luminous supersoft x-ray sources as type ia...
TRANSCRIPT
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Luminous Supersoft X-RaySources as Type Ia progenitors
Are there enough of them?
Rosanne Di StefanoKITP20 March 2007
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With help from my friends…
• Population synthesis and evolution:S.A.Rappaport, L. Nelson, J.D. Smith, T. Wood,W. Lee
• Observations: J. Greiner, A.K.H. Kong, F.A.Primini, M.R. Garcia, S. Murray, P. Barmby,M. Orio, T. Nelson, B. Patel, T. Russo, S. Scoles,S. Curry
See also workshop presentations by E. Van den Heuvel and L. Nelson
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SSSs: phenomenological definitionEarly 1990’s edition
• kT : 10 eV - 100 eV
• L : 10^37 - 10^38 erg/s
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SSSs: physical natureEarly 1990’s edition
• 1/2 of the observed sources have counterpartswith hot WDs: recent novae, symbiotics.
• 1/2 have counterparts which are close binaries:0.4 d < P < 1 d.
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Their effective radii, and the association withnova, symbiotics, and one planetary nebulasuggest:
SSSs are nuclear-burning white dwarfs (NBWDs).
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Nomoto 1982; Iben1982
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The connection between SSSs and Type Ia SNe
• Are Type Ia progenitiors SSSs? At some point in their evolution,
virtually all progenitors are NBWDs thatcan potentially be observed as SSSs. SSSbehavior can help to identify Type Iaprogenitors.
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In single-degenerate models, SSS behavior couldoccur during the epoch of mass increase.
This is the epoch of interest to us here: are theprogenitors detectable as SSSs during theepoch of maximum mass gain?
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In the early 1990’s it was established that galaxies,such as M31 and the Milky Way have large SSSpopulations. (RD & Rappaport 1994)
For ellipticals, the population could only be estimatedbased on diffuse emission. (Fabbiano, Kim andcollaborators)
This was independent of the nature of the sources.
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• NBWDs require high rates of masstransfer.
• This can happen in close binaries and widebinaries; through Roche-lobe overflow orthrough winds.
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Close-Binary SSS model (CBSS)
van den Heuvel et al. 1992 M_dot ~ 10^-7 m_sun/yr
To produce the high accretionrate, the donor must be moremassive than the WD and/or
slightly evolved.
The luminosity is caused by thenuclear burning of accretedhydrogen.
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First predictions of the rate of Type Ia due to SSSs(Rappaport, Di Stefano, \& Smith 1994)
• 0.6 per century
• 0.3 per century
• 0.008 per century
• M_dot in recurrentnova range:
• M_dot in or abovesteady-burning region
• M_dot in steady-burning range
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• To refine the calculations, need to conductbinary evolution calculations. (Di Stefano,Nelson, Rappaport, Wood, & Lee 1996;
Di Stefano & Nelson 1996)
Following 3 slides from Nelson s KITP workshop talk.
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• Result: If there are winds which carry modest
angular momentum per unit mass,common envelopes can be avoided formany progenitors.
The rate is comparable to the needed rate.
The winds are energetically possible.
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Progress
Winds: Hachisu, Kato, & Nomoto (1996) found them to be viable.
Wide-binary SSSs have been considered (Hachisu, Kato, Nomoto 1999).
Radiative-driven winds from the donor (van Teeseling & King 1998)
More comprehensive population synthesis (Yungelson 2005)
CBSS calculations with winds (Han & Podsiadlowski 2004)
The result still holds: It is possible that accreting NBWDs are theprimary class of progenitors.
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Massive NBWDs are the hottest and the most luminous.
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High-mass NBWDs in nearby galaxies can bedetected by Chandra, because they have high T and L
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Numbers observed
• M101• M83• M51• M104• NGC4472• NGC4697
• SSS: 42; QSS: 21; other: 65• SSS: 28; QSS: 26: other: 74• SSS: 15; QSS: 21; other: 56• SSS: 5; QSS: 17; other: 100• SSS: 5; QSS: 22; other: 184• SSS: 4; QSS: 15; other: 72
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• If single-degenerate Chandrasekhar-massmodels are the principal channel throughwhich most Type Ia supernova are formed,are there enough SSSs?
• We derive the answer: NO!!!!
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• If single-degenerate Chandrasekhar-mass modelsare the principal channel through which most Type Iasupernova are formed, are there enough SSSs?
• We derive the answer: NO!!!!
• Existing Chandra data falsifies the hypothesis that: Accreting NBWDs that reach M_c are the principal
progenitors AND that they are detected as SSSsduring the epoch of mass gain.
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Does this falsify the single-degenerate M_c model?
