Circumstellar Interaction in SN 1993J

Abstract

The radio and X-ray observations of SN 1993J during the rst year can be consistently explained as a result of interaction of the expanding ejecta with a circumstellar medium. The density of the circumstellar gas can be deduced from the free-free absorption of the radio emission and from the X-ray luminosity. During the rst two weeks, both sets of observations indicate a mass loss rate of 4 10 5 M yr 1 for a wind velocity of 10 km s 1 . The subsequent radio and X-ray observations indicate a density gradient / r s , with 1:5 < s < 1:7, as opposed to the Subject headings: circumstellar matter { -rays: general { radio: general { supernovae: individual (SN 1993J) { X-rays: general

Classification of Supernovae

“…The radio and X-ray emission of SN1993J [11,129,142] have been attributed to circumstellar interaction [54]. Another indication comes from the boxy shape of the emission lines of late time optical spectra [77,94].…”

Optical Observations of Core-Collapse Supernovae

“…SN 1993J held several more surprises. Observations at radio [59] and Xray [60] wavelengths revealed that the ejecta are interacting with relatively dense circumstellar material [61], probably ejected from the system during the course of its pre-SN evolution. Optical evidence for this interaction also began emerging at τ > ∼ 10 months: the Hα emission line grew in relative prominence, and by τ ≈ 14 months it had become the dominant line in the spectrum [53,62,63], consistent with models [31].…”

High-energy Emission from Supernovae and Remnants

“…X-ray emission from a supernova has been best studied for the case of the Type II supernova SN 1993J in M81 (Fransson, Lundqvist, & Chevalier 1996, Supernovae and Remnants 137 and references therein). Initially, a very hard burst of radiation was observed with T rv 10 9 K. The emission properties indicate expansion into a wind with M~4 X 10-5 M 0 yr-1 for a wind velocity V w = 10 km s-l, so the absorption by circumstellar gas could have been much more significant than was actually observed.…”