Delayed outflows in AT2018hyz.

As it is known, tidal forces are gravitational effects caused by a gravitational gradient applied to a body. Meaning, a force of different amplitude is being applied to different parts of a body, resulting in a tendency to change its shape.

Now, if a cosmic object passes close enough to a supermassive black hole (SMBH), that the tidal force can overcome the self-gravity of the object, it leads to a tidal disruption event (TDE).

Such an event was observed during October, 2018, when a SMBH devoured a star, forming a transition accretion disk. It was named AT2018hyz. AS TDEs are quite common and at that time it didn’t seem to be anything particularly special for AT2018hyz, researchers moved on, trying to use the precious telescope type, better.

However, about three years later, when they decided to put AT2018hyz through a routine check, they were in for a surprise. Three years after being radio-silent, AT2018hyz was flaring up the sky, again.

The delayed outburst suggest that this type of events might be common and thus leading to a new path of research, that might include rechecking previously observed TDEs, as well as extending the observations of new events.

As for theoretical explanations, which is my domain of expertise, there seem to be a few possible explanations that need to be explored. To mention a few, a density change throughout the accretion disk, a state transition and delayed accumulation of the magnetic field.

I intend to tackle this problem with a combination of an assumed perturbation of the density and the magnetic field accumulation mechanics. I keep you informed with what I come up with.

Reference: https://iopscience.iop.org/article/10.3847/1538-4357/ac88d0

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