Review: Penn State Pulsar Timing and Gravitational Wave Detection Workshop

Transcription

1 Review: Penn State Pulsar Timing and Gravitational Wave Detection Workshop Fredrick A Jenet Center for Gravitational Wave Astronomy University of Texas at Brownsville

2 Thanks to

3 Organizers Andrea Lommen Sam Fin Fredrick Jenet Michelle Larson

4 Goals of workshop Bring together researchers who are working on the problem of G-wave detection using radio pulsars Review current research Discuss ideas for making G-wave detection a reality

5 Speakers John Armstrong JPL Don Backer Berkeley Jim Cordes Cornell Oliver Dore Princeton Ron Hellings NASA Jason Hessels McGill George Hobbs ATNF Andrew Jaffe Imperial College Fredrick Jenet UTB/CGWA Judah Levine NIST Andrea Lommen Franklin-Marshall David Nice Bryn Mar

6 David Nice: What Goes Into a Pulsar Timing Model Noted: always fit a quadratic term to obtain the pulsar s period and derivative => a perturbation due to gravitational waves which is linear or quadratic in time cannot be detected Pulsar timing fits out annual terms

7 David Nice: What Goes Into a Pulsar Timing Model Apparent inverse correlation between orbital period and pulsar mass. (Nice et al., ApJ, submitted)

8 Ron Hellings: Introduction to Gravitational wave detection Type Range Run Time Sources Instrument HF 10 Hz 1000 Hz one per day compact stars bars, LIGOs MF 0.1 Hz 10Hz one per a few days? MAGGIE, lunar LIGO LF 10 mhz 10 mhz one per year binaries SMBHs LISA VLF 1 nhz 10 mhz once in a lifetime cosmic astrophysics PTA ULF 10 nhz 0 Hz snapshots only cosmic structure COBE, MAP Planck, etc.

9 Andrew Jaffe: Gravitational waves from black hole binary systems MBH Binary Dynamics Gravity waves Galaxy Merger Rates MBH demographics D. Backer

10 Andrew Jaffe: Gravitational waves from black hole binary systems Future Work Full calculation/measurement of Galaxy (MBH) merger rate Crucial especially for LISA event rate Use n-body, Press-Schecter, merger trees Measurement of high-z merger rate (DEEP2) Detection of binary MBHs Galactic Dynamics: the final parsec problem Pulsar Timing Array

11 Judah Levine: Coordinated Universal Time Post-1972 definition of UTC Duration of second defined by unperturbed cesium hyperfine transition on the rotating geoid: 9,192,631,770 cycles 1 second Atomic-time day is = s Astronomical day defined by UT1 Leap Seconds added to UTC to keep UT1- UTC < 0.9 s The times they are a-changing

12 Judah Levine: Coordinated Universal Time Not confusing enough yet? Resolution S2 (1996) of the Consultative Committee for the Definition of the Second (CCDS): Apply black-body correction to primary frequency standards. Correction for a room-temperature standard is about or about 0.6 µs/yr

13 Judah Levine: Coordinated Universal Time

14 Judah Levine: Coordinated Universal Time Arecibo s maser is about as good as my wrist watch Common View, Arecibo-NIST Time Difference (ns)

15 Oliver Dore: Detecting Gravity Waves via the CMB, the next frontier for cosmology CMB polarization measurements can infer the presence of a cosmological G- wave background. Provide strong evidence for inflation.

16 Jason Hessels:Finding Fast Pulsars today and Tomorrow Arecibo L-band Feed Array Surveys (1400 MHz): (Cordes et al. 2005, submitted) 7-beam receiver. Start with Galactic plane, but higher-latitude surveys are planned. Detailed simulations indicate that a plane survey (-5 o < b < 5 o ) will discover MSPs. This part of the survey has already begun and should be complete in 5-7 years. Future surveys extending the coverage to 15 o above and below the plane should discover another MSPs. Such a mid-latitude survey was proposed for at the last Arecibo proposal deadline, and could begin later this year.

