Figures for the DEEP2 press release at the APS



The DEEP2 project is a redshift survey of 50,000 distant galaxies utilizing the DEIMOS spectrograph on the Keck II telescope.  It is designed to study the evolution of both galaxies and large-scale structure over half the age of the Universe. Please refer to the credits page for a list of our sources of funding, participating institutions, and how to acknowledge the use of DEEP2 data in scientific publications.

We are releasing two figures:

1) A comparison of maps of the Universe from DEEP2 (which is studying distant galaxies far back in time) and the Sloan Digital Sky Survey (which is investigating the local Universe).

2) An illustration of how we test for changes in the Fine Structure Constant with DEEP2 data.

colormapsTwo surveys of the visible universe at very different distances from our Milky Way galaxy.

(Left) The Sloan Digital Sky Survey (SDSS) is a large survey of galaxies in the nearby universe. (Top) The DEEP2 Galaxy Redshift Survey is a smaller survey of much more distant galaxies. Their distance from us (7 billion light years or more) means that the light we see today left these galaxies when the universe was less than half as old as it is today. The galaxies observed by DEEP2 appear much fainter than those observed by SDSS, requiring the largest telescopes on Earth to study them; it would take more than 5,000 years for SDSS to complete this new survey. (Expanded regions) The top panel magnifies a small region of the DEEP2 survey. Note that, even at this early era, galaxies are clustered into filamentary structures, separated by empty voids. The middle panel shows a small region of the SDSS, using a scale that has expanded along with the universe since the era of DEEP2. Note that galaxies here are clustered into denser structures, with somewhat larger voids between them. The bottom panel shows a region of the SDSS of the same physical size as the portion of DEEP2 shown — that is, it is on the same scale as measured with a standard, fixed ruler. Even as galaxies have become more densely clustered together, these clusters have moved farther apart from each other as the universe expands. The strength of these effects depends on cosmological parameters, allowing us to study dark energy by comparing groups and clusters of galaxies at low and high redshift. Credit: Brian Gerke, UC Berkeley
  
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changingalpha
Measuring the evolution of the fine structure constant with DEEP2.

Shown in black is a small portion of an actual spectrum from the DEEP2 Galaxy Redshift Survey, showing the intensity of light recorded by the DEIMOS spectrograph as a function of wavelength (color). This light was actually observed in the red part of the visible spectrum (~8000 Angstroms), but the wavelength scale has been transformed to match the wavelengths with which it was initially emitted (i.e., to the galaxy’s rest frame). Oxygen III ions emit light at specific wavelengths set by the spacing between their energy levels; this produces the narrow peaks seen in the spectrum. If the Fine Structure Constant changes, the spacing between energy levels, and therefore the wavelengths of light emitted, will also change. This is illustrated by the red dashed curve, which shows how the DEEP2 spectrum would appear different if alpha changes by 5%. DEEP2 data indicate that any change in the Fine Structure Constant over the last 7 billion years must be at least 800 times smaller than that shown here. Credit: Jeffrey Newman, Lawrence Berkeley National Laboratory

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created by J. Newman
last updated 2005apr15