"Most upgrades have increased laser power," says Jolien Creighton, a professor at the University of Wisconsin Milwaukee and a member of the LIGO collaboration. "This has improved sensitivity." Each LIGO detector has a giant L-shape, and instruments are waiting for gravitational waves to distort and measure the length of each arm of the detector by letting lasers bounce along their length. Researchers are also researching the physical limits of the detector, which according to Creighton are limited by the principle of quantum uncertainty. To increase the sensitivity even further, the laser beam through the experiment "squeezing". "This puts him in an interesting quantum mechanical state that allows us to see the arm length of the detector," more precisely than before.
Virgo and KAGRA's additional detectors will allow researchers to more accurately triangulate sources in the sky The two LIGO detectors can manage alone. Jungfrau will be online throughout the next year of observation, while KAGRA is still operational but could join as early as autumn 201
The upgraded LIGO will look for the same events it has done before: collisions of two black holes, two neutron stars, or mixtures of both. Creighton says that he is personally excited about binary neutron stars, since these systems mostly have counterparts that can be observed simultaneously by traditional observatories, at wavelengths from visible to visible, to gamma rays. "Seeing more of them gives you more insight into the nature of gamma-ray bursts and the formation of elements of the universe," says Creighton. He points out that fusions can also teach astronomers how matter behaves when compressed more tightly than an atomic nucleus, a state that exists only in neutron stars. "We can investigate this by observing the interactions of neutron stars just before the merger. It is a basic nuclear physics laboratory in outer space. "
Creighton says he is confident that many more events can be seen in the collision of black holes, a phenomenon that LIGO has seen several times. "We hope to see a binary pair of a neutron star and a black hole," says Creighton, but since no one has ever seen one, it's hard to figure out how common or rare they are and what is the likelihood that LIGO will be discovered will be one next year. But LIGO will continue to look into the universe, "so that rare things should be observed," says Creighton.
Other possible objects that LIGO might spy on would be a supernova explosion or a fast-spinning neutron star. "If it's not perfectly symmetrical, that twisting distortion would create gravitational waves," says Creighton. The signal would be weak but constant. The longer LIGO looks, the more likely it is to find a source like this. Even more subtle would be a sky-wide, weak reverberation from the Big Bang, similar to the microwave background, which is present in radiation and the researchers suspect that it could exist in gravitational waves.
"There is always hope that we will do this See something completely unexpected," adds Creighton. "These are the things you can not predict in any way."
The upcoming run of LIGO will take about a year. At this time, further upgrades will be made for a year, and hopefully the cycle will start again from the beginning ready to witness even more spectacular and invisible events.