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Distant Universe

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Galaxy clusters are enormous collections of hundreds or even thousands of galaxies and vast reservoirs of hot gas embedded in massive clouds of dark matter, invisible material that does not emit/absorb light but can be detected through its gravitational effects.

To learn more about clusters, including how they grow via collisions, astronomers have used some of the world's most powerful telescopes, looking at different types of light. They have focused long observations with these telescopes on a half-dozen galaxy clusters. The name for this galaxy cluster project is the “Frontier Fields.”



Located ~ 4.3 billion ly from Earth, MACS J0416 is a pair of colliding galaxy clusters that will eventually combine to form an even bigger cluster. MACS J0717, one of the most complex and distorted galaxy clusters known, is the site of a collision between 4 clusters. It is located ~ 5.4 billion ly away from Earth.

These new images of MACS J0416 and MACS J0717 contain data from three different telescopes: NASA’s Chandra X-ray Observatory (diffuse emission in blue), Hubble Space Telescope (red, green, and blue), and the National Science Foundation's Karl G. Jansky Very Large Array (VLA) (diffuse emission in pink). Where the X-ray and radio emission overlap, the image appears purple. Astronomers also used data from the Giant Metrewave Radio Telescope in India to study the properties of MACS J0416.

The Chandra data shows gas in the merging clusters with temperatures of millions of degrees. The optical data shows galaxies in the clusters and other, more distant, galaxies lying behind the clusters. Some of these background galaxies are highly distorted because of gravitational lensing, the bending of light by massive objects. This effect can also magnify the light from these objects, enabling astronomers to study background galaxies that would otherwise be too faint to detect. Finally, the structures in the radio data trace enormous shock waves and turbulence. The shocks are similar to sonic booms, generated by the mergers of the clusters.

MACS J0416

An open question for astronomers about MACS J0416 has been: are we seeing a collision in these clusters that is about to happen or one that has already taken place? Until recently, scientists have been unable to distinguish between these two explanations. Now, the combined data from these telescopes is providing new answers.

In MACS J0416 the dark matter (which leaves its gravitational imprint in the optical data) and the hot gas (detected by Chandra) line up well with each other. This suggests that the clusters have been caught before colliding. If the clusters were being observed after colliding, the dark matter and hot gas should separate from each other, as seen in the famous colliding cluster system known as the Bullet Cluster.

The cluster in the upper left contains a compact core of hot gas, most easily seen in a specially processed image, and also shows evidence of a nearby cavity, or hole, in the X-ray emitting gas. The presence of these structures also suggests that a major collision has not occurred recently; otherwise these features would likely have been disrupted. Finally, the lack of sharp structures in the radio image provides more evidence that a collision has not yet occurred.

In the cluster located in the lower right, the observers have noted a sharp change in density on the southern edge of the cluster. This change in density is most likely caused by a collision between this cluster and a less massive structure located further to the lower right.

MACS J0717

In VLA images of this cluster, 7 gravitationally-lensed sources are observed, all point sources or sources that are barely larger than points. This makes MACS J0717 the cluster with the highest number of known lensed radio sources. Two of these lensed sources are also detected in the Chandra image. The researchers are only aware of two other lensed X-ray sources behind a galaxy cluster.

All of the lensed radio sources are galaxies located between 7.8-10.4 billion ly from Earth. The brightness of the galaxies at radio wavelengths shows that they contain stars forming at high rates. Without the amplification by lensing, some of these radio sources would be too faint to detect with typical radio observations. The two lensed X-ray sources detected in the Chandra images are likely active galactic nuclei (AGN) at the centers of galaxies. AGN are compact, luminous objects powered by gas heated to millions of degrees as it falls toward supermassive black holes. These two X-ray sources would have been detected without lensing but would have been two or three times fainter.

The large arcs of radio emission in MACS J0717 are very different from those in MACS J0416 because of shock waves arising from the multiple collisions occurring in the former object. The X-ray emission in MACS J0717 has more clumps because there are 4 clusters violently colliding.
 
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2 pretty interesting videos from Hubble Space Telescope channel about colliding galaxies and Universe



and 2 cool videos about IR light and EM spectrum


 
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A research team using ALMA has detected the faintest millimeter-wave source ever observed.

