An analysis of the time-frequency structure of several bursts from FRB121102 detected with MeerKAT

Abstract

We present a detailed study of the complex time-frequency structure of a sample of previously reported bursts of FRB 121102 detected with the MeerKAT telescope in September 2019. The wide contiguous bandwidth of these observations have revealed a complex bifurcating structure in some bursts at $1250$ MHz. When de-dispersed to their structure-optimised dispersion measures, two of the bursts show a clear deviation from the cold plasma dispersion relationship below $1250$ MHz. We find a differential dispersion measure of $\sim 1-2$ pc cm${}^{-3}$ between the lower and higher frequency regions of each burst. We investigate the possibility of plasma lensing by Gaussian lenses of $\sim 10$ AU in the host galaxy, and demonstrate that they can qualitatively produce some of the observed burst morphologies. Other possible causes for the observed frequency dependence, such as Faraday delay, are also discussed. Unresolved sub-components in the bursts, however, may have led to an incorrect DM determination. We hence advise exercising caution when considering bursts in isolation. We analyse the presence of two apparent burst pairs. One of these pairs is a potential example of upward frequency drift. The possibility that burst pairs are echoes is also discussed. The average structure-optimised dispersion measure is found to be $563.5\pm 0.2(\text{sys})\pm 0.8(\text{stat})$ pc cm${}^{-3}$ $-$ consistent with the values reported in 2018. We use two independent methods to determine the structure-optimised dispersion measure of the bursts: the DM_phase algorithm and autocorrelation functions. The latter $-$ originally developed for pulsar analysis $-$ is applied to FRBs for the first time in this paper.

13 pages, 12 figures. Accepted for publication in MNRAS

References in corpus (30)

• A bright millisecond radio burst of extragalactic origin
• The direct localization of a fast radio burst and its host
• The Host Galaxy and Redshift of the Repeating Fast Radio Burst FRB 121102
• Fast Radio Burst Discovered in the Arecibo Pulsar ALFA Survey
• Fast radio bursts as synchrotron maser emission from decelerating relativistic blast waves
• A repeating fast radio burst source localised to a nearby spiral galaxy
• The Repeating Fast Radio Burst FRB 121102 as Seen on Milliarcsecond Angular Scales
• A Second Source of Repeating Fast Radio Bursts
• Possible periodic activity in the repeating FRB 121102
• Nine New Repeating Fast Radio Burst Sources from CHIME/FRB
• A Multi-telescope Campaign on FRB 121102: Implications for the FRB Population
• Repeating behaviour of FRB 121102: periodicity, waiting times and energy distribution
• A sample of low energy bursts from FRB 121102
• FRB 121102 is coincident with a star forming region in its host galaxy
• Implications of a "Fast Radio Burst" from a Galactic Magnetar
• High time resolution and polarisation properties of ASKAP-localised fast radio bursts
• A search for optical bursts from the repeating fast radio burst FRB 121102
• On the Time-Frequency Downward Drifting of Repeating Fast Radio Bursts
• Detection of Repeating FRB 180916.J0158+65 Down to Frequencies of 300 MHz
• Dispersion Measure Variation of Repeating Fast Radio Burst Sources
• Simultaneous multi-telescope observations of FRB 121102
• Large magnetic field variations towards the Galactic Centre magnetar, PSR J1745-2900
• Faraday conversion and magneto-ionic variations in Fast Radio Bursts
• On the magnetospheric origin of Repeating Fast Radio Bursts
• A simple relationship for the spectro-temporal structure of bursts from FRB 121102
• Detection of 15 bursts from FRB 180916.J0158+65 with the uGMRT
• Evidence of a shared spectro-temporal law between sources of repeating fast radio bursts
• H$\alpha$ intensity map of the repeating fast radio burst FRB 121102 host galaxy from Subaru/Kyoto 3DII AO-assisted optical integral-field spectroscopy
• Scintillation can explain the spectral structure of the bright radio burst from SGR 1935+2154
• Propagation effects in the FRB 20121102A spectra

Cited by in corpus (21)

• FAST observations of an extremely active episode of FRB 20201124A: I. Burst morphology
• Magnetospheric curvature radiation by bunches as emission mechanism for repeating fast radio bursts
• Arecibo observations of a burst storm from FRB 20121102A in 2016
• Circularly polarized radio emission from the repeating fast radio burst source FRB 20201124A
• Comprehensive analysis of a dense sample of FRB 121102 bursts
• Binary comb models for FRB 121102
• Spectropolarimetric variability in the repeating fast radio burst source FRB 20180301A
• A sample of Fast Radio Bursts discovered and localised with MeerTRAP at the MeerKAT telescope
• Burst properties of the highly active FRB 20201124A using uGMRT
• A Nançay Radio Telescope study of the hyperactive repeating FRB 20220912A
• A highly magnetized long-period radio transient exhibiting unusual emission features
• Narrow spectra of repeating fast radio bursts: A magnetospheric origin
• The Statistical Polarization Properties of Coherent Curvature Radiation by Bunches: Application to Fast Radio Burst Repeaters
• Plasma lensing near the eclipses of the Black Widow pulsar B1957+20
• Statistical properties and lensing effect on the repeating fast radio burst FRB 180916.J0158+65
• The Multiple Images of the Plasma Lensing FRB
• An activity transition in FRB 20201124A: methodological rigor, detection of frequency-dependent cessation, and a geometric magnetar model
• Comprehensive analysis of the Apertif Fast Radio Burst sample: similarities with young, energetic neutron stars
• A LOFAR sample of luminous compact sources coincident with nearby dwarf galaxies
• Observational effects of banded repeating FRBs
• Detection of Partial Coherence due to Multipath Propagation for FRB 20220413B with CHIME/FRB