Low-energy Radio Bursts from Magnetar XTE J1810$-$197: Implications for Fast Radio Bursts

TL;DR

This study analyzes over 97,000 radio bursts from magnetar XTE J1810$-$197 over 4.5 years, revealing its potential to produce FRB-like giant pulses and providing insights into their emission mechanisms.

Contribution

It offers the first extensive analysis of low-energy bursts from XTE J1810$-$197, linking magnetar activity to FRB emission possibilities and characterizing their temporal and spectral properties.

Findings

Magnetar XTE J1810$-$197 emits bursts with energies comparable to FRBs.

The magnetar switches between pulsar-like and giant-pulse-like states.

Lack of periodicity in FRB bursts may be due to emission across wide spin phases.

Abstract

Magnetars are the leading candidate sources of fast radio bursts (FRBs). However, the observational probes of the connections between magnetars and FRBs are severely limited by the paucity of detection of highly energetic radio events from magnetars -- to date, only one radio burst as energetic as FRBs has been detected from a Galactic magnetar. Here, we present a detailed analysis of a large sample of low-energy bursts detected from the magnetar XTE J1810$-$197, and probe their implications for FRB emission from magnetars. We report detection of over 97000 bright radio pulses from 242 observations of the magnetar XTE J1810$-$197 over 4.5 years and two decades in frequency (300 MHz to 6.15 GHz), using the Giant Meterwave Radio Telescope and the Green Bank Telescope, after its recent outburst onset in December 2018. We present detailed analysis of the burst fluence distributions and their trends with time as well as frequency, and the waiting time distribution. We show that XTE J1810$-$197 rapidly switches between pulsar-like and giant-pulse-like emission states, and magnetars like XTE J1810$-$197 remain viable and likely emitters of FRBs, in the form of giant-pulses with energies comparable to FRBs. We also demonstrate that the lack of the detection of an underlying periodicity in the bursts from repeating FRBs might be caused by emission across a wide range of spin phases.