This is a cosmological simulation of the distant universe. The image shows the light emitted by hydrogen atoms in the cosmic web in a region roughly 15 million light-years across. A number of point sources can be seen: These are galaxies in the process of forming their first stars.
This is a cosmological simulation of the distant universe. The image shows the light emitted by hydrogen atoms in the cosmic web in a region roughly 15 million light-years across. A number of point sources can be seen: These are galaxies in the process of forming their first stars.
Jeremy Blaizot/projet SPHINX
CNN  — 

Scientists have discovered a “myriad” galaxies that were of previously undetected. The newly found systems were observed with the world’s most advanced optical telescope.

Cosmological models had long predicted the existence of filaments – gas in which galaxies are created – but no images had been captured of the phenomenon, except in the vicinity of quasars, which are astronomical objects of high luminosity found in the centers of some galaxies.

One of the hydrogen filaments (in blue) discovered by MUSE in the Hubble Ultra-Deep Field is shown.
One of the hydrogen filaments (in blue) discovered by MUSE in the Hubble Ultra-Deep Field is shown.
Roland Bacon/David Mary/ESO/NASA

Using a 3D spectrograph known as the MUSE instrument, installed on the European Southern Observatory’s Very Large Telescope in Chile, scientists have for the first time observed filaments of the cosmic web, revealing a multitude of “unsuspected” dwarf galaxies hidden in the depths of the universe. The instrument’s moniker is short for Multi Unit Spectroscopic Explorer.

The cosmic web is the building block of the cosmos – consisting primarily of dark matter and laced with gas – on which galaxies are built.

Using the MUSE instrument, scientists studied a region in the sky called the Hubble Ultra-Deep Field for some 140 hours, over eight months. The area is the site where the deepest images of the cosmos had ever been obtained.

This photo shows a phenomenon known as zodiacal light. At lower left, a glowing patch extends to the upper right in the direction of Jupiter, the bright object left of center. Zodiacal light is caused by sunlight reflecting off tiny dust particles in the inner solar system—the disintegrated remains of comets and asteroids. Attempts to measure how dark space is using telescopes like Hubble have been thwarted by this ambient glow. As a result, astronomers relied on NASA's distant New Horizons spacecraft to observe the sky free from zodiacal light. The faint background they measured is the equivalent of seeing a neighbor's refrigerator light from a mile away. This very wide, multi-frame panorama was taken in October 2014 at Canyon de Chelly National Monument in northeast Arizona. The zodiacal light is at left, with the northern Milky Way to the right. The Orion constellation is at top right. Jupiter is the brighter object left of center, while a similarly bright object to the right (below Orion) is Sirius. M44 (the Praesepe Cluster) is just above Jupiter. On the horizon, a yellow glow marks the location of the nearby town of Chinle, Arizona.
This photo shows a phenomenon known as zodiacal light. At lower left, a glowing patch extends to the upper right in the direction of Jupiter, the bright object left of center. Zodiacal light is caused by sunlight reflecting off tiny dust particles in the inner solar system—the disintegrated remains of comets and asteroids. Attempts to measure how dark space is using telescopes like Hubble have been thwarted by this ambient glow. As a result, astronomers relied on NASA's distant New Horizons spacecraft to observe the sky free from zodiacal light. The faint background they measured is the equivalent of seeing a neighbor's refrigerator light from a mile away. This very wide, multi-frame panorama was taken in October 2014 at Canyon de Chelly National Monument in northeast Arizona. The zodiacal light is at left, with the northern Milky Way to the right. The Orion constellation is at top right. Jupiter is the brighter object left of center, while a similarly bright object to the right (below Orion) is Sirius. M44 (the Praesepe Cluster) is just above Jupiter. On the horizon, a yellow glow marks the location of the nearby town of Chinle, Arizona.
Zolt Levay/Space Telescope Science Institute

Related article There may be fewer galaxies in the universe than we thought

“The galaxies in the sky and the universe are not distributed the same everywhere,” lead study author Roland Bacon, an astrophysicist and researcher at the Centre de Recherche Astrophysique de Lyon in France, told CNN.

