Tidal disruption events

6 problems

• Why do many TDEs produce radio outflows years later?

  Open

  Many tidal disruption flares start to shine in radio waves years after the visible flare, showing that fast-moving gas appears late. Why the black hole would launch matter so late is unknown.

• Why do only a few TDEs launch relativistic jets?

  Open

  Only a handful of tidal disruption events have produced jets moving near light speed, for example Swift J1644+57 in 2011. What makes these few different is unknown.

• Where is the missing radiated energy of tidal disruption events?

  Open

  If half the torn star falls into the black hole, the flare should release one hundred to one thousand times more energy than is seen. The missing energy may escape in light that is hard to observe, in winds, or into the black hole.

• Shocks or reprocessed accretion as the source of TDE optical light

  Contested

  Tidal disruption flares glow in visible light from a region much larger than the expected disk of infalling gas. That light could come from colliding streams of star debris or from a gas cloud that absorbs and re-emits light from the disk.

• Why are tidal disruptions overrepresented in post-starburst galaxies?

  Open

  Tidal disruptions happen unusually often in galaxies that stopped forming stars after a recent burst. These galaxies are rare, so something about them must send stars toward the central black hole.

• What fraction of tidal disruption events develop quasi-periodic eruptions?

  Open

  Quasi-periodic eruptions are X-ray bursts that repeat every few hours from some galaxy centers, and several have now appeared in galaxies that earlier had a tidal disruption flare. They might come from a star or small black hole crossing the disk left by the disruption.