The cosmic microwave background radiation (CMB) is known as the "afterglow" of the Big Bang. According to a recent report on the website of the British journal Nature, the Cerro Toco Observatory, located at an altitude of 5300 meters in the Atacama Desert in northern Chile, will be completed in a few weeks. It will be capable of producing a more detailed "portrait" of the CMB.
The sensitivity of this observatory will be ten times that of the European Planck satellite. Joe Dunkley, a cosmologist at Princeton University and one of the main members of the observatory team, pointed out that it will provide astronomers with the best observations of the CMB to date and will search for the "faint traces" of gravitational waves originating from the Big Bang, thereby revealing the secrets of cosmic inflation.
The Simon's Observatory, seen here with its front-facing receiver, stands as the largest facility ever constructed for observing the cosmic microwave background (CMB). Image Source: University of Pennsylvania
Inflation Remains a Mystery
The Simon's Observatory, costing $109.5 million, is led by five U.S. universities and Lawrence Berkeley National Laboratory. One of its primary missions is to search for the gravitational wave signatures left in the CMB by the cosmic inflation, providing the first unequivocal evidence of cosmic inflation. In 2014, the "Background Imaging of Cosmic Extragalactic Polarization" (BICEP2) experiment team at the CMB observation site in Antarctica claimed to have detected inflationary features, only to later discover they were seeing galactic dust.
Cosmic inflation lasted an incredibly short time, during which the universe expanded exponentially. Scientists believe that during this period, quantum fluctuations on microscopic scales seeded the large-scale structures in the universe, including the distribution of galaxy clusters seen in the universe today.
Many cosmologists consider inflation the most reasonable mechanism for endowing the universe with its structure. However, the nature and characteristics of inflation remain a mystery. In light of this, scientists have proposed numerous theories predicting various features of the gravitational waves with different intensities.
Seeking Definitive Evidence of Cosmic Inflation
The Simon's Observatory comprises four telescope arrays. These include three 0.4-meter Small Aperture Telescopes (SAT) and one 6-meter Large Aperture Telescope (LAT). Together, they will map out subtle variations in the temperature of the CMB in every patch of the sky, as well as the preferred orientation of the radiation's electric field as it propagates through space.
The three SATs will focus on observing 20% of the southern sky, studying large-scale swirls in the polarization field of the CMB, with hopes of detecting the B-mode in the polarization maps, indicating a signal of cosmic inflation.
The LAT, on the other hand, will map out 40% of the sky with higher resolution, recording both the temperature fluctuations and polarization of the CMB. Cosmologists involved in the Planck mission and other CMB projects will be able to extract a wealth of information by mapping the intensity of these temperature fluctuations and the area they cover across the sky.
The data provided by the LAT will also help scientists detect signals of cosmic inflation within the low-resolution polarization images produced by smaller telescopes. Mark Devlin, a cosmologist at the University of Pennsylvania and co-director of the Simon's Observatory, explains that the data captured by the LAT is crucial for separating the B-mode from spurious signals generated by dust in the Milky Way. The experiment's sensitivity to polarization patterns will be six times greater than previous measurement methods.
Shouldering Multiple Missions
Searching for signals of cosmic inflation is just one of the goals of the Simon's Observatory. The team plans to extract more scientific information from the high-resolution CMB maps obtained from the observatory to study the effects on the CMB during its 13.8-billion-year journey through space before reaching Earth.
The CMB can be distorted due to the influence of massive galaxy clusters and dark matter gravity, a phenomenon known as gravitational lensing, with relevant data used to create 3D maps of these galaxy clusters. In a recent study, the Simon's team will reconstruct the gravitational lensing experienced by the CMB and determine how much of it was caused by cosmic neutrinos. This will enable the research team to calculate the mass of these particles.
Given that the LAT will rescan the same sky areas over the "course of a lifetime," it will also be able to track the movements of asteroids within the solar system and the activity of active galactic nuclei in other galaxies. Dunkley notes that they will be able to monitor the "behavior" of 20,000 or more active galactic nuclei, believed to be supermassive black holes with jets.
Reportedly, the observatory will operate in two rounds, each lasting about four years, during which the management team plans to spend $53 million on upgrades. Following the project's conclusion, the CMB-S4 project, led by the U.S. Department of Energy and the National Science Foundation, will "take over" to continue the hunt for cosmic inflation.