“Galaxies in the early time of the universe, they formed through gas. Gas, mostly hydrogen, is the fuel which forms stars, and in the end forms the galaxy,” he explained. “The galaxies will form in these very long filaments of gas.”

There was some indirect evidence that gas was present in the region, Bacon said. When the team studied quasars they sometimes found the light was obscured, which they believed was due to the presence of gas.

The team’s analysis of the images captured with the telescope revealed light from the hydrogen filaments.

“The best explanation is that the light that we see from the images is not due to the ultraviolet background – it is coming from billions of tiny galaxies forming stars, called dwarf galaxies,” Bacon said.

http://www.spitzer.caltech.edu/images/1923-ssc2008-10a-A-Roadmap-to-the-Milky-Way Like early explorers mapping the continents of our globe, astronomers are busy charting the spiral structure of our galaxy, the Milky Way. Using infrared images from NASA's Spitzer Space Telescope, scientists have discovered that the Milky Way's elegant spiral structure is dominated by just two arms wrapping off the ends of a central bar of stars. Previously, our galaxy was thought to possess four major arms. This artist's concept illustrates the new view of the Milky Way, along with other findings presented at the 212th American Astronomical Society meeting in St. Louis, Mo. The galaxy's two major arms (Scutum-Centaurus and Perseus) can be seen attached to the ends of a thick central bar, while the two now-demoted minor arms (Norma and Sagittarius) are less distinct and located between the major arms. The major arms consist of the highest densities of both young and old stars; the minor arms are primarily filled with gas and pockets of star-forming activity. The artist's concept also includes a new spiral arm, called the "Far-3 kiloparsec arm," discovered via a radio-telescope survey of gas in the Milky Way. This arm is shorter than the two major arms and lies along the bar of the galaxy. Our sun lies near a small, partial arm called the Orion Arm, or Orion Spur, located between the Sagittarius and Perseus arms.
http://www.spitzer.caltech.edu/images/1923-ssc2008-10a-A-Roadmap-to-the-Milky-Way Like early explorers mapping the continents of our globe, astronomers are busy charting the spiral structure of our galaxy, the Milky Way. Using infrared images from NASA's Spitzer Space Telescope, scientists have discovered that the Milky Way's elegant spiral structure is dominated by just two arms wrapping off the ends of a central bar of stars. Previously, our galaxy was thought to possess four major arms. This artist's concept illustrates the new view of the Milky Way, along with other findings presented at the 212th American Astronomical Society meeting in St. Louis, Mo. The galaxy's two major arms (Scutum-Centaurus and Perseus) can be seen attached to the ends of a thick central bar, while the two now-demoted minor arms (Norma and Sagittarius) are less distinct and located between the major arms. The major arms consist of the highest densities of both young and old stars; the minor arms are primarily filled with gas and pockets of star-forming activity. The artist's concept also includes a new spiral arm, called the "Far-3 kiloparsec arm," discovered via a radio-telescope survey of gas in the Milky Way. This arm is shorter than the two major arms and lies along the bar of the galaxy. Our sun lies near a small, partial arm called the Orion Arm, or Orion Spur, located between the Sagittarius and Perseus arms.
NASA/JPL-Caltech

Related article A stream of nearly 500 stars in the Milky Way is actually a family

Our large galaxy, the Milky Way, is orbited by more than 50 other, smaller galaxies, including dwarf galaxies.

Whereas the Milky Way now houses between 200 billion and 400 billion stars, dwarf galaxies contain between 100 million and several billion.

Dwarf galaxies merged in the early universe to form the larger galaxies that populate it today, including the Milky Way.

“We cannot see these galaxies, because they are intrinsically faint and too far: we are observing them 2 billion years after the Big Bang – at a distance of 11 billion light-years. But there are so many that we can see the integrated light produced by them,” he said.

The study was published in the journal Astronomy & Astrophysics.