Moon's orbit proposed as a gravitational wave detector
Date:
March 17, 2022
Source:
Universitat Autonoma de Barcelona
Summary:
Researchers propose using the variations in distance between
the Earth and the Moon, which can be measured with a precision
of less than a centimeter, as a new gravitational wave detector
within a frequency range that current devices cannot detect. The
research could pave the way for the detection of signals from the
early universe.
FULL STORY ========================================================================== Researchers from the UAB, IFAE and University College London propose
using the variations in distance between the Earth and the Moon, which
can be measured with a precision of less than a centimeter, as a new gravitational wave detector within a frequency range that current devices cannot detect. The research, which could pave the way for the detection
of signals from the early universe, was published recently in Physical
Review Letters.
========================================================================== Gravitational waves, predicted by Albert Einstein at the start of the 20th century and detected for the first time in 2015, are the new messengers of
the most violent processes taking place in the universe. The gravitational
wave detectors scan different frequency ranges, similar to moving a dial
when tuning into a radio station. Nevertheless, there are frequencies
that are impossible to cover with current devices and which may harbour
signals that are fundamental to understanding the cosmos. One particular example can be seen in microhertz waves, which could have been produced
at the dawn of our universe, and are practically invisible to even the
most advanced technology available today.
In an article recently published in the journal Physical Review Letters, researchers Diego Blas from the Department of Physics at the Universitat Auto`noma de Barcelona (UAB) and the Institut de Fi'sica d'Altes Energies (IFAE), and Alexander Jenkins from the University College London (UCL),
point out that a natural gravitational wave detector exists in our
immediate environment: the Earth-Moon System. The gravitational waves constantly hitting this system generate tiny deviations in the Moon's
orbit. Although these deviations are minute, Blas and Jenkins plan on
taking advantage of the fact that the Moon's exact position is known
with an error of at most one centimeter, thanks to the use of lasers
sent from different observatories which are continuously reflected upon
mirrors left on the surface of the Moon by the Apollo space mission and
others. This incredible precision, with an error of one billionth of a
part at most, is what may allow a small disturbance caused by ancient gravitational waves to be detected. The Moon's orbit lasts approximately
28 days, which translates into a particularly relevant sensitivity when
it comes to microhertz, the frequency range researchers are interested in.
Similarly, they also propose using the information other binary systems
in the universe may provide as gravitational wave detectors. This is
the case of pulsar binary systems distributed throughout the galaxy,
systems in which the pulsar's radiation beam allows obtaining the
orbit of these stars with incredible precision (with a precision of
one millionth). Given that these orbits last approximately 20 days, the
passing of gravitational waves in the microhertz frequency range affect
them particularly. Blas and Jenkins concluded that these systems could
also be potential detectors of these types of gravitational waves.
With these "natural detectors" in the microhertz frequency range, Blas
and Jenkins were able to propose a new form of studying gravitational
waves emitted by the distant universe. Specifically, those produced by
the possible presence of transitions in highly energetic phases of the
early universe, commonly seen in many models.
"What is most interesting perhaps is that this method complements future
ESA/ NASA missions, such as LISA, and observatories participating in
the Square Kilometer Array (SKA) project, to reach an almost total
coverage of the gravitational waves from the nanohertz (SKA) to the
centihertz (LIGO/VIRGO) frequency ranges. This coverage is vital to
obtaining a precise image of the evolution of the universe, as well as
its composition," Diego Blas explains.
"Covering the microhertz frequency range is a challenge, which
now may be feasible without the need of building new detectors, and
only observing the orbits of systems we already know. This connection
between fundamental aspects of the universe and more mundane objects is particularly fascinating and can eventually lead to the detection of the earliest signals we have ever seen, and thus change what we know about
the cosmos," he concludes.
========================================================================== Story Source: Materials provided by
Universitat_Autonoma_de_Barcelona. Note: Content may be edited for style
and length.
========================================================================== Journal Reference:
1. Diego Blas, Alexander C. Jenkins. Bridging the mHz Gap in the
Gravitational-Wave Landscape with Binary Resonances. Physical
Review Letters, 2022; 128 (10) DOI: 10.1103/PhysRevLett.128.101103 ==========================================================================
Link to news story:
https://www.sciencedaily.com/releases/2022/03/220317094755.htm
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