  The missing baryons are usually thought to reside in galaxy filaments as
warm-hot intergalactic medium (WHIM). From previous studies, giant radio
galaxies are usually associated with galaxy groups, which normally trace the
WHIM. We propose observations with the powerful SKA1 to make a census of giant
radio galaxies in the southern hemisphere, which will probe the ambient WHIM.
The radio galaxies discovered will also be investigated to search for dying
radio sources. With the highly improved sensitivity and resolution of SKA1,
more than 6,000 giant radio sources will be discovered within 250 hours.
