http://arxiv.org/abs/1711.06312
Recent observations of the gravitational wave by LIGO motivates investigations for the existence of Primordial Black Holes (PBHs) as a candidate for the dark matter. We propose quasar gravitational microlensing observations in Infrared to the sub-millimeter wavelengths by sub-lunar PBHs as lenses. The advantage of observations in the longer wavelengths is that the Schwarzschild radius of the lens is of the order of the wavelength (i.e. $R_{\rm sch}\simeq \lambda$), so the wave optics features of gravitational lensing can be seen on the cosmological scales. In the wave optics regime, the magnification has a periodic profile rather than monotonic one in the geometric case. This observation can break the degeneracy between the lens parameters and determine uniquely the lens mass as well as its distance from the observer. We estimate the wave optics optical-depth and number of detectable events for sub-lunar lenses and propose a long-term survey of quasars with cadence $\sim$ hour to probe possible fraction of dark matter in form of sub-lunar PBHs.
T. Naderi, A. Mehrabi and S. Rahvar
Mon, 20 Nov 17
54/56
Comments: 6 pages, 4 figures, comments welcome