Astronomy

Why can we still see 10 billion year old galaxies?

Why can we still see 10 billion year old galaxies?



We are searching data for your request:

Forums and discussions:
Manuals and reference books:
Data from registers:
Wait the end of the search in all databases.
Upon completion, a link will appear to access the found materials.

I've never fully understood why we can still see galaxies that are 10 billion light years away. The age of the universe is calculated to be 13.9 billion years old and we live on a planet that it is roughly 4 billion years old. The universe came into existence 13.9 billion years ago and expanded incredibly quickly but those galaxies that were created in those early years are still visible to us via the amazing Hubble telescope (see the latest from Hubble). Those galaxies would surely have long gone so why can we still see the light from so long ago? How can we see further and further back to the beginning of the universe because surely the light from the moment of the big bang and subsequent eons would have past by us long ago?


How can we see further and further back to the beginning of the universe because surely the light from the moment of the big bang and subsequent eons would have past by us long ago?

A simple intuitive way to understand that part of your question: Bigbang happened everywhere, in all of space. As time passes we see more distant parts of the bigbang, or rather, of the microwave background which is the furthest away phenomena we can see. The bigbang as it happened for example 1 billion years ago has passed by us long ago. Today we see the bigbang as it happened 13.8 billion years ago.


The deepest we look into the space the further in the past we look. So if we take pictures of galaxies that are 10 billion ly away we see them as they were 10 billion years ago.


Those galaxies were 10 billion light years away from Earth. So light would take much more time to reach here and that light which is now 10 billion years older can be seen now. Even light from the Sun takes 8 minutes to reach to us. So if somehow sun disappears suddenly(very unlikely) we wouldn't know for 8 minutes.


We can't see how those galaxies look right now. If a galaxy appears to be 10 billion light years away, that also means that the light took 10 billion years to reach us. It's a bit confusing that "distance" and "time" are sometimes the same thing in astronomy.

So the light which the galaxies emit today (if they still exist) will reach us in another 10 billion years. What we see right now is light that was emitted 10 billion years in the past.

This also means that by looking at the farthest possible distance, we can see light which was created shortly after the big bang. One such source of light is the ubiquitous background radiation which was probably created by the big bang itself. It's easy to see because it fills all the gaps between the celestial objects.

Unfortunately, this also means that we always get an "outdated" view of the universe. If aliens started to blowing stars at the far side of our galaxy, it would take us 100'000 years to see the light.


Rocky Planet Found Around 10 Billion-Year-Old Star

By: Monica Young January 13, 2021 1

Get Articles like this sent to your inbox

Astronomers have found an Earth-size (but not at all Earth-like) planet around an ancient star that has a nice high view of our galaxy.

This artist’s rendition shows TOI-561, one of the oldest, most metal-poor stars known in the Milky Way Galaxy. This star hosts a hot, rocky exoplanet (center) as well as two gas planets (to the left).
W. M. Keck Observatory / Adam Makarenko

Astronomers have discovered three planets orbiting a star about 10 billion years old — one of them rocky. The star, TOI 561 (meaning it was the 561st object of interest from the Transiting Exoplanet Survey Satellite), is in our galaxy’s older thick disk, which means its planets have a nice view from on high of the Milky Way’s spiral.

The star has three planets, with diameters 1.45, 2.9, and 2.3 times Earth’s. The innermost one is rocky, with three times Earth’s mass, but on a period of 0.44 days, it’s anything but Earth-like. Its dayside surface temperature is around 2500K (4,000°F). That’s at least twice as hot as Earth’s magma, and it’s surely molten. What it actually looks like is uncertain, because as lead scientist Lauren Weiss (University of Hawaii, Manoa) notes, “It exceed temperatures where geophysicists have made lava in the lab.”

Illustration showing the structural components of the Milky Way galaxy. The star TOI 561 is located in the thick disk (marked in red-orange), which contains a sparse, older population of stars.
Kaley Brauer / MIT

Astronomers have found planets around old stars before, and even around chemically poor stars that have a paucity of heavy elements. Yet the mere fact that this planet came to be is of interest to astronomers. “We now have evidence that the universe has been forming rocky planets for the last 10 billion years, more than double the age of our own solar system, and nearly since the origin of the universe itself,” Weiss says.


The Andromeda Galaxy Has Been Devouring Other Galaxies Since It Was a Baby (And Earth Is Next)

The cannibal next door has an even mightier appetite than we thought.

