Abstract Details
Laboratory spectroscopy of non-thermal plasma photo-ionized by mimic astrophysical compact object
Author: Shinsuke Fujioka
Requested Type: Oral Only
Submitted: 2009-03-12 01:24:29
Co-authors: N. Yamamoto, H. Nishimura, D. Salzmann, F. Wang, Y. Li, Y. Rhee, H. Takabe, K. Mima
Contact Info:
Osaka University
2-6 Yamada-oka
Suita, Osaka 565-087
Japan
Abstract Text:
Photoionized plasmas are encountered in astrophysics, wherever low-temperature gas is bathed in a strong radiation field. X-ray line emissions in spectral range of several-keV were observed from accreting clouds of binary systems, for example CYGNUS X-3 and VELA X-1, in which high intensity x-ray continuum from the compact objects (neutron stars, blackholes, or white dwarfs) irradiates the cold and rarefied accreting clouds. The model of photoionized plasma gives an efficient description to the accreting clouds, nevertheless, laboratory experiment of photoionized plasma is scarce, mainly owing to the lack of a high flux x-ray source. Here we report the generation of photoionized plasma in the laboratory under well-characterized conditions by utilizing high-power laser facility. The novelty of the presented experiment is the notion that laser-driven implosion can create a flash of brilliant continuum x-ray source, which can be used to simulate a miniature of astronomical compact object. A blackbody radiator at temperature of 500-eV was created by means of laser-driven implosion. The emerging x-rays irradiate a low density (ne < 1 × 10^(20) cm^(−3)) and low temperature (Te < 30 eV) silicon (Si) plasma generated in vicinity of the blackbody radiator. Line emissions from helium-like Si ions were clearly observed from a thermally cold Si plasma in the 1.8 - 1.9 keV spectral region, the plasma is very far from normal thermal equilibrium conditions. This result can be interpreted only by assuming photoionization in the plasma. There are similar characteristics between spectra from photoionized plasma in laboratory and VELA X-1 observed with Chandra on-board spectrometer. Detail of x-ray spectra will be discussed.
Comments: