenti & & GualandrisGualandris 2002] 2002]

tint = 54 h!

((HesselsHessels et al. 2006)et al. 2006)

(Ransom et al. 2005)

GBT Search of Globular Cluster GBT Search of Globular Cluster TerzanTerzan 55

• 5.9h obs with 82 µs sampling• Smin ~ 15 µJy• 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 µJy• Binary, circular orbit, Pb = 1.09 d

• Eclipsed for ~40% of orbit

• mc > 0.14 M

PSR J1748-2446ad

Interpulse

NotNot onlyonly stellar stellar matesmates -- Discovery of Discovery of the first planet pulsar the first planet pulsar PSR B1257+12 PSR B1257+12 (1992)(1992)

[[WolcszczanWolcszczan & Frail 1992]& 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 ZoologyBinary Pulsars Zoology [ Stairs 2004 ] [ Stairs 2004 ]

An An intriguing intriguing zoo for zoo for stydyingstydyingstellar stellar

and and binary binary

EvolutionEvolution

[ Stairs 2004 ]

[ Stairs 2004 ]

FunFun fromfrom twotwoDiscovery of Discovery of the first the first

double pulsar double pulsar J0737J0737--3039 3039

(2003)(2003)[[BurgayBurgay et al. 2003]et al. 2003]

[[LyneLyne et al. 2004]et al. 2004]©Saverio Ceravolo

©©Saverio

Saverio Ceravolo

Ceravolo

The discovery of PSR J0737The discovery of PSR J0737--3039A (April 2003)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 Huge periastronperiastron advance (16.88 deg/yr)advance (16.88 deg/yr)

[ [ BurgayBurgay, , DD’’AmicoAmico, Possenti , Possenti etet al.al. 2003]2003]

Pulsations from PSR J0737Pulsations from PSR J0737--3039B (Oct 2003) 3039B (Oct 2003)

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

[ [ LyneLyne, , BurgayBurgay, , KramerKramer, Possenti , Possenti etet al.al. 2004]2004]

©©How

e

How

e ––

ATNF

ATNF

22.7 ms22.7 ms

1.7 x 101.7 x 10--1818

210 210 MyrMyr

6 x 106 x 1099 GG

1,080 km1,080 km

5 x 105 x 1033 GG

6 x 106 x 103333 erg serg s--11

301 km s301 km s--11

AA

2.77 s2.77 s

0.88 x 100.88 x 10--1515

50 50 MyrMyr

1.6 x 101.6 x 101212 GG

1.32 x 101.32 x 1055 kmkm

0.7 G0.7 G

1.6 x 101.6 x 103030 erg serg s--11

323 km s323 km s--11

PP

PP

SpinDownSpinDown ageage

BBsurfsurf

RRLCLC

BBLCLC

EErotationalrotational

Mean Orbit Mean Orbit VelocityVelocity

BBBasic ParametersBasic Parameters

.

.

The basic parameters Period, SpinDown age and Bsurffit with the evolutionary path to the double pulsar systems suggested since long ago

The basic The basic parametersparameters PeriodPeriod, , SpinDownSpinDown ageage and and BBsurfsurf

fit fit withwith the the evolutionaryevolutionary pathpath toto the the doubledouble pulsar pulsar systemssystems suggestedsuggested sincesince long agolong ago [[vanvan denden HeuvelHeuvel & & deLooredeLoore 1975]1975]

©©How

e

How

e ––

ATNF

ATNF

MassMass--mass diagram for J0737mass diagram for J0737--3039A&B3039A&B

©©Kramer

Kramer --JBO

JBO

Mass function A


©©Kramer

Kramer --JBO

JBO

Mass function B


©©Kramer

Kramer --JBO

JBO

Kepler’s 3rd lawKeplerKepler’’ss 33rdrd lawlawTo 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

=+===

−+−

=

γενπ

νε

…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


©©Kramer

Kramer --JBO

JBO

Periastron

advance

GR!

Theory

dependent!


