Skip to main content
Type of talk
Seminar
Speaker
Mr Pulak Mohapatra, PhD student at NCRA
Affiliation
NCRA
Date and Time of Talk
Venue
Auditorium
Abstract
Fast Radio Bursts (FRBs) are bright, extragalactic, millisecond-duration bursts of unknown origin, with magnetars being the leading progenitor candidate. FRBs are broadly divided into two classes: Repeating and One-off (Non-repeating) FRBs. Whether these classes belong to the same population or represent distinct populations is a burning topic of discussion in the FRB community. The burst rate distributions as well as the host environment properties are roughly consistent across the classes. Moreover, the energy distributions for some of the repeating FRBs seem to match the One-offs at high energies, which suggests that the One-offs might represent the high energy tail of the entire FRB population. However, the plethora of morphological distinctions generally prevents establishing them as a single population. For example, statistically,
repeating FRBs have broader temporal widths and narrower spectral bandwidths compared to one-offs. Moreover, non-repeating FRBs happen to be brighter than repeating ones. Recently, a group of "atypical
repeaters" were identified with low activity rates exhibiting properties similar to one-off events. This gives rise to a hypothesis unifying the repeaters and non-repeaters that we have explored: potentially these morphological features are intrinsically linked to the source's activity level, suggesting a single unified population of FRBs whose morphology evolves as a function of burst rate.To probe this hypothesis, we utilize the 2nd CHIME catalog and find a significant correlation between the burst rate of repeating FRBs and various morphological parameters. Instead of using a standard correlation analysis used in the literature, we have used linear mixed models to look for any linear trend, respecting the natural hierarchical structure of the data. We observe that repeaters with lower burst rates generally display morphological features akin to non-repeaters, further strengthening our hypothesis. We find a positive correlation of burst rate with temporal width and negative correlation with spectral running (a proxy for spectral curvature), bandwidth and the peak flux density. We also explore rigorous statistical tests to validate this unifying hypothesis. We also see that given the uncertainty on the fits as well as the observational uncertainties on the non-repeaters, both the populations look consistent with each other. Our results suggest the physical mechanism responsible for one-off FRBs need not fundamentally differ from that of repeaters. Any proposed emission model must therefore account for morphological features varying as a function of burst rate, placing constraints on FRB emission mechanisms. Physically, these variations can be explained by a combination of beaming angle, beaming geometry as well as the alignment between the rotation and magnetic axis of the neutron star.
Email Speaker
pulakmohapatra02@gmail.com
About Speaker

Mr Pulak Mohapatra, PhD student at NCRA

Email Host
kuntal@aries.res.in
Host Name
Dr. Kuntal Mishra
Host Phone (ext/mob)
742