Saturday, October 27, 2007

05/30/07: Chandra: 3C438 and Surrounding Galaxy Cluster.

Video, Mpeg, 2.5 MB Credit: X-ray: NASA/CXC/CfA/R.P.Kraft; Optical: Pal.Obs. DSS; Radio: NRAO/VLA/A.H.Bridle, R.G.Strom

Chandra's image of 3C438, the central galaxy within a massive cluster, reveals evidence for one of the most energetic events in the local Universe. An arc-like feature to the lower left in the cluster's hot gas is about 2 million light years long. VLA Radio Image of 3C438 Astronomers have determined that an enormous amount of energy would be required to produce such a large structure. One plausible scenario is that two massive clusters collided at high velocity and later merged. This would have created a shock front in the hot gas that could account for the ridge seen in the Chandra data.

Credit: X-ray: NASA/CXC/CfA/R.P.Kraft; Optical: Pal.Obs. DSS

Another intriguing feature in the Chandra data is the possible detection of a cavity in the hot gas. This structure, seen in the upper left of the image, would require a tremendous amount of energy to produce. There are also hints of a similar structure on the other side of the central galaxy. Images of 3C438 and Surrounding Galaxy Cluster Astronomers think such X-ray cavities are usually generated when large amounts of matter funnel into a supermassive black hole. The black hole inhales much of the matter but expels some of it outward in a high-speed jet, carving e into the hot gas. If the cavity was generated by a supermassive black hole, then it would be the most powerful event of its kind ever seen.

A further interesting aspect of the Chandra data is that the temperature of the gas was measured to be about 170 million degrees Celsius. This cluster is therefore one of the hottest ever seen, another sign of colossal upheaval.

Chandra X-ray Image of 3C438

Evidence for an awesome upheaval in a massive galaxy cluster was discovered in an image made by NASA's Chandra X-ray Observatory. The origin of a bright arc of extremely hot gas extending over two million light years requires one of the most energetic events ever detected. There are also hints of a cavity in the hot gas to the upper left. Scale: Image is 8.4 arcmin per side. Credit: NASA/CXC/CfA/R.P.Kraft

VLA Radio Image of 3C438

This radio image from NRAO's Very Large Array shows the inner-most region of 3C438. Jets seen in the radio data do not point in the same directions as the cavity structure seen in the X-ray, adding more mysteries about this system. Credit: Radio: NRAO/VLA/A.H.Bridle & R.G.Strom; X-ray: NASA/CXC/CfA/R.P.Kraft

DSS Optical Image of 3C438

This cropped Digitized Sky Survey (DSS) image (left) shows how different 3c438 looks in optical light. The X-ray image (see #1 above) shows a much different structure from the optical image, including a massive arc-like structure to the lower left. There are also hints of a cavity in the hot gas to the upper left. Scale: Cropped image is 8.4 arcmin per side; Full field is 50 arcmin per side. Credit: Pal.Obs.