Most Distant X-Ray Jet Yet Discovered Provides Clues To Big Bang

The Chandra image (left) of the quasar GB1508+5714 reveals a jet of high-energy particles that extends more than 100,000 light years from the supermassive black hole powering the quasar. At a distance of 12 billion light years from Earth, this is the most distant jet ever detected. The discovery of this jet is especially significant because it provides astronomers with a way to measure the intensity of the cosmic background radiation about one billion years after the Big Bang.

Quasars are thought to be galaxies that harbor an active central supermassive black hole fueled by infalling gas and stars. This accretion process is often observed to be accompanied by powerful high-energy jets. As the electrons in the jet fly away from the quasar at near the speed of light, they move through the sea of cosmic background radiation left over from the hot early phase of the universe. When a fast-moving electron collides with one of these background photons, it can boost the photon's energy up into the X-ray band.

The observed X-ray brightness of the jet, which depends on the power in the electron beam and the intensity of the background radiation, is consistent with the predictions of the standard Big Bang model. The jet's brightness also implies that enormous amounts of energy were deposited in the outer regions of the host galaxy of the quasar at a very early stage. This energy input could have had a profound effect on the evolution of the galaxy by triggering the formation of stars, or inhibiting the accretion of matter from intergalactic space.

The visible-light image (center) of GB1508+5714 was taken by the Hubble Space Telescope's Wide Field and Planetary Camera 2 on July 22, 1995. No source is present in the jet region. This archival HST image helps rule out the possibility that the jet in GB1508+5714 is due to a foreground galaxy or a gravitationally lensed image of the quasar.

The radio image (right) of the quasar GB1508+5714 was taken on July 14, 1995 with NRAO's Very Large Array (VLA) at 1.4 GHz. The data then went into the VLA archive and was reanalyzed by Teddy Cheung at Brandeis University. The detection of the similar feature in the radio data confirmed the existence of the jet associated with the quasar GB1508+5714 and provided clues about the process that created it.