Abstract

Unlike the luminous objects observed, dark matter does not emit light but can be only detected by its gravitational effect. Modern cosmology considers that most matter in Universe is dark matter. However, it is still not clear what the dark matter was. Two origins have been proposed by astrophysicists, astrophysics candidates and particle physics candidates. The most differences are their morphology, the former are compact objects and the latter are dispersed. Under Einstein’s theory of general relativity, light bends as it passes near a compact object, creating a convergence effect like a lens. When background light source, intervening lense and the observer lie on a straight line, the brightness of the background source will be significantly magnified. In astrophysics, this effect is called microlensing. If compact dark matter is abundant in the universe, it is possible to frequently observe “microlensing” events when observing high redshift objects, i.e. the objects temporarily brighten for a certain time. The microlensing technique has been applied to study the dark matter in halo of Milky Way. The difficulty occurs when applying to study the cosmic dark matter as the crossing time of cosmic microlensing events is too long for observations. Apparent superluminal jets in bright quasars are idea background objects, significantly enhancing the efficiency of cosmic microlensing survey. Here, we tentatively designed an observational experiment to study the morphology of dark matter in Universe via statistics of microlensing events towards luminous quasars with apparent superluminal jets.

Highlights

  • If the above requirement is adopted, the compact dark matter object whose light source velocity is more than 0.5 times the speed of light and whose lens mass is less than 1 solar mass can be well observed by using the microlensing event

  • We need to use the cosmological concept of coactive volume. It is the volume defined in the case that the volume density of a celestial body does not change with the evolution of the universe (Hogg, 2000)

  • Since the speed of the background light source is fast, it greatly increases the volume of the universe scanned by the sightline within a certain time and enhances the ratio of event detection to an extent that every gamma-ray burst afterglow creates a microlensing event with a certain intensity [7]

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Summary

Discovery of Dark Matter

During the measurement, they found that the velocity of rotation of cold gas in stars and halos within the galaxies is too fast, which is known as the “rotation curve of galaxy” issue. The image shows that the rotation velocity curve tends to be stable when the radius is very large, that is, the rotation velocity tends to be a constant It is valid even when the distance from the center of the galaxy is huge. If the actual mass distribution of a galaxy is the same as that of the glowing matter, the rotation velocity in the galaxy periphery should be inversely proportional to the 1/2 power of the radius. The excessive mass over the glowing matter is called dark matter

Composition and Evolution of the Universe
Status of Dark Matter Research
Physics of Microlensing Events
Cosmological Distance Calculation
Background Light Source of Apparent Superluminal Motion
Cosmic Microlensing Events of Compact Dark Matter
Analysis of the Crossing Time of the Cosmic Microlensing Events
Findings
Estimation of Detection Probability
CONCLUSIONS AND PROSPECTS
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