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X-ray and observational Astronomy

X-ray and observational Astronomy. Detection limits for close eclipsing and transiting sub-stellar and planetary companions to white dwarfs in the WASP survey. Francesca Faedi Richard West, Matt Burleigh, Mike Goad, Leslie Hebb. 17 th European White Dwarf Work Shop – 20/08/2010. Outline.

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X-ray and observational Astronomy

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  1. X-ray and observational Astronomy Detection limits for close eclipsing and transiting sub-stellar and planetary companions to white dwarfs in the WASP survey Francesca Faedi Richard West, Matt Burleigh, Mike Goad, Leslie Hebb 17th European White Dwarf Work Shop – 20/08/2010

  2. Outline X-ray and observational Astronomy 1) Sub-stellar and Planetary companions to WDs - Simulation - Detection algorithm - Results from the analysis of 194 WDs in WASP companion’s Frequency 2) Monitoring WD variability with WASP - Photometric variability for our WD sample 17th European White Dwarf Work Shop – 20/08/2010

  3. The WASP survey X-ray and observational Astronomy - 8 Canon lenses 200mm f/1.8 - CCD array 20482 13.5μm per pixel - Field of view 7.8 x 7.8 deg2 per camera - magnitude limit V ≈15 - photometric accuracy better than 1% down to V ≈12 42 confirmed transiting planets 17th European White Dwarf Work Shop – 20/08/2010

  4. Motivation X-ray and observational Astronomy All stars with mass ≤ 8M will evolve to white dwarfs What is the fate of known planetary systems? 17th European White Dwarf Work Shop – 20/08/2010

  5. Motivation X-ray and observational Astronomy Rwd~ R Deep transit signals 3 < δ< 70 % δ =100% BD/Gas Giant Terrestrial companions 17th European White Dwarf Work Shop – 20/08/2010

  6. Simulations X-ray and observational Astronomy Synthetic dataset Rpl , RWD , Porb Parameters: MWD = 0.6M and RWD = 0.013R WASP data: ~150 days per season 8 min sampling, 30 sec exposure Period range 2 h – 15 d ~ 0.3 – 12 R Moon BD/Gas giants Companion size 17th European White Dwarf Work Shop – 20/08/2010 17th European White Dwarf Work Shop – 20/08/2010

  7. X-ray and observational Astronomy MS solar-type star White dwarf Gas giant companion Orbital Period = 2.52 days 17th European White Dwarf Work Shop – 20/08/2010

  8. Results X-ray and observational Astronomy White noise Red noise transit + Gaussian noise of standard deviation σ real WASP data Detection algorithm Classic BLS Our implementation Modified Box-Least Square (BLS) + down weighting Details in Faedi et al. 2010 • S/Npeak> 6.3 SDE • PBLS within 0.003d of the corrected (inserted) period Empirical criteria detection 17th European White Dwarf Work Shop – 20/08/2010

  9. Results X-ray and observational Astronomy Results from simulations Results for V≈12 Results for V≈15 see Faedi et al. 2010 for detailed tables on detection limits 17th European White Dwarf Work Shop – 20/08/2010

  10. Data analysis X-ray and observational Astronomy - Our WD sample consists of 194 stars - WASP multi-season light-curves (2004 - 2008) No evidence of transiting sub-stellar and planetary companions were found We use our null result to estimate an upper limit to the frequency of companions to WDs 17th European White Dwarf Work Shop – 20/08/2010

  11. Limits on companion frequency X-ray and observational Astronomy Combining the three magnitude-specific maps from simulations into a single averaged map by interpolating/extrapolating according to the magnitude of each object in the sample. For a perfect survey Using our simulations 17th European White Dwarf Work Shop – 20/08/2010

  12. conclusion X-ray and observational Astronomy 1) My Key result is transits of terrestrial rocky bodies in short period orbits are detectable in current ground-based photometric surveys such as WASP none found as yet … ! • Future surveys such as NGTS, Pan-STARRS, LSST, Plato • Increase sample size • Sampling rate (high cadence) • Baseline ~1100 WDs 15 <V< 17 McCook & Sion 2) Our analysis of 194 WDs found no evidence of companion. Constraints can only be put on Gas giants and sub-stellar objects in orbits with P< 0.1 − 0.2 days, similar to WD0137−349 (Maxted et al. 2006), these objects must certainly be rare (∼ < 10%) 17th European White Dwarf Work Shop – 20/08/2010

  13. Monitoring WDs variability with WASP X-ray and observational Astronomy • Same sample of 194 WDs • Variability search: Two-step method • Lomb-Scargle periodogram + CLEANedperiodogram analysis • selected only objects with period detected in both periodograms • + • Individual eye-balling of the folded light-curves • + • Phase Dispersion Minimisation (PDM) for objects showing non-sinusoidal variations 17th European White Dwarf Work Shop – 20/08/2010

  14. Interesting objects X-ray and observational Astronomy 17th European White Dwarf Work Shop – 20/08/2010

  15. X-ray and observational Astronomy 17th European White Dwarf Work Shop – 20/08/2010

  16. X-ray and observational Astronomy 17th European White Dwarf Work Shop – 20/08/2010

  17. X-ray and observational Astronomy Thank you!! 17th European White Dwarf Work Shop – 20/08/2010

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