Subscribe to the gold package and get unlimited access to Shamra Academy
Register a new userLimits on compact halo objects as dark matter from gravitational microlensing
177
0
0.0
(
0
)
Authors
Philippe Jetzer
Ask ChatGPT about the research
No Arabic abstract
Microlensing started with the seminal paper by Paczynski in 1986, first with observations towards the Large Magellanic Cloud and the galactic bulge. Since then many other targets have been observed and new applications have been found. In particular, it turned out to be a powerful method to detect planets in our galaxy and even in the nearby M31. Here, we will present some results obtained so far by microlensing without being, however, exhaustive.
rate research
Read More
If a significant fraction of dark matter is in the form of compact objects, they will cause microlensing effects in the gravitational wave (GW) signals observable by LIGO and Virgo. From the non-observation of microlensing signatures in the binary black hole events from the first two observing runs and the first half of the third observing run, we constrain the fraction of compact dark matter in the mass range $10^2-10^5~{M_odot}$ to be less than $simeq 50-80%$ (details depend on the assumed source population properties and the Bayesian priors). These modest constraints will be significantly improved in the next few years with the expected detection of thousands of binary black hole events, providing a new avenue to probe the nature of dark matter.
The dramatic size evolution of early-type galaxies from z ~ 2 to 0 poses a new challenge in the theory of galaxy formation, which may not be explained by the standard picture. It is shown here that the size evolution can be explained if the non-baryonic cold dark matter is composed of compact objects having a mass scale of ~10^5 M_sun. This form of dark matter is consistent with or only weakly constrained by the currently available observations. The kinetic energy of the dark compact objects is transferred to stars by dynamical friction, and stars around the effective radius are pushed out to larger radii, resulting in a pure size evolution. This scenario has several good properties to explain the observations, including the ubiquitous nature of size evolution and faster disappearance of higher density galaxies.
The radiation emitted by horizonless exotic compact objects (ECOs), such as wormholes, 2-2-holes, fuzzballs, gravastars, boson stars, collapsed polymers, superspinars etc., is expected to be strongly suppressed when compared to the radiation of black holes. If large primordial curvature fluctuations collapse into such objects instead of black holes, they do not evaporate or evaporate much slower than black holes and could thus constitute all of the dark matter with masses below $M < 10^{-16}M_odot.$ We reevaluate the relevant experimental constraints for light ECOs in this mass range and show that very large new parameter space down to ECO masses $Msim 10,{rm TeV}$ opens up for light primordial dark matter. A new dedicated experimental program is needed to test this mass range of primordial dark matter.
We study gravitational lensing of gravitational waves from compact object binaries as a probe of compact dark matter (DM) objects such as primordial black holes. Assuming a point mass lens, we perform parameter estimation of lensed gravitational wave signals from compact object binaries to determine the detectability of the lens with ground based laser interferometers. Then, considering binary populations that LIGO-Virgo has been probing, we derive a constraint on the abundance of compact DM from non-observation of lensed events. We find that the LIGO-Virgo observations imply that compact objects heavier than $M_l = 50M_odot$ can not constitute all DM and less than $15%$ of DM can be in compact objects heavier than $M_l = 200M_odot$. We also show that the DM fraction in compact objects can be probed by LIGO in its final sensitivity for $M_l > 20M_odot$ reaching $0.7%$ of the DM abundance at $M_l > 100M_odot$, and by ET for $M_l > 0.4M_odot$ reaching DM fraction as low as $3times 10^{-5}$ at $M_l > 20M_odot$.
Dark matter could be composed of compact dark objects (CDOs). A close binary of CDOs orbiting in the interior of solar system bodies can be a loud source of gravitational waves (GWs) for the LIGO and VIRGO detectors. We perform the first search ever for this type of signal and rule out close binaries, with separations of order 300 m, orbiting near the center of the Sun with GW frequencies (twice the orbital frequency) between 50 and 550 Hz and CDO masses above $approx 10^{-9} M_odot$. This mass limit is eight orders of magnitude lower than the mass probed in a LIGO search at extra galactic distances.
Log in to be able to interact and post comments
comments
Fetching comments
Sign in to be able to follow your search criteria