17 Jason Hessels:Finding Fast Pulsars today and Tomorrow 350-MHz Surveys at the GBT: (Swindburne, McGill/NRAO) GBT beam at 350 MHz is ~0.6 o 50 MHz of clean bandwidth at 350 MHz Pilot surveys, using the SPIGOT card and the CGSR coherent machine have begun at low and high Galactic latitudes at dec > 35 o This portion of the sky has not been well surveyed, and may still contain a number of relatively bright MSPs.

18 Jason Hessels:Finding Fast Pulsars today and Tomorrow Very bright MSPs: J is unique. It is unlikely that we will find another very bright MSP at such a low DM. Previous all-sky surveys may have missed bright (S1400 > 5mJy) MSPs with DM > 80 pc cm -3 Ongoing surveys with better spectral resolution are more sensitive to MSPs with 80 pc cm -3 < DM < 150 pc cm -3.

19 Jason Hessels:Finding Fast Pulsars today and Tomorrow MSPs in the Arecibo sky: There is the possibility of finding as many as 80 MSPs in the Arecibo sky in the next 5+ years using the Arecibo L-band Feed Array (ALFA). MSPs in the GBT sky: Low-frequency surveys covering large areas of the GBT sky will likely greatly increase the number of MSPs known above 40 o declination (currently only 2 are known with P < 10ms).

20 Jason Hessels:Finding Fast Pulsars today and Tomorrow MSPs in the southern sky: Most of the sky above 30 o from the Galactic plane has not been surveyed to the sensitivity achieved by other Parkes multibeam surveys. Although the Parkes multibeam Galactic plane survey found an unprecedented number of pulsars, it lacked the spectral resolution to find MSPs at high DM.

21 Jason Hessels:Finding Fast Pulsars today and Tomorrow MSPs in the southern sky: Discussion in Canada about building a 200-m SKA prototype, the Canadian Large Adaptive Reflector (CLAR). 350-MHz survey planned with the Giant Meter- Wave Radio Telescope (GMRT) in India, which has a collecting area comparable to Arecibo. For info on SKA, see Jim Corde s talk!

22 Fredrick Jenet: Using an Array of Radio pulsars to Detect Gravitational Waves 1. The pulsar timing residuals will be correlated between multiple pulsars pulsar, 100 nano-seconds RMS, 5-10 years

23 Andrea Lommen: What can you do with a single pulsar? PSR B currently places the best limit on the energy density in the stochastic gravitational wave background Ω g h 2 PSR B also places meaningful limits on 'nearby' sources of G-waves. Globular Cluster pulsars present an interesting case of a detector (a pulsar) near a G-wave source, and the near-field effect significantly enhances the magnitude of the induced residuals.

24 Willem Van Straten:Improving Pulsar Timing Arrival Time Estimation Frequency domain (Taylor 1992) Multi-component Gaussian (Kramer et al. 1994) Invariant interval (Britton et al. 2000) Full polarization (van Straten 2004) Time vs. frequency domain (Hotan et al. 2005) Higher order moments (Jenet & Hobbs 2005)

25 Willem Van Straten:Improving Pulsar Timing Preliminary results for the Stokes timing algorithm Pulsar Benefit J (1) (6) B (3) (8)

26 George Hobbs: Pulsar Timing Phenomenology 1. Pulsar timing residuals for slow pulsars show a lot of fluctuation. 2. For most MSPs, the residuals are white. 3. The MSP timing residuals should be dominated by the G- wave background.

27 Jim Cordes: the SKA Timeline for construction -> 2020 Frequency range from 0.1 -> 25 GHz 5 key science projects described in New Astronomy Reviews vol 48 Described technique to correct for intrinsic pulsar fluctuations use correlations of pulse shape perturbation with TOA uncertainties improve timing by factor of ~2

28 John Armstrong: Spacecraft Doppler Tracking DSS25 and Cassini

29 John Armstrong: Spacecraft Doppler Tracking All-Sky Sinusoidal Sensitivity

30 John Armstrong: Spacecraft Doppler Tracking Time-Frequency analysis Wavelets, chirplets, Gabor transforms Template independent Useful in Doppler tracking to characterise nonstationary time series Multi-taper spectral analysis Achieves optimum resolution with very low spectral leakage Automatic to distinguish periodic signals in the presence of a steep continuum

31 Final Discussion Need for sharing data Include pulsar timing data as part of NVO