Gravitational microlensing as a probe for dark matter clumps

Abstract

Extended dark matter (DM) substructures may play the role of microlenses in the Milky Way and in extragalactic gravitational lens systems (GLSs). We compare microlensing effects caused by point masses (Schwarzschild lenses) and extended clumps of matter using a simple model for the lens mapping. A superposition of the point mass and the extended clump is also considered. For special choices of the parameters, this model may represent a cusped clump of cold DM, a cored clump of self-interacting dark matter (SIDM) or an ultra compact minihalo of DM surrounding a massive pointlike object. We built the resulting micro-amplification curves for various parameters of one clump moving with respect to the source in order to estimate differences between the light curves caused by clumps and by point lenses. The results show that it may be difficult to distinguish between these models. However, some region of the clump parameters can be restricted by considering the high amplification events at the present level of photometric accuracy. Then we estimate the statistical properties of the amplification curves in extragalactic GLSs. For this purpose, an ensemble of amplification curves is generated yielding the autocorrelation functions (ACFs) of the curves for different choices of the system parameters. We find that there can be a significant difference between these ACFs if the clump size is comparable with typical Einstein radii; as a rule, the contribution of clumps makes the ACFs less steep.

The Present and Future Status of Heavy Neutral Leptons

“…Gravitational lensing (and microlensing) is a promising way to probe the presence of substructures directly (c.f. [715][716][717][718][719][720][721][722][723][724][725][726][727]). The detection of low mass halos within the main lensing halo [see e.g.…”

Sterile Neutrino Dark Matter

“…Gravitational lensing (and microlensing) is the promising way to probe the presence of substructures directly (c.f. [309,[352][353][354][355][356][357][358][359][360][361]). A large sample of lenses together with a robust way to predict the average distribution of sub-halos is required in order to make a statistically robust prediction…”

Determining the parameters of high amplification microlensing events by means of statistical machine learning techniques

“…High amplification microlensing events (HAME) due to stellar-mass objects on the lightcurves of stars of extraglactic objects can give us possibility to reconstruct the density profile of a microlens. In the WDM cosmology, we may predict the non existence of DM gravitational microlensing, CDM and SIDM clumps have different density profiles distiguishable from each other as well as from the point mass microlens, as we had shown in Fedorova et al (2016). The other interesting situation we can meet is a star or a star-mass black hole surrounded by a dense cloud od DM trapped by its gravity, or ultra compact mini halo (UCMH) proposed by Zhang (2011).…”