Context: 

Scientists have suggested sending an object into the ergosphere of a black hole  and allow it to accelerate there along the black hole’s direction of rotation

What Is An Ergosphere?

• Ergosphere comes from the  Greek word  ‘ergon’, meaning ‘work’.  It got its name because it is possible to get energy and even mass from this place.
• An “ergosphere” is the region in between the event horizon and the stationary limit.
• • A “stationary limit” is a surface around the outside of a rotating black hole. 
  • Event  Horizon: It is a sphere around the singularity of a Black Hole. When anything enters this sphere, it can’t escape unless it travels faster than light (which is impossible).
• Shape: An Ergosphere is shaped  like an oblate spheroid, or a pumpkin.
  • At the top and bottom of the black hole, it touches the event horizon, but as you move the middle part, it goes out farther.
• Features Of Ergosphere
  • It is a bigger sphere surrounding the Event Horizon  that an object can enter and then leave if it’s moving fast enough, but still less than the speed of light
  • It  is possible to extract matter and energy from the ergosphere, but not from beyond the event horizon.
• Significance: Scientists have suggested a  possibility of  sending  objects into the ergosphere and allow it to accelerate there along the black hole’s direction of rotation, so that it comes out moving faster. This energy ‘gain’ will translate to the black hole losing some angular momentum.

News Source: The Hindu