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Credit: John Sarkissian. Pulsars + Parkes = Awesome. Ryan Shannon Postdoctoral Fellow, CSIRO Astronomy and Space Science. Outline. Post main sequence stellar evolution A few of the properties of pulsars that make them hella cool. Pulsar timing: the bread and butter of pulsar observing - PowerPoint PPT Presentation

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  • Pulsars + Parkes = AwesomeRyan Shannon Postdoctoral Fellow, CSIRO Astronomy and Space ScienceCredit: John Sarkissian

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  • OutlinePost main sequence stellar evolution

    A few of the properties of pulsars that make them hella cool.

    Pulsar timing: the bread and butter of pulsar observing

    What I like about pulsars: Get to work on a lot of different areas of physics and astrophysics

    Crab Pulsar Wind Nebula

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  • End of Stellar EvolutionMain sequence starCompact RemnantWhite dwarf 0.1 to ~ 1.2 MsunDegenerate electron pressure0.1 to 8 Msun8 to 20 (?) Msun> 20 MsunNeutron star 1.3 to < 3 MsunDegenerate neutron pressureBlack hole >3 MsunGravity winsComplications: mass exchange in binary systems

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  • Background:1931:understanding of white dwarfs (Chandrasekhar)1932:neutron discovered (Chadwick)1933:neutron stars (Baade & Zwicky)1939:first models (Oppenheimer & Volkoff)

    Detectable?Thermal radiation (106 K, 10 km) bleak1967:Radio pulsars (serendipitous)Gamma-ray bursts (ditto)

    1968:Pulsar discovery announcedCrab pulsar discovered

    1969:Crab pulsar spindown measured& clinched the NS hypothesis (T. Gold)Historical background

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  • How to build a pulsar in 50 Mega yearMaser

    Massive Star

    Supernova explosion

    Neutron StarConservation of angular momentum: spins fastConservation of magnetic flux: high magnetic fields.Compact ~ 1.4 solar masses of material in 10 km.Assymetric SN explosion- pulsar has high velocity (mashes up ISM)

    Pulsar: a class of neutron star that emits pulsed radiationRotation powered -

    Supernova 1987a, in the LMC

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  • Pulsar radiation is pulsedPeriodicity of the emission: rotation period of neutron starSpin period for radio-bright neutron stars 1 ms to 10 s

    Emission region: located near magnetic pole of star

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  • Pulsar radiation is pulsedPeriodicity of the emission: rotation period of neutron starSpin period for radio-bright neutron stars 1 ms to 10 s

    Emission region: located near magnetic pole of star

    Single pulses from PSR B0834+06

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  • Pulsar radiation is periodically pulsedEach pulsar has a unique fingerprint (pulse profile)Pulsed emission averages towards a standard that is usually statistically identical at all observing epochs

    If the profile stays the same, we can very accurately track the rotation history of the pulsarsPrecision pulsar timing: most powerful use of pulsars (next to CMB, the most powerful use of any form of astrophysical radiation)

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  • Pulsars have unique Period and Period derivativesTwo fundamental observables of pulsarsPeriod Period derivative

    Describe the pulsar population

    Estimate other properties based on P and Pdot.Age (103 109 yr)Surface magnetic field strength (108 to1015 G)Surface voltage potential (1012 V) MSPsCanonical PulsarsSome pulsars are recycled

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  • Pulsar radiation is erraticSingle pulses vary in shape

    Some pulsars show ultra-bright giant pulses

    Some pulsars occasionally miss pulses (nulling)

    Some pulsars only occasionally emit pulses (rotating radio transients RRATS)

    Bhat et. al.

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  • Pulsar radiation is dispersedWarm plasma in the ISM is refractive, and the index of refraction depends on RF. At higher frequencies pulsed emission arrive earlierLevel of dispersion depends on total column density along the line of sight (Dispersion measure DM).

    Dispersion is an excellent discriminatorAllows us to distinguish pulsars from RFI (radar, microwaves, guitar hero)

    Corollary: Pulsars can be used to study ISM and Galactic Structure0 < DM < 1200 for known pulsars

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  • Pulsar Radiation is Multi-wavelengthNon-thermal emission observed across entire EM spectrumSome pulsars are prodigious producers of gamma-ray emission.The number of high energy pulsars has grown by a factor of 10 since the launch of the Fermi space telescope.

