Tag Archives: galaxy cluster

This NASA/ESA Hubble Space Telescope image shows the massive galaxy cluster MACSJ 1206. Embedded within the cluster are the distorted images of distant background galaxies, seen as arcs and smeared features. These distortions are caused by the dark matter in the cluster, whose gravity bends and magnifies the light from faraway galaxies, an effect called gravitational lensing. This phenomenon allows astronomers to study remote galaxies that would otherwise be too faint to see. (NASA, ESA, G. Caminha (University of Groningen), M. Meneghetti (Observatory of Astrophysics and Space Science of Bologna), P. Natarajan (Yale University), the CLASH team, and M. Kornmesser (ESA/Hubble))

Astronomers Investigate Dark Matter’s Missing Ingredient

Our understanding of dark matter and its behavior could be missing a key ingredient. More gravitational lensing, the curving of spacetime and light by massive objects, could lead to the perfect recipe to solve this cosmic mystery. 

Despite comprising anywhere between 70–90% of the Universe’s total mass and the fact that its gravitational influence literally prevents galaxies like the Milky Way from flying apart, science is still in the dark about dark matter

As researchers around the globe investigate the nature and composition of this elusive substance, a study published in the journal Science suggests that theories of dark matter could be missing a crucial ingredient, the lack of which has hampered our understanding of the matter that literally holds the galaxies together. 

The presence of something missing from our theories of dark matter and its behavior emerged from comparisons of observations of the dark matter concentrations in a sample of massive galaxy clusters and theoretical computer simulations of how dark matter should be distributed in such clusters. 

Astronomers measured the amount of gravitational lensing caused by this cluster to produce a detailed map of the distribution of dark matter in it. Dark matter is the invisible glue that keeps stars bound together inside a galaxy and makes up the bulk of the matter in the Universe. (NASA, ESA, G. Caminha (University of Groningen), M. Meneghetti  (Observatory of Astrophysics and Space Science of Bologna), P. Natarajan (Yale University), and the CLASH team.)


Using observations made by the Hubble Space Telescope and the Very Large Telescope (VLT) array in the Atacama Desert of northern Chile, a team of astronomers led by Massimo Meneghetti of the INAF-Observatory of Astrophysics and Space Science of Bologna in Italy have found that small-scale clusters of dark matter seem to cause lensing effects that are 10 times greater than previously believed.

“Galaxy clusters are ideal laboratories in which to study whether the numerical simulations of the Universe that are currently available reproduce well what we can infer from gravitational lensing,” says Meneghetti. “We have done a lot of testing of the data in this study, and we are sure that this mismatch indicates that some physical ingredient is missing either from the simulations or from our understanding of the nature of dark matter.”

Just Add Gravitational Lensing

The lensing that the team believes accounts for dark matter discrepancies is a factor of Einstein’s theory of general relativity which suggests that gravity is actually an effect that mass has on spacetime. The most common analogy given for this effect is the distortion created on a stretched rubber sheet when a bowling ball is placed on it.

This effect in space that results from a star or even a galaxy curving space and thus bending the path of light as it passes the object. Otherwise known as gravitational lensing it is commonly seen when a background object–which could be as small as a star or as large as a galaxy– moves in front of a foreground object and curves light from it giving it an apparent location in the sky. 

The gravitational lensing of a distant quasar by an intermediate body forms a double image seen by astronomers on Earth. (Lambourne. R, Relativity, Gravitation and Cosmology, Cambridge Press, 2010)

In extreme cases, where this lensing causes the paths of light to change in such a way that its arrival time at an observer is different, it can cause a background object to appear in the night sky at various different points. A beautiful example of this is an Einstein ring, where a single object appears multiple times forming a ring-like arrangement.

Because dark matter only interacts via gravity, ignoring even electromagnetic interactions — hence why it can’t be seen — gravitational lensing is currently the best way to infer its presence and map the location of dark matter clusters in galaxies.

