Makeup of Universe Before and After Planck Research

Planck's high-precision cosmic microwave background map has allowed scientists to extract the most refined values yet of the Universe's ingredients. Normal matter that makes up stars and galaxies contributes just 4.9% of the Universe's mass/energy inventory. Dark matter, which is detected indirectly by its gravitational influence on nearby matter, occupies 26.8%, while dark energy, a mysterious force thought to be responsible for accelerating the expansion of the Universe, accounts for 68.3%.

The 'before Planck' figure is based on the WMAP 9-year data release presented by Hinshaw et al., (2012).

Illustration credit: ESA

Note: For more information, see Last Command Sent to ESA's Planck Space Telescope; also, PIA17449: Planck and the Cosmic Microwave Background (Artist Concept) and Last Command Sent to Planck Space Telescope.

Gravitational Lensing of CMB Light

This artist’s impression shows how photons in the Cosmic Microwave Background (CMB, as detected by ESA’s Planck space telescope) are deflected by the gravitational lensing effect of massive cosmic structures as they travel across the Universe. Gravitational lensing creates tiny, additional distortions to the mottled pattern of the CMB temperature fluctuations. A small fraction of the CMB is polarized; one component of this polarized light, B-modes, have been given an additional signature by gravitational lensing. This imprint has been found for the first time by combining data from the ground-based South Pole Telescope and ESA’s Herschel space observatory.

Image credit: ESA and the Planck Collaboration

Note: For more information, see PIA17448: Ancient Light Deflected, Long-Sought Pattern of Ancient Light Detected and Herschel Throws New Light on Oldest Cosmic Light.

E-Modes and B-Modes in the CMB Polarization from SPT and Herschel Data

A small portion of the Cosmic Microwave Background (CMB) is polarized, and the pattern observed in the polarized fraction can be split in two components, called E-modes and B-modes. These carry very different and complementary information about both the early and the late Universe. This image shows the data from the National Science Foundation's South Pole Telescope (SPT) and ESA's Herschel Space Observatory that were used to achieve the first detection of B-modes in the CMB polarization.

When the CMB photons travel through the large-scale structure of the Universe, they get deflected by large concentrations of mass such as galaxies, galaxy clusters and the dark matter halos in which these are embedded. One of the effects of this distortion is a mixing of E- and B-modes: part of the signal contained in E-modes is transferred to the B-modes.

The left panel shows the E-mode component of the polarized CMB as detected by SPT. The E-modes are affected by gravitational lensing, and the effect of such distortion is encrypted in the image.

The central panel shows the projected gravitational potential of the large-scale distribution of matter present on the line of sight to the CMB in the same field as the one observed by SPT. The gravitational potential has been inferred using data from Herschel, which probed the light emitted by stars and re-radiated by cosmic dust in all galaxies across cosmic history.

Since gravitational lensing turns part of the E-modes into B-modes, it is possible to combine the observed (and distorted) E-modes with the intervening gravitational potential that distorts them, to estimate the resulting B-modes caused by the gravitational lensing effect. The right panel shows the B-modes of the CMB polarization estimated in this way.

Image credit: D. Hanson, et al., 2013, Physical Review Letters

Note: For more information, see Herschel Throws New Light on Oldest Cosmic Light.

The Hubble Sequence Throughout the Universe's History

This image shows "slices" of the Universe at different times throughout its history (present day, and at 4 and 11 billion years ago). Each slice goes further back in time, showing how galaxies of each type appear. The shape is that of the Hubble tuning fork diagram, which describes and separates galaxies according to their morphology into spiral (S), elliptical (E), and lenticular (S0) galaxies. On the left of this diagram are the ellipticals, with lenticulars in the middle, and the spirals branching out on the right side. The spirals on the bottom branch have bars cutting through their centers.

The present-day Universe shows big, fully formed and intricate galaxy shapes. As we go further back in time, they become smaller and less mature, as these galaxies are still in the process of forming.

