This is a composite image showing the location of the largest known quasar group and associated galaxies. The massive galaxy concentration is located just south of the heart of the constellation Leo the Lion, represented here by a line connecting the stars that comprise the constellation. The cluster spans a region up to two by five degrees -- or forty times the area of the full moon. Its location and approximate apparent size in the sky is represented by the square on the bottom left side of the image, beneath the constellation Leo. The galaxy cluster is contained within a large quasar group, which measures about 600 million light years across, making it the largest structure known in the early Universe. (A light year is the distance traveled by light in a year, about six trillion miles.)
The smaller square in the bottom left square is a photograph of the galaxy field associated with the large quasar group. The field was observed using the Big Throughput Camera (BTC) on the National Science Foundation's 4-meter (159 inch) Blanco telescope at the Cerro Tololo Inter-American Observatory (CTIO) in Chile during April 1998. A blowup (right image) of a small portion of this field reveals hundreds of galaxies, seen as fuzzy, multi-colored specks. Not all the galaxies seen here are part of the large quasar group and galaxy cluster. Because the large quasar group is so remote, some of the galaxies in the image are in front of it, and therefore closer to the Earth.
IMAGE CREDIT: National Science Foundation National Optical Astronomy Observatory, Chris Haines, Gerard Williger
|
(48
MEG JPG IMAGE) - Caution: FOUS - File of Unusual Size
|
This image is a photograph of the galaxy field associated with the large quasar group. The field was observed using the Big Throughput Camera (BTC) on the National Science Foundation's 4-meter (159 inch) Blanco telescope at the Cerro Tololo Inter-American Observatory (CTIO) in Chile during April 1998. A larger version of the photo (see links at the bottom of the image) will reveal thousands of galaxies as fuzzy, multi-colored specks. The larger, red and yellow dots are foreground stars. Not all the galaxies seen here are part of the large quasar group and galaxy cluster. Because the large quasar group is so remote, some of the galaxies in the image are in front of it, and therefore closer to the Earth.
(more information about this image)
IMAGE CREDIT: National Science Foundation National Optical Astronomy Observatory, Chris Haines, Gerard Williger
This image is a diagram representing how galaxies that are part of the large quasar group reveal themselves by blocking some of the light from quasars behind them. The purple dot represents a quasar, a galaxy with an exceptionally bright core, possibly powered by a giant black hole, that shines with the light of a trillion Suns. The red, green, and blue lines represent light of different colors emitted by the quasar. An intervening galaxy (white swirl in middle image) absorbs light of a certain color, represented by the green line, while letting the rest of the light from the quasar pass through.
The galaxies themselves are faint and have not yet been directly seen. However, magnesium atoms in the halo gas of the galaxies absorb light coming from quasars behind the cluster. This produces "shadows" in front of the quasars, thus revealing both the existence of the galaxies and an accurate distance for them.
Image Credit: NASA, Gerard Williger