 Returning to the ‘rubber sheet’ analogy from above, as you can imagine, a cannonball will make a more extreme ‘dent’ in the sheet than a bowling ball, which in turn makes a bigger dent than a golf ball. Likewise, the larger the cluster of dark matter — the greater the mass — the more extreme the curvature of space and therefore, light.

The gravitational microlensing effect results from the bending of space-time near an object of given mass that is predicted by Einstein’s general theory of relativity. An object, such as a star, crossing our line of sight to a more distant source star will affect the light from that star just like a lens, producing two close images whose total brightness is enhanced. If the lensing star is accompanied by a planet, one can (potentially) observe not only the principal effect from the star, but also a secondary, smaller effect resulting from perturbation by the planet. ( Beaulieu et al)

But now imagine what would happen if the bowling ball on the rubber sheet was surrounded by marbles. Though their individual distortions may be small, their cumulative effect could be considerable. The team believes this may be what is happening with smaller clusters of dark matter. These small scale clumps of dark matter enhance the overall distortion. In a way, this can be seen as a large lens with smaller lenses embedded within it.

Cooking Up A High-Fidelity Dark Matter Map

The team of astronomers was able to produce a high-fidelity dark matter map by using images taken by Hubble’s Wide Field Camera 3 and Advanced Camera Survey combined spectra data collected by The European Southern Observatory’s (ESO) VLT. Using this map, and focusing on three key clusters — MACS J1206.2–0847, MACS J0416.1–2403, and Abell S1063 — the researchers tracked the lensing distortions and from there traced out the amount of dark matter and how it is distributed.

This image from the NASA/ESA Hubble Space Telescope shows the galaxy cluster MACS J0416.1–2403. A team of researchers used almost 200 images of distant galaxies, whose light has been bent and magnified by this huge cluster, combined with the depth of Hubble data to measure the total mass and dark matter content of this cluster more precisely than ever before. (ESA/Hubble, NASA, HST Frontier Fields)

“The data from Hubble and the VLT provided excellent synergy,” says team member Piero Rosati, Università Degli Studi di Ferrara in Italy. “We were able to associate the galaxies with each cluster and estimate their distances.”

This led the team to the revelation that in addition to the dramatic arcs and elongated features of distant galaxies produced by each cluster’s gravitational lensing, the Hubble images also show something altogether unexpected–a number of smaller-scale arcs and distorted images nested near each cluster’s core, where the most massive galaxies reside.

The team thinks that these nested lenses are created by dense concentrations of matter at the center of individual cluster galaxies. They used follow-up spectroscopic observations to measure the velocity of the stars within these clusters and through a calculation method known as viral theorem, confirmed the masses of these clusters, and in turn, the amount of dark matter they contain. 

Abell S1063, a galaxy cluster, was observed by the NASA/ESA Hubble Space Telescope as part of the Frontier Fields programme. The huge mass of the cluster acts as a cosmic magnifying glass and enlarges even more distant galaxies, so they become bright enough for Hubble to see. (NASA, ESA, and J. Lotz (STScI))

This fusion of observations from these different sources allowed the team to identify dozens of background lensed galaxies that were imaged multiple times. The researchers then took this high-fidelity dark matter map and compared it to samples of simulated galaxy clusters with similar masses, located at roughly the same distances.

These simulated galaxy clusters did not show the same dark matter cluster concentrations — at least not on a small scale that is associated with individual cluster galaxies. 

The discovery of this disparity should help astronomers design better computer simulation models and thus develop a better understanding of how dark matter clusters. This improved understanding may ultimately lead to the discovery of what this abundant and dominant form of matter actually is. 


Original research: Meheghetti. M., Davoli. G., Bergamini. P., et al, ‘An excess of small-scale gravitational lenses observed in galaxy clusters,’ Science, [2020], 

Astronomers find the most massive black hole in the local universe

In a galaxy far, far away… astronomers have discovered the most massive black hole in the local observable universe. According to recent observations, the black hole at the center of the Holm 15A galaxy has a staggering 40 billion solar masses. For comparison, the Milky Way’s supermassive black hole measures only 4 million solar masses.

