Black Holes and Neutron Stars - Why are These so Important?

Recently, scientists captured a very rare occurrence - a black hole swallowing a neutron star. What can scientists do with this research and how can it help space exploration advance?

By Vanathi Kanth, Edited by Juee Deshmukh, Aarav Navani & Ameya Aneja

In 1916, Albert Einstein predicted the existence of gravitational waves, or ripples in spacetime that happen when the most massive objects in the universe collide. These waves were first detected in September 2015 when two black holes had struck. January 2021, however, was the first time that there was evidence showing two black holes swallowing massive neutron stars. As the black holes and neutron stars collided, massive gravitational waves were produced which took about one billion years to reach Earth. (Strickland, 2021).

Up until now, scientists have predicted that a black hole swallowing a neutron star was possible but couldn’t prove it until interferometers, which are gravitational wave detectors, provided solid evidence of such collisions. Interferometers are prevalent in a growing field of research known as gravitational astronomy, where scientists study minor distortions of spacetime to understand how the universe works.

Researchers hope to fill in the grey area between our knowledge and these complexities using specific gravitational wave data. So far, scientists know that when massive stars die, they collapse under their gravity to leave behind black holes. On the other hand, the stars can also explode and leave remnants known as neutron stars (Hanna, 2020). Furthermore, there’s so much unknown: how big or small they can get, how they pair off, or how fast they can spin. Based on the statistics the gravitational wave data gives, scientists hope to ultimately discover how the extremes in our universe are made (Fishbach, 2021).

From the Virgo gravitational-wave observatory in Italy, where some of the most sensitive observational instruments lie, researchers found the mass and location of the collision just from the nature of the waves. They found that the black holes and neutron stars were much heavier than the sun and several million years from Earth, outside the Milky Way galaxy. Although this might seem small in the scope of the entire universe, even the minute discoveries help us understand the nature of different binary systems of the universe and why they don’t exist in the Milky Way. (Lamberts, 2021).

Despite all of the new data acquired from the gravitational waves, everything is still uncertain since there are only two signals from a black hole swallowing a neutron star. To make better observations and models, scientists hope to observe more indicators of this event. With the newer data, however, previous models of the neutron star and black hole merger can be refined, potentially leading to a better comprehension of the formation and evolution of objects in space.

Understanding these objects in space is beneficial as it expands our view of the universe and helps evaluate scientific theories on Earth. Frequently, the objects in space turn out to be extreme examples of existing concepts on Earth. Seeing these concepts play out in the universe helps scientists figure out any effects on Earth. With the black hole and neutron star colliding, scientists can find how a black hole affects Earth, for instance. With more data, scientists can start by understanding objects in space and later develop this knowledge into something new.

art by Juee Deshmukh