Long-term monitoring of repeating FRB 20220912A with the uGMRT at low radio frequencies

TL;DR

This study presents a two-year monitoring of the hyperactive repeating FRB 20220912A using uGMRT, revealing sustained high activity, consistent energy distribution features with other repeaters, and supporting young magnetar progenitor models.

Contribution

It provides the first long-term low-frequency observational campaign of FRB 20220912A, demonstrating persistent activity and energy distribution characteristics similar to other known repeaters.

Findings

Detected 643 bursts over two years in 300-750 MHz range.

Sustained active phase for over 500 days with activity modulations.

Energy distributions show a break and are consistent across frequencies and time.

Abstract

Some repeating FRBs exhibit occasional extreme repetition rates, but very few show a sustained high activity level. One such hyperactive repeater is FRB 20220912A, which was discovered by CHIME/FRB Collaboration on 2022 September 12. Here, we present results from a long-term monitoring campaign of FRB 20220912A using the upgraded Giant Metrewave Radio Telescope (uGMRT) in the frequency range from 300 to 750 MHz. Over the course of nearly two years, we detected a total of 643 bursts in this frequency range. The source exhibited extreme activity for a few months after its discovery and sustained its active phase for over 500 days, with unsystematic modulations in the activity during this phase. The cumulative energy distributions in both bands show a break, consistent with other active repeaters like FRB 20121102A, FRB 202011124A, etc., suggesting common underlying emission mechanisms. Moreover, we show that the energy distribution shape for FRB 20220912A remains broadly same across a large range of frequencies and over time. Overall, the extended high activity, estimated total energy output, persistent power-law tails in the energy distributions, and the lack of detectable short timescale periodicity favor progenitor models invoking young dynamic magnetars, potentially emitting pulses across large rotation phase ranges.