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

M51 ULX7 is among a small group of known ultraluminous X-ray pulsars (ULXP).The neutron star powering the source has a spin period of 2.8s, orbits itscompanion star with a period of 2 days, and a super-orbital period of 38 daysis evident in its X-ray lightcurve. Here we present NuSTAR and XMM-Newton dataon the source from 2019 obtained when the source was near its peak brightness.We detect the pulsations, having spun up at a rate of 3$\pm0.5\times10^{-10}$ ss$^{-1}$ since they were previously detected in 2018. The data also provide thefirst high-quality broadband spectrum of the source. We find it to be verysimilar to that of other ULXPs, with two disk-like components, and a highenergy tail. When combined with XMM-Newton data obtained in 2018, we explorethe evolution of the spectral components with super-orbital phase, finding thatthe luminosity of the hotter component drives the super-orbital fluxmodulation. The inclination the disk components appear to change with phase,which may support the idea that these super-orbital periods are caused by diskprecession. We also reexamine the super-orbital period with 3 years ofSwift/XRT monitoring, finding that the period is variable, increasing from38.2$\pm0.5$ days in 2018--2019 to 44.2$\pm0.9$ days in 2020--2021, which rulesout alternative explanations for the super-orbital period.

Evolution of the spin, spectrum and super-orbital period of the ultraluminous X-ray pulsar M51 ULX7