X-ray flares from the stellar tidal disruption by a candidate supermassive black hole binary

Area of Science:

• Astronomy and Astrophysics
• High-Energy Astrophysics

Background:

• Optical transient surveys have identified numerous stellar tidal disruption events (TDEs).
• Most TDEs exhibit weak or no X-ray emission during follow-up observations.
• The central massive black holes in galaxies are key targets for studying TDEs.

Purpose of the Study:

• To investigate the X-ray emission properties of TDEs.
• To understand the reasons behind the lack of early X-ray detections in most TDEs.
• To explore potential explanations for unusual TDE light curves, such as supermassive black hole binaries.

Main Methods:

• Utilizing optical transient survey data to identify TDE candidates.
• Conducting X-ray follow-up observations of TDEs.
• Analyzing the temporal evolution of X-ray flux, including delayed brightening and flux dips.

Main Results:

• Discovery of delayed X-ray brightening around 140 days post-optical outburst in the TDE OGLE16aaa.
• Observed several flux dips during the X-ray decay phase of OGLE16aaa.
• These unusual X-ray properties deviate from standard TDE behavior.

Conclusions:

• The delayed X-ray emission suggests early X-rays might be obscured by radiation-dominated ejecta.
• The observed properties are consistent with scenarios involving a supermassive black hole binary or patchy obscuration.
• X-ray observations are crucial for understanding TDE early evolution and potentially detecting supermassive black hole binaries.