# Distinct properties of the radio burst emission from the magnetar XTE J1810-197

## TL;DR

This study investigates the radio burst emission properties of magnetar XTE J1810-197 during its recent outburst, revealing unique spectral structures and burst characteristics that may link to fast radio bursts.

## Contribution

It provides the first detailed analysis of low-frequency radio bursts from XTE J1810-197 during an outburst, highlighting spectral structures and burst widths.

## Key findings

- Bursts have intrinsic widths of 0.5-0.7 ms.
- Spectral structures are observed that are not due to interstellar effects.
- Spectral structures evolve over the outburst phases.

## Abstract

XTE J1810-197 (PSR J1809-1943) was the first ever magnetar which was found to emit transient radio emission. It has recently undergone another radio and high-energy outburst. This is only the second radio outburst that has been observed from this source. We observed J1810-197 soon after its recent radio outburst at low radio frequencies using the Giant Metrewave Radio Telescope. We present the 650 MHz flux density evolution of the source in the early phases of the outburst, and its radio spectrum down to frequencies as low as 300 MHz. The magnetar also exhibits radio emission in the form of strong, narrow bursts. We show that the bursts have a characteristic intrinsic width of the order of 0.5-0.7 ms, and discuss their properties in the context of giant pulses and giant micropulses from other pulsars. We also show that the bursts exhibit spectral structures which cannot be explained by interstellar propagation effects. These structures might indicate a phenomenological link with the repeating fast radio bursts which also show interesting, more detailed frequency structures. While the spectral structures are particularly noticeable in the early phases of the outburst, these seem to be less prominent as well as less frequent in the later phases, suggesting an evolution of the underlying cause of these spectral structures.