Neutron Star Collision

Log Entry 2

I woke up from my hibernation (yes, things got a bit boring) and could hear the controls beeping owing to the ripple in space-time, the gravitational-wave detectors picked up some signals. I expected it to be a pair of huge blackholes quickly spiralling into each other, but no, I was wrong. The new siren lasted longer, for about 100 seconds with frequencies rising up to thousands of cycles per second (it lasts only for a few secs and frequencies up to tens of cycles for blackhole merging)

What I saw was a bright spot of light, that faded from bright blue to dim red and eventually disappeared, it was emitting X-rays and radio waves after initial couple of weeks. There was gravitational waves and electromagnetic radiation both coming out of a single source. I was startled at the sight, not able to make sense of what I was witnessing. Little did I know I’d seen a rare event that occurs about once in 50,000 years… yes you read that right, ONCE IN 50,000 YEARS. It was a collision of two Neutron Stars.

Collision Of 2 Neutron Stars – Seen For First Time – Spews Massive Cloud Of  Gold, Heavy Elements : The Two-Way : NPR

What I witnessed as light from it, was the “kilonova” – produced as a debris from the merger, expanded and cooled.

Neutron stars collision is a rare phenomenon, where two neutron stars close enough to each other, spiral around each other rapidly and eventually merge into a singularity forming a blackhole. It is the origin of gamma ray bursts (second most powerful event known) shorter than two seconds.

As the two neutron stars twirl together and rip each other apart, they expel neutron-rich atomic nuclei, forming a shroud of matter totalling a few percent of a solar mass. Those nuclei gobble neutrons in rapid succession and then quickly change their chemical identities through radioactive decay. This is the so-called r-process—or rapid neutron capture process—that makes the shroud glow for a few days, and its light reddened by heavy elements that soak up blue wavelengths. This is what is called the kilonova.

Thanks to the colliding neutron stars we have gold, silver and platinum for the origin of half the elements heavier than iron, including silver, gold, and platinum are generated in the r-process.

I remember, a Neutron Star Collision was observed for the first time on 17th August, 2017. The LIGO picked up unlikely waves at 12:41 universal time. Scientists all over the world observed this phenomenon for several weeks, the neutron stars swirled around each other, coming closer and closer. From passing about 30 times each second, the pair reached a point around 100 seconds later when they were swirling 2,000 times each second. After that, there was a short pause when nothing was detected by LIGO. Then, the stars violently collided, most likely creating a black hole; making that, probably, the first time, scientists have witnessed a black hole being made.

After witnessing this mind-boggling phenomenon I’m heading towards a new place, feeling relieved of the fact that the phenomenon occurred far away from our dear Earth, else the burst of gamma rays would have catastrophically stripped half the Earth’s upper atmosphere.

Received by Shilpashree

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