Quasars, the Cosmic Web, and Dark Matter

Computer simulation of cosmic web illuminated by quasars

            Astronomers at the University of California, Santa Cruz have discovered evidence for the network of filaments theorized to connect galaxies. Using the Keck I Telescope at the W.M. Keck Observatory these astronomers have detected a very large very distant nebula that stretches about 2 million light years across. The nebula is twice as big as any previously detected nebula and is being illuminated by a very luminous quasar. This enormous nebula of diffuse gas is, for the first time, showing the structure of a portion of the network of filaments in the cosmic web. Current theory, along with computer simulation, predict that galaxies should form along this web of filaments that consist of mainly dark matter. The gravitational attraction of the dark matter should cause ordinary matter, such as the diffuse gas in the nebula, to follow the web pattern seen in computer simulations.  The nebula consists of mainly, if not all, hydrogen gas that is emitting ultraviolet light. It is the very luminous quasar that is exciting the hydrogen to emit Lyman alpha wavelength radiation. Because the quasar and nebula are so far away, the light it emits is being stretched so that the ultraviolet light, which cant be seen with naked eye, reaches the Earth as a visible violet color. The astronomers used a filter to observe the nebula at the visible wavelength seen at Earth. After analyzing the nebula they concluded that it contained ten times the amount of gas as predicted by computer models.  

http://www.sciencedaily.com/releases/2014/01/140119142452.htm

Designing new telescope optics to find new Earths

http://www.nasa.gov/topics/technology/features/SpaceTechOpticsBelikov.html

          NASA is currently developing more advanced coronagraphs that will better allow for direct imaging of planets around its host star. A coronagraph works by blocking out the light from the host star so that the stars luminosity does not overpower any light from the planet. However, there is still a glare left from the host star that makes the image of the planet a less desirable one. The technology that NASA is developing will better block the host stars light. They are also testing non-spherical lenses that better reduce the left over glare. The lenses have the property that they concentrate the left over light from the host star into a much smaller spot which in effect does not appreciably disturb the light from the planet. NASA also plans to use adaptive optics with these more advanced coronagraphs to get the most clear direct image of planets we have. There are plans to use this technology on a smaller telescope first and to look for larger Jupiter like planets because they are much easier to find and image since they are larger and may be found further away from the host star. Then, with this technology perfected, it will be used with much larger telescopes. When this happens the hunt for exo-Earths will begin. With this precious light from the exo-planets we can begin to do spectroscopic analysis of the planets. This will allow us to detect certain key light signatures of important molecules for life such as water and methane in the atmospheres of these Earth like planets. NASA says they expect to have data on virtually all planets in the habitable zone for the nearest hundreds of stars to us by 2030.

Using Distant Quasars to Illuminate Interstellar Medium

Astronomers at The University of Illinois have recently gathered evidence  for swirling clouds of gas surrounding other galaxies that are much more dynamic than predicted. It was previously thought any significant change in these gas clouds would take longer than a human lifetime and therefore would not be noticeable. Spectroscopic analysis of the absorption spectrum of gas clouds analyzed by astronomers provide evidence otherwise. These astronomers are using distant quasars to illuminate gas that is between the quasar and earth; the quasars illuminate the gas and the gas clouds absorb the light in a specific way depending on its composition. By analyzing the same quasars (and gas clouds) more than once over a period of about 5 years, the astronomers were able to show that the clouds are changing. One possible explanation is that the gas clouds are small, much smaller than theory predicts. Here is a link to the article  http://www.sciencedaily.com/releases/2014/01/140108154517.htm .