Related papers: A new direction for dark matter research: intermed…
I show that a recently discovered star cluster near the center of the ultra-faint dwarf galaxy Eridanus II provides strong constraints on massive compact halo objects (MACHOs) of >~5 M_sun as the main component of dark matter. MACHO dark…
The recent astrometric data of hundreds of millions of stars from Gaia DR3 has allowed a precise determination of the Milky Way rotation curve up to $28$~kpc. The data suggests a rapid decline in the density of dark matter beyond $19$~kpc.…
It has been shown by Paczy\'nski that gravitational microlensing is potentially a useful method for detecting the dark constituents of the halo of our galaxy, if their mass lies in the approximate domain $10^{-6} < M/M_{\odot} < 10^{-1}$.…
If MACHOs are black holes of mass about 0.5 solar mass, they must have been formed in the early universe when the temperature was about 1 GeV. We estimate that in this case in our galaxy's halo out to about 50kpc there exist about half…
One of the possible explanations for dark matter is that of compact dark objects of baryonic origin, such as black holes or even planets. Accumulating evidence, including the discovery of merging stellar mass black holes through…
Primordial black holes (PBHs) form from large-amplitude initial density fluctuations and may comprise some or all of the dark matter. If PBHs have a broadly extended mass spectrum, or in mixed PBH-particle dark matter scenarios, the extreme…
We discuss the implications of the recent upward revision of the LMC microlensing rate by the MACHO Collaboration. We conclude: (i) A good case for the existence of baryonic dark matter in the halo has been made; (ii) The case for the…
It has been argued in a number of recent papers that dark matter is in the form of Jupiter mass primordial black holes which betray their presence by microlensing quasars. This lensing accounts for a number of characteristic properties of…
Dark matter is a vital component of the current best model of our universe, $\Lambda$CDM. There are leading candidates for what the dark matter could be (e.g. weakly-interacting massive particles, or axions), but no compelling observational…
Supermagnified stars are gravitationally lensed individual stars that are located close to a caustic of a lensing galaxy cluster, and have their flux magnified by a large enough factor (typically ~ 1000) to make them detectable with present…
About one-fourth of the universe is thought to consist of dark matter. Yet there is no clear understanding about the nature of these particles. Commonly discussed dark matter candidates includes the so called WIMPs or weakly interacting…
The nature of dark matter remains one of the biggest open questions in physics. Intriguingly, it has been suggested that dark matter may be explained by another recently observed phenomenon: the detection of gravitational waves by LIGO.…
Dark matter is the dominant form of matter in the universe, but its nature is unknown. It is plausibly an elementary particle, perhaps the lightest supersymmetric partner of known particle species. In this case, annihilation of dark matter…
If the dark matter in galactic halos is made up of compact, macroscopic objects (MO), such as black holes with $M_\MO >>M_{stars}$, gravitational scattering will lead to kinematic heating of the stars. Observational constraints on the…
Black hole-like objects with mass greater than $10 M_{\odot}$, as discovered by gravitational antennas, can produce long time-scale (several years) gravitational microlensing effects. Considered separately, previous microlensing surveys…
The gravitational wave detectors have unveiled a population of massive black holes that do not resemble those observed in the Milky Way and whose origin is debated. According to one possible explanation, these black holes may have formed…
The Universe was nearly smooth and homogeneous before a redshift of z = 100, about 20 million years after the Big Bang. After this epoch, the tiny fluctuations imprinted upon the matter distribution during the initial expansion began to…
It has been proposed that the MACHOs in our galaxy could be clumped in globular cluster--like associations or RAMBOs (robust associations of massive baryonic objects) (Moore \& Silk 1995). Here we investigate the effect such clustering has…
Numerous microlensing survey programs have constrained the possibility of dark matter existing in the form of compact objects within the Galactic halo. These constraints on the dark matter fraction were derived under the assumption of…
Ultracompact minihalos would be formed if there are larger density perturbations ($0.0003 < \delta\rho/\rho < 0.3$) in the earlier epoch. The density profile of them is steeper than the standard dark matter halos. If the dark matter can…