Hard X-ray Emitting Symbiotics: Candidates for Type Ia Supernova Progenitors

Talk presented at American Physical Society (APS) April Meeting, Session Z09: Stars, White Dwarfs, & Thermonuclear Supernovae, Abstract id.Z09.006, Virtual Meeting, USA, April 20, 2021

Transcript

1. Ashkbiz Danehkar
   Department of Astronomy, University of Michigan
   danehkar@umich.edu
   In Collaborations with: Margarita Karovska, Jeremy Drake, Vinay Kashyap
   Hard X-ray emitting symbiotics
   candidates for type Ia supernova progenitors
   Credit: NASA, ESA, and D. Berry (STScI)
   

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2. 2
   Talk Outline
   Symbiotic Stars
   – Hard X-ray Emitting Symbiotics
   X-ray Variability: Low/Hard and High/Soft States
   X-ray Features of Symbiotic Star RT Cru
   – Hard X-ray Component
   – Soft X-ray Component
   WD Mass based on X-ray Observations
   Potential Candidate for Type Ia SN
   – Possible Implication for GW research
   

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3. 3
   Symbiotic Stars
   Symbiotics: interacting binaray system
   – A Hot accreting compact object (WD)
   – A Cool red giant star
   A White dwarf (WD) accreting
   materials from red giant,
   typically having a soft or
   supersoft X-ray emission
   However, a few of them
   show hard X-ray emission,
   so called
   Hard X-ray Emitting Symbiotics
   Credit: Atrononomy.com, Kavli IPMU
   

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4. 4
   Hard X-ray Emitting Symbiotics
   Hard X-ray Symbiotics:
   – RT Cru
   – CH Cyg
   – T CrB
   – CD-57 3057 (SS73 17)
   – MWC 560
   Having Hard X-ray emission (50 > keV)
   The origin of X-ray not well understood
   – Indicator of a Massive WD close to the Chandrasekhar mass (Luna & Sokoloski 2007)
   – Candidate for Type Ia SN progenitor
   Ducci et al. 2016
   RT Cru
   

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5. 5
   RT Cru: X-ray Variability
    non-periodic
    Changes between:
   – Low/hard state
   – High/soft state
   – S: 0.3-4 keV, H: 4-8 keV
   – HR1=H/S
   – HR2=(H-S)/(S+H)
   Danehkar et al. 2021
   

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6. 6
   Hard X-ray Emitting RT Cru
   Hard X-ray Component ~ 10 keV
   – Luna & Sokoloski 2007
   – Danehkar et al 2021
   Soft X-ray Component ~ 1.3 keV
   – Danehkar et al 2021
   Maximum Temperature
   of Cooling Flow
   – ~ 37 keV (Kennea et al 2009)
   – ~ 28 keV (Eze 2014)
   – ~ 51 keV (Ducci et al. 2016)
   – ~ 53 keV (Luna et al. 2018)
   so a WD mass of 1.25 M☉
   Danehkar et al. 2021
   

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7. 7
   RT Cru: X-ray Components
    Soft thermal emission ~ 1.3 keV
    Hard thermal emission ~ 10 keV
   Danehkar et al. 2021
   

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8. 8
   RT Cru: X-ray Components
   Soft and Hard thermal components in Hard X-ray Emitting Symbiotics:
    RT Cru
   – 1.3 keV (Danehkar et al 2021)
   – 9.6 keV (Luna & Sokoloskil 2007; Danehkar et al 2021)
    CH Cyg:
   – 0.2, 0.7 & 7.3 keV (Ezuka et al 1998)
    MWC 560:
   – 0.18 & 11.26 keV (Stute & Sahai 2009)
    SS73 17 (CD-57 3057):
   – 1.12 & 9.9 keV (Eze et al. 2010)
   

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9. 9
   RT Cru: Minimum White Dwarf Mass
   Maximum Temperature of Cooling Flow
   – Tmax ~ 37 keV (Kennea et al 2009)
   – Tmax ~ 51 keV (Ducci et al. 2016)
   – Tmax ~ 53 keV (Luna et al. 2018) → WD mass of 1.25 M☉
   Mass-Accretion Rate:
   – ~ 2 x 10-9 M☉/yr (Danehkar et al 2021)
   (Aizu 1973; Hoshi 1973)
   (Nauenberg 1972)
   (Luna & Skoloski 2007)
   

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10. 10
    RT Cru: Minimum White Dwarf Mass
    Hachisu & Kato 2002
    White Dwarf Masses of other Hard X-ray Emitting Symbiotics
    – T CrB: WD mass of 1.37 M☉
    

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11. 11
    Type Ia Supernova
    Wang & Han 2012
    

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12. 12
    GW from Type Ia Supernova
    

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13. 13
    Summary
    Hard X-ray Emitting Symbiotic Star RT Cru
    Variable X-ray
    – Low/Hard and High/Soft States (Danehkar et al 2021)
    X-ray Components
    – Hard Component ~ 10 keV (Luna & Sokoloski 2007; Danehkar et al 2021)
    – Soft Component ~ 1.3 keV (Danehkar et al 2021)
    WD Mass ~ 1.25 M☉ (Luna et al. 2018)
    Possible Candidate for Type Ia SN (Luna & Sokoloski 2007)
    – may produce gravitational waves
    

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14. Credit: NASA, ESA, and D. Berry (STScI)
    Thank you for your attention
    

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