Looking at gravitational waves with the black matter?

Monika Sachan

Gravitational waves are an interruption in the curvature of space-time, generated by high masses that propagate waves at the speed of light. It is an invisible ripple of the fabric in space-time was discussed in 1916 by Albert Einstein in published his theory of general relativity which established the modern perspective of gravity waves. The theory predicted that objects interact with the gravity that disturbed and sent ripples across in fabric. This is a new age of astronomy that is allowing the scientist to see the abnormal phenomenon that sees the part of the universe that is invisible, such as black holes, dark matter, and theoretical subatomic particles called axions.

Two-dimensional illustration of how mass in the universe using gravitational waves.
[Credit: NASA]

An object interacts with gravity that can create gravitational waves. But for detection use the catastrophic cosmic event that makes gravitational waves powerful. The observatories record gravitational waves regularly and scientists are discussing how dark matter interacts with other matter only through gravity that might create gravitational waves strong enough to be found. 

Gravitational waves were first detected in 2015 by scientists working on the Laser Interferometer Gravitational Waves Observatory (LIGO) and received the Nobel Prize in physics. 

Gravitational waves are abnormal in astronomy, using the sources; Scientists are used to detecting this with help of electromagnetic spectrums like light, radio waves, or gamma rays. Black holes don’t emit any such radiation in the dark matter but the collision of black holes emits energy endless and turns into the form of gravitational wave energy.

So understanding this term, it’s possible to check the energy signal of such distant events here on earth billions of years after they happen. Then finally scientists successfully detected the first gravitational waves in September 2015 at the LIGO observatory in the United States.

‘The deformation propagates out like ripples on a lake, these are gravitational waves.’ explained Professor Paolo Pani, a theoretical physicist at Sapienza University of Rome, Italy

But the detection of these waves is provided by astronomers with new ways to attempt at the universe. Prof. Pani is leading the DarkGRA in the project that uses gravitational waves and dark matter to research some of the biggest mysteries of the universe, like heavy exotic stars, dark matter, and black holes themselves.

In the early years, according to astrophysicists’ research, they force the presence of black holes by looking at the material’s behaviors which could be dark matter. There are several super-heavy collapsed stars and they produce gravity so great that not even light escapes. Anything that passes the boundary of a black hole, is known as the event horizon. 

‘This is why we cannot see black holes, instead, we see an absence of light from them. Black holes are a big mystery still.’ said Prof. Pani.

Scientists like Prof. Pani’s point of view and that is interesting. ‘They are sort of a messenger of the space-time around these objects, without using any intermediate,’ he said.

By understanding and studying these waves then it is possible to get information about the mass, rotation, and speed of the invisible objects. ‘The goal of our project is to understand the gravitational-wave observations from very compact objects, so we can rule out or confirm other types of objects’ said Prof. Pani.

The Professor believes that dark matter interacts very little with anything else, so is very difficult to test in the lab.

According to the general theory of relativity, the merger of two very compact objects – like white dwarfs, neutron stars, or black holes – will cause the ultimate object to collapse to form a black hole. But there are alternative theories that predict they might also form objects of an identical mass and radius to black holes, but without an occasion horizon. These mysterious compact objects would therefore have a surface that might reflect gravitational waves.

‘If there is a surface, after a merger of the objects, there should be gravitational wave echoes, so a signal that is reflected from the surface,’ Prof Pani explained. It should be possible to detect these echoes within the signals picked over here on Earth.

Dark matter:

Dark matter is a part of matter that accounts for approximately 85% of the matter and at least 25% of the total mass-energy density in the universe. Its presence is equal to several astrophysical observations including gravitational wave effects and that cannot be explained by accepted theories of gravity unless more matter is present in the object.

This is an explanation that leads to black holes suddenly producing echoes or other unexplained gravitational wave features like mass, rotation, and speed of the invisible objects they could be done by dark matter. This can be producing a different tell-tale gravitational wave. 

‘Dark matter interacts very little with anything else, so is very difficult to test in the lab,’ said Prof. Pani. But by looking for well-defined signals in the gravitational waves so, the scientist sees the first time.

Some gravitational observations can only be explained in two ways first the presence of dark matter, or second by changing our laws of a gravitational wave. Professor Ulrich Sperhake, a theoretical physicist at the University of Cambridge, UK, and lead scientist in the StronGrHEP project, described gravitational waves as a ‘new window onto the universe’ that can help to solve many mysteries like this.

‘I would say axions are one of the best candidates for dark matter,’ he said. The next step is to apply his models to the data that LIGO gathers to see if theory and observation are a match. 


  1. https://horizon-magazine.eu/article/gravitational-waves-helping-expose-black-holes-dark-matter-and-theoretical-particles.html
  2. https://www.thenakedscientists.com/articles/science-features/whats-next-gravitational-waves
  3. https://www.aavso.org/other-high-energy-phenomena
  4. https://en.wikipedia.org/wiki/Dark_matter
  5. https://en.wikipedia.org/wiki/Gravitational_wave


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