X-ray line emission from supernova ejecta fragments

Abstract

Abstract. We show that fast moving isolated fragments of a supernova ejecta composed of heavy elements should be sources of K α X-ray line emission of the SN nuclear-processed products. Supersonic motion of the knots in the intercloud medium will result in a bow-shock/knot-shock structure creation. Fast nonthermal particles accelerated by Fermi mechanism in the MHD collisionless shocks diffuse through a cold metallic knot, suffering from Coulomb losses and producing the X-ray emission. We modeled the X-ray emission from a fast moving knot of mass M ∼ 10 −3 M , containing about ∼10 −4 M of any metal impurities like Si, S, Ar, Ca, Fe. The accelerated electron distribution was simulated using the kinetic description of charged particles interacting with a strong MHD shock. We accounted for nonlinear effects of shock modification by the nonthermal particle pressure. The K α line emission is most prominent for the knots propagating through dense molecular clouds. The bow shock should be a radiative wave with a prominent infrared and optical emission. In that case the X-ray line spectrum of an ejecta fragment is dominated by the low ionization states of the ions with the metal line luminosities reaching L x > ∼ 10 31 erg s −1 . High resolution XMM-Newton and Chandra observations are able to detect the K α and K β line emission from the knots at distances up to a few kpcs. The knots propagating through tenuous interstellar matter are of much fainter surface brightness but long-lived. The line spectra with higher ionization states of the ions are expected in that case. Compact dense knots could be opaque for some X-ray lines and that is important for their abundances interpretation. The ensemble of unresolved knots of galactic supernovae can contribute substantially to the iron line emission observed from the Galactic Center region and the Galactic ridge.

Nonthermal particles and photons in starburst regions and superbubbles

“…Fast moving metal rich fragments of supernova ejecta may be sources of both 6.4 keV Fe line emission as well as the high charge state Fe K-shell lines in 6.7-6.9 keV range (Bykov 2002. Cataclysmic variables and coronally active binaries comprising a numerous population in the Galactic ridge are likely X-ray sources with prominent Fe lines and were proposed by Revnivtsev et al (2009) to contribute substantially to the Galactic Center X-ray emission observed by Muno et al (2009) in deep Chandra exposure.…”

XMM-Newton study of hard X-ray sources in IC 443

“…Decourchelle et al 2001). A model of X-ray line emission from fast moving ejecta fragments predicts that the fragments interacting with molecular clouds are the brightest and they could be detected from a few kpc distances (Bykov 2002).…”

Correlation between SiO and X-ray emission in the galactic center

“…However, such a high column density for the molecular gas is incompatible with our estimates by nearly two orders of magnitude (see Table 1). In this scenario, the SiO enhancement could be produced by the same process that also accelerates the electrons, i.e., shocks generated by SNe [14]. Metal-rich ejecta blobs from a SN that propagates through the ambient medium create shocks, which accelerate the electrons.…”