Evolution of quasi-periodic eruptions in the post-tidal disruption event accretion disk perturbed by an orbiting star

Résumé fourni par la source

Context. Quasi-periodic eruptions (QPEs) are a recently discovered class of highly variable X-ray bursts originating in galactic nuclei. These high-amplitude bursts exhibit a periodicity ranging from tens of minutes to several days and they are also characterized by variable peak amplitudes that can vary by a factor of few. While multiple physical models have been proposed to explain QPE light curves, none of them can fully account for all the observed features. A possible connection between QPEs and tidal disruption events (TDEs) has been suggested, particularly due to past optical/UV outbursts that can be traced back for several sources, the long-term decay in the continuum luminosity, and the soft, thermal-dominated X-ray spectrum. Aims. Our primary goal is to verify whether the long-term decrease in eruption amplitudes detected for some QPE sources is consistent with a scenario where the accretion disk had been formed following a TDE. Methods. In this work, we adopted a simplified extreme mass ratio inspiral (EMRI) scenario, where a solar-type star orbits a supermassive black hole (SMBH) and collides with an accretion disk twice per orbit, generating eruptions. We assumed a post-TDE disk that follows a temporal power-law decline in mass accretion (∝ t − p , p > 0). As our aim is to develop a toy-model scenario, we used purely analytical methods, without considering all intervening processes in their full scope. Results. Our results indicate that (i) the observed long-term decline in QPE amplitudes can be reproduced if the first monitored epoch occurs years to a few decades after the tidal disruption; and (ii) stellar mass loss caused by ablation can play an important role in the evolution of QPE amplitudes in systems with heavy main sequence stars.

Ce résumé expose les affirmations des auteurs. BNTIC ne l’interprète pas comme une validation indépendante des résultats.