Astronomy transformed in the 2020s to rapid event response with real time observations

The world currently has three gravitational wave detectors (two LIGO detectors and the Virgo detector. These were used last month to detect and spot the location of a neutron star collision 300 million light years away. This was the first time that a neutron star collision has been detected and observed with x-ray, gamma ray, gravitational and visible light telescopes.

* The neutron stars, whose masses were between 1.17 and 1.60 times that of the sun, probably collapsed into a black hole, although LIGO scientists were unable to determine the stars’ fate for certain.
* Scientists spotted a phenomenon called a short gamma-ray burst, a brief spurt of high-energy light, less than two seconds long. Short gamma ray bursts appear in the sky about 50 times a year.
* By studying how the neutron stars spiraled inward, astrophysicists also tested the “squishiness” of neutron star material for the first time. This extreme substance is so dense that a teaspoonful of it would have a mass of around a billion metric tons, and scientists don’t fully understand how it responds when squeezed, a property known as its “equation of state.” Measuring this property could give scientists a better understanding of the strange material. Although the results couldn’t pin down whether the neutron stars were squishy, some theories that predicted ultrasquishy neutron stars were ruled out.
* new measurement from the collision indicates that distantly separated galaxies are spreading apart at about 70 kilometers per second for each megaparsec between them
* At least 28 Jupiter masses’ worth of material was converted into energy via E = mc2. We’ve never seen neutron star-neutron star mergers in gravitational waves before. In black hole-black hole systems of equivalent mass, up to 5% of the total mass gets converted into energy. In neutron star systems, its expected to be less, because the collision occurs between nuclei, not between singularities; the two masses can’t get as close. Still, at least 1% of the total mass was converted into pure energy via Einstein’s mass-energy equivalence.

Regular observation of such stellar collisions will reveal a lot about physics, space, time and astronomy.

Over the coming years, LIGO will get slightly more sensitive, Virgo will do better, and two additional LIGO-like detectors, KAGRA in Japan and LIGO-India, will come online. Instead of half a day, we may be soon talking about response times in a matter of minutes or even seconds.

The delay of around 11 hours from the merger to the first optical and infrared signatures isn’t due to physics, but due to our own instrumental limitations here. As our analysis techniques improve, and more events are discovered, we’ll learn exactly how long it takes before visible light signatures are created by neutron star-neutron star mergers.

To improve their measurements and understanding, scientists will have to spot many more neutron-star mergers. LIGO and Virgo are still being fine-tuned to increase their sensitivity. Harvard’s Edo Berger is optimistic. “It is clear that the rate of occurrence is somewhat higher than expected,” he said. “By 2020 I expect at least one to two of these every month. It will be tremendously exciting.”

Gamma Ray Bursters are detected every day. It is believed that the neutron star and blackhole collisions are the source of Gamma Ray Bursters. With systems that can detect far beyond 300 million light years then it could ultimately mean collision detection and observation nearly every day.

Interstellar object probes

We also just detected the first interstellar object. Improved observational capability could also enable frequent detection of interstellar objects passing through the solar system.

It is technologically feasible for 2.7 megawatt laser propulsion systems to be created and placed into space for the launching of small solar sail probes.


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