We study the effects of additional cooling due to the emission of a dark matter candidate particle, the dark photon, on the final phases of the evolution of a 15 Me star and resulting modifications of the pre-supernova neutrino signal. For a substantial portion of the dark photon parameter space the extra cooling speeds up Si burning, which results in a reduced number of neutrinos emitted during the last day before core collapse. This reduction can be described by a systematic acceleration of the relevant timescales and the results can be estimated semi-analytically in good agreement with the numerical simulations. Outside the semi-analytic regime we find more complicated effects. In a narrow parameter range, low-mass dark photons lead to an increase in the number of emitted neutrinos because of additional shell-burning episodes that delay core collapse. Furthermore, relatively strong couplings produce a thermonuclear runaway during O burning, which could result in a complete disruption of the star but requires more detailed simulations to determine the outcome. Our results show that pre-supernova neutrino signals are a potential probe of the dark photon parameter space.
Bibliographical noteFunding Information:
This work was supported in part by the US Department of Energy [DE-FG02-87ER40328 (UM)]. Calculations were carried out at the Minnesota Supercomputing Institute. E.R. was supported by the NSF (PHY-1630782) and the Heising–Simons Foundation (2017-228). G.G. acknowledges support from the Academia Sinica by Grant No. AS-CDA-109-M11. We thank Alexander Heger for providing access to the KEPLER code.
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