Publications

Recent Publications

2024

An X-Ray and Radio View of the 2022 Reactivation of the Magnetar SGR J1935+2154

Ibrahim, A. Y., et al.

The Astrophysical Journal, 965:87

We present X-ray and radio observations following SGR J1935+2154's October 2022 outburst. Using XMM-Newton and NuSTAR data, we found persistent emission well-described by a blackbody (kTBB ≈ 0.4 keV, RBB ≈ 1.9 km) plus power-law model up to 25 keV. We detected X-ray pulsations and measured a spin-down rate of Ṗ = 5.52×10−11 s s−1, 3.8 times larger than after its 2014 outburst. Despite 92.5 hours of radio monitoring with 25-32m telescopes, no radio bursts or pulsed emission were detected.

SGR J1935+2154 Magnetar
Spectra of the persistent emission of SGRJ1935. The 0.5-10 keV XMM-Newton/EPIC-pn and the 3-25 keV NuSTAR/FPMA spectra are jointly fit with an absorbed blackbody plus power-law model.
2023

Deep X-Ray and Radio Observations of the First Outburst of the Young Magnetar Swift J1818.0–1607

Ibrahim, A. Y., et al.

The Astrophysical Journal, 943:20

We present a long-term X-ray monitoring campaign of Swift J1818.0−1607, a very young radio-loud magnetar (P=1.36s, B≈3×1014G) using XMM-Newton, NuSTAR, and Swift, from its 2020 March outburst through 2021 October. The 1-10 keV spectrum is modeled with an absorbed blackbody (kTBB≈1.1 keV) showing a shrinking emitting region (0.6 to 0.2 km). We observed large torque variability and detected bright diffuse X-ray emission extending 50″-110″ around the source. VLA observations revealed a radio counterpart (4.38±0.05 mJy at 3 GHz) and a half-ring radio structure ~90″ west of the magnetar, potentially associated with its supernova remnant.

Swift J1818.0-1607 Magnetar
3 GHz VLA radio image of Swift J1818 and the surrounding diffuse emission.
2024

Long-term Study of the 2020 Magnetar-like Outburst of the Young Pulsar PSR J1846-0258 in Kes 75

R. Sathyaprakash, et al.

The Astrophysical Journal, 976:56

This study examines PSR J1846−0258, a young 327 ms radio-quiet pulsar with high rotational power (~8×1036 erg s-1) at the center of supernova remnant Kes 75. After 14 years of quiescence following its 2006 magnetar-like outburst, the source underwent a second outburst between May-June 2020. Our multi-telescope observations reveal the pulsed flux increased by a factor >6, with significant variability in the spin-down rate. We found evidence for oscillations in the frequency derivative with a 50-60 day timescale before returning to stable quiescence. As one of the rare high-magnetic-field pulsars showing both magnetar and radio pulsar characteristics, PSR J1846−0258 provides crucial insights into the emission mechanisms and evolutionary connections between these neutron star classes.