Evidence of young magnetars in massive binary embedded in a supernova remnant as sources of active fast radio bursts

TL;DR

The paper tackles the puzzle of diverse DM and RM variations in repeating FRBs with PRS associations by proposing a unified model: young magnetars in massive binaries are embedded in SNRs, and their winds, ejecta, and magnetar energy output shape the observed DM, RM, and PRS luminosities. The authors develop analytic expressions for DM and RM contributions from stellar winds and SNR ejecta, and test the framework by applying it to multiple FRB sources using MCMC fits to DM and RM histories; key results include a ~14-year age estimate for FRB 20190520B and a ~10-year age for FRB 20121102A, with RM/dm evolution explained by wind-SNR interactions. The findings suggest a continuum of environments and evolutionary stages, where younger systems have brighter PRSs and larger RM variations, while older systems show diminished MWN luminosity and stochastic DM/RM behavior dominated by wind effects. Overall, the work supports a unified FRB population in dynamic magnetized environments and highlights the role of binary companions and SNR evolution in driving FRB activity and its observable signatures.

Abstract

Fast radio bursts (FRBs) are intense pulses with unknown origins. A subclass of repeating FRBs show some common features, such as associated compact persistent radio sources (PRSs), high burst rates, and large host-galaxy dispersion measures (DMs). Meanwhile, they show diverse DM and rotation measure (RM) variations, which cannot be explained by current models. A unified model urgently needs to be established. Here we show the first evidence for a supernova remnant surrounding the FRB 20190520B source. We then demonstrate that the five active repeating FRB sources associated with PRSs can be understood within a single model in which central objects are young magnetars in massive binary systems embedded in supernova remnants. This model naturally predicts distinct variations of DM and RM for repeating FRBs. Crucially, young magnetar wind nebulae can generate bright PRSs. As a magnetar becomes older, the luminosity of a PRS will fade, which can naturally explain less-luminous PRSs for some active FRBs. Our results support a unified population of active FRBs in dynamic magnetized environments.

Figures (6)

• Figure 1: A schematic diagram of the unified model.a, A young magnetar-massive star binary embedded in a magnetar wind nebula and supernova remnant. FRBs are powered by the activity of the magnetar. Radio signals propagate through the stellar wind and supernova ejecta, which can caused DM and RM variations. The magnetar injects magnetic energy or rotational energy into the magnetar wind nebula generating synchrotron radiation, observed as the persistent radio source. b, Geometry of the collision between the stellar wind of massive star companion and the magnetar wind. The bow shock generated by the collision can power multi-band radiation, analog to high-mass gamma-ray binaries. In addition to the stellar wind, some Oe/Be stars can possess an equatorial decretion disk, which can contribute DM and RM.
• Figure 2: The fits of DM and RM variations for FRB 20190520B with the unified model.a, The temporal DM variation for FRB 20190520B. The red line shows the result of MCMC fit with the unified model. The observed DM value is shown as points Niu2022Anna-Thomas2023. b, The temporal RM variation for FRB 20190520B. The red line shows the result of MCMC fit with the unified model, in which both the SNR and stellar wind contribute significantly to the RM variation. The observed RM value is shown as points Niu2022Anna-Thomas2023.
• Figure 3: The fitting result for FRB 20121102A with the unified model.a, The temporal DM variation of FRB 20121102A. The red line shows the result of MCMC fit with the unified model. The observed DM value is shown as points 65Spitler2018Michilli2018Oostrum2020Li2021WangP2025Snelders2025. b, The red line shows the RM fit with the unified model. The points represent the observed RM Michilli2018Hilmarsson2021Plavin2022WangP2025.
• Figure 4: The RM fit of FRB 20190417A using the unified model. The RM variation is mainly contributed by the stellar wind. The points represent the observed RM variation $\Delta \rm RM_{obs}=RM_{obs}-RM_0$Feng2022Feng2025Moroianu2025, where RM$_0$ is constant RM contributed by other terms.
• Figure 5: Two-dimension posterior corner plot for the parameters of the unified model for FRB 20190520B. The histograms indicate the posterior probability of each parameter. The plots show the explored parameter space, with $1\sigma$ and $2\sigma$ contours.