Galaxy z8_GND_5296 (seen in the inset) is the earliest galaxy that astronomers have measured the distance to accurately. It formed approximately 700 million years after the Big Bang, and is forming stars at an incredibly rapid rate. [Credit: V. Tilvi (Texas A&M), S. Finkelstein (UT Austin), the CANDELS team, and HST/NASA]
“The farthest galaxy yet seen!” Haven’t we heard that one before? (See here and here, for example.) While it’s true that astronomers keep pushing farther back in time with better instruments, there are fundamental challenges both in observing and measuring the distances to the earliest galaxies in the cosmos.
That’s why this new observation of a galaxy that formed about 700 million years after the Big Bang is significant. While scores of galaxies have been identified that formed in that era, astronomers have only measured accurate distances for five of them. This galaxy marks the sixth, and it is the farthest of the bunch. Perhaps even more important than the distance measurement, researchers determined that this galaxy gave birth to new stars at more than 100 times the rate the Milky Way does today. That indicates early galaxies may have been more aggressive with star-formation than previously believed. Continue reading “Taking Measure: A ‘New’ Most Distant Galaxy”
The evidence that the Universe began with the Big Bang is very compelling. 13.8 billion years ago, the entire Universe was compressed into a microscopic singularity that grew exponentially into the vast cosmos we see today. But what does the future hold? How will the Universe end?
Astronomers have been pondering the ultimate fate of the Universe for thousands of years. In the last century, cosmologists considered three outcomes for the end of everything, and it all depended on the critical density of the Universe. If this critical density was high, then there was enough mutual gravity to slow and eventually halt the expansion. Billions of years in the future, it would then collapse in on itself again, perhaps creating another Big Bang. This is known as a closed Universe, and the final result is the Big Crunch.
If the critical density was low, then there wouldn’t be enough gravity to hold things together. Expansion would continue on forever and ever. Stars would die, galaxies would be spread apart, and everything would cool down to the background temperature of the Universe. This is an open Universe, and the end is known as the Big Freeze.
And if the critical density was just right, the Universe’s expansion goes on forever, but it’s always slowing down, reaching a dead stop in an infinite amount of time. This creates a Flat Universe… also a Big Freeze.
Fortunately, astronomers were able to measure the critical density of the Universe, using NASA’s WMAP spacecraft, and they discovered that the actual density of the Universe predicts a flat Universe. So that’s it, right? Of the three choices, the answer is #3.
Unfortunately, nature had other plans, and came up with a reality that nobody expected. In 1998, a team of astronomers were observing distant supernovae to get a sense of how fast the Universe is slowing down and they made an amazing discovery. Instead of decelerating, as predicted by the critical density of the Universe, the expansion of the Universe is actually speeding up.
Some mysterious force is pushing galaxies faster and faster away from each other, accelerating the expansion of the Universe. We now call this force “dark energy”, and for the time being, astronomers have no idea what it is. All we know is that it’s pushing the Universe apart. Distant galaxies are being accelerated away from us, and in trillions of years from now, they will cross the beyond the cosmic horizon and disappear from view. The evidence that we live in a vast Universe will disappear with them.
Galaxies spinning farther and farther away from each other
But there’s a further unsettling possibility about dark energy. Maybe the expansion pressure will increase, eventually overwhelming gravity on a local level. Galaxies will get torn apart, and then Solar Systems, and eventually atoms themselves will be shredded by the increasing dark energy – this idea is known as the Big Rip.
So how will the Universe end? The force of dark energy will continue to accelerate the expansion of the Universe until distant galaxies disappear. Galaxies will use up all the gas and dust for stars and go dark, perhaps becoming black holes. Those black holes will decay and maybe matter itself will decay into pure energy. The entire Universe will become a cold, quiet place, where single photons are stretched across light years of space.
Don’t worry, though, that won’t be for quadrillions of years from now.
