Charge Exchange X-Ray Emission Detected in Multiple Shells of Supernova Remnant G296.1–0.5

Abstract

Recent high-resolution X-ray spectroscopy revealed the possible presence of charge exchange (CX) X-ray emission in supernova remnants (SNRs). Although CX is expected to take place at the outermost edges of SNR shells, no significant measurement has been reported so far due to the lack of nearby SNR samples. Here we present an X-ray study of SNR G296.1−0.5, which has a complicated multiple-shell structure, with the Reflection Grating Spectrometer on board XMM-Newton. We select two shells in different regions and find that in both regions the O vii line shows a high forbidden-to-resonance (f/r) ratio that cannot be reproduced by a simple thermal model. Our spectral analysis suggests a presence of CX and the result is also supported by our new radio observation, where we discover evidence of molecular clouds associated with these shells. Assuming G296.1−0.5 has a spherical shock, we estimate that CX is dominant in a thin layer with a thickness of 0.2%–0.3% of the shock radius. The result is consistent with a previous theoretical expectation and we therefore conclude that CX occurs in G296.1−0.5.

A Monte Carlo Simulation on Resonant Scattering of X-Ray Line Emission in Supernova Remnants

“…H-like and He-like ions give the most prominent line features in the thermal X-ray spectra, and the He-like ion line ratios prove to be valuable tools in high-resolution spectral analysis (e.g., Porquet et al 2010). However, there are unresolved issues in modeling these lines, such as high G-ratios, the ratio of the intercombination (i) line and forbidden (f) line to the resonance (r) line (Gabriel & Jordan 1969), of He-like triplet in some SNRs (e.g., Uchida et al 2019;Suzuki et al 2020;Koshiba et al 2022;Tanaka et al 2022). So far two candidate mechanisms have been suggested for interpretation.…”

“…So far two candidate mechanisms have been suggested for interpretation. One is charge exchange (CX) between ions and neutral atoms (e.g., Katsuda et al 2012;Tanaka et al 2022), which usually occurs when the hot plasma interacts with cold gas and strengthens the f line (e.g., Zhang et al 2019). Another one is RS (e.g., Miyata et al 2008;Amano et al 2020), which changes the r line flux when the plasma is optically thick to the line emission (e.g., Porquet et al 2010).…”

Двойное Комптоновское Рассеяние Фотона Атомным Ионом

“…В качестве объекта исследования взят гелиеподобный ион атома неона (Ne 8+ , заряд ядра Z = 10, конфигурация и терм основного состояния [0] = 1s 2 [ 1 S 0 ]). Выбор обусловлен сферической симметрией основного состояния иона Ne 8+ , его доступностью в газовой фазе при проведении высокоточных экспериментов, например, с рентгеновским лазером на свободных электронах [13] и ярко выраженным присутствием его (r, i, f )-триплета Kα-линий в наблюдаемых спектрах рентгеновской эмиссии от горячих астрофизических объектов [14,15].…”