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  • Step 1: Finding PulsarsThe Parkes radio telescope has found more than twice as many pulsars as the rest of the worlds telescopes put together.Talk to Mike Keith

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  • 26 May 2011UWashington*Repeat for L epochs spanning N=T/P spin periods (T=years)N ~ 108 1010 cycles in one year Period determined toPulsar Timing: The Basics of Pulsars as ClocksStack M pulses (M=1000s) Time-tag using template fitting

    PMPWJ1909-3744: eccentricity < 0.00000013 (Jacoby et al. 2006)B1937+21: P = 0.00155780649243270.0000000000000004 s

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  • What influences pulse arrival times?Pulsar spindown

    Random spindown variations

    Intrinsic variation in shape and/or phase of emitted pulse (jitter)

    Reflex Motion from companions

    Gravitational Waves

    Pulsar position, proper motion, distance

    Warm electrons in the ISM

    Solar systemMass of planets (Champion et al. 2010)Location of solar system barycentre (John Lopez)PulsarEarthGoal: including as many of the perturbations as possible in timing model.

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  • What influences pulsar arrival times?te = tr D/c2 + DM/2+ R + E + S - R - E - S+ TOAISM+ TOAorbit noise+ TOAspin noise+ TOAgrav. waves + Path lengthPlasma dispersion (ISM)Solar system (Roemer, Einstein, Shapiro)Binary pulsar (R,E,S delays)ISM scattering fluctuationsOrbital perturbations Intrinsic spin (torque) noise Gravitational wave backgroundsWant to include as many of these perturbations as possible in model

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  • Relative Amplitudes of Contributions

    Simulated TOAs for MSP J1713+0747pulsarEarth20 ms10 s500 nsRelative DayRelative DayRelative Day5 msRelative DayNo SpindownProper motion off by 1 mas/yrParallax off by 1 masRA off by 1TTTT010000100001000Relative Day01000

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  • Reflex Motion

    Konacki & Wolszczan (2004): Three planets around MSP B1257+12: 4.3 MEarth, 3.9 MEarth, and 0.02 MEarth199020022 ms20 s20 s

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  • Example: What pulsar residuals ought to look like: PSR B1855+09Arecibo UpgradeAO PaintingThe Residuals are quite white! (Time series from D. Nice)Year19862010T (s)6-6

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  • Example: What Residuals from Most Pulsars Look LikeOrigin: Intrinsic spin instabilities (spin noise)Asteroid belt?

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  • Applications of pulsar timing

    Neutron stars with companionsKnown companions: white dwarfs, neutron stars, planetsNeed to incorporate general relativity to model orbits of WD and NS binary systemsTests of general relativity

    Holy grails: A pulsar orbiting another pulsar (two clocks, dude)Pulsar orbiting a black holeDirect detection of gravitational waves

    What Ryan works on: understanding astrophysical noise in timing observations

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  • First binary pulsar: The Hulse-Taylor Binary B1913+16Pulse period: 59 msOrbital Period: 7h 45mDouble neutron-star systemVelocity at periastron: ~0.001 of velocity of lightPeriastron advance: 4.226607(7) deg/year (same advance in a day as Mercury advances in a century)

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  • CSIRO. Gravitational wave detection Prediction based on measured Keplerian parameters and Einsteins general relativity due to emission of gravitational waves (1.5cm per orbit)After ~250 MYr the two neutron stars will collide!(Weisberg & Taylor 2003)Gravitational Radiation from B1913+16

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  • The Next Grail: A double pulsar system

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  • First Double Pulsar: J0737-3939 Pb=2.4 hrs, d/dt=17 deg/yr MA=1.337(5)M, MB=1.250(5)MLyne et al.(2004)Now to 0.05%

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  • The Future: Pulsar Black Hole Systems Pulsar-BH binaries in the field

    Pulsars orbiting Sag A* (Massive black hole in centre of Galaxy)

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  • Gravitational Wave Detection with Pulsars

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  • Status of gravitational wave detections:Number of known gravitational wave sources:0

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  • Spin-down irregularitiesNo angular signature

    Inser