This image is illustrative. the Hubble images of nearby and distant galaxies used were selected based on their appearance; their individual distances are only approximate.

Illustration credit: NASA, ESA, M. Kornmesser

Note: For more information, see Hubble Explores the Origins of Modern Galaxies - Astronomers See True Shapes of Galaxies 11 Billion Years Back in Time.

SN 1006

SN 1006: A supernova remnant whose progenitor explosion was seen from Earth over a thousand years ago.

A long Chandra observation reveals SN 1006 supernova remnant in exquisite detail. By overlapping ten different pointings of Chandra's field-of-view, astronomers have stitched together a cosmic tapestry of the debris field that was created when a white dwarf star exploded, sending its material hurtling into space as seen from Earth over a millennium ago. In this new Chandra image, low, medium, and higher-energy X-rays are colored red, green, and blue respectively. Since SN 1006 belongs to the class of supernovas used to measure the expansion of the Universe, the new Chandra data provide insight into these important objects.

Scale: Image is 34 arcmin across. (about 70 light years)

Image credit: NASA/CXC/Middlebury College/F.Winkler

Note: For more information, see SN 1006: X-Ray View of A Thousand-Year-Old Cosmic Tapestry.

All-Sky Map of Dark Matter Distribution in the Universe

This all-sky image shows the distribution of dark matter across the entire history of the Universe as seen projected on the sky. It is based on data collected with ESA's Planck satellite during its first 15.5 months of observations. Dark blue areas represent regions that are denser than the surroundings, and bright areas represent less dense regions. The gray portions of the image correspond to patches of the sky where foreground emission, mainly from the Milky Way but also from nearby galaxies, is too bright, preventing cosmologists from fully exploiting the data in those areas.

The image was compiled by analyzing the tiny distortions imprinted on the photons of the Cosmic Microwave Background (CMB) by the gravitational lensing effect of massive cosmic structures. As photons traveled through these structures, which consist primarily of dark matter, their paths were bent, slightly changing the pattern of the CMB.

The reconstruction technique used to compile this image relies on deviations of the shapes of hot and cold spots in the CMB from their 'typical' shape, and it is impossible to avoid the introduction of statistical 'noise' in the reconstruction; approximately half of the modes in this image are due to this noise.

This image is the first measurement performed over almost the entire sky of the gravitational potential that distorts the CMB, and is one of the highlights of Planck's cosmological results. With these unique data, cosmologists can investigate 13 billion years of the formation of structure in the Universe. The data agree very well with the expectations from the leading cosmological model that describes the origin and evolution of cosmic structure in the Universe.

Image credit: ESA and the Planck Collaboration

Note: For more information, see Planck Sees a Cosmic Journey 13 Billion Years in the Making.

Cosmic Microwave Background Map by Planck

This map shows the oldest light in our universe, as detected with the greatest precision yet by the Planck mission. The ancient light, called the cosmic microwave background, was imprinted on the sky when the universe was 370,000 years old. It shows tiny temperature fluctuations that correspond to regions of slightly different densities, representing the seeds of all future structure: the stars and galaxies of today.

By analyzing the light patterns in this map, scientists are fine tuning what we know about the universe, including its origins, fate and basic components.

Image credit: ESA and the Planck Collaboration

Note: This is a major, major story, and there is a lot of coverage. I will provide only a partial list of articles available, as long as this partial list is:
* PIA16874: The Universe Comes into Sharper Focus
* PIA16875: Map of Matter in the Universe
* PIA16876: The Story of Our Universe
* PIA16877: Peculiar Features in Patterns of Ancient Light
* PIA16878: Refining the Ingredients of Our Universe
* PIA16879: The Universe, Summed Up in a Squiggly Line
* PIA16880: Through the Universe's Looking Glass
* PIA16881: Sounds of the Ancient Universe
* PIA16882: A Journey of Light Through Space and Time
* Planck Mission Brings Universe Into Sharp Focus
* Supercomputer Helps Planck Mission Expose Ancient Light
* Universe Older Than Previously Thought
* Planck CMB
* Cosmic Microwave Background Seen by Planck
* Planck Maps the Dawn of Time
* Power Spectrum of Temperature Fluctuations in the CMB
* Replay: Planck's Cosmic Microwave Background map Media Briefing
* Replay of Planck media briefing - Part 2
* Planck Reveals 'Almost Perfect' Universe

