Astronomers Detect Black Hole and Neutron Star merger: First of its Kind

Spread the love

There was a time when the scientific community used to think that the concept of gravitational waves only exists in Einstein’s Dreamworld. However, with the help of highly sophisticated detectors like LIGO or Virgo, in the year 2015, we finally spotted the first gravitational waves from the merger of two black holes.

Gravitational waves are nothing but ripples created in space-time due to the merger or collision between two massive objects. As per Einstein’s Vision, the colliding pair can be either two black holes or two neutron stars.

In fact, it can also be a pair of one black hole and a neutron star. Well, theoretically speaking, there can be so many different compositions for these kinds of extragalactic phenomena.


Black Hole and Neutron Star Merger: First of its Kind

As I said, the very first detection of gravitational waves was done in 2015. This cataclysmic event took place due to the collision of a pair of black holes also known as Binary Black holes. Next, in 2017, what we saw was the collision between neutron stars.

Since no one is happy with what we have, we desire more and more. Therefore, as a result, physicists and astronomers held their hope high and thought that maybe in the near coming future, they could even detect the merger of the black hole and a neutron star.

Guess, what??? For the first time, the galactic event of a black hole merging with a neutron star has been spotted by LIGO-VIRGO Gravitational Wave Detector. Well, not once, but twice in the period of 10 days.

Not Once, But Twice

Yup, you heard me right…!!! We have detected two distinct collisions between a black hole and a neutron star. Just to mention, astronomers concluded that both of these extraordinary events occurred some 900 million lightyears away from Earth.

As per the Scientific paper published on AstroPhysical Journal Letters, the first event was observed by LIGO Livingston and Virgo. And, the other one was observed by all of the three LIGO-VIRGO gravitational waves detectors.


The first event abbreviated as GW200105 was detected on January 5, 2020. Just after 10 days, the second event abbreviated as GW200115 was detected on January 15, 2020. However, the final report of both of these events was published on June 29, 2021.

GW200105 – Observation and Analysis

As per the published analysis for the event of GW200105, the size of the black hole was about 8.9 times the solar mass. On the other hand, the size of the neutron star was about 1.9 times the sun’s mass. Just to mention, a solar mass is the mass of the sun that exists in our solar system.

The report further added that the credibility of the black hole mass is about more than 90%. On the other hand, the credibility of the mass of a neutron star is about 89 to 96%.

Since this event was only detected by the LIGO Livingston and VIRGO detectors, astronomers were not able to pinpoint its origin. However, they were only able to narrow down its location in the sky to an area of about 34,000 times the size of a full moon.

GW200115 -Observation and Analysis

According to the observation and analysis for the event GW200115, the size of the black hole was about 5.7 times the solar mass. On the other hand, the size of the neutron star was about 1.5 times the mass of the sun.

The credibility of both the mass of the black hole and neutron star is about more than 90 percent. Additionally, since the event was detected by all the three LIGO-VIRGO detecting pairs, astronomers were able to pinpoint its origin with more certainty.

They were able to narrow down its location in the sky to an area of about 2900 times the size of the full moon, which is definitely higher than the GW200105.


Just a Dull Affair

As per general relativity, the merging of two neutron stars generates gravitational waves and a celestial light show. On the contrary, nothing, not even the light can escape from the event horizon of the black hole, therefore, as a result, there is no visible light signal in the case of the binary black hole mergers.

So, what about a black hole and neutron star merger? Well, we are certain that it would definitely generate gravitational waves. However, as far as the celestial light show is concerned, nothing is clear. All we have is different speculations.

Such that, some astronomers say that maybe just because the observation was not done properly, we weren’t able to pinpoint the specific location. Hence, there was no light show to see. On the other hand, according to the black hole area theorem, there is no chance for a light show if one of the merging objects is a black hole.


In other words, when the black hole swallows down the neutron, it itself becomes a black hole. And, since black holes contain no matter that might radiate light, therefore, as a result, the combined object cannot radiate gamma rays burst like in the case of binary neutron stars merger.

LIGO members say:

Astrid Lamberts of LIGO explains that Simulations suggest that the neutron star would be swallowed whole, not shredded. It might just disappear into the black hole.

Similarly, LIGO spokesperson Patrick Brady at the University of Wisconsin-Milwaukee says that these were not events where the black holes munched on the neutron stars like the cookie monster and flung bits and pieces about.

That ‘flinging about’ is what would produce light, and we don’t think that happened in these cases. What do you think? Should the merger of a black hole and a neutron star radiate light or not???


Future Plans and Expectations

As I already said earlier, no one is happy with what we have, we desire more…!!! As Nelson Christensen, also a LIGO researcher at OCA explains, “We’ve seen binary black holes, we’ve seen binary neutron stars and now we’ve definitely seen a binary with both. Now we need a supernova or a spinning pulsar. That’ll be the next big deal.”

Therefore, as a result, the next observational run for LIGO-VIRGO Detectors is set to begin in mid to late 2022. Just to mention, at the time of the detection of GW200105 and GW200115, we only had three gravitational waves detectors. These are LIGO Livingston, LIGO Hanford, and, VIRGO.

But now we do have a fourth observatory -KAGRA in Japan that became operational from February 2020. Not to mention, we do have LIGO- India project in the pipeline. This project is scheduled to be completed by 2024.


That’s it for this post. If you like this article, share it if you like, like it if you share it. You can also find us on Mix, Twitter, Pinterest, and Facebook. Hey man, If you have come this far, do give us feedback in the comment section. It would make my day. You can also make a donation. Your donations will help us to run our website and serve you BETTER. Cheers!!!

You might also like:

Spread the love

I am a mechanical engineer by profession. Just because of my love for fundamental physics, I switched my career, and therefore I did my postgraduate degree in physics. Right now I am a loner (as ever) and a Physics blogger too. My sole future goal is to do a Ph.D. in theoretical physics, especially in the field of cosmology. Because in my view, every aspect of physics comes within the range of cosmology. And I love traveling, especially the Sole one.

Leave a Comment