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| The Milky Way contains approximately 150 observed globular clusters, such as M30, shown here, as imaged by the Hubble Space Telescope. Globular clusters are dense environments containing millions of stars packed tightly together. These clusters are efficient factories of gravitational wave sources that can be observed by detectors such as LIGO and the upcoming space-based observatory, LISA. A new Northwestern University study predicts approximately 50 binaries in the clusters will be detectable by LISA. These binary sources would contain all combinations of black hole, neutron star and white dwarf components. Photo: ESA/Hubble |
By Shubham Sharma, International Business Times - Business
etection of gravitational waves from distant corners of our galaxy and even beyond is critical for understanding the universe. Scientists have been using the Earth-bound Laser Interferometer Gravitational-Wave Observatory (LIGO) for capturing these signals and have successfully detected sources like colliding black holes or a pair of neutron stars these past few years.
However, in order to ramp-up the search and detect more of these events in less time, scientists will need an upgrade with enhanced sensitivity. This is where the Laser Interferometer Space Antenna (LISA) observatory, currently being developed by the European Space Agency and NASA, comes in.
LISA, when launched in 2034, will scour depths of cosmos from space and detect gravitational wave frequencies much lower than those detected by LIGO at present. In fact, according to a study from the Northwestern University in the United States, the observatory will be able to detect dozens of binaries or pairs of orbiting objects in distant globular clusters of our galaxy. This might include anything — from black hole pairs to neutron stars or components of white dwarfs.
The detection of these binaries in spherical clusters of old, gravitationally-bound stars holds importance as many of these sources might have different features than those observed in isolated regions, far from stellar clusters.
"LISA is sensitive to Milky Way systems and will expand the breadth of the gravitational wave spectrum, allowing us to explore different types of objects that aren't observable with LIGO," Kyle Kremer, the first author of the study, said in a statement.
Till now, some 150 globular clusters have been discovered in our galaxy and if the predictions made in the latest study are anything to go by, the upcoming observatory might detect one source of gravitational wave in every three of these clusters. The team behind the study also predicted the observatory will also detect eight black hole binaries in Andromeda galaxy, our closest galactic neighbor.
Knowing in advance what to expect from observatories and science experiments is critical to the success of the project. Astrophysicists across the globe proposed theoretical predictions for LIGO and now, Northwestern University researchers are doing the same for LISA.
"We do our computer simulations and analysis at the same time our colleagues are bending metal and building spaceships so that when LISA finally flies, we're all ready at the same time," Shane L. Larson, another author of the study, said in the statement. "This study is helping us understand what science is going to be contained in the LISA data." The group developed a tool for creating realistic computer models of fully evolved globular star clusters at the university’s Center for Interdisciplinary Exploration and Research in Astrophysics (CIERA) to make their predictions for LISA.
The study, "LISA Sources in Milky-Way Globular Clusters," was published May 11 in the journal Physical Review Letters.
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