The Universe looks dark in the parts between stars and galaxies. However, astronomers have found that there is faint but uniform light, called the “cosmic background emission,” coming from all directions. This background emission consists of 3 main components; Cosmic Optical Background (COB), Cosmic Microwave Background (CMB), and Cosmic Infrared Background (CIB). The COB comes from a huge number of stars, and the CMB comes from hot gas just after the Big Bang. However, the origin of the CIB was still to be solved.

The team discovered 133 faint objects, including an object 5 times fainter than any other ever detected. The researchers found that the entire CIB can be explained by summing up the emissions from such objects.

What is the nature of those sources? By comparing the ALMA data with the data taken by the Hubble Space Telescope and the Subaru Telescope, the team found that 60% of them are galaxies which can also be seen in the optical/infrared images. Dust in galaxies absorbs optical/infrared light and re-emits the energy in longer mm waves which can be detected with ALMA.



“However, we have no idea what the rest of them are. I speculate that they are galaxies obscured by dust. Considering their darkness, they would be very low-mass galaxies.” Masami Ouchi explained passionately. “This means that such small galaxies contain great amounts of dust. That conflicts with our current understanding: small galaxies should contain small amounts of dust. Our results might indicate the existence of many unexpected objects in the distant Universe. We are eager to unmask these new enigmatic sources with future ALMA observations”.
 
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Researchers at the University of Alabama-Huntsville analyzed X-ray emissions of more than 300 galaxy clusters in an attempt to learn more about dark matter and dark energy. It turns out that the emission profiles and sizes happened to be the same. To explain the significance of the finding, lead cosmologist of the study Andrea Morandi joins RT America's Manila Chan.

 
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An international team of scientists has detected and confirmed the faintest early-Universe galaxy ever using the W. M. Keck Observatory on the summit on Maunakea, Hawaii.

The detection was made using the DEIMOS instrument fitted on the 10-m Keck II telescope, and was made possible through a phenomenon predicted by Einstein in which an object is magnified by the gravity of another object that is between it and the viewer. In this case, the detected galaxy was behind the galaxy cluster MACS2129.4-0741, which is massive enough to create 3 different images of the object [the light from this galaxy was magnified by factors of 11, 5 and 2].

The team detected the galaxy as it was 13 billion years ago, or when the Universe was a toddler on a cosmic time scale. It lies near the end of the reionization epoch, during which most of the hydrogen gas between galaxies transitioned from being mostly neutral to being mostly ionized (and lit up the stars for the first time).


Three spectra of the multiply imaged systems have peaks at the same wavelength, hence showing that they belong to the same source.
 
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But those three graphs ar nothing alike, I fail to see how the sample at witch they were compiled might indicate that,also that huge discrepancy in its positions due gravity lensing that much? I'l go read the arcticle now.
 
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Yes; yet that picture looks like I'm seeing triple as if seeing it stupidly drunk, there are quite big offsets from single point observations, that might be because I missed the arc/sec scale on the picture or lack thereoff.
Got it : thats a composite of two observations with 100k years inbetween, but dont hold me on that.
Anyways, at ~13By would give an augmented distance today of what 30-40Bly?
 
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Offsets are inevitable because of warped space around massive galaxy cluster.

Do you mean proper distance? Yes, proper distance is < 40 Gly (comoving distance is 13 Gly)
 
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As the most abundant element in the Universe and the raw fuel for creating stars, hydrogen is used by radio astronomers to detect and understand the makeup of other galaxies. An international team of scientists has pushed the limits of radio astronomy to detect a faint signal emitted by hydrogen gas in a galaxy > 5 billion ly away-almost double the previous record.



Hubble Space Telescope image of the galaxy with overlay of the hydrogen emission that was recently discovered.


*******************

A multinational team of astronomers have found a new Einstein Ring, a rare image of a distant galaxy lensed by gravity.
Light arriving at the Earth today left the Einstein ring 8 billion years ago, so we see the ring as it was 5 billion years after the Big Bang. Despite its relatively small apparent size (it stretches across an angle on the sky of 4.5 arcseconds or ~ 1/800th of a degree), it's larger than most of the other rings found to date.