Artist's conception of the event horizon of a black hole. Credit: Victor de Schwanberg/Science Photo Library
Could the famed “Big Bang” theory need a revision? A group of theoretical physicists suppose the birth of the universe could have happened after a four-dimensional star collapsed into a black hole and ejected debris.
Before getting into their findings, let’s just preface this by saying nobody knows anything for sure. Humans obviously weren’t around at the time the universe began. The standard theory is that the universe grew from an infinitely dense point or singularity, but who knows what was there before?
“For all physicists know, dragons could have come flying out of the singularity,” stated Niayesh Afshordi, an astrophysicist with the Perimeter Institute for Theoretical Physics in Canada who co-authored the new study.
So what are the limitations of the Big Bang theory? The singularity is one of them. Also, it’s hard to predict why it would have produced a universe that has an almost uniform temperature, because the age of our universe (about 13.8 billion years) does not give enough time — as far as we can tell — to reach a temperature equilibrium.
Most cosmologists say the universe must have been expanding faster than the speed of light for this to happen, but Ashford says even that theory has problems: “The Big Bang was so chaotic, it’s not clear there would have been even a small homogenous patch for inflation to start working on.”
Representation of the timeline of the universe over 13.7 billion years, from the Big Bang, through the cosmic dark ages and formation of the first stars, to the expansion in the universe that followed. Credit: NASA/WMAP Science Team.
This is what the physicists propose:
The model they constructed has the three-dimensional universe floating as a membrane (or brane) in a “bulk universe” that has four dimensions. (Yes, this is making our heads hurt as well, so it might be easier to temporarily think of the brane as two-dimensional and the “bulk universe” as three-dimensional when trying to picture it.) You can read the more technical details in this 2000 paper on which the new theory is based.
So if this “bulk universe” has four-dimensional stars, these stars could go through the same life cycles as the three-dimensional ones we are familiar with. The most massive ones would explode as supernovae, shed their skin and have the innermost parts collapse as a black hole.
The 4-D black hole would have an “event horizon” just like the 3-D ones we are familiar with. The event horizon is the boundary between the inside and the outside of a black hole. There are a lot of theories of what goes on inside a black hole, although nothing has ever been observed.
In a 3-D universe, the event horizon appears as a two-dimensional surface. So in a 4-D universe, the event horizon would be a 3-D object called a hypersphere.
So basically, what the model says is when the 4-D star blows apart, the leftover material would create a 3-D brane surrounding a 3-D event horizon, and then expand.
The long and the short of it? To bring this back to things that we can see, it is clear from observations that the universe is expanding (and indeed is getting faster as it expands, possibly due to the mysterious dark energy). The new theory says that the expansion comes from this 3-D brane’s growth. But there is at least one limitation.
This artist’s impression shows the surroundings of the supermassive black hole at the heart of the active galaxy NGC 3783 in the southern constellation of Centaurus (The Centaur). New observations using the Very Large Telescope Interferometer at ESO’s Paranal Observatory in Chile have revealed not only the torus of hot dust around the black hole but also a wind of cool material in the polar regions. Credit: ESO/M. Kornmesser
The new model differs from these CMB readings by about four percent, so the researchers are looking to refine the model. They still feel the model has worth, however. Planck shows that inflation is happening, but doesn’t show why the inflation is happening.
“The study could help to show how inflation is triggered by the motion of the universe through a higher-dimensional reality,” the researchers stated.
You can read more about their research on this prepublished Arxiv paper. The Arxiv entry does not specify if the paper has been submitted to any peer-reviewed scientific journals for publication.
Water, ammonia, methanol and carbon dioxide could have come to Earth from cometary sources, according to a new study. Source: Lawrence Livermore National Laboratory
The energy of comets smashing into Earth billions of years ago could have generated life out of the building blocks of life that those extraterrestrial objects brought, according to new experiments published in a peer-reviewed study.
The finding comes after a team “shock compressed” an icy slush similar in composition to that found on comets, which are sometimes called “dirty snowballs” because they are a mixture of ice and rock. The compression, which researchers say is similar in intensity to comets hitting the Earth, generated amino acids – considered the basic bits of life.
