2024-11-01 Abstract
Title: Statistical Insights into Hidden Repetition and Correlation in Fast Radio Bursts
Speaker: Shotaro Yamasaki (NCHU)
Date: November 1 at 14:30
Location: R521, General Building II
Abstract:
Fast Radio Bursts (FRBs) are brief, bright, cosmological radio flashes of mysterious origin. With global surveys, we now have around 1,000 detected FRB sources and 10,000 bursts from well-known repeaters, making it the right time to dive into FRB statistics. In this talk, I will present statistical analyses that reveal hidden repetition properties and correlations in FRB burst time series. The first half of my talk focuses on our recent work on FRB repetition using CHIME survey data. Although only a few percentage of FRBs are confirmed repeaters, one of the biggest questions remains: how much fraction of FRBs repeat? By analyzing and modeling the time evolution of source counts from uniform (about 600) CHIME samples of repeaters and non-repeaters, we found that over 50% of apparent non-repeaters are actually repeaters with low rates (~1 burst per 3,000 hours). This suggests a much higher repeater prevalence than previously thought, challenging current FRB models. In the second half of my talk, I will present our preliminary correlation function analysis of nearly 4,500 bursts from three active repeaters. This large dataset allows us to explore hidden correlations between burst occurrence times and other properties. We find evidence of a universal time-frequency correlation between burst pairs at short time separations (<0.1s). Remarkably, aftershocks tend to have lower peak frequencies than main bursts. This downward frequency shift is a new phenomenon that could provide valuable insights for distinguishing between different FRB models and deepen our understanding of this enigmatic burst phenomenon.