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Over the past decade, a consensus picture has emerged in which roughly a quarter of the universe consists of dark matter. The observational evidence for the existence of dark matter is reviewed: rotation curves of galaxies, weak lensing…
The nature of the dark matter in the halo of our Galaxy is still largely unknown. The microlensing events found so far towards the Large Magellanic Cloud suggest that at most about 20% of the halo dark matter is in the form of MACHOs…
We investigate induced oscillations by the gravitational field of a fast stellar object, such as a neutron star or a black-hole in a near miss collision with another star. Non-adiabatic collision conditions may lead to large amplitude…
Dark stars are compact massive objects, described by Einstein gravitational field equations with matter. The type we consider possesses no event horizon, instead, there is a deep gravitational well with a very strong redshift factor.…
Too light primordial black holes evaporate and are therefore strongly constrained by various bounds, e.g. Cosmic Microwave Background distortion. However, if they are formed strongly clustered, the corresponding haloes may collapse in…
Searches for dark matter imprints are one of the most active areas of current research. We focus here on light fields with mass $m_B$, such as axions and axion-like candidates. Using perturbative techniques and full-blown nonlinear…
The nature of dark matter, the invisible substance making up over $80\%$ of the matter in the Universe, is one of the most fundamental mysteries of modern physics. Ultralight bosons such as axions, axion-like particles or dark photons could…
The existence of dark matter is supported by multiple astrophysical observations, yet its particle nature remains unknown. The development of gravitational wave astronomy, especially with future space-based detectors such as LISA, provides…
The formation and growth of black holes can strongly influence the distribution of dark matter around them. I discuss here the different types of dark matter overdensities around black holes, including dark matter cusps, spikes, mounds,…
The detection of microlensing events from stars in the Large Magellanic Cloud and in the Galactic bulge raise important constraints on the distribution of dark matter and on galactic structure, although some events may be due to a new type…
Astronomical and cosmological observations of the past 80 years build solid evidence that atomic matter makes up only a small fraction of the matter in the universe. The dominant fraction does not interact with electromagnetic radiation,…
Dark matter in the form of axions is expected to form miniclusters, and their dense regions can harbor compact axion stars. Such axion stars could be discovered by microlensing events. In particular, some candidate events reported by Subaru…
Stellar pulsation is nowadays a widely understood subject. However, there has been no research about the effects of pulsations on the star's orbital dynamics throughout the galaxy. We investigate whether these oscillations can cause chaotic…
Perturbations to stellar systems can reflect the gravitational influence of dark matter substructures. On scales much smaller than the size of a stellar system, we point out analytic connections between the stellar and dark matter…
If compact baryonic objects contribute significantly to the dark matter in our Galaxy, their mass function will present vital clues for galaxy formation theories and star formation processes in the early Universe. Here we discuss what one…
Dark matter (DM) comes from long-range gravitational observations, and it is considered as something that does not interact with ordinary matter or emits light. However, also on much smaller scales, a number of unexpected observations of…
We consider small-scale spheroidal clusters of weakly interacting massive particles in our Galaxy as non-compact gravitational microlenses and predict the appearance of caustics in the plane of a lensed source. The crossing of these…
Starting from the evidence that dark matter indeed exists and permeates the entire cosmos, various bounds on its properties can be estimated. Beginning with the cosmic microwave background and large scale structure, we summarize bounds on…
Neutron stars offer powerful astrophysical laboratories to probe the properties of dark matter. Gradual accumulation of heavy, non-annihilating dark matter in neutron stars can lead to the formation of comparable-mass black holes, and…
The presence of dark matter has been ascertained through a wealth of astrophysical and cosmological phenomena and its nature is a central puzzle in modern science. Elementary particles stand as the most compelling explanation. They have…