“Our work shows that the basic building blocks of life can be assembled anywhere in the Solar System and perhaps beyond,” stated Zita Martins, a co-author of the paper who is with Imperial College London’s department of Earth science and engineering.
“However, the catch is that these building blocks need the right conditions in order for life to flourish. Excitingly, our study widens the scope for where these important ingredients may be formed in the Solar System and adds another piece to the puzzle of how life on our planet took root.”
An object entering a planet’s atmosphere. Credit: Imperial College London
Whether life arose on Earth, or was imported from other locations in the Solar System or universe, has been a hot-button topic for decades. Learning the answer not only has implications for our own planet, but also for understanding how likely it is that life exists in other Solar System planets and moons — not to mention moons or planets in other star systems.
The new experiment — which the researchers say uncovers evidence of a “cosmic factory” process for starting life — saw the team at the University of Kent and the Imperial College using a gas gun to send a projectile into an ice combination similar to what one would find a comet. After the impact, the researchers saw amino acids forming.
The work builds on research initially done by Nir Goldman, a scientist with the Lawrence Liverpool National Laboratory, who predicted the results based on simulations in the laboratory’s supercomputer. Goldman found that comets could have imported life’s building blocks (ammonia, methanol, carbon dioxide and water). Then, as they smashed into Earth, the energy produced could be enough to jump-start life.
The building blocks of proteins are molecules called amino acids. Most types of amino acids can exist in two different forms, one that is ‘left-handed’ and the other as ‘right-handed.’ Credit: NASA
“This process demonstrates a very simple mechanism whereby we can go from a mix of simple molecules, such as water and carbon-dioxide ice, to a more complicated molecule, such as an amino acid,” stated Mark Price, a co-author and physicist from the University of Kent.
“This is the first step towards life. The next step is to work out how to go from an amino acid to even more complex molecules such as proteins.”
You can read the research paper, which was published Sept. 15, on Nature Geoscience.
A while back we introduced you to Zogg the alien from Betelgeuse. Zogg has been busy helping aliens understand bizarre human concepts like “rituals” and “vision”, but he took a side journey to help everyone understand the geometry of the Universe. What does it mean to have a flat, finite Universe? How could you travel in one direction and return to your starting point?
The first episode was fantastic, and now serves as my favorite link to send people when they’re having trouble wrapping their head around the concept of a finite Universe. How the Universe can be expanding, without expanding into anything. Seriously, if you haven’t seen Part 1, stop and go watch it now.
True to his word, Zogg released this second episode, detailing the geometries of the Universe. What do cosmologists mean when they say the Universe is “curved” or “flat”. What could the curvature look like.
An ultracold vacuum chamber ran a simulation of the early universe and came up with some interesting findings about how the environment looked shortly after the Big Bang occurred.
Specifically, the atoms clustered in patterns similar to the cosmic microwave background — believed to be the echo of the intense burst that formed the beginning of the universe. Scientists have mapped the CMB at progressively higher resolution using several telescopes, but this experiment is the first of its kind to show how structure evolved at the beginning of time as we understand it.
The Big Bang theory (not to be confused with the popular television show) is intended to describe the universe’s evolution. While many pundits say it shows how the universe came “from nothing”, the concordance cosmological model that describes the theory says nothing about where the universe came from. Instead, it focuses on applying two big physics models (general relativity and the standard model of particle physics). Read more about the Big Bang here.
CMB is, more simply stated, electromagnetic radiation that fills the Universe. Scientists believe it shows an echo of a time when the Universe was much smaller, hotter and denser, and filled to the brim with hydrogen plasma. The plasma and radiation surrounding it gradually cooled as the Universe grew bigger. (More information on the CMB is here.) At one time, the glow from the plasma was so dense that the Universe was opaque, but transparency increased as stable atoms formed. But the leftovers are still visible in the microwave range.
