Recent publications by SFU Cosmology Group members are listed on Preprints Page.
Simulating the Big Bang
The idea of inflation (a period of rapid quasi-exponential expansion of the Universe) neatly solves several issues in cosmology. While the Universe is inflating, its contents is cold. Eventually, inflation ends and the field driving the inflation decays, depositing energy into high-energy particles. This process, known as reheating, starts the hot big bang as we know it, and could allow a glimpse of physics at energies we know very little about. Andrei Frolov (SFU) is investigating how reheating have happened. In his work, he uses 3D computer simulations to gain insight into field dynamics and provide quantitative predictions for different models.
Origins of Cosmic Acceleration
The cosmic acceleration could be caused by some type of repulsive Dark Energy or be a manifestation of Gravity obeying different laws on largest scales. Levon Pogosian (SFU) works on developing tests of Dark Energy that will maximally utilize the information contained in the data. He also studies some of the models of modified gravity with the focus on their predictions for the clustering of cosmic matter. Future telescopes will be able to track the evolution of clustering back in time. His research involves understanding the capabilities of planned and proposed observations and making detailed forecasts of the extent to which they will help us be distinguish between different theories.
Fundamental Physics from CMB
The Cosmic Microwave Background (CMB) radiation is essentially a snapshot of our Universe at the age of 400,000 years and bears signatures of events that happened before and after the snapshot was taken. Andrei Frolov (SFU) is a member of Planck and Simons Observatory, and works both on data analysis for those experiments as well as constraining models of inflation and reheating in the early universe with observations. Levon Pogosian (SFU) uses the CMB data to gain insight into the fundamental physics in the early and late universe. For example, looking for signatures of cosmic strings in the CMB can lead to constraints on Brane Inflation, which is a working example of how inflation can be realized within the framework of String Theory -- a leading candidate for a fundamental theory of all particle interactions.
Gravitational Waves
Gravitational waves are predicted by Einstein's General Relativity. When observed, they will open a totally new window into the Universe we live in. Emitted in violent astrophysical events, or perhaps generated in phase transitions in the early Universe, they can travel enormous distances through anything -- with no absorption or distortion of the signal carried. However, they are weak and extremely hard to detect. Andrei Frolov (SFU) works both on practical signal processing aspects of gravitational wave detectors (designing filters to optimize separation of signal from noise) and theoretical studies of possible gravitational wave sources.
Black Holes and Accretion Disks
Black holes have gravitational pull so strong that even light cannot escape from within them. They are both most extreme and most simple objects in General Relativity, and are an interesting place to look for changes when one studies modified theories of gravity. While you cannot see black holes directly as no light is coming out, a lot of gravitational binding energy is released when matter falls into them, usually making them quite bright X-ray sources. Both spectral and timing observations of black holes are available, in particular in accreting X-ray binary systems which show luminosity modulation at a number of characteristic frequencies. Andrei Frolov (SFU) is interested in all aspects of black hole physics.
Topological Defects
Topological defects, such as magnetic monopoles, cosmic strings and domain walls, are observed in condensed matter systems and may have been formed during phase transitions at the early stages in the history of the universe. Levon Pogosian and Tanmay Vachaspati (CWRU) studied monopoles and domain walls, and their interactions, in the context of grad unified theories (GUTs). They have found novel types of domain wall solutions in systems which have a large continuous symmetry in addition to a broken discrete symmetry. What is remarkable about them is that the symmetry inside their cores is lower than that of the vacuum outside.
Modified by Andrei Frolov <frolov@sfu.ca> on 2023-05-19