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 17 th European White Dwarf Work Shop – 20/08/2010

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

3. X-ray and observational Astronomy 17 th European White Dwarf Work Shop – 20/08/2010 The WASP survey - 8 Canon lenses 200mm f/1.8 - CCD array 2048 2 13.5 μm per pixel - Field of view 7.8 x 7.8 deg 2 per camera - magnitude limit V ≈15 - photometric accuracy better than 1% down to V ≈12 42 confirmed transiting planets

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

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

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

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

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

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

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

11. X-ray and observational Astronomy 17 th European White Dwarf Work Shop – 20/08/2010 For a perfect survey 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. Using our simulations Limits on companion frequency

12. X-ray and observational Astronomy 17 th European White Dwarf Work Shop – 20/08/2010 conclusion 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%) Future surveys such as NGTS, Pan-STARRS, LSST, Plato Increase sample size Sampling rate (high cadence) Baseline 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 … ! ~1100 WDs 15 <V< 17 McCook & Sion

13. X-ray and observational Astronomy 17 th European White Dwarf Work Shop – 20/08/2010 Monitoring WDs variability with WASP  Same sample of 194 WDs  Variability search:Two-step method Lomb-Scargle periodogram + CLEANed periodogram 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

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

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

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

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