WMAP data of the Cosmic Microwave Background. Credit: NASA
The new research used ultracold cesium atoms in a vacuum chamber at the University of Chicago. When the team cooled these atoms to a billionth of a degree above absolute zero (which is -459.67 degrees Fahrenheit, or -273.15 degrees Celsius), the structures they saw appeared very similar to the CMB.
By quenching the 10,000 atoms in the experiment to control how strongly the atoms interact with each other, they were able to generate a phenomenon that is, very roughly speaking, similar to how sound waves move in air.
“At this ultracold temperature, atoms get excited collectively,” stated Cheng Chin, a physics researcher at the University of Chicago who participated in the research. This phenomenon was first described by Russian physicist Andrei Sakharov, and is known as Sakharov acoustic oscillations.
So why is the experiment important? It allows us to more closely track what happened after the Big Bang.
Atom density is greater at left (the beginning of the experiment) than 80 milliseconds after the simulated Big Bang. Credit: Chen-Lung Hung
The CMB is simply a frozen moment of time and is not evolving, requiring researchers to delve into the lab to figure out what is happening.
“In our simulation we can actually monitor the entire evolution of the Sakharov oscillations,” said Chen-Lung Hung, who led the research, earned his Ph.D. in 2011 at the University of Chicago, and is now at the California Institute of Technology.
Both Hung and Chin plan to do more work with the ultracold atoms. Future research directions could include things such as how black holes work, or how galaxies were formed.
Have a discussion about the origins of the Universe and, ere long, someone will inevitably use the term “the Big Bang” to describe the initial moment of expansion of everything that was to everything that is. But in reality “Big Bang” isn’t a very good term since “big” implies size (and when it occurred space didn’t technically exist yet) and there was no “bang.” In fact the name wasn’t ever even meant to be an official moniker, but once it was used (somewhat derisively) by British astronomer Sir Fred Hoyle in a radio broadcast in 1949, it stuck.
Unfortunately it’s just so darn catchy.
This excellent video from minutephysics goes a bit more into depth as to why the name is inaccurate — even though we’ll likely continue using it for quite some time. (Thanks to Sir Hoyle.)
And you have to admit, a television show called “The Everywhere Stretch Theory” would never have caught on. Bazinga!
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. Credit: NASA, ESA, M. Kornmesser
What we’re gonna’ do here is go back. Way back into time. Back to when the only thing that existed was… galaxies? When astronomers employed the power of Hubble’s CANDELS survey to observe different galaxy types from the distant past, they expected to see a variety of spiral, elliptical, lenticular and peculiar structures, but what they didn’t expect was that things were a whole lot more “peculiar” a long time ago!
Known as the Hubble Sequence, astronomers use this classified system for listing galaxy sizes, shapes and colors. It also arranges galaxies according to their morphology and star-forming activity. Up to the present, the Hubble Sequence covered about 80% of the Universe’s history, but the latest information shows that the sequence was valid as much as 11 billion years ago! Out of what we currently know, there are two dominant galaxy types – spiral and elliptical – with the lenticular structure as a median. Of course, this is constrained to the regions of space which we can readily observe, but how true did the sequence hold back when the Universe theoretically began?
“This is a key question: when and over what timescale did the Hubble Sequence form?” says BoMee Lee of the University of Massachusetts, USA, lead author of a new paper exploring the sequence. “To do this you need to peer at distant galaxies and compare them to their closer relatives, to see if they too can be described in the same way.”
Using the Hubble Space Telescope, astronomers took on the sequence challenge to peer back 11 billion years in time to study galaxy structure. Up until now, researchers could confirm the sequence was valid as long ago as 8 billion years, but these new studies pushed CANDELS, the Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey, to the outer limits. It is simply the largest project ever, and soaked up 902 assigned orbits of observing time. Using the WFC3 and ACS cameras, the team examined structures that existed less than one billion years after the Big Bang. While earlier studies had aimed for lower-mass galaxies in this era, no study had really taken on serious observation of mature structures – ones similar to our own galaxy. Now the new CANDELS observations show us that all galaxies, regardless of size, fit into a totally different classification!
“This is the only comprehensive study to date of the visual appearance of the large, massive galaxies that existed so far back in time,” says co-author Arjen van der Wel of the Max Planck Institute for Astronomy in Heidelberg, Germany. “The galaxies look remarkably mature, which is not predicted by galaxy formation models to be the case that early on in the history of the Universe.”
Just what did this study see that’s so different? Just the power of two. Galaxies were either complex, with blue star forming regions and irregular structures, or they were like our nearby neighbors: massive red galaxies that exhibit no new star-formation. In the early Universe, galaxies like the Milky Way were uncommon. With so little to study, it was nearly impossible to get a large enough sample to sufficiently catalog their characteristics. Early research could only peer back in visible light, a format which emphasized star formation and revealed the red-shifted ultraviolet emission of the galaxies. This information was inconclusive because galaxy structure appeared disrupted and unlike the formations we see near to us. Through the use of infra-red, astronomers could observe the now red-shifted massive galaxies in their visible rest frame. Thanks to CANDELS lighting the way, astronomers were able to thoroughly sample a significantly larger amount of mature galaxies in detail.
“The huge CANDELS dataset was a great resource for us to use in order to consistently study ancient galaxies in the early Universe,” concludes Lee. “And the resolution and sensitivity of Hubble’s WFC3 is second to none in the infrared wavelengths needed to carry out this study. The Hubble Sequence underpins a lot of what we know about how galaxies form and evolve — finding it to be in place this far back is a significant discovery.”
The FastSound project's 3D map of the large-scale structure of a region in the Universe about 4.7 billion years after the Big Bang. This area covers 2.5 times 3 degrees of the sky, with a radial distance spanning 12-14.5 billion light years in comoving distance or 8-9.6 billion light years in light travel distance. Credit: NAOJ, SDSS, CFHT.
I remember seeing the Hubble 3-D IMAX movie in 2010 and literally gasping when the view pulled back from zooming into distant stars and galaxies to show clusters and superclusters of galaxies interwoven like a web, creating the large scale structure of the Universe. In 3-D, the structure looks much like the DNA double helix or a backbone.
Now, a new project that aims to map the Universe’s structure has looked back in time to create a 3-D map showing a portion of the Universe as it looked nine billion years ago. It shows numerous galaxies and interestingly, already-developed large-scale structure of filaments and voids made from galaxy groups.
The map was created by the FastSound project, which is surveying galaxies in the Universe using the Subaru Telescope’s new Fiber Multi-Object Spectrograph (FMOS). The team doing the work is from Kyoto University, the University of Tokyo and the University of Oxford.
The team said that although they can see that the clustering of galaxies is not as strong back when the Universe was 4.7 billion years old as it is in the present-day Universe, gravitational interaction will eventually result in clustering that grows to the current level.
The new map spans 600 million light years along the angular direction and two billion light years in the radial direction. The team will eventually survey a region totaling about 30 square degrees in the sky and then measure precise distances to about 5,000 galaxies that are more than ten billion light years away.
But the FastSound project hopes to create a 3-D map of the very distant Universe by covering the volume of the Universe farther than ten billion light years away. FMOS is a wide-field spectroscopy system that enables near-infrared spectroscopy of over 100 objects at a time, with an exceptionally wide field of view when combined with the light collecting power of the 8.2 meter primary mirror of the telescope.
The map released today is just the first from FastSound. The final 3-D map of the distant Universe will precisely measure the motion of galaxies and then measure the rate of growth of the large-scale structure as a test of Einstein’s general theory of relativity.
Although scientists know that the expansion of the Universe is accelerating, they do not know why – whether it is from dark energy or whether gravity on cosmological scales may differ from that of general relativity, this mystery is one of the biggest questions in contemporary physics and astronomy. A comparison of the 3D map of the young Universe with the predictions of general relativity could eventually reveal the mechanism for the mysterious acceleration of the Universe.