 Image of Abell 85 cluster of galaxies. The core of the central bright galaxy Holm15A is home to the most massive black hole in the local universe. Credit: Max Planck.

The discovery came to light while a team of astronomers, from the Max Planck Institute for Extraterrestrial Physics and the University Observatory Munich, was surveying Abell 85. It is a galaxy cluster located about 740 million light-years from Earth, which consists of more than 500 individual galaxies.

Holm 15A came to the researchers’ attention when they noticed a huge dark patch at its center. For a galaxy whose stars are equivalent to 2 trillion solar masses — in other words, a very bright galaxy — this was highly surprising to see.

Observations suggested that the murky and diffuse center of Holm 15A is almost as large as the Large Magellanic Cloud, a big clue hinting towards the presence of a black hole with a very high mass.

“There are only a few dozen direct mass measurements of supermassive black holes, and never before has it been attempted at such a distance,” said Jens Thomas, a Max Planck researcher and the lead author of the study. “But we already had some idea of the size of the Black Hole in this particular galaxy, so we tried it.”

With the help of the observatory at the University Observatory Munich and the MUSE instrument at the Very Large Telescope in Chile, the astronomers were able to estimate the black hole’s mass by measuring the motion of stars around the galaxy’s core. The results suggest that at the heart of Holm 15A lies a behemoth with 40 billion solar masses — the most massive black hole yet known to scientists in the local universe.

“This is several times larger than expected from indirect measurements, such as the stellar mass or the velocity dispersion of the galaxy,” says Roberto Saglia, senior scientist at the Max Planck Institute for Extraterrestrial Physics.

The diffuse galactic core also suggests that Holm 15A formed after two smaller galaxies merged. Both had supermassive black holes at their center, so when the galaxies merged, so did the black holes. As the black hole became more massive, so did the rate at which stars were expelled from the center due to the gravitational interactions between the merging elements, a physical process known as core-scouring. And, because there is no gas left in the galactic core to form new stars, it will look depleted, dim, and diffuse.

“The newest generation of computer simulations of galaxy mergers gave us predictions that do indeed match the observed properties rather well,” Thomas said. “These simulations include interactions between stars and a black hole binary, but the crucial ingredient is two elliptical galaxies that already have depleted cores. This means that the shape of the light profile and the trajectories of the stars contain valuable archaeological information about the specific circumstances of core formation in this galaxy—as well as other very massive galaxies.”

This diagram shows the distribution of the surface brightness of the central cluster galaxy Holm 15A. Compared to other galaxies, the core of the galaxy has a very low surface brightness and extends over a diameter of about 15,000 light years. Credit: Max Planck Society

The study’s key insight lies in the newly established relationship between black hole mass and a galaxy’s surface brightness. In the future, astronomers could use this insight to estimate a black hole’s mass in more distant galaxies where our instruments are unable to measure stellar motions in the vicinity of a galactic core.

The results are due to be published in The Astrophysical Journal. The findings were published in the preprint server ArXiv.

Credit: ESA/Hubble & NASA.

Hubble finds ‘smiley face’ drawn by galactic objects

Credit: ESA/Hubble & NASA.

Credit: ESA/Hubble & NASA.

Outer space can be an intimidating and downright frightening thing to contemplate, which is why it helps to encounter a friendly face once in a while. In a new image captured by NASA’s Hubble Space Telescope, the elements of a galaxy cluster called SDSS J0952+3434 have aligned in such a way as to draw a smiley face many light-years across.

The ‘eyes’ of the smiley face are comprised of two yellow-hued blobs which hang atop a sweeping arc of light. The arc-shaped object is actually a galaxy whose shape has been distorted because its light passed near a massive object en route to Earth. This effect is known as gravitational lensing and requires that the three participants (the light source, the massive structure, and the observer — which is on Earth) be aligned in a straight-line configuration called a syzygy.

According to general relativity, light follows the curvature of spacetime. Consequently, when light passes around a massive object, it bends. This means that the light from an object on the other side will bend towards an observer’s eye, as it does through an ordinary lens. But unlike an optical lens, a gravitational lens has no single focal point, but a focal line. Scientists have been exploiting gravitational lensing — which is actually quite a common astronomical technique nowadays — in order to image distant cosmic objects that would have otherwise appeared as faint dots to our instruments.

Hubble stumbled across the friendly-looking galactic shape while it was searching for new stellar nurseries to study. Stars are born out of giant clouds of gas which eventually grow unstable, collapsing under gravity. Hubble’s Wide Field Camera 3 (WFC3) allows astronomers to analyze the luminosity, size, and formation rate of different stellar nurseries, which will one day allow them to understand the formation of new stars in finer detail than before. It’s important to study stellar formation within different galaxies to gain a richer context, which is why Hubble had its gaze fixed on a galaxy cluster.

The incredible Fornax Galaxy Cluster, home to more than 50 galaxies. Credit: ESO.

Massive 2.3-gigapixel image of Fornax Galaxy Cluster documents galactic ‘serial killer’

The incredible Fornax Galaxy Cluster, home to more than 50 galaxies. Credit: ESO.

The incredible Fornax Galaxy Cluster, home to more than 50 galaxies. Credit: ESO.

Astronomers working with the VLT Survey Telescope (VST) at ESO’s Paranal Observatory in Chile obtained an unparalleled detailed image of the Fornax Galaxy Cluster.  It is the second richest galaxy cluster within 100 million light-years, after the considerably larger Virgo Cluster, containing thousands of galaxies.

Do you feel small yet?

Some of the galaxies in the 2.3-gigapixel image appear monstrously large, dominating the foreground, while others are less conspicuous appearing as pinpricks. It’s astounding to picture that even these tiny specks house millions and millions of stars, each in turn home to various planets, some possibly habitable.

Inside the cluster, comprising of more than 50 galaxies, we can also find a galactic ‘serial killer’ that has been on astronomers’ most wanted list since the 1970s. The lenticular galaxy NGC 1316 has a rich and dynamic history being formed by the merger of multiple smaller galaxies. Scientists are aware of this turbulent past due to the ripples, loops, and arcs embedded in the galaxy’s starry outer envelope.

One 2014 study found that the unusual dust lanes embedded within the large envelope of stars, as well as an unusually small globular star cluster, suggest NGC 1316 swallowed a dust-rich spiral galaxy about three billion years ago. Subsequent observations revealed NGC 1316 annexed other galaxies and suggest that the disruptive behavior is continuing.

Closeup of NGC 1316 and its neighbor, NGC 1317. Credit: ESO.

Closeup of NGC 1316 and its neighbor, NGC 1317. Credit: ESO.

Through a combination of imaging and modeling, ESO scientists were now able to observe the finer details of NGC 1316’s unusual structure. They learned that the galactic gobbling caused a massive influx of gas which fuels a supermassive black hole at the heart of NGC 1316. The exotic object is a staggering 150 million times more massive than the Sun. As matter accretes around the supermassive black hole, powerful jets of high-energy particles are spewed into the cosmos, making NGC 1316 the fourth-brightest radio source in the sky.

Astronomers also found that NGC 1316 is home to four Ia supernovae. This type of supernova — the extremely bright, super-powerful explosion of a dying star — are important astrophysical events that are often used to measure the distance to a host galaxy. In our case, NGC 1316 lies 60 million light-years away from Earth.

Scientific reference: E. Iodice et al. The Fornax Deep Survey with VST. II. Fornax A: A Two-phase Assembly Caught in the Act, The Astrophysical Journal (2017). DOI: 10.3847/1538-4357/aa6846

galaxy cluster star

Incredibly active galaxy cluster creates 800 stars every year

An international team from CalTech has discovered an incredibly active cluster of galaxies which gives birth to about 800 stars every year. The gargantuan primordial cluster is 9.8 billion light years away from us, houses at least 27 galaxies and has a combined mass equal to 400 trillion Suns.

galaxy cluster star

A massive cluster of galaxies, called SpARCS1049+56, can be seen in this multi-wavelength view from NASA’s Hubble and Spitzer space telescopes. Photo: Nasa/STScI/ESA/JPL-Caltech/McGill

A galaxy cluster is a group of galaxy that usually consists of hundreds of galaxies bound together by gravitational attraction. Our own galaxy, the Milky Way, resides in a cluster known as the Local Group, which itself is a member of the massive Laniakea supercluster. However, our cluster only creates 2-3 stars every year.

The discovery, made with the help of the Nasa/ESA Hubble Space Telescope, is quite possibly the biggest stellar nursery known to date.

“We think the giant galaxy at the centre of this cluster is furiously making new stars after merging with a smaller galaxy,” said lead author Tracy Webb of McGill University in Canada.

The galaxy was initially discovered using NAS’s Spitzer Space Telescope and the Canada-France-Hawaii Telescope, located on Mauna Kea in Hawai’i and confirmed using the W.M. Keck Observatory, also on Mauna Kea.

“For this research, we had to look closely at what we call ‘empty pixels,’ the pixels between galaxies and stars,” study author Asantha Cooray, a professor of physics at the University of California, Irvine, said in a news release. “We can separate noise from the faint signal associated with first galaxies by looking at the variations in the intensity from one pixel to another. We pick out a statistical signal that says there is a population of faint objects. We do not see that signal in the optical [wavelengths], only in infrared,” Cooray noted. “This is confirmation that the signal is from early times in the universe.”

Journal Reference: Tracy Webb et al – An extreme starburst in the core of a rich galaxy cluster at z=1.7.  The Astrophysical Journal, Volume 809, Number 2.

 

Abell 2744, Pandora's Cluster. Photo: : NASA, ESA, and J. Lotz, M. Mountain, A. Koekemoer, and the HFF Team

Hubble goes farther than ever before: images reveal deepest view of the Universe yet

Abell 2744, Pandora's Cluster. Photo: : NASA, ESA, and J. Lotz, M. Mountain, A. Koekemoer, and the HFF Team

Abell 2744, Pandora’s Cluster. Photo: : NASA, ESA, and J. Lotz, M. Mountain, A. Koekemoer, and the HFF Team. Huge resolution photo here.

This year Hubble will embark on one its most ambitious projects yet, as it’s scheduled to glimpse farther away into the Universe than ever before. Six new “deep field” images are slated, and recently astronomers at Hubble have delivered the first to the public. The image reveals extremely faint, tiny galaxies that may be more than 12 billion light-years away, and offer tantalizing clues of things to come in the next parts of the project – findings that could show how the Universe looked like in its infancy and how the cosmos formed in its present form.

“It is the deepest view of the universe ever taken,” says project leader Jennifer Lotz of the Space Telescope Science Institute (STScI) in Baltimore. “We’re seeing things 10 or 20 times fainter than anything we’ve seen before.” Lotz and her colleagues presented the image today here at the 223rd meeting of the American Astronomical Society.

The image is shows the massive galaxy cluster Abell 2744, the deepest ever made of any cluster of galaxies. Some of the faintest and youngest galaxies ever detect in space are shown, after the telescope used 50 hours of light exposure. Some 3,000 ancient galaxies can be found in the cluster – their exact distance from Earth will be determined following observations taken by NASA’s Spitzer and Chandra space telescopes, which see in infrared and x-ray light, respectively.

A deep view

Hubble started its first Deep Field images in 1996, and since then thousands of previously undiscovered galaxies were identified in “blank patches” of space. In the new project, called Hubble “Frontier Fields,” researchers plan on peering farther than ever before, making use of advanced cameras mounted on the space telescope, combined with natural occurring gravitational lenses.

Gravitational lenses naturally magnify views of distant galaxies the lie behind very massive objects, like galaxy clusters. These massive objects cause light to warp and curve, so any object behind them will look brightened and magnified to observers on Earth. It’s a neat trick, one that astronomers are keen to exploit to make the best and deepest images of the Universe.

So far, data is preliminary and starting May this year, Hubble will collect more data on this first field, bringing the photo’s total exposure time to 103 hours, and over the next three years it will examine the other five Frontier Fields, which were chosen at spots where nature’s most powerful gravitational lenses lie.

