English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

We report on the hard X-ray burst and the first ~100 days NICER monitoring ofthe soft X-ray temporal and spectral evolution of the newly-discovered magnetarSwift J1818.0-1607. The burst properties are typical of magnetars with aduration of $T_{90}=10\pm4$ ms and a temperature of $kT=8.4\pm0.7$ keV. The2--8 keV pulse shows a broad, single peak profile with a pulse fractionincreasing with time from 30% to 43%. The NICER observations reveal strongtiming noise with $\dot{\nu}$ varying erratically by a factor of 10, with anaverage long-term spin-down rate of$\dot{\nu}=(-2.48\pm0.03)\times10^{-11}$~s$^{-2}$, implying an equatorialsurface magnetic field of $2.5\times10^{14}$ G and a young characteristic ageof $\sim$470 yr. We detect a large spin-up glitch at MJD 58928.56 followed by acandidate spin-down glitch at MJD 58934.81, with no accompanying fluxenhancements. The persistent soft X-ray spectrum of Swift~J1818.0-1607 can bemodeled as an absorbed blackbody with a temperature of ~1 keV. Its flux decayedby ~60% while the modeled emitting area decreased by ~30% over the NICERobserving campaign. This decrease, coupled with the increase in the pulsefraction points to a shrinking hot spot on the neutron star surface. Assuming adistance of 6.5 kpc, we measure a peak X-ray luminosity of $1.9\times10^{35}$erg/s, lower than its spin-down luminosity of $7.2\times10^{35}$ erg/s. Itsquiescent thermal luminosity is $\lesssim 1.7\times10^{34}$ erg/s, lower thanthose of canonical young magnetars. We conclude that Swift J1818.0-1607 is animportant link between regular magnetars and high magnetic field rotationpowered pulsars.

NICER Observation of the Temporal and Spectral Evolution of Swift J1818.0-1607: a Missing Link between Magnetars and Rotation Powered Pulsars