Microlensing of x-ray pulsars: A method to detect primordial black hole dark matter

Primordial black holes (PBHs) with a mass from 10−16 to 10−11  M⊙ may comprise 100% of dark matter. Due to a combination of wave and finite source size effects, the traditional microlensing of stars does not probe this mass range. In this paper, we point out that x-ray pulsars with higher photon ene...

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Bibliographic Details
Published in:Physical review. D 2019-06, Vol.99 (12), p.1, Article 123019
Main Authors: Bai, Yang, Orlofsky, Nicholas
Format: Article
Language:English
Subjects:
Black holes
Dark matter
Magellanic clouds
Microlenses
Pulsars
Size effects
X ray telescopes
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Summary:Primordial black holes (PBHs) with a mass from 10−16 to 10−11  M⊙ may comprise 100% of dark matter. Due to a combination of wave and finite source size effects, the traditional microlensing of stars does not probe this mass range. In this paper, we point out that x-ray pulsars with higher photon energies and smaller source sizes are good candidate sources for microlensing for this mass window. Among the existing x-ray pulsars, the Small Magellanic Cloud (SMC) X-1 source is found to be the best candidate because of its apparent brightness and long distance from Earth. We have analyzed the existing observation data of SMC X-1 by the RXTE telescope (around 10 days) and found that PBH as 100% of dark matter is close to but not yet excluded. Future longer observation of this source by x-ray telescopes with larger effective areas such as AstroSat, Athena, Lynx, and eXTP can potentially close the last mass window where PBHs can make up all of dark matter.
ISSN:2470-0010
2470-0029
DOI:10.1103/PhysRevD.99.123019