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تسجيل مستخدم جديدProspects of direct detection of $^{48}$V gamma-rays from thermonuclear supernovae
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Detection of gamma-rays emitted by radioactive isotopes synthesized in stellar explosions can give important insights into the processes that power transients such as supernovae, as well as providing a detailed census of the abundance of different isotope species relevant to the chemical evolution of the Universe. Observations of nearby supernovae have yielded observational proof that $^{57}$Co powered the late-time evolution of SN1987As lightcurve, and conclusive evidence that $^{56}$Ni and its daughter nuclei power the light curves of Type Ia supernovae. In this paper we describe the prospects for detecting nuclear decay lines associated with the decay of $^{48}$V, the daughter nucleus of $^{48}$Cr, which is expected to be synthesised in large quantities - $M_{mathrm{Cr}}sim1.9times10^{-2},mathrm{M_odot}$ - in transients initiated by explosive helium burning ($alpha$-capture) of a thick helium shell. We calculate emergent gamma-ray line fluxes for a simulated explosion model of a thermonuclear explosion of carbon-oxygen white dwarf core of mass $0.45,M_{odot}$ surrounded by a thick helium layer of mass $0.21,M_{odot}$. We present observational limits on the presence of $^{48}$V in nearby SNe Ia 2014J using the textit{INTEGRAL} space telescope, excluding a $^{48}$Cr production on the surface of more than $0.1,mathrm{M_{odot}}$. We find that the future gamma-ray mission AMEGO will have an approximately 5 per cent chance of observing $^{48}$V gamma-rays from such events during the currently-planned operational lifetime, based on our birthrate predictions of faint thermonuclear transients. We describe the conditions for a $3sigma$ detection by the gamma-ray telescopes textit{INTEGRAL}/SPI, COSI and AMEGO.
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