“We’re really interested in knowing what happened in that first billion years of the universe,” Lotz says. “The thing that Frontier Fields is going to do is look for the galaxies that were basically small enough in those first billion years to turn into our Milky Way Galaxy. We want to know, when did galaxies like the Milky Way first come to be?”

via Scientific American

These are NASA Hubble Space Telescope natural-color images of four target galaxy clusters that are part of an ambitious new observing program called The Frontier Fields. NASA's Great Observatories are teaming up to look deeper into the universe than ever before. The foreground clusters range in distance from 3 billion to 5 billion light-years from Earth. (c) NASA/ESA

NASA’s great observatories combine to probe deeper in the Universe

These are NASA Hubble Space Telescope natural-color images of four target galaxy clusters that are part of an ambitious new observing program called The Frontier Fields. NASA's Great Observatories are teaming up to look deeper into the universe than ever before.  The foreground clusters range in distance from 3 billion to 5 billion light-years from Earth. (c) NASA/ESA

These are NASA Hubble Space Telescope natural-color images of four target galaxy clusters that are part of an ambitious new observing program called The Frontier Fields. NASA’s Great Observatories are teaming up to look deeper into the universe than ever before. The foreground clusters range in distance from 3 billion to 5 billion light-years from Earth. (c) NASA/ESA

Each of NASA’s Great Observatories – Hubble, Spitzer and Chandra – have been designed to peer through the Universe in a characteristic manner. The telescopes have provided along the years massive amount of astronomical data and have helped scientists make important discoveries. What if you combine each of the telescopes’ strong points to assemble one massive probe capable of seeing farther in the Universe than ever before? That’s exactly what  The Frontier Fields ambitious space program will undertake in the following three years, combining the observational power of all three major NASA telescopes along with natural gravitational lenses to study six massive clusters of galaxies.

“The Frontier Fields program is exactly what NASA’s Great Observatories were designed to do; working together to unravel the mysteries of the universe,” said John Grunsfeld, associate administrator for NASA’s Science Mission Directorate in Washington. “Each observatory collects images using different wavelengths of light with the result that we get a much deeper understanding of the underlying physics of these celestial objects.”

The program will tackle galaxy clusters that are among the most massive assemblages of matter known. Because of their humongous mass, these galaxy clusters (hundreds to thousands of galaxies bound together by gravity), exert powerful gravitational fields which can be used to brighten and magnify more distant galaxies so they can be observed. This is called gravitational lensing  and because of it  light rays that would have otherwise not reached the observer are bent from their paths and towards the observer.

Pandora’s Cluster. (c) NASA

Pandora’s Cluster. (c) NASA

The first object the astronomers will be directing their view towards is  Abell 2744 or  Pandora’s Cluster. This giant cluster is actually thought to be the result of four distinct galaxy clusters that piled-up over the span of 350 million years.  Studying this cluster, astronomers hope they can discover galaxies that were formed just a few hundred millions years after the Big Bang.

“The idea is to use nature’s natural telescopes in combination with the great observatories to look much deeper than before and find the most distant and faint galaxies we can possibly see,” said Jennifer Lotz, a principal investigator with the Space Telescope Science Institute in Baltimore, Md.

Each Great Observatory will have its role to play. Hubble tells astronomers in which way to direct their view and how many galaxies or stars are born in a system. Spitzer can relay how old these cosmic bodies are. Chanda, using its  X-ray wavelengths instruments, will image the clusters and tell astronomers what their  mass and gravitational lensing power is.

“We want to understand when and how the first stars and galaxies formed in the universe, and each great observatory gives us a different piece of the puzzle,” said Peter Capak, the Spitzer principal investigator for the Frontier Fields program at NASA’s Spitzer Science Center at the California Institute of Technology, Pasadena.

 

Hubble captures Dorado galaxy [PHOTO]

Located some 62 million-light years away, the Dorado constellation is home to a galaxy cluster, called the Dorado Group, comprised of around 70 galaxies. A pretty massive figure by all accounts, considering the Local Group, which also include the Milky Way, contains a mere 30 galaxies under its belt.