A Swarm of Dark Matter Around the Milky Way

These illustrations, taken from computer simulations, show a swarm of dark matter clumps around our Milky Way galaxy. Some of the dark-matter concentrations are massive enough to spark star formation. Dark matter is an invisible substance that accounts for most of the universe's mass.

In the first panel, thousands of clumps of dark matter coexist with our Milky Way galaxy, shown in the center.

The green blobs in the second panel are those dark-matter chunks massive enough to obtain gas from the intergalactic medium and trigger ongoing star formation, eventually creating dwarf galaxies.

In the third panel, the red blobs are ultra-faint dwarf galaxies that stopped forming stars long ago. New Hubble Space Telescope observations of three of the puny galaxies reveal that star-making in these faint galaxies shut down more than 13 billion years ago.

The synchronized shutdown is evidence that a global event, such as reionization, swept through the early universe. Reionization is a transitional phase in the early universe when the first stars burned off a fog of cold hydrogen.

Popular theory predicts that most of the Milky Way's satellites contain few, if any, stars and are instead dominated by dark matter. More than a dozen small-fry galaxies have been found so far, all by the Sloan Digital Sky Survey, which scanned just a quarter of the sky.

Illustration credit: J. Tumlinson (STScI)

Note: For more information, see Hubble Unmasks Ghost Galaxies.

Ancient White Dwarf Stars

Pushing the limits of its powerful vision, NASA's Hubble Space Telescope uncovered the oldest burned-out stars in our Milky Way Galaxy in this image from 2002. These extremely old, dim "clockwork stars" provide a completely independent reading on the age of the universe without relying on measurements of the expansion of the universe.

The ancient white dwarf stars, as seen by Hubble, turn out to be 12 to 13 billion years old. Because earlier Hubble observations show that the first stars formed less than 1 billion years after the universe's birth in the big bang, finding the oldest stars puts astronomers well within arm's reach of calculating the absolute age of the universe.

Though previous Hubble research sets the age of the universe at 13 to 14 billion years based on the rate of expansion of space, the universe's birthday is such a fundamental and profound value that astronomers have long sought other age-dating techniques to cross-check their conclusions.

The new age-dating observations were done using Hubble to hunt for elusive ancient stars hidden inside a globular star cluster located 5,600 light-years away in the constellation Scorpius.

Photo credit: NASA and H. Richer (University of British Columbia)

Hypothesized Formation of the First Stars

Scientists are simulating how the very first stars in our universe were born. This diagram shows a still from one such simulation. The cube on the right is a blown up region at the center of the box on the left.

The stars we see today formed out of collapsing clouds of gas and dust. In the very early universe, however, the stars had fewer ingredients available. There wasn't any dust yet, or heavy elements, both of which help cool the gas in a cloud so that it can collapse. Instead, the very first stars formed from nothing but hydrogen and helium gas. Astronomers theorize that, in order to overcome their lack of cooling ingredients, these stars would have needed more mass to form. The first stars were thought to have been more massive than even the most massive stars observed today.

At the very center of each box shown here is the forming star - the star itself is too small to see at this scale. The red areas show hot gas with temperatures as high as 50,000 Kelvin (90,000 degrees Fahrenheit), heated by, and surrounding, the forming star. Blue shows much cooler gas, with the darkest blue showing the densest portions of cool gas, shaped like a disk surrounding the seedling star.

As the star pulls matter from the disk onto it, it grows more massive. Meanwhile, some gas -- shown in the red areas -- is so hot that it expands and escapes. Eventually, large amounts of the surrounding gas become too hot and escape. At this point, the star stops growing -- it has finished "baking."

