In 2015, the Laser Interferometer Gravitational-wave Observatory (LIGO) made a groundbreaking discovery by detecting gravitational waves for the first time. This discovery, predicted by Einstein’s Theory of General Relativity, has revolutionized the field of astronomy and allowed scientists to study the mergers of massive objects in space. With the introduction of new observatories like the Laser Interferometer Space Antenna (LISA), this field is expected to advance even further in the coming years.
As part of their planning for the future, the European Space Agency (ESA) is considering several mission themes for 2050, including GW astronomy. A team of researchers from the ESA’s Mission Analysis Section and the University of Glasgow has proposed a new concept called LISAmax, which builds on LISA and could potentially improve GW sensitivity by two orders of magnitude. The team, led by Dr. Waldemar Martens and including Michael Khan and Dr. Jean-Baptiste Bayle, has published their findings online and is awaiting peer review in the journal Classical and Quantum Gravity.
Since the historic detection of gravitational waves by LIGO in 2015, researchers have made significant progress in detecting different types of GW events. This has been made possible through the efforts of observatories such as Virgo in Italy and KAGRA in Japan, which have joined forces with LIGO to form the LVK Collaboration. With improved sensitivity and upgrades, these observatories have detected a greater number of GW events and have been able to trace some of them back to their origins.
According to Dr. Martens, the detection of gravitational waves has opened up new avenues for astronomy research. However, future progress depends on space-based observatories, as Earth-based detectors are limited in their sensitivity to certain sources. For instance, super-massive black holes that exist in the centers of galaxies produce gravitational waves that are beyond the sensitive range of current detectors.
To detect these sources, an observatory like LISA with an arm length of 2.5 million km is necessary. So far, GW events caused by binary black holes and neutron stars have been detected, but many other sources are still unexplored. Detecting these sources could help us gain a better understanding of the Universe, including the production of primordial gravitational waves during the early moments after the Big Bang. To achieve this, detectors with higher sensitivity and different frequency bands are being considered for future missions like Voyage 2050.
The European Space Agency’s Scientific Program is a crucial and mandatory initiative that all member states must participate in. This program aims to provide a long-term funding horizon that allows member states to plan their priorities in advance and offer the European scientific community a clear vision of which research areas merit investment and development. Planning cycles, each lasting approximately 20 years, have been used since the 1980s to prepare ambitious space missions.
The first cycle, Horizon 2000, led to several missions between the mid-1990s and the early 21st century, including the Solar and Heliospheric Observatory (SOHO), Cluster, Rosetta, XMM-Newton, and Herschel. The Cosmic Vision cycle was launched in 2005, and its mission proposals will be realized between 2015 and 2025. This cycle paved the way for the recent launches of the JUpiter ICy moons Explorer (JUICE) and the Advanced Telescope for High Energy Astrophysics (ATHENA) X-ray observatory, as well as the LISA mission planned for launch by the 2030s.
The most recent cycle, Voyage 2050, was initiated to choose scientific properties to follow up on the ATHENA and LISA missions. Although these missions will be game-changing, Dr. Martens and his colleagues propose enhancing the LISA mission further with the concept of LISAmax. LISAmax is designed to detect GWs at even lower frequencies than LISA can. This requires increasing the laser arms of the detector to be sensitive to these frequencies. LISAmax spacecraft will be placed close to the triangular Lagrange points in the sun-Earth system, giving the detector an arm length of 259 million km. This makes LISAmax sensitive to GWs in the micro-Hertz band, opening a new window for GW astronomy.
The European Space Agency’s (ESA) Scientific Program is the mandatory program that all member states must contribute to, and its planning cycles aim to provide a long-term funding horizon for the European scientific community. The most recent planning cycle, Voyage 2050, was initiated to select scientific properties that will follow up on previous missions, including ATHENA and LISA.
Dr. Martens and his colleagues propose a new concept called LISAmax, which aims to enhance the capabilities of the LISA mission by detecting gravitational waves (GWs) at even lower frequencies. This could allow for the detection of more GW events and tracing them back to their sources, while also providing new insights into the laws of physics and the interiors of extreme objects.
The proposal for LISAmax is one of several GW concepts submitted to the ESA for the Voyage 2050 program, including a space-based interferometer, observations in the decihertz range, and high-angular astronomy. The program also aims to explore the physics of the early universe by examining the GWs created during the inflationary epoch.
Through these ambitious missions and proposals, the ESA hopes to expand the range of GW events that can be detected, deepen our understanding of the universe, and provide a clear vision of what research areas deserve investment and development for the European scientific community.
Source: Universe Today