In this color composite image, the central lensing galaxy is shown in red and the blue Einstein ring, the distorted image of a distant galaxy, is visible all around it.
 
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South African super telescope finds hundreds of previously undetectable galaxies


MeerKAT's images, taken of a patch of sky covering < 0.01% of the total, reveal > 1300 galaxies in the distant universe, where only ~ 70 had been previously detected.



In this image taken by the MeerKAT radio telescope, we see a galaxy ~ 200 million ly away where hydrogen gas is being used up to form stars in large numbers.



A "Fanaroff-Riley Class 2" (FR2) object: a massive black hole in the distant universe (matter falling into it produces the bright dot at the center) launching jets of powerful electrons moving at close to the speed of light.




 
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Today's really insane day. First we're told that there's a potentially habitable planet right under our noses and now this:

The international University of California, Riverside-led SpARCS collaboration has discovered 4 of the most distant clusters of galaxies ever found, as they appeared when the Universe was only 4 billion years old.

Clusters are rare regions of the Universe consisting of hundreds of galaxies containing trillions of stars, as well as hot gas and mysterious Dark Matter. Spectroscopic observations from the W. M. Keck Observatory on Maunakea, Hawaii and the Very Large Telescope in Chile confirmed the 4 candidates to be massive clusters. This sample is now providing the best measurement yet of when and how fast galaxy clusters stop forming stars in the early Universe.

The study found that ~ 30% of the galaxies which would normally be forming stars have been quenched in the young distant clusters, compared to the much higher value of ~ 50% found in much older nearby clusters.

While it had been fully expected that the percentage of cluster galaxies which had stopped forming stars would increase as the Universe aged, this latest work quantifies the effect.



Color images of the central regions of z > 1.35 SpARCS clusters. Cluster members are marked with white squares.
 
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Scientists discover a galaxy that's 99.99% Dark Matter

Whatta :eek:



Even though it's relatively nearby, astronomers had missed the galaxy, named Dragonfly 44, for decades because it's very dim.

It has so few stars that it would quickly be ripped apart unless something was holding it together. Motions of the stars tell you how much matter there is. They don't care what form the matter is, they just tell you that it's there. The faster the stars move, the more mass their galaxy will have.

The Gemini data show that a relatively large fraction of the stars are in the form of very compact clusters.

Dragonfly 44's mass is estimated to be 1 trillion times the mass of the Sun, or 2 tredecillion kg (a 2 followed by 42 zeros), which is similar to the mass of the Milky Way. However, only 0.01% of that is in the form of stars and “normal” matter. The other 99.99% is in the form of dark matter.

Source 1: Gemini

Source 2: Yale University

Source 3: Keck Observatory
 
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This image contains the most distant galaxy cluster, a discovery made using data from NASA's Chandra X-ray Observatory and several other telescopes. The galaxy cluster, known as CL J1001+0220, is located ~ 11.1 billion ly from us and may have been caught right after birth, a brief, but important stage of cluster evolution never seen before.

In addition to its extraordinary distance, CL J1001 is remarkable because of its high levels of star formation in galaxies near the center of the cluster. Within ~ 250000 ly of the center of the cluster (its core), 11 massive galaxies are found and 9 of those display high rates of formation. Specifically, stars are forming in the cluster core at a rate equivalent to ~ 3400 Suns per year.

These results suggest that elliptical galaxies in clusters may form their stars through more violent and shorter bursts of star formation than elliptical galaxies outside clusters.
 
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An international team of astronomers, including Carnegie's Eric Persson, has charted the rise and fall of galaxies over 90% of cosmic history.

The FourStar Galaxy Evolution Survey (ZFOURGE) has built a multicolored photo album of galaxies as they grow from their faint beginnings into mature and majestic giants. They did so by measuring distances and brightnesses for > 70000 galaxies spanning >12 billion years of cosmic time, revealing the breadth of galactic diversity.

Perhaps the most surprising result is that galaxies in the young Universe appear as diverse as they are today, when the Universe is older and much more evolved.

10 billion years ago, galaxies like our Milky Way were much smaller, but they were forming stars 30 times faster than they are today.

 

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Observable Universe contains 10 times more galaxies than previously thought

mindblowing.......bring on the James Webb.
 
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