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 unprecedented short-term variations detected in the optical fluxfrom the black hole binary system, V4641 Sgr. Amplitudes of the opticalfluctuations were larger at longer time scales, and surprisingly reached ~60%around a period of ~10 min. The power spectra of fluctuations are characterizedby a power law. It is the first case in black hole binaries that the opticalemission was revealed to show short-term and large-amplitude variations givenby such a power spectrum. The optical emission from black hole binaries isgenerally dominated by the emission from the outer portion of an accretiondisc. The rapid optical fluctuations however indicate that the emission from aninner accretion region significantly contributes to the optical flux. In thiscase, cyclo-synchrotron emission associated with various scales of magneticflares is the most promising mechanism for the violently variable opticalemission.Comment: 5 pages, 2 figures, accepted for publication in PAS

Rapid Optical Fluctuations in the Black Hole Binary V4641 Sagittarii