©©Kramer

Kramer --JBO

JBO

Grav. Redshift

+ 2nd order Doppler

GR!

Theory

dependent!


©©Kramer

Kramer --JBO

JBO

Shapiro delay in PSRShapiro delay in PSR--A arrival timesA arrival times

( )

= −

+∆ ψφ

sinsin1cos1

lni

ecRt g

Shap

[ [ LyneLyne, , BurgayBurgay, , KramerKramer, Possenti , Possenti etet al.al. 2004]2004]

Shapiro s

GR!

Theory

dependent!


©©Kramer

Kramer --JBO

JBO

Shapiro r GR!

Theory

dependent!


©©Kramer

Kramer --JBO

JBO


©©Kramer

Kramer --JBO

JBO

MassMass--mass diagram for J0737mass diagram for J0737--3039 @ Feb 20043039 @ Feb 2004

at June 2007

@ Kramer

@ Kramer

@ Kramer

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!

MassMass--mass diagram for J0737mass diagram for J0737--3039 @ Jun 20073039 @ Jun 2007

What What will bewill be feasible to measure:feasible to measure:Geodetic PrecessionGeodetic Precession

Precession periods only ~70 yearsPrecession periods only ~70 years [ [ BurgayBurgay et al. 2003 ]et al. 2003 ]

~ ~ 44 time time shortershorterthan in any otherthan in any other

double neutron star:double neutron star:much easier tomuch easier tobe detected,be detected,

thence imposing strongthence imposing strongconstraints toconstraints tothe geometrythe geometry

of the pulsar beamof the pulsar beam

©©Kramer

Kramer --JBO

JBO

What will be feasible to measure: Aberration

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

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.

[ ] [ ] ωω

ωωcos)(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 delaysare usually absorbed in Roemer delays

[ [ DamourDamour & & DeruelleDeruelle 1986 ]1986 ]

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

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

Total Total periastronperiastron advance to 2PN level:advance to 2PN level:

[ ]BS

BS

AS

AS

T

tot ggfe

k ββββββ00

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

πβ =

EquationEquation--ofof--StateState

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

[ [ DamourDamour & Schaefer 1988 ]& Schaefer 1988 ]

[ [ LattimerLattimer & & SchutzSchutz 2004 ]2004 ][ Morrison et al. 2004][ Morrison et al. 2004]

A 10% accuracy on IA 10% accuracy on Iwould exclude most would exclude most EoSEoS

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

magnetosphere of B ( 1st evidence )

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 )

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

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

Superior

conjunction

Superior

conjunction

B phase 1.00B phase 1.00



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

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

magnetosphere of B ( 2nd evidence )

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 ( 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]

[[BurgayBurgay, Possenti , Possenti etet al.al. 2005]2005]

Nov04 Jul04 Apr04 Jan04 Sep03 Jul03

Nov04 Jul04 Apr04 Jan04 Sep03 Jul03

High High brightessbrightess phases of phases of B are changing !B are changing !

Possibility of removing Possibility of removing degeneracy between degeneracy between

different models checking different models checking their predictions about their predictions about evolution in a humanevolution in a human--

scale time !scale time !

SpinSpin--Powered Pulsars: A CensusPowered Pulsars: A Census

• 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 [ @ Manchester –– ATNF ]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 ∆ν∆ν∆ν∆ν ∆∆∆∆t

