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 Plus monthly

Global: Zendy Tools annual

Global: Zendy Tools monthly

Global: Zendy Free Plan

WR 20a is the most massive close-in binary known in our Galaxy. It iscomposed of two $\approx$80 M$_\odot$ Wolf-Rayet stars with a short period of$\approx$3.7 days in the open cluster Westerlund 2. As such, WR 20a presents uswith a unique laboratory for studying the currently uncertain physics of binaryevolution and compact object formation as well as for studying the windcollision region in an massive eclipsing binary system. We use deep Chandraobservations of WR 20a to study the time variability of the wind collisionregion between the two Wolf-Rayet stars and are able to produce an X-ray lightcurve covering $\approx$2/3 of its orbital period. We find that the X-ray lightcurve is asymmetric because the flux of one peak is 2.5$\sigma$ larger than theflux of the other peak. This asymmetry could be caused by asymmetric mass-lossfrom the two stars or by the lopsidedness of the wind collision region due tothe unusually fast rotation of the system. The X-ray light curve is alsoshifted in phase space when compared to the optical light curves measured byTESS and ASAS-SN. Additionally, we explore the ultimate fate of this system bymodeling the resultant binary black hole merger expected at the end of the twostars' lives. We conclude that this system will evolve to be a representativeof the sub-population of LIGO progenitors of fast-spinning binary black holemerger events.

A Multiwavelength Study of the Massive Colliding Wind Binary WR 20a: A Possible Progenitor for Fast-Spinning LIGO Binary Black Hole Mergers