The Unique Formation and Evolution of Magnetars and Constraining Fast Radio Burst Progenitors with Polarization

Author: Sherman, Myles Bradford

Year: 2026

Degree: Dissertation (Ph.D.)

Advisor: Ravi, Vikram

Committee Members: Fuller, James; Harrison, Fiona A.; Bellan, Paul Murray; Cordes, James M.; Ravi, Vikram

Option: Physics

Abstract

Magnetars, the most highly magnetized subset of neutron stars, remain enigmatic in nature; while likely formed through Core-collapse Supernovae (CCSNe), the origin of their large (>10¹³ G) magnetic fields and relationship to radio pulsars are unclear. Beyond the wide variety of emission states observed in Galactic magnetars, including periodic short bursts, Giant Flares, and outbursts, magnetars are considered the leading candidates for the origins of multiple unidentified phenomena, such as Long Period Radio Transients (LPRTs) and extragalactic Fast Radio Bursts (FRBs). In this thesis, I use multi-wavelength data to explore the formation of magnetars, and investigate the origins and emission properties of FRBs and LPRTs.

Through an archival search of radio, optical, and infrared data, we identify two new candidates for magnetar-massive star binaries that have been disrupted by CCSNe. We find the CCSNe formation scenario requires a high progenitor merger rate(~70-80%) to explain the lack of such unbound systems, and suggests they may preferentially form from massive stellar mergers.

We then use the 64-antenna prototype Deep Synoptic Array (DSA-110) radio telescope to explore the polarization properties of FRBs. With a custom baseband analysis pipeline, we find that FRBs’ high (>70%) linear polarization closely resembles that of young (<100 kyr) Galactic pulsars, suggesting that they inhabit similar environments. This supports the magnetar scenario, as they have typical characteristic ages below <100 kyr. FRB rotation measures also indicate that FRB environments are more highly magnetized than those of typical Galactic pulsars.

To investigate the magnetar origin of LPRTs, Galactic events which have periods from minutes to hours and burst widths up to 30 seconds, I have implemented a real-time search for single-pulses between 0.134 - 160.8 seconds for the completed 96-antenna DSA-110. A pilot survey of the galactic plane (GP) region (>1.2 Jy flux limit at 25\sigma) places constraints on the White-Dwarf binary model while failing to rule-out the magnetar model, a result which supports the multiple-progenitor LPRT theory.

Looking ahead, we use population synthesis to predict that the next-generation DSA-2000 radio telescope will detect→ 23,000 new radio pulsars and radio magnetars with full polarization information. This sample will enable a more holistic view of magnetar evolution and their relationship to radio pulsars, FRBs, and LPRTs.