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 Tools annual

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 monthly

Global: Zendy Plus monthly

Presents the access of premium content as premium feature

Premium Content

Global: Zendy Plus annual

Global: Zendy Free Plan

We investigate the X-ray spectrum, variability and the surrounding ionizedbubble of NGC1313 X-2 to explore the physics of super-Eddington accretion.Beyond the Eddington luminosity, the accretion disk of NGC1313 X-2 is truncatedat a large radius ($\sim$ 50 times of innermost stable circular orbit), anddisplays the similar evolution track with both luminous Galactic black-hole andneutron star X-ray binaries. In super-critical accretion, the speed ofradiatively driven outflows from the inner disk is mildly relativistic. Suchultra-fast outflows would be over ionized and might produce weak Fe Kabsorption lines, which may be detected by the coming X-ray mission {\itAstro-H}. If the NGC1313 X-2 is a massive stellar X-ray binary, the highluminosity indicates that an ephemeral feast is held in the source. That is,the source must be accreting at a hyper-Eddington mass rate to give thesuper-Eddington emission over $\sim 10^{4}-10^{5}$ yr. The expansion of thesurrounding bubble nebula with a velocity of $\sim$ 100 km~s$^{-1}$ mightindicate that it has existed over $\sim 10^{6}$ yr and is inflated by theradiatively driven outflows from the transient with a duty cycle of activity of$\sim$ a few percent. Alternatively, if the surrounding bubble nebula isproduced by line-driven winds, less energy is required than the radiativelydriven outflow scenario, and the radius of the Str\"{o}mgren radius agrees withthe nebula size. Our results are in favor of the line-driven winds scenario,which can avoid the conflict between the short accretion age and the apparentlymuch longer bubble age inferred from the expansion velocity in the nebula.

Super-Eddington Accretion in the Ultraluminous X-ray Source NGC1313 X-2: An Ephemeral Feast