One of the most interesting space studies, after the 2015-detection of gravitational waves from collisions with a black hole, was titled "Limits on Stellar-Mass Compact Objects as Dark Matter from Gravitational Lensing of Type Ia Supernovae," and it was published in the Physical Review Letters journal.
The research was led by Miguel Zumalacarregu, a Marie Curie Global Fellow at the Berkeley Center for Cosmological Physics (BCCP), with the support of Uros Seljak, a professor of cosmology and the co-director of the BCCP.
A Brilliant Discovery
The nature of dark matter (DM) remains unknown despite very precise knowledge of its abundance in the universe. Astronomers now believe that black holes do not comprise the universe’s "missing" dark matter. Specifically, the results of the new study suggest that none of the dark matter consists of black holes or any similar object.
Dark matter is one of the most intriguing mysteries facing astronomers, today. Despite the fact that DM comprises 84.5 percent of the matter in the universe, no one can really pinpoint it in this cosmos.
The main proposal of many theorists is that dark matter is divided into different types, a phenomenon that makes models too complex. “I can imagine it being two types of black holes, very heavy and very light ones, or black holes and new particles. But in that case one of the components is orders of magnitude heavier than the other, and they need to be produced in comparable abundance. We would be going from something astrophysical to something that is truly microscopic, perhaps even the lightest thing in the universe, and that would be very difficult to explain,” said lead author Miguel Zumalacárregui, a Marie Curie Global Fellow at the Berkeley Center for Cosmological Physics.
Black Holes – From Albert Einstein to Stephen Hawking
Black holes were theorized in the 18th century. John Michell, in 1783, gave a talk on the gravitational force of stars. Later, Piere Simon de Laplace created many theorems and questions via his book published in 1796, Exposition du Système du Monde, about dark bodies and the wave theory of light. Einstein’s theory of relativity, both general relativity and special relativity, described the gravitational field of bodies with mass, 'm,' when velocities are generated comparable to that of light.
After these hypotheses, many innovative theories about the functions of black holes were generated. It was John Archibald Wheeler who dubbed these strange objects “black holes.” But Einstein was not pleased, as he believed that these ideas came from incomplete physical understanding. In 1916, Schwarzschild, after reading Einstein’s paper on general relativity, solved the scientist's equation for the region outside a massive spherical object.
Today we accept the existence of black holes and their formalization under specific circumstances - they are not made up of matter and have a great ability to distort space and time.
Are black holes actually made up of dark energy stars, and not dark matter? (Image Source: NASA)
The present, state-of-the-art, set of theories allow us to calculate the specific behavior of a particle inside or near a black hole (BH). With the many theories about astronomical black holes, astrophysicists have extracted valuable knowledge about the physical phenomena, under extreme conditions. In addition, BHs do not clash with other physical laws.
Quantum mechanics is based on the assumption that every physically-allowed configuration must be included as taking part in a quantum process. Theoretical physicists have attempted to include the theory of black holes in the general picture of quantum mechanical interactions. Specifically, Stephen Hawking tried to describe relativistic quantized fields in the vicinity of a black hole.
But how are black holes related to dark matter?
The Theory of Dark Matter
The theory of dark matter was officially adopted in the 1970s, during the Golden Age of Relativity, to account for the discrepancies between the apparent mass of objects in the universe and their observed gravitational effects.
It appears that half a century later, we are still trying to track down this mysterious, invisible mass. But with every study, additional constraints are being placed on DM, and possible candidates are being eliminated.
The team of UC Berkeley physicists conducted a statistical analysis of 740 of the brightest supernovas discovered (as of 2014) in order to determine if any of them had been magnified or brightened by the presence of an intervening black hole.
Supernovas are the light that is believed to originate from the explosion of a star, which has reached the end of its life. This phenomenon, where the gravitational force of a large object magnifies the light coming from more distant objects, is known as gravitational lensing.
An animation of a gravitational lens moving in a galaxy by a technique called gravitational lensing. (Source: NASA Video/YouTube)
Results of the UC Berkeley study suggest that none of the universe’s dark matter consists of heavy black holes, and we are now ready to understand how the cosmos has evolved, through its mysterious formalization.
“The past, like the future, is indefinite and exists only as a spectrum of possibilities.” - Stephen Hawking
Top Image: The Andromeda galaxy. In a new study, scientists have dismissed the theory that black holes constitute the universe’s “missing” dark matter. (Source: Adam Evans – M31/Wikipedia)
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