Chandra Resolves X-ray Background
Images and Video to Support the AAS Press Release
Chandra peers to the edge of the Universe. This Chandra image of the constellation Canes Venatici (close to the Big Dipper) may contain the most distant galaxies ever detected, some not seen by Hubble Space Telescope and the Keck Observatory. The observation suggests that the Hubble Deep Field may have missed a large population of Active Galaxies.
Credit: NASA/GSFC/R.Mushotzky et al.
Now you don't see it; now you do. The invisible swath of X-ray radiation that baths the Universe arises in large part from X-ray-bright, optically faint galaxies at extremely far distances. Above, the "big three" -- Hubble Space Telescope, Keck Observatory and The University of Hawaii 2.2 meter telescope -- detect no or little evidence of any light source. The Chandra X-ray Observatory, peering in the same deep field, spots the culprits. The observation suggests that the Hubble Deep Field may have missed a large population of Active Galaxies.
Credit: NASA/GSFC/R.Mushotzky et al.
This is an optical image of the Chandra x-ray field. The circles indicate regions when Chandra has detected an X-ray source. Note that many circles (6,8,16,21) do not show an optical source at their center.
Credit: NASA/GSFC/R.Mushotzky et al.
An animated video: The Chandra X-ray Observatory has resolved what was once a veil or diffuse glow of X-ray radiation across the entire Universe into distict point sources, or galaxies, many of which represent new classes of astronomical objects.
Credit: NASA/Goddard Space Flight Center
This video depicts a virtual voyage to one of the new class of objects that Chandra discovered -- a galaxy whose core glows in X-rays but not in visible light. Galaxies with bright cores are called Active Galactic Nuclei or AGN. A quasar is one well known example of AGN. The core glows so brightly because a supermassive black hole (with the mass of millions to billions of suns compressed into a region no larger than our solar system) pulls in interstellar gas at nearly light speeds. The transfer of gas glows in radio waves, IR, optical, UV and X-ray.
In this new type of AGN discovered by Chandra, the core only glows in X-ray. The spiral arms outside the core glow feebly in optical light, but not bright enough to be seen by most telescopes. Perhaps the core glows in optical light, but that light cannot escape through the dust that enshrouds the core. The X-rays can penetrate this dust, thus they become visible to Chandra. Because AGN surveys comprise only optical AGN and because Chandra has found new Xray-only AGN, scientists may have underestimated the true number of AGN (black holes) in the Universe.
Credit: NASA/Goddard Space Flight Center
This is an optical image with X-ray data superimposed.
Credit: NASA/GSFC/R.Mushotzky et al.
Build your own comparison. These are three optical counterparts within the X-ray field shown above. From the above image clockwise, we have a Hubble Space Telescope image (top right), a Keck Observatory image (bottom right), and the University of Hawaii 2.2 meter (left). Please note that these images coorespond to a small region within the background, as shown above. Draw your focus to the very center of each optical image; the optical field is empty.
Credit: University of Hawaii, L. Cowie
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