The team said their 3-D map shown in this release uses a measure of “comoving” distance rather than light travel distance. They explained:
Light travel distance refers to the time that has elapsed from the epoch of the observed distant galaxy to the present, multiplied by the speed of light. Since the speed of light is always constant for any observer, it describes the distance of the path that a photon has traveled. However, the expansion of the Universe increases the length of the path that the photon traveled in the past. Comoving distance, the geometrical distance in the current Universe, takes this effect into account. Therefore, comoving distance is always larger than the corresponding light travel distance.
In the lead image above from FastSound, the colors of the galaxies indicate their star formation rate, i.e., the total mass of stars produced in a galaxy every year. The gradation in background color represents the number density of galaxies; the underlying mass distribution (which is dominated by invisible dark matter that accounts for about 30% of the total energy in the Universe) and how it would look like this if we could see it. The lower part of the figure shows the relative locations of the FastSound and the Sloan Digital Sky Survey (SDSS) regions, indicating that the FastSound project is mapping a more distant Universe than SDSS’s 3D map of the nearby Universe.
This artist's illustration depicts a gamma-ray burst illuminating clouds of interstellar gas in its host galaxy. By analyzing a recent gamma-ray burst, astronomers were able to learn about the chemistry of a galaxy 12.7 billion light-years from Earth. They discovered it contains only one-tenth of the heavy elements (metals) found in our solar system. Credit: Gemini Observatory/AURA, artwork by Lynette Cook
Once upon a time, more than 12.7 billion years ago, a star was poised on the edge of extinction. It made its home in a galaxy too small, too faint and too far away to even be spotted by the Hubble Space Telescope. Not that it would matter, because this star was going to end its life before the Earth formed. As it blew itself apart, it expelled its materials in twin jets which ripped through space at close to the speed of light – yet the light of its death throes outshone its parent galaxy by a million times.
“This star lived at a very interesting time, the so-called dark ages just a billion years after the Big Bang,” says lead author Ryan Chornock of the Harvard-Smithsonian Center for Astrophysics (CfA).
“In a sense, we’re forensic scientists investigating the death of a star and the life of a galaxy in the earliest phases of cosmic time,” he adds.
When this unsung star expired, it created one of the scariest things in astronomy… a gamma-ray burst (GRB). However, it wasn’t just a normal, garden variety GRB – it was long one, lasting more than four minutes. After century upon century of travel, the light reached our little corner of the Universe and was detected by NASA’s Swift spacecraft on June 6th. Chornock and his team quickly organized follow-up observations by the MMT Telescope in Arizona and the Gemini North telescope in Hawaii.
“We were able to get right on target in a matter of hours,” Chornock says. “That speed was crucial in detecting and studying the afterglow.”
Time to kick back and have a smoke? In a sense. The “afterglow” of a GRB happens when the jets impact the surrounding gas in an almost tsunami-like effect. As it sweeps up the material, it begins to heat and glow. As this light traverses the parent galaxy, it impacts clouds of interstellar gas, illuminating their spectra. Through these chemical signatures, astronomers are able to ascertain what gases the distant galaxy may have contained. As we know, all chemical elements heavier than hydrogen, helium, and lithium are the product of stars. Researchers refer to this as “metal content” and it takes a certain amount of time to accumulate. In the scheme of creation, the elements necessary for life – carbon and oxygen – didn’t exist. What Chornock and his team discovered was the GRB galaxy was host to only about a tenth of the “metals” in our solar system. What does that mean? In the eyes of the astronomers, rocky planets might have been able to form in that far away galaxy, but chances are good that life could not.
“At the time this star died, the universe was still getting ready for life. It didn’t have life yet, but was building the required elements,” says Chornock.
At a redshift of 5.9, or a distance of 12.7 billion light-years, GRB 130606A is one of the most distant gamma-ray bursts ever found.
“In the future we will be able to find and exploit even more distant GRBs with the planned Giant Magellan Telescope,” says Edo Berger of the CfA, a co-author on the publication.
