Solar wind bremsstrahlung off dark matter in our solar system at three wavelengths

Using Monte Carlo techniques, we calculate the bremsstrahlung spectrum that protons and electrons in the solar wind would produce when encountering dark matter (DM) particles within the solar system. We consider two types of interactions for the DM: one where a spin-<a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"><a:mrow><a:mn>1</a:mn><a:mo>/</a:mo><a:mn>2</a:mn></a:mrow></a:math> neutral DM particle interacts with matter through the exchange of a lighter neutral scalar DM particle and one where a scalar neutral DM particle interacts directly with the matter particle. We consider three wavelengths: 21 cm, 3 mm, and <c:math xmlns:c="http://www.w3.org/1998/Math/MathML" display="inline"><c:mrow><c:mn>12</c:mn><c:mtext> </c:mtext><c:mtext> </c:mtext><c:mi mathvariant="normal">μ</c:mi></c:mrow></c:math>. To estimate the significance of the signal, we compare our results to experimental results from ARCADE2 and PLANCK and consider the sensitivities of three telescopes: VLA, ALMA, and KECK. We find that in order to produce an observable signal in the first scenario the neutral fermion must have a mass comparable to the solar wind particle while the exchanged particle must have a mass typically <f:math xmlns:f="http://www.w3.org/1998/Math/MathML" display="inline"><f:mrow><f:mi>few</f:mi><f:mo>×</f:mo><f:msup><f:mrow><f:mn>10</f:mn></f:mrow><f:mrow><f:mn>5</f:mn></f:mrow></f:msup></f:mrow></f:math> smaller. The scalar direct interaction, however, appears beyond reach for any reasonable coupling.