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)
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
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
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
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
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
7. 7 RT Cru: X-ray Components  Soft thermal emission ~ 1.3 keV  Hard thermal emission ~ 10 keV Danehkar et al. 2021
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)
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)
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☉
11. 11 Type Ia Supernova Wang & Han 2012
12. 12 GW from Type Ia Supernova
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
14. Credit: NASA, ESA, and D. Berry (STScI) Thank you for your attention