We

P − We√√√√ √Tsys = system noise temperature

Tsky = sky temperature

G = antenna gain

Np = number of polarizations

∆ν∆ν∆ν∆ν = total bandwidth

∆∆∆∆t = total integration time

P = pulsar period

We = effective pulse width

WWee = W= W22 + + δδδδδδδδtt22 + + δδδδδδδδtt22DMDM + + δδδδδδδδtt22

scattscatt

δδδδδδδδt = sampling time t = sampling time

δδδδδδδδttDMDM = dispersion smearing = dispersion smearing

δδδδδδδδttscattscatt = scattering smearing= scattering smearing

Smin ∼∼∼∼Tsys + Tsky

G Np ∆ν ∆t

We

P − We√ √

δδδδtDM =1.2 10−−−−4

δνδνδνδννννν3

DM

δδδδtscatt ∼∼∼∼ 1νννν4

δδδδtsamp

Nch = ∆ν/δν…but…

…but… S ∼ ν −1.7

…but… Nsamp = ∆t/δtsamp

We = W2 + δt2samp + δt2DM + δt2scatt

G →→→→ large aperture

Tsky ∼∼∼∼ νννν−−−−2.7 (r.a. & dec) ↔↔↔↔ Spsr ∼∼∼∼ νννν −−−−1.7

0

You are here

Better use high ν

δtDM ∼∼∼∼ ν −3

δtscatt ∼∼∼∼ ν −4

Tsky ∼∼∼∼ ν −2.7

Narrow beam ∼Ok Deep surveys in the diskDeep surveys in the disk

In order to find many pulsars we have to search large volumesIn order to find many pulsars we have to search large volumes

You are here

Better use low ν

Large telescope beam !

Spsr ∼∼∼∼ ν −1.7

Away from the Galactic plane:

Low DM

Scattering negligible

Tsky ∼ 30 °KWide allWide all --sky surveyssky surveys

In order to find many pulsars we have to search large volumesIn order to find many pulsars we have to search large volumes

Standard search techniqueStandard search technique

time

time

Rad

io

freq

uenc

y

Power spectrum

Fluctuation frequency

DMk

FFT Pulse phase

Integrated pulse profile

Folding

time

Pulse phase


Folding

s/n

If the code picked If the code picked up the correct up the correct apparent pulse apparent pulse

repetition period P repetition period P

time

Pulse phase


Folding

s/n

If the If the code code

picked up picked up a a slighltyslighltywrong wrong

apparent apparent pulse pulse

repetition repetition 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 changing not changing too quickly too quickly along the along the

observation, observation, the code the code can still can still pick P pick P

KnowningKnowningexactly how exactly how P changes, P changes, one can one can easily easily

recover the recover the pulse profilepulse profile

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

time

Power spectrum


FFT

time

Power spectrum


FFTNo pulsar

suspect !

But if the Doppler acceleration is too high, the But if the Doppler acceleration is too high, the signal is not picked up in the fluctuation spectrum !signal is not picked up in the fluctuation 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 Nr of FFTsFFTs = N= NDMDM x x NNaccacc

Coherent (linear) acceleration searchCoherent (linear) acceleration search

[ [ CamiloCamilo et al 2000 et al 2000 ]]

Segmented FFT procedure helpsSegmented FFT procedure helps

[ Faulkner, PhD Thesis 2004

[ Faulkner, PhD Thesis 2004 ]]

Segmented Segmented vsvs standard searchstandard search

[ 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 searchPhase modulation VS segmented search

[ 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 or wide or

deepdeep) and the amount of ) and the amount of computational capabilities result in a computational capabilities result in a different sampling of evolutionary different sampling of evolutionary stage of pulsars and hence of the stage of pulsars and hence of the

PP--P diagramP diagram..

ParkesParkes 64 m radiotelescope64 m radiotelescope

MultibeamMultibeam receiverreceiver

System parameters:System parameters:

•• 13 beams

• Tsys ~ 25 °K

• ∆ν ∼ 288 MHz @ 1.4GHz

• δν = 13 x 96 x 3 MHz

• δν = 512 x 0.5 MHz

The The ParkesParkes multibeammultibeam surveyssurveys

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

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

SwinSwin Group:Group: Swinburne, CaltechSwinburne, Caltech

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

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

[ Manchester et al 2001, Morris et al 2002, Kramer et al 2003

[ Manchester et al 2001, Morris et al 2002, Kramer et al 2003

Hobbs et al 2004,

Hobbs et al 2004, Faukner

Faukneret al 2004,

et al 2004, Lorimer

Lorimeret al 2006

et al 2006]]

