| There is a certain type of cosmic explosion that becomes, in a flash, the brightest thing in the universe, emitting for a few seconds as much radiation as a million galaxies. Don't bother looking for one in the sky, though, since most of the light is in the gamma-ray part of the spectrum, a realm we can't see.
Astronomers observe these colossal gamma-ray bursts with space-based telescopes, however.
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They generally agree that only the birth of a black hole could supply enough spark for one of these intense flashes, but there remains a great deal of uncertainty over what converts the newborn black hole's energy into the radiation that astronomers detect.
Recent observations suggest that this "converter" is a high-powered magnetic beam, and not--as many theorists believe--a high-speed jet of hot material.
This is just the latest debate over these exceptionally luminous objects called gamma ray bursts. Researchers previously argued whether GRBs come from inside or outside our galaxy, then whether they emerge from a dying star or two neutron stars merging.
The current consensus is that most GRBs are the death knell of a massive star in a faraway galaxy. After exhausting its fuel supply, the star's core collapses into a black hole (or a comparatively dense neutron star), which acts as a "central engine" for two jets spouting out of the poles.
These jets are where the energy of the collapse is transformed into gamma rays, but we only observe a GRB if we happen to be lined up with the barrel of one of the jets.
This overall picture is fairly well-established, but the big question, according to Tsvi Piran of the Hebrew University in Jerusalem, is what makes up the jets.
When you're a jet
The widely-accepted fireball model assumes that the outer shells of the dying star are heated to very high temperature. This hot material expands outward in all directions, but the expansion is easiest along the star's rotational axis. Hence, fast moving material emerges from the poles as twin jets.
But the Swift satellite, NASA's dedicated GRB observatory, has detected a number of GRBs that appear to defy the fireball model.
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