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Does this falsify the single-degenerate M_c model?
• Possibly--we should take this possibility seriously.
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Does this falsify the single-degenerate M_c model?
• Possibly--we should take this possibility seriously.
• Sub-Chandrasekhar models may help, but theycould also be ruled out soon.
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Does this falsify the single-degenerate M_c model?
• Possibly--we should take this possibility seriously.
• Sun-Chandrasekhar models may help, but theycould also be ruled out soon.
• But this result may also be consistent with winds,which seem to be required by the model.
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Does this falsify the single-degenerate M_c model?
• Possibly--we should take this possibility seriously.
• Sun-Chandrasekhar models may help, but theycould also be ruled out soon.
• But this result may also be consistent with winds,which seem to be required by the model.
• Photospheric effects could also come into play.
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Does this falsify the single-degenerate M_c model?
• Possibly--we should take this possibility seriously.
• Sun-Chandrasekhar models may help, but they could alsobe ruled out soon.
• But this result may also be consistent with winds, whichseem to be required by the model.
• Photospheric effects could also come into play.
• Input assumptions could be incorrect.
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Other tests of the single-degenerate M_c model?
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Other tests of the single-degenerate M_c model?
• Effects of winds on the surroundings.
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Other tests of the single-degenerate M_c model?
• Effects of winds on the surroundings.
• SSS nebulae (RD, Paerels, & Rappaport 1995; RD 1996)
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Other tests of the single-degenerate M_c model?
• Effects of winds on the surroundings.
• SSS nebulae (RD, Paerels, & Rappaport 1995; RD 1996)
• Post-explosion signatures..e.g., in SNR (Badenes2007)
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Other tests of the single-degenerate M_c model?
• Effects of winds on the surroundings.
• SSS nebulae (RD, Paerels, & Rappaport 1995; RD 1996)
• Signatures in SNRs (Badenes 2007)
• Lack of hydrogen in the post-explosion spectra.
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Type Ia supernovae occur far away.
• Progenitors occur nearby.
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Type Ia supernovae occur far away.
• Progenitors occur nearby.• (10-30 with M > M_sun, within 1 kpc, if the
single-degenerate model dominates.)
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Type Ia supernovae occur far away.
• Progenitors occur nearby.• (10-30 with M > M_sun, within 1 kpc, if the
single-degenerate model dominates.)• These have L > 10^38 erg/s, distinctive spectra,
and perhaps ionization and.or wind signatures.
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.
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Many cross-checks are possible.
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Summary
• If NBWDs that achieve M_c are thedominant progenitors, most are notdetectable as SSSs.
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Summary
• If NBWDs that achieve M_c are thedominant progenitors, most are notdetectable as SSSs.
• Could the winds needed to make thismodel work be responsible for absorption?
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Summary
• If NBWDs that achieve M_c are thedominant progenitors, most are notdetectable as SSSs.
• Could the winds needed to make thismodel work be responsible for absorption?
• Or photospheric effects?
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Summary
• If NBWDs that achieve M_c are thedominant progenitors, most are notdetectable as SSSs.
• Could the winds needed to make thismodel work be responsible for absorption?
• Or photospheric effects?• We can search for nearby progenitors.
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Summary
• If NBWDs that achieve M_c are thedominant progenitors, most are notdetectable as SSSs.
• Could the winds needed to make thismodel work be responsible for absorption?
• Or photospheric effects?• We can search for nearby progenitors.• And conduct a wealth of cross checks.
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Summary
• If NBWDs that achieve M_c are thedominant progenitors, most are notdetectable as SSSs.
• Could the winds needed to make thismodel work be responsible for absorption?
• Or photospheric effects?• We can search for nearby progenitors.• And conduct a wealth of cross checks.
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Single-degenerate models with hydrogen-rich donors may face their ultimatelimits from limits on hydrogen post-explosion.
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SSSs: phenomenological definitionLate 1990 s edition
• kT: 10 eV - 100 eV
• L: 10^36 - 10^38 erg/s (low-L extension)
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The connection between SSSs and Type Ia SNe
• Are Type Ia progenitiors SSSs? At some point in their evolution, virtually all
progenitors are NBWDs that can potentially beobserved as SSSs. SSS behavior can help toidentify Type Ia progenitors.
• Are SSSs Type Ia progenitors? Some are, and some are not even WDs.
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SSSs: phenomenological definition21st century edition
• kT: 10 eV-100 eV + QSS extension
• L: 10^36 - 10^38 erg/s + ULX extension
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SSSs: phenomenological definition20th century edition
• kT: 10 eV - 100 eV + high T extension quasisoft sources (QSSs)
• L: 10^36 - 10^42 erg/s (high-L extension)
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