期刊
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
卷 493, 期 3, 页码 3632-3641出版社
OXFORD UNIV PRESS
DOI: 10.1093/mnras/staa407
关键词
gravitational lensing: micro; dark matter; cosmology: theory
资金
- World Premier International Research Center Initiative (WPI Initiative), Ministry of Education, Culture, Sports, Science and Technology (MEXT), Japan
- Japan Society for Promotion of Science (JSPS) KAKENHI [JP15H03654, JP15H05887, JP15H05893, JP15K21733, 19H00677]
- Grants-in-Aid for Scientific Research [19H00677] Funding Source: KAKEN
Microlensing of stars, e.g. in the Galactic bulge and Andromeda galaxy (M31), is among the most robust, powerful method to constrain primordial black holes (PBHs) that are a viable candidate of dark matter. If PBHs are in the mass range M-PBH less than or similar to 10(-10)M(circle dot), its Schwarzschild radius (r(Sch)) becomes comparable with or shorter than optical wavelength (lambda) used in a microlensing search, and in this regime the wave optics effect on microlensing needs to be taken into account. For a lensing PBH with mass satisfying r(Sch) similar to lambda, it causes a characteristic oscillatory feature in the microlensing light curve, and it will give a smoking gun evidence of PBH if detected, because any astrophysical object cannot have such a tiny Schwarzschild radius. Even in a statistical study, e.g. constraining the abundance of PBHs from a systematic search of microlensing events for a sample of many source stars, the wave effect needs to be taken into account. We examine the impact of wave effect on the PBH constraints obtained from the r-band (6210 angstrom) monitoring observation of M31 stars in Niikura et al., and find that a finite source size effect is dominant over the wave effect for PBHs in the mass range M-PBH similar or equal to [10(-11), 10(-10)]M-circle dot. We also discuss that, if a denser cadence (10 s), g-band monitoring observation for a sample of white dwarfs over a year time-scale is available, it would allow one to explore the wave optics effect on microlensing light curve, if it occurs, or improve the PBH constraints in M-PBH less than or similar to 10(-11)M(circle dot) even from a null detection.
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