Recently, Hubble captured a splendid photo of NGC 1483, a barred spiral galaxy located in the southern constellation of Dorado. The nebulous galaxy features a bright central bulge, hence the barred spiral term used to describe it, and diffuse arms filled with young stars to its margins. Astronomers hypothesize that these bars, which are commonly formed in around two out of three spiral galaxies, actually show that a galaxy is fully matured.

The zoom in rectangle shows the brightest galaxy so far found through a gravity lens. It's 20 times larger and over three times brighter than typically lensed galaxies.The rounded outlines that form an arc are actually the remnant distortions discussed in the article. (c) NASA

Astronomers use massive objects in space as huge telescopes, find brightest galaxy via gravity lens

Whenever a massive object, with an equally massive gravitational pull, like black holes or galaxy clusters, falls between an observer, say a telescope, and a distant target in the background to be observed, than a gravitational lens is formed. Light emitted from the distant object gets twisted by the massive object, and ends up distorted at the telescope – this can be magnified, like if the light passed through a huge telescope. Gravity lenses are critical to astronomical observations of distant objects, which aid scientists learn more about how early galaxies formed, and how the Universe came to be.

Illustration showing how a foreground galaxy cluster that stands between Hubble and the background galaxy to be imaged acts like a lens in space, warping space like a funhouse mirror due to massive gravity. The resulting image is stretched into an arc, which scientists need to correct for an accurate view. (c) NASA

Illustration showing how a foreground galaxy cluster that stands between Hubble and the background galaxy to be imaged acts like a lens in space, warping space like a funhouse mirror due to massive gravity. The resulting image is stretched into an arc, which scientists need to correct for an accurate view. (c) NASA

Recently, the Hubble Space Telescope harnessed such a gravitational lens, created by a cluster of closer galaxies located about 5 billion light-years away, and captured a distant galaxy 10 billion light-years away. The researchers found it was  three times brighter than any other seen through a gravity lens, and like many great scientific discoveries, it was all discovered by accident.

“This observation provides a unique opportunity to study the physical properties of a galaxy vigorously forming stars when the universe was only one-third its present age,” NASA officials explained

The problem with gravitational lenses is the distortion itself, which makes zooming possible in the first place. Astronomers aimed the space telescope at the galaxy cluster RCS2 032727-132623, which is surrounded by a nearly 90-degree arc of bright light from an even more distant galaxy. Because of the distortions, the image of the background galaxy is repeated several times. Using Hubble data, astronomers carefully removed the distortions and instead left an clear and enchanting sight of the distant galaxy filled with star-forming areas that shine brighter than similar spots in our own Milky Way.

The zoom in rectangle shows the brightest galaxy so far found through a gravity lens. It's 20 times larger and over three times brighter than typically lensed galaxies.The rounded outlines that form an arc are actually the remnant distortions discussed in the article. (c) NASA

The zoom in rectangle shows the brightest galaxy so far found through a gravity lens. It's 20 times larger and over three times brighter than typically lensed galaxies.The rounded outlines that form an arc are actually the remnant distortions discussed in the article. (c) NASA

“Hubble’s view of the distant background galaxy is significantly more detailed than could ever be achieved without the help of the gravitational lens,” NASA officials wrote.

source

Hubble Spies Building Blocks of Most Distant Galaxy Cluster. Click for high resolution. (c) NASA

Hubble captures photo of earliest galaxy cluster ever found

Hubble Spies Building Blocks of Most Distant Galaxy Cluster. Click for high resolution. (c) NASA

Hubble Spies Building Blocks of Most Distant Galaxy Cluster. Click for high resolution. (c) NASA

The ever scientifically productive Hubble just came out with another gem that will help scientists unravel the mysteries of the Universe, after the telescope snapped a photo of a couple of galaxy far, far away, wrapped together in a cosmic dance which most likely led in  in the forming of a galaxy cluster – the oldest so far found.

