By default, Maya scenes do not contain light sources.
However, Maya’s default lighting helps you to visualize objects in Shaded display in the Scene view (press 5). If you turn default lighting off and have no lights in the scene, the scene appears black.
To turn lights on or off, if for example, you want to see or render incandescent objects (for which no lighting is required), see Turn default lighting on or off.
Default light source at render time
If you render a scene without a light, Maya creates directional light during the render so that your objects can be seen. Without it, your objects would not be illuminated; that is, your render would be black.
This default light is parented to the rendered camera. The entire scene is illuminated no matter where the camera is facing. The surface areas directly facing the camera are bright while the surface areas hidden from the camera are dark. This provides surface contours that look realistic.
After the render completes, Maya removes the default light from the scene.
The IPR default light source that is added to the scene during rendering operates much the same way as the Maya default light source at render time.