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Accreting White Dwarfs as Supersoft X-ray Sources

Accreting White Dwarfs as Supersoft X-ray Sources. Mariko KATO (Keio Univ., Japan). Madrid 2009.5. Response of Accreting WD. Mass Accretion rate:. low nuclear burning: unstable -> nova outburst. (2) intermediate stable -> steady H burning. (3) high

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Accreting White Dwarfs as Supersoft X-ray Sources

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  1. Accreting White Dwarfs as Supersoft X-ray Sources Mariko KATO (Keio Univ., Japan) Madrid 2009.5

  2. Response of Accreting WD Mass Accretion rate: • low • nuclear burning: unstable -> nova outburst (2)intermediate stable -> steady H burning (3) high steady wind occurs (accretion wind)

  3. Stability analysis of accreting WDs • Static analysis: envelope mass • Iben (1982) 259, 244 • Sala & Hernanz (2005) • Thermal stability: • Sienkiewicz (1975,1980) • Nomoto, Saio, Kato & Hachisu (2007) • Numerical calculation: shell flash • Townsley & Bildsten (2004) ApJ, 600, 390 • Prialnik et al. (1979, 1986, 1995) • Starrfiled, Sparks, Truran (1974, 1979) • Nariai, Nomoto, Sugimoto (1980)

  4. H shell flash in accreting WD Iben (1982), 258,244

  5. Analysis of thermal stability : accreting WDs 1.38 Mo stable • Sienkiewicz, 75, 80 • Nomoto et al. 2007 ApJ,663,1269 0.8 Mo 0.5 Mo unstable

  6. Starrfield et al. (2004) ApJ, 612,L53“surface H burning” No nova occurs for Nomoto, Saio, Kato,&Hachisu (2007) ApJ, 663,1269 = 10-9– 8x10-7 Mo/yr Wrong results too small mesh point too large time-step accreting 1.35 Mo is stable become Type Ia SN

  7. HR Diagram wind blows stable unstable

  8. Response of Accreting WDs Nova Hachisu & Kato (2001) ApJ 558,323

  9. Dynamical calculations of nova • Prialnik et al. 1979, 1986,1995 • Sparks, Starrfiled, Truran 1974,1979 • Nariai, Nomoto, Sugimoto 1980 • etc. cannot obtain the light curve numerical difficulty:rezone, take of outermost mesh point, small number of mesh points etc.

  10. Optically thick wind theory mass loss:continuum radiation-driven wind The unique method to calculate nova light-curve • quasi-evolution: sequence of steady-state solutions • Solve equations of motion, continuity, diffusion, energy conservation obtain accurate mass-loss rate, Tph,Lph, etc. Kato & Hachisu (1994), Hachisu & Kato (2006) Hachisu & Kato (2006) ApJ,167,59 for light curve analysis

  11. Nova light curve 0.6Mo Hachisu & Kato, submitted 1.2 Hachisu & Kato, 2009, submitted

  12. HR diagram Kato & Hachisu （1994）

  13. HR diagram for CO novae Decay phase of classical novae Wind mass loss fast nova moderately fast nova slow nova CO nova : X=0.35, Y=0.33, C=0.1 O=0.2, Z=0.02 Kato & Hachisu (1994)

  14. X-rays from novae Wind mass loss continuously occurs hard X Mukai et al (2008) UV All novae undergo supersoft X-ray stage supersoft X-ray

  15. optical →UV　→　Soft X-ray wind • Timescale depends on • MWD • envelope composition Multi-wavelength observation is important

  16. Dependence on WD mass CN

  17. Tidal force determines the nova duration MacDonald, Taam Leading hypothesis in 80’~90’ broken 1980’standard In classical nova MWD > 1.3 Mo Nova occurs in all MWD after 1990OPAL opacity Wind blows no tidal force

  18. V1974 Cyg: light curve fitting determine WD mass Hachisu & Kato (2006) UV 1455 Å continuum: Cassatella, Altamore, Gonzalez-Riestra (2002)

  19. V1974 Cyg: best fit parameters Hachisu & Kato 2005, 2006 WD mass: 0.95 Mo for X=0.35,CO=0.2, Ne=0.1, Z=0. 1.05 Mo for X=0.55, CNO=0.1, Ne=0.03,Z=0.02 Distance: 1.8 kpc from UV 1455Å fitting

  20. V1668 Cyg WD mass: 0.95 Mo for, X=0.35, CNO=0.35 Z=0.02

  21. GQ Mus 0.75 Mo for X=0.55, CNO=0.2 0.7 Mo for X=0.45, CNO=0.35 0.65 Mo for X=0.35, CNO=0.3 Hachisu, Kato, Cassatella, (2008), ApJ,687,1238

  22. V838 Her (1991) Kato, Hachisu & Cassatella (2009) submitted WD mass: 1.35Mo for X=0.55, O=0.03, Ne=0.07, Z=0.02

  23. WD mass in IUE novae MWD > 1.0 Mofor Ne nova MWD < 1.0 Mo for CO nova Kato, Hachisu & Cassatella (2009) ApJ, submitted

