Giant radio pulses in the magnetar XTE J1810-197 detected with the IAR's telescopes

Artikel i vetenskaplig tidskrift, 2026

Context. XTE J1810-197 is one of the six magnetars that exhibit radio emission, sometimes visible only during periods of increased activity or outbursts. XTE J1810-197 underwent its latest outburst in December 2018. Aims. We analyzed the population of single pulses of XTE J1810-197 in radio, characterized its timing properties, and explored the potential connection between magnetars and fast radio bursts (FRBs). Methods. We observed XTE J1810-197 between 29 September 2022 and 14 July 2023 with the radio telescopes at the Argentine Institute of Radioastronomy (IAR). We searched for single pulses in time series at a dispersion measure (DM) range of 100-400 pc cm(-3), with a signal-to-noise ratio (S/N) threshold of 8. We folded each observation to obtain an integrated pulse profile. We also analyzed archival X-ray observations of the MAXI instrument from the same period, and studied the flux evolution and the magnetar's activity. Results. We found 249 giant pulses (GPs) at a DM mean value of 178.8 +/- 0.1 pc cm(-3). We measured peak flux densities up to 119 Jy, and fluences up to 58 Jy ms. We fitted a power-law distribution to the flux density, obtaining an index of -4.0 +/- 0.3. We observed a maximum rate of approximately 15 pulses per hour on 20 February 2023, followed by an abrupt disappearance of transient radio emission, indicating a transition to a less active state. The brightest single pulses are limited to similar to 2% of the rotational phase and have similar fluence values to the reported intermediate FRB-like bursts of SGR 1935+2154. No significant X-ray activity in the MAXI data was detected during the radio observing period. Conclusions. This is the first study of single radio pulses of a magnetar using IAR data, showing the potential of the upgraded telescopes for investigating the transient radio sky. The properties of the single pulses detected here show the magnetar transient nature and capability to emit high-luminosity pulses. We compared the detected emission to FRB-like bursts and single pulses emitted by SGR 1935+2154. Even though the mechanism producing all the events should be coherent, the luminosity of the events, features on the dynamic spectra, and the difference between being phase confined or not, indicate that XTE J1810-197 presents GP emission, while SGR 1935+2154 only shows normal single pulses or FRB bursts. This could indicate that the conditions for producing each type of event differ.