Scientists at MIT are looking forward to using the improved imaging capability of the Hubble Space Telescope to look at distant clusters of galaxies, active galactic nuclei and quasar jets. The Hubble was upgraded recently by astronauts on the space shuttle Columbia.
Two of the astronauts installing the upgraded equipment were MIT alumni--John M. Grunsfeld (S.B. in physics 1980) and Michael J. Massimino (S.M. 1988, M.E., Ph.D.). (See accompanying article on this page.)
Julia Lee, a postdoctoral associate in the Center for Space Research (CSR), is planning joint observations of active galactic nuclei and the environment around them. She will use Hubble's space telescope imaging spectrograph (STIS) to measure absorption in the UV spectrum, and Chandra's High Energy Transmissions Grating (HETG) in conjunction with the Advanced CCD Imaging Spectrograph (ACIS) to measure absorption in the X-ray spectrum. Gerard Kriss (S.B. 1978, Ph.D.) of the Space Telescope Science Institute is the principle investigator for the simultaneous observations using Hubble, Chandra and the FUSE (Far Ultraviolet Spectroscopic Explorer) spacecraft.
Herman Marshall, research scientist at the CSR, is using Hubble to image quasar jets identified by the Chandra X-ray Observatory. "I look forward to using the ACS large field of view and its much more sensitive resolution to allow us to see some of the fainter quasar jets and determine if the jets are moving at relativistic speeds. Some of these jets appear to be moving at 99.5 percent of the speed of light away from the center of the galaxy. This material has probably been ejected along a narrow cone from a black hole at the galaxy's center," Marshall said.
"It's been a wonderful time to be an astronomer and have this intense curiosity about the universe," Marshall said. "Hubble just keeps getting better and Chandra is working so well. Chandra and Hubble are giving us exciting new discoveries on a regular basis. It's really quite exciting because each of the research projects we are taking on has the prospect for major scientific discovery."
Mark Bautz, principal research scientist at the CSR, is looking forward to using Hubble's new ACS instrument to study distant clusters of galaxies. These galaxies contain enormous quantities of dark matter and can act as gravitational lenses to distort the shapes of objects behind them. "Hubble's exquisite resolution is sensitive to very subtle distortions of this kind," Bautz said. "The distortions tell us, among other things, about the amount of dark matter in the intervening cluster.
"We can also use the Chandra X-ray Observatory to quantify the dark matter in clusters, since the dark matter affects cluster X-ray emission. Because we can compare the Chandra and Hubble measurements, we have a very valuable check on our assumptions," Bautz said. "The new Hubble ACS will make it possible to perform these complementary observations on much more distant objects."
A version of this article appeared in MIT Tech Talk on March 13, 2002.