The map reveals a loose network of dark matter filaments, gradually collapsing under the relentless pull of gravity, and growing clumpier over time.

The three axes of the box correspond to sky position (in right ascension and declination), and distance from the Earth increasing from left to right (as measured by cosmological redshift). Note how the clumping of the dark matter becomes more pronounced, moving right to left across the volume map, from the early Universe to the more recent Universe.

Credits: NASA, ESA and R. Massey (California Institute of Technology)

The map reveals a loose network of dark matter filaments, gradually collapsing under the relentless pull of gravity, and growing clumpier over time. This confirms theories of how structure formed in our evolving Universe, which has transitioned from a comparatively smooth distribution of matter at the time of the big bang. The dark matter filaments began to form first and provided an underlying scaffolding for the subsequent construction of stars and galaxies from ordinary matter. Without dark matter, there would have been insufficient mass in the Universe for structures to collapse and galaxies to form.

[Top] - Three slices through the evolving distribution of dark matter. The dataset is created by splitting the background source galaxy population into discrete epochs of time (like cutting through geologic strata), looking back into the past. This is calibrated by measuring the cosmological redshift of the lensing galaxies used to map the dark matter distribution, and binning them into different time/distance “slices”. Each panel represents an area of sky nine times the angular diameter of the full Moon. Note that this fixed angle means that the survey volume is a really a cone, and that the physical area of the slices increases (from 60 million light-years on a side to 100 million light-years on a side) from left to right.

[Bottom] - When the slices across the Universe and back into time are combined, they make a three-dimensional map of dark matter in the Universe. The three axes of the box correspond to sky position (in right ascension and declination), and distance from the Earth increasing from left to right (as measured by cosmological redshift). Note how the clumping of the dark matter becomes more pronounced, moving right to left across the volume map, from the early Universe to the more recent Universe.

Credits: NASA, ESA and R. Massey (California Institute of Technology)

At full resolution the image would be 100,800 x 100,800 pixels. The image was taken in hear-infrared light (Hubble’s F814W, or I-band, filter).

Credits: NASA, ESA and A. Koekemoer (STScI)

Dark matter is an invisible form of matter comprising the bulk of the Universe’s mass. Because the dark matter can’t be seen directly, its distribution on the sky is measured via weak gravitational lensing. This is the distortion of light from distant galaxies (rather like the effect of a funhouse mirror), due to the gravitational warping of space by dark matter along our line of sight. The Hubble Space Telescope’s keen ability to measure these distortions allowed this map to be created with fine resolution. Constructing the entire map required the measurement of the shapes of half a million background galaxies.

The map was derived from the Hubble Space Telescope’s largest ever survey of the Universe, the Cosmic Evolution Survey (“COSMOS”), carried out by an international team of 70 astronomers. In making the COSMOS survey, Hubble photographed 575 adjacent and slightly overlapping views of the universe using the Advanced Camera for Surveys' (ACS) Wide Field Camera onboard Hubble. It took nearly 1,000 hours of observations. The distances to the galaxies were determined from their spectral redshifts, using the Subaru telescope in Hawaii. The distribution of additional gas outside galaxies was measured with the European Space Agency’s XMM/Newton telescope. The separate images can be downloaded here (Normal matter, Dark matter)

Credits: NASA, ESA and R. Massey (California Institute of Technology)

[Right] – COSMOS. The Cosmological Evolution Survey (COSMOS) is the largest Hubble mosaic of the sky. It covers two square degrees of sky. By comparison, the Earth’s moon is one-half degree across. The survey detected over 2 million galaxies spanning 75 percent of the age of the Universe. The field is being imaged by most major space-based and ground-based telescopes. [Left] - Several survey fields are shown for comparison.

GEMS Galaxy Evolution from Morphology and Spectral Energy Distributions (GEMS) imaged an area of 900 square minutes of arc on the sky with the Hubble Space Telescope’s Advanced Camera for Surveys. This contiguous field is centred on the Chandra Deep Field South, a deep X-ray telescope survey of the universe. GEMS contains roughly 10,000 galaxies down to a depth of 24th magnitude.

GOODS The Great Observatories Origins Deep Survey (GOODS) unites extremely deep observations from Hubble with NASA's other space observatories (the Spitzer Space Telescope and the Chandra X-ray Observatory, and the XMM-Newton telescope), as well as observations by the most powerful ground-based telescopes. GOODS covers a total of roughly 320 square arc minutes.

HUDF The Hubble Ultra Deep Field is humankind’s farthest view into to the Universe in visible light, uncovering several thousand galaxies down to 31st magnitude. The field of view is one Hubble Advanced Camera for Surveys wide field frame.

Credits: NASA, ESA and Z. Levay (STScI)