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SDSS finds the period minimum spike

SDSS finds the period minimum spike. Boris G änsicke. John Southworth John Thorstensen. Ilse Decoster. M Dillon, P Rodr í guez-Gil, A Aungwerojwit, TR Marsh, P Szkody, SCC Barros, J Casares, D de Martino, PJ Groot, P Hakala, U Kolb, SP Littlefair,

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SDSS finds the period minimum spike

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  1. SDSS finds the period minimum spike Boris Gänsicke John Southworth John Thorstensen Ilse Decoster M Dillon, P Rodríguez-Gil, A Aungwerojwit, TR Marsh, P Szkody, SCC Barros, J Casares, D de Martino, PJ Groot, P Hakala, U Kolb, SP Littlefair, IG Martínez-Pais, G Nelemans, MR Schreiber

  2. CV Evolution in a nutshell • Angular momentum loss MB/GR • Porb decreases down to Pmin GR MB • Donor becomes degenerate BD • Porb increases again Howell et al. (2001)

  3. Period bouncing

  4. 1% 29% 70% CV evolution in a nutshell • Angular momentum loss MB/GR • MB disrupted at P=3h • At Pmin: donor  BD • Spike at Pmin • Most systems post-bounce GR MB Howell et al. 2001, ApJ 550, 897 Kolb & Baraffe 1999, MNRAS 309, 1034

  5. Ritter 5 (1990): 167 CVs

  6. Ritter & Kolb 6 (1998): 314 CVs

  7. Ritter & Kolb 7.2 (2004): 518 CVs

  8. 80 min! CV evolution: theory & observations • Pmin≈65min • Spike @ Pmin selection effects? (Ritter & Kolb 2004)

  9. 80 polars today Of spikes and small numbers 114min Hameury et al. (1990)

  10. no spike (see Pretorius) The PG CVs - 35 CVs, of which 31 new - 31 periods determined (Ringwald PhD 1993, Thorstensen, and others)

  11. spike? ... 24 HQS CVs with Porb=3-4h ... CVs from the Hamburg Quasar Survey - 96 CVs, of which 53 new - 86 periods determined (Gänsicke, Rodríguez-Gil, Aungwerojwit, Hagen, Engels, ...)

  12. SDSS CVs Recycled slide detected … recycled slide detected … - 101 CVs, of which 90 new ITP time 2004/5 for SDSS CV follow-up: 70 nights WHT, TNG, INT, NOT & LT (Gänsicke et al.) - 45 periods determined (Szkody et al. 2002, 2003, 2004)

  13. SDSS CVs in DR7 ? - 281 CVs, of which 90 new - 126 periods determined (Szkody et al. 2002, 2003 , 2004 , 2005 , 2006 , 2007 , 2009)

  14. 10 years effort in 2 minutes Period accurate to better than 3%

  15. 10 years effort in 2 minutes Period accurate to better than 3%

  16. 10 years effort in 2 minutes Period accurate to better than 3%

  17. new SDSS CVs old SDSS CVs non-SDSS CVs SDSS CVs differ significantly from previous samples two-sided Kolmogorov-Smirnov test - old vs non: 52.2% - new vs non: 0.065% why? Gänsicke et al. 2008, MNRAS, submitted

  18. Properties of SDSS CVs

  19. V844 Her T Leo SW UMa EV UMa GG Leo “active” CVs in the spike

  20. Old (active) SDSS CVs with 80min<Porb<86min SW UMa T Leo V844 Her EV UMa

  21. New SDSS CVs with 80min<Porb<86min

  22. New (inactive) SDSS CVs with 80min<Porb<86min

  23. New (inactive) SDSS CVs with 80min<Porb<86min

  24. polar eclipsing poor data eclipsing New (inactive) SDSS CVs with 80min<Porb<86min

  25. New (inactive) SDSS CVs with Porb>86min

  26. New (inactive) SDSS CVs with Porb>86min

  27. Some comments on the space density • WD-dominated, or “WZ Sge” are often considered • post-period-bounce (candidate) systems… • Yes, SDSS finds many new “WZ Sge”… but, they are all faint (g>17.6) and far (>150pc) away… • …yet, no bias against finding nearby “WZ Sge”… - “WZ Sge”s, bouncers or not, are not very common - While Littlefair found good evidence for bouncers, they are all at Pmin - Even SDSS has not found the predicted large population of period bouncers

  28. SDSS finds the period spike because of depth “SDSS all” “SDSS Quasar Survey” “Hamburg Quasar Survey” “Palomar Green”

  29. Completeness: the QSO exclusion boxes while excluded from the QSO programme, there are sufficient spectra to inspect the kind of objects they contain. • WD box: one faint CV • A-star box: no CV • WMDS box: 5 CVs with Porb>150min  no effect on the period spike discussed here

  30. QSO survey limit non-SDSS-discovered CVs in the SDSS footprint

  31. QSO survey limit SDSS CV (re)identification efficiency CV has re-discovered ~90% of the previously known CVs with 17<g<19

  32. Testing CV completeness by colour proximity i<19.1: 66% complete 19.1<i<23: 13% complete

  33. all WD-cut QSO-cut CV 67 67 63 11.3% WD 601 169 113 31.5% WDMS 398 368 308 55.2% QSO 371 363 74 13.3% Total 1437 967 558 Selecting CV candidates via p.m. from GALEX/SDSS 1437 objects with - 5 p.m. - GALEX fluxes - SDSS spectra

  34. Selecting CV candidates via p.m. from GALEX/SDSS 3713 objects with - 5 p.m. - GALEX fluxes - no SDSS spectra 1689 candidates, expect - 191 CVs - 532 WDs - 932 WDMS binaries - 225 QSO

  35. Summary • SDSS goes deeper than any survey before, and the SDSS CV • population exhibits a period spike at Pmin=80min, but need • accurate orbital periods • The spectra of the majority of “spike” CVs are WD dominated, • “WZ Sge”-like, but SDSS has still not found the predicted • large population of period-bouncers. • The SDSS CV population is 66-90% complete for 17<i<19, • but completeness drops quickly below i=19.1 … and that’s • where the WD-dominated CVs become more numerous! • The “missing” SDSS CV population can be targeted via a • selection combining optical/UV colours and proper motion

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