BN4 - End of white dwarfs and type Ia Supernova |
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Speaker |
Hayashi, Takayuki |
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| Talk Title |
White dwarf mass estimation with X-ray observation |
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Abstract |
A white dwarf (WD) mass is important astrophysical quantity because the WD explodes as a type Ia supernova when its mass reaches the Chandrasekhar mass limit of 1.4 solar mass. Many WD masses in intermediate polars (IPs) were measured with their X-ray spectra emitted from plasma flows channeled by strong magnetic fields of the WDs. For the present WD mass estimation, multi-temperature X-ray spectral models have been used which made by summing up X-ray spectra emitted from the top to the bottom of the plasma flow. I newly calculated the physical quantity distributions of the plasma flow, which are base of the X-ray spectral model, with parameterizing the WD mass and accretion rate per unit area (call hspecific accretion rateh) and taking account the non-equipartition between electron and ion and the dipolar geometry. Then, I revised the multi-temperature X-ray spectral model based on my plasma flow calculation. On the other hand, X-ray reflection from the WD surface is another important component in the IP spectrum which makes fluorescent lines e.g. Fe Kalpha and their Compton shoulder and Compton hump around 25 keV. However, the reflection component have been insufficiently modeled. Then, I modeled the reflection component from the WD surface by the Monte-Carlo simulation. I will talk about the latest method of the white dwarf mass estimation with X-ray using Suzaku satellite data. |
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