Scientists at NASA's Jet Propulsion Laboratory, Pasadena, California, have used these simulations to show that the first stars, during their formation, had a greater impact on surrounding gas than previously thought. The higher gas temperatures would have caused the stars to stop growing sooner. As a result, the first stars were not likely hundreds of times the mass of the Sun, but only tens of times its mass.

None of these first stars still exist today. After a few million years they exploded in fiery supernovae, spewing heavier elements cooked in their interiors out into the surrounding gas.

For technical details and videos visit http://www-tap.scphys.kyoto-u.ac.jp/~hosokawa/firststarstop_e.html.

Photo credit: NASA/JPL-Caltech/Kyoto University

Galaxies at the End of the Era of Reionization

This artist’s impression shows galaxies at a time less than a billion years after the Big Bang, when the Universe was still partially filled with hydrogen fog that absorbed ultraviolet light. New observations with the ESO Very Large Telescope are probing this important phase of the early Universe by studying the light from some of the most distant galaxies ever detected.

Illustration credit: ESO/M. Kornmesser

Note: For more information and photos, see Distant Galaxies Reveal The Clearing of the Cosmic Fog.

Growing Galaxies Gently

New observations from ESO’s Very Large Telescope have, for the first time, provided direct evidence that young galaxies can grow by sucking in the cool gas around them and using it as fuel for the formation of many new stars. In the first few billion years after the Big Bang the mass of a typical galaxy increased dramatically and understanding why this happened is one of the hottest problems in modern astrophysics. The results appear in the 14 October issue of the journal Nature.

The first galaxies formed well before the Universe was one billion years old and were much smaller than the giant systems — including the Milky Way — that we see today. So somehow the average galaxy size has increased as the Universe has evolved. Galaxies often collide and then merge to form larger systems and this process is certainly an important growth mechanism. However, an additional, gentler way has been proposed.

A European team of astronomers has used ESO’s Very Large Telescope to test this very different idea — that young galaxies can also grow by sucking in cool streams of the hydrogen and helium gas that filled the early Universe and forming new stars from this primitive material. Just as a commercial company can expand either by merging with other companies, or by hiring more staff, young galaxies could perhaps also grow in two different ways — by merging with other galaxies or by accreting material.

The team leader, Giovanni Cresci (Osservatorio Astrofisico di Arcetri) says: “The new results from the VLT are the first direct evidence that the accretion of pristine gas really happened and was enough to fuel vigorous star formation and the growth of massive galaxies in the young Universe.” The discovery will have a major impact on our understanding of the evolution of the Universe from the Big Bang to the present day. Theories of galaxy formation and evolution may have to be re-written.

The group began by selecting three very distant galaxies to see if they could find evidence of the flow of pristine gas from the surrounding space and the associated formation of new stars. They were very careful to make sure that their specimen galaxies had not been disturbed by interactions with other galaxies. The selected galaxies were very regular, smoothly rotating discs, similar to the Milky Way, and they were seen about two billion years after the Big Bang (at a redshift of around three).

In galaxies in the modern Universe the heavy elements [1] are more abundant close to the center. But when Cresci’s team mapped their selected distant galaxies with the SINFONI spectrograph on the VLT [2] they were excited to see that in all three cases there was a patch of the galaxy, close to the center, with fewer heavy elements, but hosting vigorously forming stars, suggesting that the material to fuel the star formation was coming from the surrounding pristine gas that is low in heavy elements. This was the smoking gun that provided the best evidence yet of young galaxies accreting primitive gas and using it to form new generations of stars.

Notes:
[1] The gas filling the early Universe was almost all hydrogen and helium. The first generations of stars processed this primitive material to create heavier elements such as oxygen, nitrogen and carbon by nuclear fusion. When this material was subsequently spewed back into space by intense particle winds from massive young stars and supernova explosions the amounts of heavy elements in the galaxy gradually increased. Astronomers refer to elements other than hydrogen and helium as “heavy elements.”

