The concept has already been proven by the LISA Pathfinder mission, which used only a spacecraft and two mirrors to…
The concept has already been proven by the LISA Pathfinder mission, which used only a spacecraft and two mirrors to test the technology behind the larger LISA endeavor, “said Larson. The mission’s goal was to determine whether changes between the two mirrors could be measured to the precision necessary for LISA to detect gravity waves. “It was hugely successful,” he says. “We exceeded what LISA needed to do, so we are very excited. It was a huge boost for us. And so, that’s really a lot of driving, along with the LIGO detections, it really made everyone push full steam ahead right now. ”
LISA will detect gravity waves in the range of 0.1 mHz and 1 Hz; LIGO works as a comparison with the frequency range 1
0 to 1000 Hz. Just like light has several different wavelengths or frequencies, and each type of light (like optical, infrared and x-ray) tells astronomers something different, gravitational waves span a variety of frequencies as well. LISA will be able to detect binaries that spread gravitational waves in wider lanes and with heavier masses than LIGO, open a new window on the universe to study objects like white dwarf binaries and super massive black holes. As soon as it is turned on, LISA will discover a “hum” of sources in all directions, giving researchers a treasure chest of data that will highlight many new and different aspects of the universe we live in.
LISA is currently in Phase A, says Larson, which means that entrepreneurs have looked at what the researchers want to do and come back in about one and a half years of design on how to achieve it. When these patterns have been left, he says, the project will choose one and move forward. LISA is spearheaded by the European Space Agency (ESA), with NASA serving as a junior partner in the mission.
If LISA will discover so many sources at once, how should astronomers ever distinguish them? It’s a bit, says Larson in his conversation, like how to pick out individual voices in a room during a party. My background noise allows you to easily focus on the conversation you have because it’s happening nearby. Astronomers will use several techniques to do the same, isolating signals to the background to pinpoint a certain source of gravity waves.
One of these techniques is based on the Doppler effect. Think of a pair of white dwarfs or white dwarf neutron stars that circle and emit gravity waves. As the Earth – and LISA – circle the sun, it will come closer and further from the couple. It will cause the pitch to fluctuate, higher as we get closer and lower as we get longer. That emphasis will allow astronomers to determine where in the sky the binary is located, which helps them to map the many, many white dwarf binaries that are expected to baptize the Milky Way. (White dwarfs are the star remnants of sun-like and smaller stars, which are common.)
Larson’s team also expects to hear super-massive black holes in the merging of galaxies collide. The mergers will lead to a sudden high surge in gravity waves – a characteristic “chirp” that should be quite obvious to the white dwarf background. In that case, he says it’s like picking out a very loud person in the room, as you can always hear no matter where you are.