39. Cosmic Background (WMAP) The Microwave Sky The detailed, all-sky picture of the infant universe from three years of WMAP data. The image reveals 13.7 billion year old temperature fluctuations (shown as color differences) that correspond to the seeds that grew to become the galaxies. http://map.gsfc.nasa.gov/m_or.html
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44. Observable Universe The Hubble Radius today is about 13.7 billion light-years away in all directions. Inset: This HST Deep Field Telescope image shows some of the most distant galaxies we have seen.
45. Slice of Universe? This shows the slice of the universe surveyed by the 2dF Galaxy Redshift Survey. Every dot is a galaxy, with the Milky Way at the centre; distance from the centre is redshift and angle around the circumference is angle on the sky. There are 221,283 galaxies in this slice, which shows the highly-structured nature of the galaxy distribution. http://msowww.anu.edu.au/news/archive/2003/03_mar/
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Editor's Notes
FIGURE 18-22 Dimmer Distant Supernova (a) These Hubble Space Telescope images show the galaxy in which the supernova SN 1997ff occurred. This supernova, more than 10 Bly away, was dimmer than expected, indicating that the distance to it is greater than the distance it would have if the universe had been continually slowing down since the Big Bang. This supports the notion that an outward (cosmological) force is acting over vast distances in the universe. The arrow on the first inset shows the galaxy in which the supernova was discovered. The bright spot on the second inset shows the supernova by subtracting the constant light emitted by all the other nearby objects. (b) The distances and brightnesses of many very distant supernovae are plotted on this diagram. The location of the most distant supernovae in the upper region strongly indicates that the universe has been accelerating outward for the past 6 billion years. (a: Adam Riess, Space Telescope Science Institute, NASA)
FIGURE 18-14 The Observable Universe This diagram shows why we only see part of the entire universe. As time passes, this volume grows, meaning that light from more distant galaxies reaches us. The galaxies we see at the farthest reaches of our telescopes’ resolving power are as they were within a few hundred million years after the Big Bang (see inset ). These galaxies, formed at the same time as the Milky Way, appear young because the light from their beginnings is just now reaching us. The radius of the cosmic light horizon is equal to the distance that light has traveled since the Big Bang. Because the Big Bang occurred about 13.8 billion years ago, the cosmic light horizon today is about 13.8 billion light-years away in all directions. Inset: This image of the Hubble Deep Field shows some of the most distant galaxies we have seen. (inset: Robert Williams and the Hubble Deep Field Team, STScI and NASA)
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