  24. Ejecta　：CO rich / ONe rich ONe-rich CO-rich O Ne C O

  25. Stellar evolution calculation: a newborn WD in binary MWD < 1.08 Mo for CO WD MWD > 1.08 Mo for ONe WD Umeda et al. (1999)ApJ, 513,861

  26. WD mass from UV 1455 Å width MWD > 1.0 Mofor Ne nova MWD < 1.0 Mo for CO nova ( ) Kato, Hachisu & Cassatella (2009) ApJ, submitted

  27. WD mass in novae with X-rays MWD=1.3 Mo X=0.2 Z=0.02, CNO=0.2, Ne =0.1 Model: Hachisu & Kato (2009)ApJ,694,L103 X-ray: Page et al. (2009) in preparation

  28. V1494 Aql V382 Vel Orio et al(02), Burwitz et al(02) Ness et al(07), Drake et al(03) V5116 Sgr V574 Pup Ness et al (07) Ness et al(07a,b), Nelson et al(07)

  29. V4743Sgr V458 Vul Drake et al (08) Orio et al (03), Orio & Tepedelenlioglu (04) Ness et al(07) V2467 Cyg Ness et al (08) V598 Pup Read et al (07,08)

  30. WD mass from X-ray turn on/off time ●CO nova ●Ne nova ○no information Boundary of CO/Ne novae ～1 Mo

  31. from X-ray spectrum • duration of SSX phase • composition

  32. Recurrent nova HK: Hachisu & Kato U Sco (1.37 Mo) Hachisu et al (2000) ApJL V394 CrA (1.37 Mo) HK (2000, 2001) ApJ LMC1990#2 (1.37Mo) T CrB (1.37 Mo) HK(2001) ApJ,558,323 RS Oph (1.35 Mo) Hachisu et al. (2006, 2007) V745 Sco (1.35 Mo) HK (2001) V3890 Sgr (1.35 Mo) HK(2001) CI Aql (1.2 Mo) HK & Schaefer (2001) ApJ,584,1015 T Pyx (1.2 Mo) Type Ia supernova candidates

  33. Outburst: 1898,1933, 1958, 1967, 1985, 2006Porb : 457 days (Fekel et al. 2000) i : ~30-40 °WD: massiveRG :M0 (Anupama & Mikolajewska 1999) MIII (Evans et al. 1988)well observed : radio ~ X-ray RS Oph

  34. Hachisu et al. 2006ApJL y -magnitude observation Plateau phase H -burning stops irradiated disk

  35. Supersoft X-rays supersoft X-rays y-mag Hachisu et al (2007)

  36. RS Oph MWD～ 1.35 Mo No metal rich X-ray :Hachisu et al. 2007 y-mag: Hachisu et al. 2006 V2491 Cyg MWD~1.3 Mo metal rich model: Hachisu & Kato (2009) X-ray: Page et al (2009)

  37. RS Oph Hot ash model Hydrogen burning NewHe ash (very hot) Heat from He ash a longer X-ray lifetime Heat from He zone WD He ash Heat

  38. No ash ash modelMWD MWD H Hachisu, Kato, Luna (2007)

  39. 1863,1906,1936,1979,1987,1999, (43) (30) (43) (8) (12) 2009 (10) U Sco Plateau → Evidence of an Irradiated Disk & a hot He layer 1.37 Mo SSX phase Model: WD envelope + irradiated Disk + irradiated companion (Hachisu et al. 2000) BeppoSAX plateau

  40. U Sco vs. RS Oph detect : • SSX phase 60 days • WD rotation ? 35 sec

  41. Response of Accreting WDs Intermediate accretion rate Persistent SSS Nova Nova

  42. SSS source in HR diagram Nomoto, Saio, Kato,& Hachisu (2007) ApJ, 663,1269 CAL83 (25hr) CAL87 (10.6 hr) 1E0035 （4.1 hr) RX J0019 (15.8 hr) RX J0439 RX J0513 RX J0925 C87

  43. intermediate accretion rate= persistent X-ray source WD of steady mass accretion van den Heuvel et al. AAp, (1992) 262,97 CAL 87 Schandl, et al. (1997)

  44. SSS source in HR diagram Nomoto, Saio, Kato,& Hachisu (2007) ApJ, 663,1269 CAL83 (25hr) CAL87 (10.6 hr) 1E0035 （4.1 hr) RX J0019 (15.8 hr) RX J0439 RX J0513 RX J0925 C87

  45. Very slow nova  “persistent” SSXS SSXS phase lasts several hundred years Kahabka & Ergma (1997) 1E0035.4-7340 = SMC13 Porb: 4.1 hr (Schmidtke et al 1994) , V=20.2 UV excess (Orio et al 1994) X-ray orbital modulation (Kahabka 1996) opt X-ray Greiner (2000), Suleimanov et al (2003), Kahabka et al (1999)

  46. Response of Accreting WDs Accretion Wind High mass accretion rate Persistent SSS Nova Nova

  47. Accretion wind evolution intermediate high mass accretin rate accretion rate optically thick wind

  48. occurrence of optically thick winds Velocity Kato & Hachisu （2009)ApJin press Wind

  49. RX J0513-69 • optical high & low state • supersoft X-ray; only optical low state X-ray Cowley et al. (2002) AJ 124,2233

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