Galaxy clusters are the biggest structures in the Universe, and are typically comprised  from  50 to as much as a few thousands galaxies. The Hubble Space Telescope captured just five extremely bright galaxies, located a staggering 13.1 billion years, all of which are in the process of merging into a galactic cluster.

“These galaxies formed during the earliest stages of galaxy assembly, when galaxies had just started to cluster together,” said Michele Trenti of the University of Colorado at Boulder and the Institute of Astronomy at the University of Cambridge in the U.K. “The result confirms our theoretical understanding of the buildup of galaxy clusters. And, Hubble is just powerful enough to find the first examples of them at this distance.”

Interestingly enough, Hubble spotted the galaxies by accident, while surveying a random patch in space in infrared light. Since these ancient galaxies are so far away, the light emitted by them has stretched tremendously towards the red shift of the spectrum and thus infrared analysis is the only viable means of observing. NASA says the galaxy has likely grown into one of today’s massive “galactic cities,” comparable to the nearby Virgo cluster of more than 2,000 galaxies.

“We need to look in many different areas because the odds of finding something this rare are very small,” said Trenti, “Typically, a region has nothing, but if we hit the right spot, we can find multiple galaxies.”

Actually, almost all of the galaxies in the Universe resides in groups or clusters. The Milky Way is part of a cluster known as the Local Group, which contains about 45 separate galaxies. NASA astronomers have stated that the brightness of the galaxy cluster is an indication that the galaxies remain fairly young and have likely merged and formed the brightest central galaxy in the cluster.
“The five bright galaxies spotted by Hubble are about one-half to one-tenth the size of our Milky Way, yet are comparable in brightness,” NASA reported. “The galaxies are bright and massive because they are being fed large amounts of gas through mergers with other galaxies.”
This is the second major discovery Hubble has made within the span of a week, after the space telescope discovered the the largest cluster of galaxies seen yet in the early universe, a giant that astronomers have dubbed “El Gordo”, Spanish for “the fat one”, located around 7 billion light years away.

‘El Gordo’ – largest galaxy cluster ever seen, is colliding and growing

Galaxy clusters are the biggest stable structures in our Universe that we know of, typically containing 50 to 1000 galaxies.

El Gordo

Seven billion light years away and two million billion times heavier than our Sun lies El Gordo – which is Spanish for ‘the fat one’. Astronomers reporting at the 219th American Astronomical Society meeting said that at the moment, El Gordo is undergoing a process of growth and collision, and that it will grow even larger.

Aside from discovering it, which is really remarkable in itself, astrophysicists have set out to figure exactly how these clusters form, collide and grow – and they hope El Gordo can play a big role here.

“El Gordo is at a distance that corresponds to a distance of about seven billion light years – we’re looking at it at a time that the Universe was only half as old as it is now, when structure was forming at a different rate,” explained Jack Hughes of Rutgers University in New Jersey, US.

Stellar superlatives

Galaxy clusters hold many records, and from what we know so far, collisions like the ones in El Gordo are the most energetic events in the Universe, as incredible amounts of matter and dark matter collide at incredible speeds. Just imagine a collision between hundreds and hundreds of galaxies, all of them filled with stars and planets and dark matter, just colliding! Don’t know about you, but I find it really hard to wrap my mind around that.

Generally speaking, galaxy clusters grow by sheer force of gravity; they’re big, they’re heavy and they attract other objects – normal matter and dark matter work together here. But meanwhile, the much more mysterious dark energy works to pull the entire Universe apart at growing speeds. Understanding these connected processes is a Herculean task, and placing major galaxy clusters in this context is very important.

Big clusters, like El Gordo release energetic particles which affect the cosmic microwave background, the really faint background radiation left over from the Big Bang.

“By looking at and understanding the properties of El Gordo, we’re able to understand the time evolution of the structure formation of the Universe,” Prof Hughes said.

Right now, researchers are working on a model to show just how big the galaxy cluster will become.

El Gordo is going to continue to grow,” Prof Hughes said. “We could extrapolate what its mass will be; unfortunately the models are uncertain, but it could become the most massive cluster known about, even when we count the nearby Universe.”