X-Ray Spectra from Plasmas with High-energy Electrons: κ-distributions and e?–e? Bremsstrahlung
Cui,Xiaohong1,2; Foster,Adam R.1; Yuasa,Takayuki3; Smith,Randall K.1
Source PublicationThe Astrophysical Journal
AbstractAbstract Shocks, turbulence, and winds all influence the electron velocity distribution in hot plasmas, exciting lower-energy electrons and generating a high-energy (typically power-law) tail. This effect, typically described as a κ distribution can affect both the line and continuum X-ray spectra emitted by the plasma. Hahn & Savin proposed a “Maxwellian decomposition” to generate the rate coefficients of κ distributions. Using their method and the AtomDB atomic database, we have developed a general model to calculate the emission from a plasma with a κ distribution. We compare our κ results for the charge state distribution and spectra of oxygen with those from KAPPA package with the ion data available within the CHIANTI atomic database. Sufficiently energetic electrons, created either in a κ distribution or merely a very hot Maxwellian plasma, can also emit via electron–electron (e–e) bremsstrahlung, a process not previously included in AtomDB. We have added this process to AtomDB and apply it to calculate the temperature gradients, as well as the total spectra from the post-shock regions of an accreting magnetic cataclysmic variable. We find the contribution of e–e bremsstrahlung to the total spectra exceeds 10% at KT?~?100 keV, with the total emissivity in the post-shock accretion stream differing by more than 10% at energies above 60 keV.
KeywordWhite dwarf stars Atomic physics Atomic spectroscopy X-ray astronomy Laboratory astrophysics Nonthermal radiation sources
WOS IDIOP:0004-637X-887-2-ab5304
PublisherThe American Astronomical Society
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Document Type期刊论文
Affiliation1.Smithsonian Astrophysical Observatory, 60 Garden Street, Cambridge, MA 02138, USA
2.National Astronomical Observatories, Chinese Academy of Sciences, 20A Datun Road, Chaoyang District, Beijing, People’s Republic of China
3.Nishina Center for Accelerator-based Science, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan;
First Author AffilicationNational Astronomical Observatories, Chinese Academy of Sciences
Recommended Citation
GB/T 7714
Cui,Xiaohong,Foster,Adam R.,Yuasa,Takayuki,等. X-Ray Spectra from Plasmas with High-energy Electrons: κ-distributions and e?–e? Bremsstrahlung[J]. The Astrophysical Journal,2019,887(2).
APA Cui,Xiaohong,Foster,Adam R.,Yuasa,Takayuki,&Smith,Randall K..(2019).X-Ray Spectra from Plasmas with High-energy Electrons: κ-distributions and e?–e? Bremsstrahlung.The Astrophysical Journal,887(2).
MLA Cui,Xiaohong,et al."X-Ray Spectra from Plasmas with High-energy Electrons: κ-distributions and e?–e? Bremsstrahlung".The Astrophysical Journal 887.2(2019).
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