Talk presented at Chandra Data Science: Novel Methods in Computing and Statistics for X-ray Astronomy, Virtual Meeting, Chandra X-ray Center, USA, August 18, 2021

1. Ashkbiz Danehkar
Department of Astronomy, University of Michigan
danehkar@umich.edu
Collaborators: Margarita Karovska, Jeremy Drake, Vinay Kashyap (CfA)
Bayesian X-ray Spectral Analysis
of the Symbiotic Star RT Cru
Credit:
David
A.
Hardy
&
PPARC.

2. Chandra Data Science Workshop
Aug 18, 2021
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Hard X-ray Emitting Symbiotic Stars
Symbiotic Stars: hot accreting core + cool red giant
typically with a soft or supersoft X-ray emission
But, a few with hard X-ray emission,
called Hard X-ray Emitting Symbiotics:
Credit: Atrononomy.com, Kavli IPMU
– RT Cru
– CH Cyg
– T CrB
– CD-57 3057 (SS73 17)
– MWC 560

3. Chandra Data Science Workshop
Aug 18, 2021
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Hard X-ray Emitting Symbiotics
Hard X-ray Symbiotic Stars:
– RT Cru
– CH Cyg
– T CrB
– CD-57 3057 (SS73 17)
– MWC 560
with Hard X-ray emission (50 > keV)
Their hard X-ray emission is not properly understood
– suggested to be an indicator of a Massive WD (~ 1.3 M☉; Luna & Sokoloski 2007)
Ducci et al. 2016
RT Cru

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

5. Chandra Data Science Workshop
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RT Cru: Thermal Plasma Components
Time-averaged Spectra
Hard X-ray Component ~ 10 keV
– Luna & Sokoloski 2007
– Danehkar et al 2021
Soft X-ray Component ~ 1.3 keV
– Danehkar et al 2021
Danehkar et al. 2021
Danehkar et al. 2021
“Bayesian Low-Count X-ray Spectral Analysis
in Python” (pyBLoCXS)

6. Chandra Data Science Workshop
Aug 18, 2021
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RT Cru: Thermal Plasma Components
Time-averaged Spectra
Soft thermal emission ~ 1.3 keV
Hard thermal emission ~ 10 keV
Danehkar et al. 2021 (arXiv:2011.07390)
“Bayesian Low-Count X-ray Spectral Analysis
in Python” (pyBLoCXS)

7. Chandra Data Science Workshop
Aug 18, 2021
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RT Cru: Thermal
Components in
Low/hard State
Danehkar et al. 2021 (arXiv:2011.07390)
“Bayesian Low-Count X-ray Spectral Analysis
in Python” (pyBLoCXS)
 Soft thermal emission ~ 1.5 keV
 Hard thermal emission ~ 46 keV

8. Chandra Data Science Workshop
Aug 18, 2021
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RT Cru: Thermal
Components in
High/soft State
Danehkar et al. 2021 (arXiv:2011.07390 )
“Bayesian Low-Count X-ray Spectral Analysis
in Python” (pyBLoCXS)
 Soft thermal emission ~ 0.6 keV
 Hard thermal emission ~ 4.4 keV

9. Chandra Data Science Workshop
Aug 18, 2021
RT Cru: Thermal Plasma Components
Soft thermal emission ~ 1.3 keV in Time-Averaged HRC-S/LETG Spectrum
Danehkar et al. 2021 (arXiv:2011.07390)
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10. Chandra Data Science Workshop
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RT Cru: Thermal Plasma Components
Hard thermal emission ~ 10 keV in Time-Averaged ACIS-S/HETG Spectrum
Danehkar et al. 2021 (arXiv:2011.07390)
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RT Cru: X-ray Components
Soft and Hard components in other 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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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 in Time-Averaged Spectra
– Hard Component ~ 10 keV (Luna & Sokoloski 2007; Danehkar et al 2021)
– Soft Component ~ 1.3 keV (Danehkar et al 2021)
Soft Component (1.3 keV):
– obscured by dense materials (> 5 x 1023
cm-2
)
– Shocked Wind or Unseen Jet?
For more information, see MNRAS, 500, 4801 (arXiv:2011.07390)

13. Credit:
David
A.
Hardy
&
PPARC.
Thank you for your attention