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THE PAST few years have seen the discovery of an entirely new kind of beast
living right here in our Galaxy. These objects flicker wildly, sometimes shining
so brightly that they are the most brilliant source of X-rays in the sky. The
radiation they give off shows that within them, matter and antimatter are
colliding. And they emit jets of electrons that appear to be speeding outwards
faster than light. Welcome to the world of the microquasar.

In many ways, microquasars mimic their big cousins, quasars. Quasars proper
are the brightest things in the Universe. They look like brilliant blue stars,
and emit colossal jets of electrons that stretch out into space for millions of
light years. The current theory is that at the heart of every quasar is a black
hole heavier than 10 million Suns. As gas from the surrounding galaxy falls
inwards, it forms a hot disc that swirls around the hole in grand slow motion.
But this is still a crude picture. One of the puzzles we have still to unravel
is why quasars emit those vast jets.

In human terms, quasars are not only very big, they’re very slow. A lifetime
is too short see a full-size quasar chewing up stars and spitting them out
again. So microquasars aren’t just interesting in their own right. A microquasar
does all the exciting things a quasar does—but it’s a million times
smaller and a million times faster.

The first microquasar was tracked down because astronomers thought it was a
real quasar. Somewhere near the heart of the Milky Way is an object emitting
gamma rays with…