Dark matter capture in celestial objects: Improved treatment of multiple scattering and updated constraints from white dwarfs. (arXiv:1906.04204v1 [hep-ph])

<a href="http://arxiv.org/find/hep-ph/1/au:+Dasgupta_B/0/1/0/all/0/1">Basudeb Dasgupta</a> (Tata Inst.), <a href="http://arxiv.org/find/hep-ph/1/au:+Gupta_A/0/1/0/all/0/1">Aritra Gupta</a> (Tata Inst.), <a href="http://arxiv.org/find/hep-ph/1/au:+Ray_A/0/1/0/all/0/1">Anupam Ray</a> (Tata Inst.)

We revisit dark matter (DM) capture in celestial objects, including the

impact of multiple scattering, and obtain updated constraints on the DM-proton

cross section using observations of white dwarfs. Considering a general form

for the energy loss distribution in each scattering, we derive an exact formula

for the capture probability through multiple scatterings. We estimate the

maximum number of scatterings that $can$ take place, in contrast to the number

$required$ to bring a dark matter particle to rest. We employ these results to

compute a “dark” luminosity $L_{rm DM}$, arising solely from the thermalized

annihilation products of the captured dark matter. Demanding that $L_{rm DM}$

not exceed the luminosity of the white dwarfs in the M4 globular cluster, we

set a bound on the DM-proton cross section: $sigma_{p} lesssim 10^{-44} {rm

cm}^2$, almost independent of the dark matter mass between 100 GeV and 1 PeV

and mildly weakening beyond. This is a stronger constraint than those obtained

by direct detection experiments in both large mass $left(M gtrsim 5 ,,rm

TeVright)$ and small mass $left(M lesssim 10,, rm GeVright)$ regimes.

For dark matter lighter than 350 MeV, which is beyond the sensitivity of

present direct detection experiments, this is the strongest available

constraint.

We revisit dark matter (DM) capture in celestial objects, including the

impact of multiple scattering, and obtain updated constraints on the DM-proton

cross section using observations of white dwarfs. Considering a general form

for the energy loss distribution in each scattering, we derive an exact formula

for the capture probability through multiple scatterings. We estimate the

maximum number of scatterings that $can$ take place, in contrast to the number

$required$ to bring a dark matter particle to rest. We employ these results to

compute a “dark” luminosity $L_{rm DM}$, arising solely from the thermalized

annihilation products of the captured dark matter. Demanding that $L_{rm DM}$

not exceed the luminosity of the white dwarfs in the M4 globular cluster, we

set a bound on the DM-proton cross section: $sigma_{p} lesssim 10^{-44} {rm

cm}^2$, almost independent of the dark matter mass between 100 GeV and 1 PeV

and mildly weakening beyond. This is a stronger constraint than those obtained

by direct detection experiments in both large mass $left(M gtrsim 5 ,,rm

TeVright)$ and small mass $left(M lesssim 10,, rm GeVright)$ regimes.

For dark matter lighter than 350 MeV, which is beyond the sensitivity of

present direct detection experiments, this is the strongest available

constraint.

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