ParkesParkes PM = 725PM = 725

ParkesParkes SwinSwin = 69+25= 69+25

ParkesParkes PH = 18 PH = 18

Total = Total = 837837

Parkes GC search = 12Parkes GC search = 12

Parkes 47 Parkes 47 TucTuc search = 22search = 22

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

ParkesParkes discoveriesdiscoveries Radio pulsars in the Catalog:Radio pulsars in the Catalog: ∼∼∼∼∼∼∼∼ 17651765

131131 BinariesBinaries

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

26 26 VelaVela--likelike

8 8 Double Neutron star binariesDouble Neutron star binaries

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

∼∼∼∼∼∼∼∼ 300300--500 discoveries in 3500 discoveries in 3--5 yrs ?5 yrs ?

ParkesParkes Perseus Arm Survey at 1.4 GHz Perseus Arm Survey at 1.4 GHz

1515--30 discoveries ?30 discoveries ?

GBT Pilot Surveys at 350 MHz GBT Pilot Surveys at 350 MHz 3030--50 discoveries50 discoveries

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 55--10 discoveries ? 10 discoveries ?

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

ParkesParkes Galactic MSP Survey at 1.4 GHzGalactic MSP Survey at 1.4 GHz 5050--100 100 MSP discoveries ?MSP discoveries ?

Fun for everyoneFun for everyone: Pulsar Astrophysics : Pulsar Astrophysics with the SKA with the SKA (from 200x )(from 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

•• MultiMulti--wavelength studieswavelength studies

•• Exotic systemsExotic systems

•• Gravitational physics (SKA KSP)Gravitational physics (SKA KSP)

[ [ CordesCordes et al. 2004 et al. 2004 ]]

StrongStrong--field testsfield tests of gravity using pulsar & black holesidentified as one of five SKA Key Science Projectsone of five SKA Key Science Projects

Galactic Census with the SKAGalactic Census with the SKA

•• Discovery of almost every pulsars inDiscovery of almost every pulsars inGalaxy: in total Galaxy: in total ∼∼∼∼∼∼∼∼ 1000010000--20000 pulsars20000 pulsars

•• ~ 1000 millisecond pulsars~ 1000 millisecond pulsars

•• more and more Doublemore and more Double--Pulsar SystemsPulsar Systems

[ 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 beforeComplete new quality of science possible! Complete new quality of science possible!


[ Kramer et al. 2004

[ Kramer et al. 2004]]

Cosmological Gravitational Wave BackgroundCosmological Gravitational Wave Background

•• Pulsars discovered in Galactic Census alsoPulsars discovered in Galactic Census alsoprovide network of arms of a hugeprovide network of arms of a hugecosmic gravitational wave detectorcosmic gravitational wave detector

•• Perturbation inPerturbation inspacespace--time can betime can bedetected in timingdetected in timingresidualsresiduals

•• Sensitivity: dimensionless strainSensitivity: dimensionless strain

Tfh TOA

c

σ~)(

PulsarPulsarTimingTiming

ArrayArray

PTA:PTA:


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

and also:and also: merging massive BH binariesmerging massive BH binariesin early galaxy evolutionin early galaxy evolution

Sources:Sources:

•• InflationInflation•• String cosmologyString cosmology•• Cosmic stringsCosmic strings

•• phase transitionsphase transitions

.~)(20 constfh GWΩ

3/220 )( ffh GW ∝Ω



LISAPulsarsAdvancedLIGO

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

Further by correlation:

PSRN/1

PTA limit:

4220 ~)( ffh TOAGW σΩ

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 pulsartiming via relativistic and classical spin-orbit coupling

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

[ [ WexWex & & KopeikinKopeikin 1999 ]1999 ]

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

The last not prohibited dreamThe last not prohibited dream: a : a pulsar orbiting a Black Holepulsar orbiting a Black Hole (200?)(200?)

Happy

hunting

, folks

!!!

Happy

Happy

hunting

hunting

, , folksfolks !!!!!!

pulsars - ira.inaf.it · [sigurdsson 2003] [colpi, mapelli, possenti 2004] a double black-hole of...

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