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Magnetar outburst deciphered under the lens of NICER

Presentation #110.81 in the session “Stellar/Compact (Poster)”.

Published onApr 01, 2022
Magnetar outburst deciphered under the lens of NICER

Magnetars, isolated neutron stars with magnetic field strengths typically ~1014 G, exhibit distinctive months-long outbursts. During these active episodes, magnetars quiescent X-ray fluxes can increase by as many as three orders of magnitude, while displaying strong bursting activity, drastic spectral changes to the surface thermal and magnetospheric emission, as well as strong temporal variability in the form of timing noise, glitch activity, and altered pulse shape. Given these variability patterns, outburst epochs are thus distinctly revealing of a magnetar’s highly dynamic magnetosphere and its interplay with the surface thermal emission. In this talk, I will present the spectro-temporal properties of the X-ray emission from the magnetar SGR 1830-0645 during its 2020 outburst. Daily NICER observations resolved, for the first time, the manner in which the outburst decayed, revealing, aside from a shrinking hot spot, a pulse-peak migration that simplifies the initial triple-peaked profile to almost single-peaked 37 days later. I will discuss two possibilities to the observed outburst evolution, demonstrating that these novel datasets paint a vivid picture of the dynamics associated with magnetar outbursts, yet it also highlights the need for a more generic theoretical picture where magnetosphere and the poorly known crust must be considered in tandem.

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