1 / 19

Searching for Radio Pulsars

Vicky Kaspi, McGill University CIFAR AGM 2012. Searching for Radio Pulsars. Why Do We Need More Radio Pulsars?. Want to build a `Pulsar Timing Array’ (PTA) to detect gravitational waves

mateja
Download Presentation

Searching for Radio Pulsars

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Vicky Kaspi, McGill University CIFAR AGM 2012 Searchingfor Radio Pulsars

  2. Why Do We Need MoreRadioPulsars? • Want to build a `Pulsar Timing Array’ (PTA) to detect gravitational waves • Need many MSPs distributed ~isotropically on the sky, timed with very high precision simultaneously over many years • Also, individual objects can be astrophysically very interesting!

  3. Arecibo Observatory (credit: NAIC) The PALFA Survey • Surveying Galactic plane with 305-m Areciboradio telescope with ALFA receiver • International consortium, ~30 members • 1.4 GHz, 5 min ptgs, 64us, 1 Petabyte 7-beam PALFA Receiver

  4. PALFA Survey Status 96pulsars discovered so far, including 14 MSPs

  5. PALFA MSPs vs. ATNF Catalogue. (Credit: D. Nice)

  6. GBT Driftscan Survey • Used GBT during 2007 summer track refurbishing • Dish stuck at zenith, sky drifted overhead • 134 Tb at 350 MHz • Covered 12,000 sqdeg (1491 hrs) with gaps • 24 new pulsars, 5 msps, 20-30 RRATs!

  7. GBNCC 350 MHz Survey Green Bank North Celestial Cap Survey

  8. GBNCC 350 MHz Survey 20 pulsars so far,including 3 MSPs

  9. New Nearby GBNCC MSP! Courtesy Ryan Lynch

  10. InterestingDriftscanBinary Pulsar J0348+0432 • Based on observational work by Ryan Lynch, Paulo Freire, JohnAntoniadis, Norbert Wex • Work in preparation…allinfopreliminary • P=39ms, Porb=2.4 hr • Highly relativistic! • WD companion, mass well determined from spectrum, models: 0.172+/-0.002 sm • WD absorption lines show orbital Doppler shifts Preliminary!!!

  11. White Dwarf Radial Velocities q=11.85+/-0.10 Preliminary!!! Courtesy John Antoniadis

  12. J0348: Massive & Relativistic Preliminary!!! • Combination of q, Mc yields Mp=2.039 +/- 0.029 solar masses • Relevant to EOS; Demorest et al. 2010 • J0348: first massive NS in relativistic orbit! • Astronomical object with the strongest gravitational fields inside matter • Can test GR in new regime Courtesy John Antoniadis

  13. Testing Dipolar Radiation Damping: tensor-scalar theories • Radio timing of pulsar at GBT, Arecibo determines relativistic parameter Pbdot = (0.035+/-0.05)x10^-12 (PRELIMINARY) • PSR J0348+0432: • Note that this is better constraint that expected from GW experiments(Damour & Esposito-Farese 1998) A B Preliminary!!!

  14. J0348 and aLIGO/Virgo • To detect merging NS-binaries, need template as aLIGO/Virgo data noisy • More realistic template = greater sensitivity • Major effort to calculate post-Newtonian (PN)approximation to GR • But alternative tensor-scalar (TS) theoriescould pose problem with this strategy GR TS Courtesy Norbert Wex

  15. Merger of a 2 M NS and a 10 M BH (fISCO = 366 Hz) Number of cycles in the aLIGO/VIRGO band (10 – 1000 Hz) GR TS GR - TS PRELIMINARY 0348 today Figure courtesy Norbert Wex

  16. Merger of a 2 M NS and a 1.4 M NS (fISCO = 1293 Hz) Number of cycles in the aLIGO/VIRGO band (10 – 1000 Hz) GR TS GR - TS PRELIMINARY 0348 today Figure courtesy Norbert Wex

  17. J0348:Good News for GWs • Binary pulsars are very useful for testing TS gravity • Was true for low-mass NSs (Damour & Esposito-Farese 1998) • Now true for high-mass NSs • Good news for calculating templates: • Limit from J0348 suggests PN formalism should work for massive NSs as well

  18. Conclusions • PALFA, Driftscan, GBNCC pulsar searches in support of IPTA are yielding fruit • New MSPs for timing • Interesting binary pulsars • PSR J0348+0432: 1st high-mass neutron star in a relativistic orbit • Paper in preparation…

  19. Sky positions of all known MSPs suitable for PTA studies Courtesy D. Manchester • 63 Galactic (non-GC MSPs) • Only ~30 “good” sources

More Related