Pulsar Science with the SKA

04/19/23 Pulsar Science with the SKAPulsar Science with the SKA 1

Pulsar Science with the SKAPulsar Science with the SKA

Jim Cordes & Michael Kramer

International SKA Conference 2003Geraldton

30 July 2003


Pulsar SciencePulsar Science

• Extreme matter physics – 10x nuclear density

– High-temperature superfluid & superconductor

– B ~ Bq = 4.4 x 1013 Gauss

– Voltage drops ~ 1012 volts

– FEM = 109Fg = 109 x 1011FgEarth

• Relativistic plasma physics (magnetospheres)

• Tests of theories of gravity

• Gravitational wave detectors

• Probes of turbulent and magnetized ISM (& IGM)

• End states of stellar evolution


Why more pulsars?• Discover rare, extreme objects (odds Npsr)

• P < 1 ms P > 8 sec

• Porb < hours B >> 1013 G (link to magnetars?)

• V > 1000 km s-1 strange stars?

• NS-NS and NS-BH binaries, planets

• Extragalactic pulsars

• Galactic center pulsars orbiting Sgr A* black hole

• Large Npsr Galactic tomography of B + B, ne + ne

Branching ratios for compact object formation:• NS (normal, isolated)• NS (recycled, binaries)• NS (magnetar)• BH (hypernovae)• Strange stars?

Large N Large N Galactic tomography Galactic tomography


How to do it?How to do it?

• Find them

• Time them

• VLBI them


Blind Surveys with SKABlind Surveys with SKA• Number of pixels needed to cover

FOV: Npix~(bmax/D)2

~104-109

• Number of operationsNops~ petaops/s

• Post processing per beam:e.g. standard pulsar

periodicity analysis Dedisperse (~1024 trial DM values) +

FFT + harmonic sum (+ orbital searches + RFI excision)

• Requires signal transport of individual antennas to correlator

(pulsars, transients, ETI)

10104 4 beams neededbeams needed

for full-FOV samplingfor full-FOV sampling


Sensitivity CalculationsSensitivity Calculations

• Pulse smearing effects • Dispersive arrival times

• Scattering

• Orbital

• Instrumental

• Luminosity function for pulsars (> 5 orders of magnitude) = beaming + beam luminosity

calculated using NE2001(Cordes & Lazio 2003)


Pulsar Searching With SKA vs AreciboPulsar Searching With SKA vs Arecibo

Dmax = (Lp / Smin1)½Nh¼

Fourier search

Nh = # harmonics detectable

Pulse smearing effects from interstellar scattering

(also, orbital smearing in NS-BH binaries, etc.)


64 64 s sampless samples

1024 channels1024 channels

600 s per beam600 s per beam

~10~1044 psr’s psr’s

SKA pulsar surveySKA pulsar survey


Summary on Pulsar Summary on Pulsar SearchingSearching

• SKA can perform a Galactic census of neutron stars that will surpass previous surveys by a factor > 10.

• The discovery space includes exotic objects that provide opportunities for testing fundamental physics.

• Pulsar searches place particular demands on the ability to do full FOV sampling at high time resolution (64 s) with 1024 channels over > 400 MHz at 1-2 GHz.

• High frequencies (> 10 GHz) are needed for Galactic center searches to combat scattering.

• Further simulations are needed that use detailed information from existing pulsar surveys and particular SKA configurations.


• Galactic probes: Interstellar medium/magnetic field

Star formation history

Dynamics, grav. potential

Post-discovery SciencePost-discovery Science Very wide range of applications:Very wide range of applications:

electronelectron

distributiondistribution

electronelectron

distributiondistribution Magnetic fieldMagnetic fieldMagnetic fieldMagnetic field

Also: Scintillation Resolving Magnetosphere!

Also: Scintillation Resolving Magnetosphere!





• Extragalactic pulsars: Stellar formation & population, IGM


Giant pulsesGiant pulses

Probing the local group!Probing the local group!

Extragalactic pulsarsExtragalactic pulsars






• Solid State Physics under extreme conditions


GlitchesGlitches

NS structureNS structure

Equation-of-StateEquation-of-State



x

xbP






• Tests of theories of gravity, e.g. Black Hole properties!



Pulsar Timing Array:Pulsar Timing Array:

Look for global spatial Look for global spatial

pattern in timing residualspattern in timing residuals!!

Pulsar Timing Array:Pulsar Timing Array:

Look for global spatial Look for global spatial

pattern in timing residualspattern in timing residuals!!






• Tests of theories of gravity, e.g. Black Hole properties!

• Detection of gravitational wave background


Gravitational Wave BackgroundGravitational Wave Background• Sources: Binary BHs, Galaxy Formation, Strings, Big BangSources: Binary BHs, Galaxy Formation, Strings, Big Bang

• Pulsars = Arms of a huge gravitational wave detectorPulsars = Arms of a huge gravitational wave detector

• SensitivitySensitivity complementary to LIGO and LISAcomplementary to LIGO and LISA

Backer (priv. comm)Backer (priv. comm)

LISAPulsars AdvancedLIGO


Precision Pulsar Timing with the SKAPrecision Pulsar Timing with the SKA

• Fast(!) samplingFast(!) sampling

• High sensitivityHigh sensitivity

• Systematics, e.g. solar system ephemeredes, Systematics, e.g. solar system ephemeredes,

time standardstime standards

• Interstellar weather Interstellar weather

• Multipath scatteringMultipath scattering

• Timing noise (?)Timing noise (?)

• Profile stabilityProfile stability

Consider:Consider:

Multi-frequency: 400-10000 MHzMulti-frequency: 400-10000 MHz

Wide bandwidth (20-50%), polarizationWide bandwidth (20-50%), polarization

Strong pulsars: stabilization time-scale dominatingWeak pulsars: SNR dominating

Strong pulsars: stabilization time-scale dominatingWeak pulsars: SNR dominating

1 s (or even 10-100 ns??)1 s (or even 10-100 ns??)

Multiple FOVs!Multiple FOVs!


Multiple FOVs:Multiple FOVs: Initial Simulation ResultsInitial Simulation Results About 12,000 pulsars, ~1300 MSPsAbout 12,000 pulsars, ~1300 MSPsSimulated Population:Simulated Population:

Independent FOVs:Independent FOVs:

Sources (=beams) per FOVSources (=beams) per FOV


Simulated Population:Simulated Population:Required time for one(!) timing point:Required time for one(!) timing point:

All PulsarsAll Pulsars

Multiple FOVs:Multiple FOVs: Initial Simulation ResultsInitial Simulation Results


Simulated Population:Simulated Population:Required time for one(!) timing point:Required time for one(!) timing point:

Millisecond PulsarsMillisecond Pulsars

Multiple FOVs:Multiple FOVs: Initial Simulation ResultsInitial Simulation Results


Summary:Summary: Pulsars with the SKAPulsars with the SKA• Overwhelming science case:

New quality due to both leap in numbers and timing precision

• “Modest” frequency coverage but large bandwidth

• Large number of simultaneous beams/FOVs desirable

• Detailed requirements different for searching & timing

- both modes are necessary to obtain science!!

• Configuration: sensitive core but with very large baselines

(to enable astrometry out to 10 kpc)

• Significant post-processing requirements!

Hybrid Design:Hybrid Design:• Large instantaneous at 2 GHz

(contiguous or separated FOVs)

• searching: 50 s sampling full FOV• timing: 1 s sampling pencil beam• capability of up to 10 to 15 GHz (less than 1 SKA)

Pulsar Science with the SKA

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