Quasar Makes Ghostly Intergalactic Filament Glow
S. Cantalupo, UCSC
Quasar UM287 and the diffuse gas filament, which seems to have been adorably named the "Slug Nebula."
Andrew Cooper/W. M. Keck Observatory
March 13, 2013, marks 20 years since the W. M. Keck Observatory began taking observations of the cosmos. Located in arguably one of the most extreme and beautiful places on the planet -- atop Mauna Kea, Hawai'i, 13,803 ft (4,207 m) above sea level -- the twin Keck domes have observed everything from asteroids, planets, exoplanets to dying stars, distant galaxies and nebulae. Seen in this photograph, the Keck I and Keck II telescopes dazzle the skies with their adaptive optics lasers -- a system that helps cancel out the turbulence of the Earth's atmosphere, bringing science some of the clearest views attainable by a ground-based observatory.
To celebrate the last two decades of incredible science, Discovery News has assembled some of the most impressive imagery to come from Keck.
William Merline, SWRI / W.M. Keck Observatory
Starting very close to home, the Keck II captured this infrared image of asteroid 2005 YU55 as it flew past Earth on Nov. 8, 2011.
Larry Sromovsky (University of Wisconsin)
Deeper into the solar system, the Keck NIRC2 near-infrared camera captured this beautiful observation of the oddball Uranus on July 11-12, 2004. The planet's north pole is at 4 o'clock.
W.M Keck Observatory/NASA/JPL-G.Orton
This is a mosaic false-color image of thermal heat emission from Saturn and its rings on Feb. 4, 2004, captured by the Keck I telescope at 17.65 micron wavelengths.
Antonin Bouchez (W. M. Keck Observatory)
A nice image of Saturn with Keck I telescope with the near infrared camera (NIRC) on Nov. 6, 1998. This is a composite of images taken in Z and J bands (1.05 and 1.3 microns), with the color scaling adjusted so it looks like Saturn is supposed to look to the naked eye.
Antonin Bouchez, W.M. Keck Observatory
This is Saturn's giant moon Titan -- a composite of three infrared bands captured by the Near Infrared Camera-2 on the 10-meter Keck II telescope. It was taken by astronomer Antonin Bouchez on June 7, 2011.
W. M. Keck Observatory/SRI/New Mexico State University
Another multicolored look at Titan -- a near-infrared color composite image taken with the Keck II adaptive optics system. Titan's surface appears red, while haze layers at progressively higher altitudes in the atmosphere appear green and blue.
Mike Brown, Caltech / W.M. Keck Observatory
This image of Neptune and its largest Tritan was captured by Caltech astronomer Mike Brown in September 2011. It shows the wind-whipped clouds, thought to exceed 1,200 miles per hour along the equator.
A color composite image of Jupiter in the near infrared and its moon Io. The callout at right shows a closeup of the two red spots through a filter which looks deep in the cloud layer to see thermal radiation.
Christian Marois, NRC and Bruce Macintosh, LLNL/W. M. Keck Observatory
HR 8799: Three exoplanets orbiting a young star 140 light years away are captured using Keck Observatory's near-infrared adaptive optics. This was the first direct observation by a ground-based observatory of worlds orbiting another star (2008).
Bob Goodrich, Mike Bolte, and the ESI team
Now to the extremes -- an image of Stephan's Quintet, a small compact group of galaxies.
W.M. Keck Observatory
The Egg Nebula: This Protoplanetary nebula is reflecting light from a dying star that is shedding its outer layers in the final stages of its life.
W. M. Keck Observatory
This is WR 104, a dying star. Known as a Wolf Rayet star, this massive stellar object will end its life in the most dramatic way -- possibly as a gamma-ray burst. The spiral is caused by gases blasting from the star as it orbits with another massive star.
W. M. Keck Observatory/UCLA
Narrow-field image of the center of the Milky Way. The arrow marks the location of radio source Sge A*, a supermassive black hole at the center of our galaxy.
