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

In this letter, we present the results from further X-ray and UV observationsof the nuclear transient eRASSt J045650.3-203750 (hereafter J0456-20). Wedetected five repeating X-ray and UV flares from J0456-20, making it one of themost promising repeating partial tidal disruption event (pTDE) candidates. Moreimportantly, we also found rapid changes in the recurrence time$T_\text{recur}$ of the X-ray flares by modelling the long-term X-ray lightcurve of J0456-20. $T_\text{recur}$ first decreased rapidly from about 300 daysto around 230 days. It continued to decrease to around 190 days with anindication of a constant $T_\text{recur}$ evidenced from the latest threecycles. Our hydrodynamic simulations suggest that, in the repeating pTDEscenario, such rapid evolution of $T_\text{recur}$ could be reproduced if theoriginal star is a $1~\mathrm{M}_\odot$ main-sequence star near the terminalage and loses nearly 80-90% of its mass during the initial encounter with asupermassive black hole (SMBH) of mass around $10^5~\mathrm{M}_\odot$. Theinferred mass loss of 0.8-0.9 $\mathrm{M}_\odot$ is higher than the estimatedvalue of around 0.12 $\mathrm{M}_\odot$ from observation, which could beexplained if the radiation efficiency is low (i.e. $\ll0.1$). Our resultsindicate that repeating pTDEs could be effective tools to explore the dynamicsaround supermassive black holes beyond our own Galaxy.

Rapid evolution of the recurrence time in the repeating partial tidal disruption event eRASSt J045650.3-203750