[2] By carefully splitting up the faint light coming from a galaxy into its component colors using powerful telescopes and spectrographs, astronomers can identify the fingerprints of different chemicals in remote galaxies, and measure the amounts of heavy elements present. With the SINFONI instrument on the VLT astronomers can go one better and get a separate spectrum for each part of an object. This allows them to make a map that shows the quantity of heavy elements present in different parts of a galaxy and also determine where in the galaxy star formation is occurring most vigorously.

Illustration credit: ESO/L. Calçada

The Era of Reionization

Astronomers using ESO’s Very Large Telescope (VLT) have measured the distance to the most remote galaxy so far, UDFy-38135539, existing when the Universe was only about 600 million years old (a redshift of 8.6). At this early time, the Universe was not fully transparent and much of it was filled with a hydrogen fog that absorbed the fierce ultraviolet light from young galaxies. The transitional period when the fog was still being cleared by this ultraviolet light is known as the era of reionization, illustrated with this still from a representative scientific simulation (see Alvarez et al. (2009) for more details).

When the Universe cooled down after the Big Bang, about 13.7 billion years ago, electrons and protons combined to form neutral hydrogen gas. This cool dark gas was the main constituent of the Universe during the so-called Dark Ages, when there were no luminous objects. This phase eventually ended when the first stars formed and their intense ultraviolet radiation slowly made the hydrogen fog transparent again by splitting the hydrogen atoms back into electrons and protons, a process known as reionization. This epoch in the Universe’s early history lasted from about 150 million to 800 million years after the Big Bang. In this visualization, ionized regions are blue and translucent, ionization fronts are red and white, and neutral regions are dark and opaque.

The new study shows that the glow from UDFy-38135539 seems not to be strong enough on its own to clear out the hydrogen fog. There must be other galaxies, probably fainter and less massive nearby companions of UDFy-38135539, which also helped make the space around the galaxy transparent.

Illustration credit: M. Alvarez, R. Kaehler, and T. Abel

Furthest Galaxy (to date) UDFy-38135539

This image shows the infrared Hubble Ultra Deep Field taken by the NASA/ESA Hubble Space Telescope in 2009, in which several robust candidate distance-record-breaking objects were discovered. Confirming the distances to such faint and remote objects is however an enormous challenge and can only reliably be done using spectroscopy from very large ground-based telescopes by measuring the redshift of the galaxy’s light.

Astronomers using ESO’s Very Large Telescope (VLT) have now measured the distance to the most remote galaxy so far, UDFy-38135539 (the faint object shown in the excerpt on the left), which we see as it was when the Universe was only about 600 million years old (a redshift of 8.6). These are the first confirmed observations of a galaxy whose light is clearing the opaque hydrogen fog that filled the cosmos at this early time.

Photo credit: NASA, ESA, G. Illingworth (UCO/Lick Observatory and University of California, Santa Cruz) and the HUDF09 Team

Note: For more information, see Clearing the Cosmic Fog.

Large-Scale Structure of the Universe

This illustration depicts the large-scale distribution of galaxies as seen by the Sloan Digital Sky Survey, an ambitious project that determined the distances of about one million galaxies.

The two cones on the left of the image are a three dimensional (3D) map of the galaxies with the Earth at the center. Going from the center to the upper/lower edges of the map, more and more distant galaxies are seen, up to distances of about 2 thousand million [billion] light years. The color of the galaxies is related to their luminosity. The clumpiness in the distribution of matter is clearly visible in this representation.

The panel on the right shows a two dimensional (2D) image of galaxies in a small region of the sky. The 3D map is computed by combining the information contained in 2D images such as this one with an estimate of the distances of each individual object visible in it, derived from their spectra.

Illustration credit: Sloan Digital Sky Survey Team, NASA, NSF, DOE

3D Map of Dark Matter in the Universe

This three-dimensional map offers a first look at the web-like large-scale distribution of dark matter, an invisible form of matter that accounts for most of the Universe's mass.

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.

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