Peculiar AGN outbursts detected by Gaia
Abstract
We discuss different scenarios to explain multiple >1.5 magnitude flares in AGN detected with Gaia such as accretion disk instabilities, variable absorption in the line of sight, tidal disruption events, or a stellar-mass black hole — neutron star merger in the AGN disc. Interestingly, the rise and decay times of ~300 and ~900 days are similar for at least three events. The transients are spatially consistent with the nuclei of AGNs in all cases. We present the detailed analysis of the properties of one of the sources, with multi-wavelength X-ray, optical, NIR and IR photometry and optical spectroscopy: during its outburst the spectrum of the source shows a strong blue continuum that fades over time and broad Balmer lines with complex, multi-peaked line profiles, in contrast to its archival spectrum where the same lines showed a much simpler morphology. The timescales associated with these events and their integrated energy output are difficult to explain within the framework of known AGN variability.
- Publication:
-
American Astronomical Society Meeting Abstracts #235
- Pub Date:
- January 2020
- Bibcode:
- 2020AAS...23515108C