Dr. Mark Morris (UCLA) Keck II, Mirlen instrument
A high resolution mid-infrared picture taken of the center of our Milky Way reveals details about dust swirling into the black hole that dominates the region.
Mansi Kasliwal, Caltech and Iair Arcavi, Weizmann Institute of Science/W. M. Keck Observatory
A false-color image of a spiral galaxy in the constellation Camelopardalis.
A scintillating square-shaped nebula nestled in the vast sea of stars. Combining infrared data from the Hale Telescope at Palomar Observatory and the Keck II telescope, researchers characterized the remarkably symmetrical “Red Square” nebula.
ESA, NASA, J.-P. Kneib (Caltech/Observatoire Midi-Pyrenees) and R. Ellis (Caltech)/W. M. Keck Observatory
Galaxy cluster Abell 2218 is acting as a powerful lens, magnifying all galaxies lying behind the cluster's core. The lensed galaxies are all stretched along the shear direction, and some of them are multiply imaged.
UC Berkeley/NASA/W. M. Keck Observatory
The central starburst region of the dwarf galaxy IC 10. In this composite color image, near infrared images obtained with the Keck II telescope have been combined with visible-light images taken with NASA’s Hubble Space Telescope.
The grand “cosmic web” is a picture that has fascinated us since the beautiful Millennium Simulation was run in 2005, showing us a Universe full of matter often clumped together but intricately bound by thin filaments. For the first time, these thin filaments of gas have been directly seen using one of the largest telescopes on Earth.
Clouds of gas, by their nature, are diffuse and difficult to detect. Often, we can see gas that lies along a line of sight to distant bright object, such as a quasar. However, that only gives insight into one small piece of that cloud.
A quasar is the bright central region of a galaxy that is being powered by a supermassive black hole that is gobbling up surrounding material. A team of astronomers, with lead author Sebastiano Cantalupo, looked towards such a quasar 10 billion light years away and found it illuminating a gas cloud far too large to be part of a galaxy cluster.
This gas resides in the intergalactic medium, the spaces between galaxies. It is two million light years across, a distance equal to roughly the distance between the Milky Way Galaxy and the Andromeda Galaxy. It was detected in the faint glow given off by hydrogen atoms that were excited by the radiation of the nearby quasar using the 10-meter Keck I telescope in Hawaii.
Large image shows a slice of the Millennium simulation, showing the distribution of dark matter in a simulated Universe. Inset shows a similar such simulation with normal gas added. S. Cantalupo (UCSC); Joel Primack (UCSC); Anatoly Klypin (NMSU)
This cosmic web is not only poetic but important to the formation of galaxies and galaxy clusters. According to the Millennium Simulation, these filaments help to funnel gas into the “nodes” of the web, the sites of large galaxies and galaxy clusters. Our Milky Way Galaxy is thought to have formed in a small such node in this web.
Much of the material, over 80 percent, is dark matter, or matter that does not directly interact with electromagnetic radiation. Although we’ve detected its presence indirectly for decades due to its gravitational effects, we are no at the point where dark matter in the cosmos has been thoroughly mapped out. This gas, the “normal” matter that makes up people, stars, and planets, however, can be seen.
Since it is so diffuse, this gas proved to be a challenging target. It was found near a quasar in part because the quasar made it glow. It is also an ideal place for searching for such gas because quasars tend to inhabit the more densely populated nodes of the web, thus are likely to be surrounded by more of these filaments.
But, as always, there was a surprise in store. The mass of the gas cloud is ten times what has been predicted by simulations. A more massive cloud may have been an outlier, just the easiest to spot, but it is likely that the simulations don’t quite model reality exactly. Some factors may be missing that would create gas clouds of this larger size as is seen in these recent observations. This just goes to show that even when you think you know what you are looking for, the Universe is going to surprise you.
This research was published in Nature; and a preprint is available at arXiv.org.