Multimessenger Astrophysics: Solving the Puzzle of Space

Multimessenger Astrophysics: Solving the Puzzle of Space

Date Published: April 20, 2019
Author: Zachary Savitsky

Astronomical events millions of lightyears away from Earth teach humanity about the history of the universe and provide new insights into unexplored properties of matter.

“The field of astrophysics has two key components. It helps us discover what is happening in the universe, and it uses astrophysical objects as laboratories to learn more about the fundamental laws of nature,” said Imre Bartos, researcher and professor of astrophysics at the University of Florida.

For humanity to learn anything from these astrophysical events, there first must be a way to detect them. Traditionally, we have relied on various wavelengths in the electromagnetic spectrum, like visible light and radio waves, to gather information about cosmic events.

However, in the past few decades, multiple new sources of information have emerged to give a new perspective on what is happening in the universe. Not only do these “messengers” provide new ways of receiving information from distant events, but they actually provide different information that adds to our understanding.

“Most of my work deals with what we call multimessenger astronomy. Essentially, the goal of multimessenger astronomy is to try to understand cosmic events by collecting information from these different channels and analyzing them together to learn more than if we just studied one particular messenger,” said Bartos.

Two of the most recently discovered cosmic messengers are neutrinos and gravitational waves, both of which UF researchers, including Bartos, played key roles in discovering and testing.

One of the byproducts of high-speed particle interaction like that which occurs in the center of the sun is a group of tiny particles called neutrinos. Neutrinos are considered weakly interacting particles, meaning that they pass through space without being significantly affected by matter, making them very difficult to detect.

An international group of physicists devised a $279 million neutrino detector called IceCube, which resides 2,450 meters below the surface of the South Pole in Antarctica, according to IceCube’s home page. This seven-year construction concluded in 2011, and it has helped physicists learn information about distant cosmic events.

“The problem is that all we really get from one neutrino is its direction and energy, which is usually not enough information to tell how far away the source was,” said Bartos.

However, an even more recent discovery has provided that missing information. Until three years ago, gravitational waves, or ripples in space-time, were simply predictions from Einstein’s equations for general relativity.

In 2015, though, when the Laser Interferometer Gravitational-wave Observatory (LIGO) detected the collision of two black holes billions of light years away, that theory became reality. As it turns out, gravitational waves stretch and squeeze space-time in the form of a wave function stemming from these major astronomical events.

“Encoded in any wave function are frequency, time and amplitude. This waveform tells us everything else we needed to know about where these signals came from,” said Bartos.

Each type of cosmic messenger, from radio waves to gravitational waves, adds a new piece to the puzzle. When solved, this puzzle provides a picture of extreme cosmic events that help explain the fundamental laws of nature that govern our own planet.

“This is why multimessenger astrophysics is so important. You can combine all of this information from these different messengers to learn the comprehensive picture,” said Bartos.