G327.1-1.1: Pushing the Envelope

G327.1-1.1 is the aftermath of a massive star that exploded as a supernova in the Milky Way galaxy. A highly magnetic, rapidly spinning neutron star called a pulsar was left behind after the explosion and is producing a wind of relativistic particles, seen in X-rays by Chandra and XMM-Newton (blue) as well as in the radio data (red and yellow). This structure is called a pulsar wind nebula. The likely location of the spinning neutron star is shown in the labeled version. The large red circle shows radio emission from the blast wave, and the composite image also contains infrared data from the 2MASS survey (red, green, and blue) that show the stars in the field.

No clear explanation is yet known for the unusual nature of G327.1-1.1, including the off-center position of the pulsar wind nebula seen in the radio data and the comet-like shape of the X-ray emission. One possibility is that we are seeing the effects of a shock wave bouncing backwards off of the shell of material swept up by the blast wave produced by the explosion, the so-called "reverse shock" from the blast wave. The pulsar is moving upwards, away from the center of the explosion, but the pulsar wind nebula is being swept towards the bottom-left of the image by the reverse shock wave that is also traveling towards the bottom-left. The direction of the pulsar's motion and of the reverse shock are shown in the labeled version.

The X-ray observations allow scientists to estimate the energy released during the supernova explosion and the age of the remnant, as well as the amount of material being swept up as the blast wave from the explosion expands. The faint bubble that the pulsar appears to be creating may also be revealing the fresh pulsar wind being blown into the region cleared out by the reverse shock.

A paper describing these results appeared in The Astrophysical Journal in February 2009 with Tea Temim of the Harvard-Smithsonian Center for Astrophysics (CfA), Patrick Slane (CfA), Bryan Gaensler (University of Sydney), Jack Hughes (Rutgers) and Eric Van Der Swaluw (Royal Netherlands Meterological Institute) as authors.