Charge transfer and X-ray emission from supernova remnants

Wise, Michael; Sarazin, Craig L.

doi:10.1086/167913

Cited by 21 publications

(30 citation statements)

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“…Given that the CE and EIE rate coefficients are of order γ CE ∼ 10 −6 and γ EIE ∼ 10 −11 cm 3 s −1 , respectively, CE can be important if the neutral fraction for hydrogen is greater than ∼10 −5 or so (Wise & Sarazin 1989). This is well above the neutral fraction expected for the hot ionized plasma where the X-ray emission is thought to originate.…”

Section: Discussionmentioning

confidence: 96%

“…The emission spectral signature associated with a CE reaction generally resembles that of recombination (Wise & Sarazin 1989), because in both mechanisms, an electron is injected into a high quantum level and then cascades. The flux ratios due to pure recombination of O ix to O viii are about 4.7 and 2.6 for α/β and β/γ, respectively (using HULLAC).…”

Section: Discussionmentioning

confidence: 99%

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The X-ray spectrum of the supernova remnant 1E 0102.2-7219

Rasmussen

Behar

Kahn

et al. 2001

A&A

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Abstract. In this letter we present the soft X-ray (5-35Å) spectrum of the supernova remnant (SNR) 1E 0102.2−7219 in the Small Magellanic Cloud, acquired by the reflection grating spectrometers (RGS) aboard ESA's XMM-Newton Observatory. Because the RGS features a large dispersion angle, spatial-spectral confusion is suppressed even for moderately extended (∆θ ∼ 2 ) sources. Consequently, these data, along with the spectrum of N132d (Behar et al. 2001), provide what are probably the most detailed soft X-ray spectrum of entire SNRs. The diagnostic power of performing spectroscopy using groups of emission lines from single ions is demonstrated. In particular, the bright

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Section: Discussionmentioning

confidence: 96%

Section: Discussionmentioning

confidence: 99%

The X-ray spectrum of the supernova remnant 1E 0102.2-7219

Rasmussen

Behar

Kahn

et al. 2001

A&A

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“…The NPS is the brightest filament of the Loop I superbubble, which is known to be the largest coherent structure on the X-ray sky, probably produced by a series of supernovae and stellar winds from the nearby Sco-Cen OB association. Lallement (2009) noticed that the highest quality X-ray spectra of the NPS, obtained with XMM-Newton (Willingale et al 2003) and Suzaku (Miller et al 2008), both exhibit a peculiar feature: the emission from the (unresolved) multiplets of the He-like ions O VII and Ne IX is systematically shifted (by ∼ 10-15 eV) to lower energies relative to the H-like ions O VIII and Ne X. Exactly this behaviour is expected for charge exchange, because this process tends to brighten the flux of the spin forbidden magnetic dipole transition (at 561 eV for O VII) with respect to that of the resonance transition (at 574 eV for O VII), thus causing a systematic shift to lower energies (e.g.…”

Section: Interstellar Mediummentioning

confidence: 99%

Charge Transfer Reactions

Dennerl

2010

Space Sci Rev

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Charge transfer, or charge exchange, describes a process in which an ion takes one or more electrons from another atom. Investigations of this fundamental process have accompanied atomic physics from its very beginning, and have been extended to astrophysical scenarios already many decades ago. Yet one important aspect of this process, i.e. its high efficiency in generating X-rays, was only revealed in 1996, when comets were discovered as a new class of X-ray sources. This finding has opened up an entirely new field of X-ray studies, with great impact due to the richness of the underlying atomic physics, as the X-rays are not generated by hot electrons, but by ions picking up electrons from cold gas. While comets still represent the best astrophysical laboratory for investigating the physics of charge transfer, various studies have already spotted a variety of other astrophysical locations, within and beyond our solar system, where X-rays may be generated by this process. They range from planetary atmospheres, the heliosphere, the interstellar medium and stars to galaxies and clusters of galaxies, where charge transfer may even be observationally linked to dark matter. This review attempts to put the various aspects of the study of charge transfer reactions into a broader historical context, with special emphasis on X-ray astrophysics, where the discovery of cometary X-ray emission may have stimulated a novel look at our universe.

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“…However, the contribution of the charge-exchange induced X-ray emission produced at these interfaces has hitherto not been considered to be significant. The detailed calculations performed by Wise & Sarazin (1989), motivated by the observations of X-ray emission following chargeexchange in laboratory fusion devices, have shown that the emission is negligible in the case of an SNR fast shock. Our goal here is to investigate its relative importance in different astrophysical cases.…”

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On the contribution of charge-exchange induced X-ray emission in the ISM and ICM

Lallement¹

2004

A&A

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Abstract. X-ray emission can be generated by charge-exchange (CXE) between highly charged ions of a hot plasma and neutral species of an interacting cool/warm gas, a phenomenon recently observed in the case of the solar wind interaction with cometary, interstellar, and geocoronal neutrals (Lisse et al. 1996;Cox 1998;Cravens 1997Cravens , 2002. Charge-exchange processes are included in most theoretical models of hot interstellar plasmas interacting with partially neutral gas, resulting in a modification of the physical states of the gases in the interaction region. However, the contribution of the charge-exchange induced X-ray emission produced at these interfaces has hitherto not been considered to be significant. The detailed calculations performed by Wise & Sarazin (1989), motivated by the observations of X-ray emission following chargeexchange in laboratory fusion devices, have shown that the emission is negligible in the case of an SNR fast shock. Our goal here is to investigate its relative importance in different astrophysical cases. We simplistically consider interfaces between partially neutral and hot gas in the following cases: (a) a supernova blast wave propagating in a neutral (or partially ionized) ISM (b) a galactic wind engulfing a halo dense cloud; (c) a high velocity cloud (HVC) moving through the halo, and (c) a dense cloud moving in intra-cluster gas. Although the phenomenon is restricted to the very narrow envelopes defined by the mean free path of the neutrals through the hot plasma, it is easy to show that its efficiency is such that the volume emissivity from these interfaces can be orders of magnitude above the emissivity of the hot gas itself, and, more important, that its relative contribution increases with decreasing hot gas density. As a consequence it should be at maximum in mixing layers in very low density hot gas. Our preliminary results suggest that the charge-exchange X-ray emission from the interface does not contribute significantly in case (a), in agreement with Wise & Sarazin, except marginally for lines of sight tangent to the interfaces, but that it can be a non-negligible fraction of the hot gas emission in cases (b-d). Detailed self-consistent models of plasma and neutral atom distributions in conduction fronts or contact discontinuities are needed for better estimates. In the easiest test case of HVCs, there is a good agreement between our predicted equivalent emission measure EM ≈ 0.01 cm −6 pc for complex C-type clouds and their soft X-ray emission measured by ROSAT (e.g. Kerp et al. 1996). If confirmed by more realistic calculations, a contribution of the CXE emission may play a role in a number of astrophysical cases: (i) tight correlations between Hα and X-ray patterns; (ii) enhanced X-ray limb brightening at interfaces; (iii) spectral and abundance "anomalies", because charge-exchange spectra differ from thermal spectra and contain only emission lines, resulting in some biases when they are interpreted with classical models. Interestingly, interaction between col...

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Charge transfer and X-ray emission from supernova remnants

Cited by 21 publications

References 0 publications

The X-ray spectrum of the supernova remnant 1E 0102.2-7219

The X-ray spectrum of the supernova remnant 1E 0102.2-7219

Charge Transfer Reactions

On the contribution of charge-exchange induced X-ray emission in the ISM and ICM

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