Fast radio bursts, or FRBs, remain a profound cosmic enigma, shrouded in uncertainty regarding their origins. These potent bursts of radio energy are imperceptible to the human eye but shine brilliantly through the lens of radio telescopes.
Recent research from the University of Tokyo has unveiled intriguing distinctions in the temporal and energetic characteristics of FRBs compared to solar flares, while drawing parallels with earthquakes. These findings support the hypothesis that FRBs may result from “starquakes” on the surface of neutron stars, unveiling a window into a realm of high-density matter and nuclear physics. This groundbreaking study has been published in the journal Monthly Notices of the Royal Astronomical Society.
The cosmos, a boundless expanse, conceals a multitude of riddles. While some dream of venturing into the great unknown, there’s a wealth of knowledge to be gleaned from the confines of our home planet. Thanks to technological strides, we can explore Mars’ terrain, marvel at Saturn’s majestic rings, and eavesdrop on cryptic signals from the far reaches of the universe.
Fast radio bursts are exceptional phenomena, emitting powerful, radio waves. Initially spotted in 2007, they traverse billions of light-years yet endure for mere fractions of a second. It’s estimated that, if our observation capabilities span the entire sky, up to 10,000 FRBs may manifest each day. While many FRBs seem isolated events, roughly 50 sources have been known to produce repetitive bursts.
The true cause of FRBs remains veiled in mystery, with theories ranging from extraterrestrial origins to emissions from neutron stars. These neutron stars arise from the cataclysmic collapse of supergiant stars, transforming into superdense cores measuring a mere 20–40 kilometers across. Magnetars, a subset of neutron stars with extraordinarily powerful magnetic fields, have been implicated in FRB emissions.
Professor Tomonori Totani from the Department of Astronomy at the Graduate School of Science commented, “It was theoretically considered that the surface of a magnetar could be experiencing a starquake, an energy release similar to earthquakes on Earth.” Recent advancements in observation have enabled the detection of thousands more FRBs, offering an opportunity to scrutinize the available data sets for correlations between FRBs, earthquakes, and solar flares.
Prior investigations primarily concentrated on the distribution of time intervals between successive FRB bursts. However, Totani and graduate student Yuya Tsuzuki adopted a different approach. They examined the correlation across two-dimensional space, analyzing the time and emitted energy of nearly 7,000 bursts from three distinct repeater FRB sources. The same method was applied to scrutinize the time-energy interplay of earthquakes (utilizing Japanese data) and solar flares (employing records from the Hinode international sun study mission), enabling a comparative analysis of these phenomena.
In a surprising turn, the research demonstrated a striking resemblance between FRBs and earthquake data but displayed distinct differences when compared to solar flares. Totani elaborated, “The results show notable similarities between FRBs and earthquakes in the following ways: First, the probability of an aftershock occurring for a single event is 10–50%; second, the aftershock occurrence rate decreases with time, as a power of time; third, the aftershock rate is always constant even if the FRB-earthquake activity (mean rate) changes significantly; and fourth, there is no correlation between the energies of the main shock and its aftershock.”
These findings strongly suggest the presence of a solid crust on neutron stars’ surfaces and propose that sudden starquakes occurring on these crusts unleash massive energy, which we perceive as FRBs. The research team intends to persist in analyzing new FRB data to ascertain the universality of these observed similarities. As Totani stated, “By studying starquakes on distant ultradense stars, which are completely different environments from Earth, we may gain new insights into earthquakes.”
The interior of a neutron star stands as one of the most densely packed regions in the universe, akin to the heart of an atomic nucleus. Starquakes within neutron stars offer a gateway to exploring the intricacies of high-density matter and the fundamental principles of nuclear physics.
Source: University of Tokyo