Scientists are getting closer to finding dark matter and gravitational-wave backgrounds using pulsar

Monika Sachan

The detection of the gravitational waves is done with two methods like LIGO and Gravitational-wave detectors at different frequencies. Using this gravitational wave effect, researchers find to spot the dark matter’s properties dark matter will have on the speed at which stars are moving in the milky way galaxy with the help of galactic lighthouses of beam called Pulsar timing arrays, which is a rotating star that emits the radio waves.

Scientists might be closer to discovering the hidden cosmic secrets like the nature of dark matter using pulsars, this was reported by the researcher at the 237th American Astronomical Society meeting, held on January 2021.

Pulsar timing arrays:

Pulsars are rotating stars or spinning neutron stars. A pulsar emits beams of radio waves like to be lighthouse beams, in the sky as the result of watching that pulsar rotates. It emits the signal detected by the radio telescopes which constantly give the pulses. It may explain the variety of cosmic mysteries, such as how galaxies can spin fast so they do without getting ripple generated.

Pulsar detection chain
[Credit: D. Lorimer]

Gravitational waves affect the time taken by the pulses to travel between pulsars to the earth’s telescope. This uses the millisecond pulsars to discover the disturbance because of gravitational waves in measurements of the arrival of time on pulses. Gravitational waves detect by pulsar timing arrays search the visible pattern of correlation and dispersion technique in several pulsars. Pulsar pulses take thousands of years to reach the earth.

“It may be a very small number we are trying to measure in the real world, in terms of change in velocity, it’s just a couple of centimeters per second, or roughly the speed of a crawling baby, and not a fast baby at that.” study lead author Sukanya Chakrabarti, an astrophysicist at the Rochester Institute of Technology in New York, said during a session held on January 2021.

The research found the amount of dark matter around the galaxy, is lower than previously assumpted prediction and it contained the volume of the earth is only around 740 grams. These findings help the current experiments directly detect the dark matter particles, said Chakrabarti. In early research, it suggests dark matter could be made by an unknown particle, when they collide with each other then it generates high-energy gamma rays. New research concludes that an unusually high number of gamma rays from the center of the Milky Way to see if they collide with dark matter.

The primary principle of gravitational waves in which pulsar timing arrays are sensitive is supermassive black hole binaries made from the collision of the galaxies and an individual binary system is the probabilistic background of the gravitational wave that is made from the addition of gravitational waves from many galaxies.

 There are three active pulsar timing array projects at present time. Pulsars spin at very steady rates, so, essentially like the ticks of a clock. by monitoring little variations in the spin of 14 pulsars, the researchers might conclude the speeds and reduction of the gravitational force that dark matter is applied to them.

Gravitational-wave background:

By merging galaxies and other cosmic events that generate the gravitational wave background and detecting mysteries like how galaxies have grown over time. These waves are quite huge, which gives a major challenge because in the current time gravitational wave observatories on earth are designed to detect the gravitational waves in seconds long and ripples from the gravitational wave background are in years.

Now researchers say that may have detected a strong signal of the gravitational wave background and it is published by a U.S. and Canadian combined project called the North American Nanohertz Observatory for Gravitational Waves (NANOGrav) using the pulsar.

“We have the significant evidence for this signal, unfortunately, we can’t quite say what it is yet.” said lead author Joseph Simon, an astrophysicist at the University of Colorado Boulder that studies this gravitational-wave background.

NANOGrav uses telescopes to monitor dozens of pulsars. Gravitational waves can alter the stable blinking pattern of light from pulsars, squeezing and expanding the distances from these rays travel through space. Analyzing this pulsar light can help scientists detect signs of the gravitational wave background.

“By monitoring these signals from a large number of pulsars, we should be creating a galaxy-sized gravitational-wave detector within our own Milky Way,” Simon said.

NANOGrav scientists have searched the pulsar to observe as many of them. So far, they have observed 45 pulsars for at least three years, and in rare cases, for more than a dozen years.

Now the researchers said that have detected possible evidence of a process deforming the light from many of the pulsars. As of now, they cannot verify it, “but we also don’t have evidence against it,” Simon said.

If the researchers can verify they have detected the gravitational wave background, they next want to process what causes these waves and what such signals can tell scientists about the universe.

Atomic Experiment for Dark Matter and Gravity Exploration in Space (AEDGE):

This experiment was hosted by CERN, Geneva, Switzerland. The researcher proposed a concept for a space experiment using the cold atoms to search for ultra-light dark matter particles, and also to detect gravitational waves in the frequency range between the most sensitive ranges and high ranges in the experiments. This experiment, called Atomic Experiment for Dark Matter and Gravity Exploration (AEDGE), will also compare other planned searches for dark matter.

They give the example of the extended range of sensitivity to ultra-light substance offered by AEDGE, and the way its gravitational-wave measurements could explore the assembly of super-massive black holes, and first-order phase transitions within the early universe, and cosmic strings. AEDGE is going to be based upon technologies now being developed for terrestrial experiments using cold atoms and can enjoy the space experience obtained with, e.g., LIGO and cold atom experiments in microgravity.

Reference:

1. https://www.space.com/astronomers-chasing-cosmic-secrets-with-pulsar

2. https://en.wikipedia.org/wiki/Gravitational_wave_background

3. https://epjquantumtechnology.springeropen.com/articles/10.1140/epjqt/s40507-020-0080-0

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