Like most big galaxies, the Milky Way is a cold-blooded cannibal, with a history of gobbling up smaller galaxies in order to maintain its lovely spiral figure. But, a few billion years from now, our cosmic home could meet its match with an equally hungry neighbor called Andromeda.

Andromeda, the nearest large galaxy to ours, is on a crash course to merge with the Milky Way about 4.5 billion years from now. How will the monstrous smash-up change the shapes of the participating galaxies? That's anyone's guess. But, given Andromeda's size, astronomers know our neighbor is no slouch when it comes to playing galactic tug-of-war — and, according to new research published today (Oct. 2) in the journal Nature, Andromeda may have a far more cannibalistic past than scientists gave it credit for.

Using observations from five different telescopes, the study authors observed the diffuse halo of stars at the edge of Andromeda's orbit and detected at least two clusters of stars with distinct trajectories and velocities that didn't seem to match each other, or the rest of the galaxy. Based on the estimated ages of these clusters, the team determined they were the remnants of two ancient dwarf galaxies that Andromeda had devoured long ago — one, gobbled up just a few billion years ago, and the other swallowed nearly 10 billion years ago.

These findings, based on just a small fraction of Andromeda's constituent stars, might similarly represent a small fraction of the cosmic leftovers of other mergers throughout the galaxy's 10-billion-year life span.

"Andromeda has a much bigger and more complex stellar halo than the Milky Way, which indicates that it has cannibalized many more galaxies, possibly larger ones," lead study author Dougal Mackey, an astronomer at Australian National University, said in a statement. "Knowing what kind of a monster our galaxy is up against is useful in finding out the Milky Way's ultimate fate."

In the new study, Mackey and his colleagues focused their observations on 92 clusters of stars that had been identified in previous Andromeda surveys. Each of these clusters was located in the galaxy's halo, more than 81,000 light-years away from the galactic center, where the unusual movements of shredded galactic remnants would be easiest to spot. (Andromeda is about 110,000 light-years across, while estimates for the Milky Way's girth put it at between 100,000 and 200,000 light-years.)

The researchers estimated the velocities and apparent orbits of 77 of these clusters, finding two distinct groups — one older cluster, swirling perpendicular to the galaxy's disk, and one younger cluster orbiting at about a 90-degree angle to the oldsters. The researchers interpreted these groups as the remnants of two ancient merger events that occurred billions of years apart.

These findings don't do much to settle the question of "Who would win in a galaxy fight: Andromeda or the Milky Way?" Fortunately, astronomers have a few billion more years to work that one out.


Hubble Reveals Universe's Oldest Galaxies

The new Frontier Fields images show 13-billion-year-old stars.

Hubble Space Telescope astronomers Tuesday released views of the oldest galaxies yet seen, about 13.2 billion years old. They offer intriguing glimpses of the chaotic birth of the first stars.

The images are the first in a series called Frontier Fields.

Explaining the earliest stars would answer astronomers' questions about how galaxies such as our own Milky Way arose and how stars such as our sun came to reside within a galaxy.

The universe is about 13.7 billion years old. Since 1995, the Hubble Space Telescope has provided astronomers with glimpses of galaxies ever closer in age to the early days of the cosmos. Hubble started with a Deep Field image produced by focusing toward the Big Dipper for 43 hours, uncovering galaxies more than 12 billion years old.

The latest images, presented at the American Astronomical Society meeting in Washington, D.C., show galaxies some 500 million years more ancient than those once groundbreaking images.

At this early time, galaxies were "bright blue blobs, closer [together], smaller—and they're everywhere," says astronomer Garth Illingworth of the University of California, Santa Cruz, who presented a look at four surprisingly bright galaxies from this early era, seen by both Hubble and NASA's Spitzer Space Telescope.

While these early galaxies weighed only about one percent as much as the Milky Way, they likely produced stars about 50 times more frequently than our galaxy does now.

"It's very important to understand how these earliest galaxies formed to understand our own galaxy today," says astronomer Eilat Glikman of Vermont's Middlebury College.

As Einstein showed a century ago, gravity bends light. The Hubble First Frontier images rely on the gravity of a closer, tightly packed group of several hundred galaxies, called Abell 2744, to bend the light from more distant and ancient galaxies.

The bending effect focuses the light from the ancient galaxies, making them appear 10 to 20 times larger than they would otherwise appear. This gravitational lens allows Hubble to see the more distant ancient galaxies.

"There's an enormous amount of science that will come out of the Frontier Fields," says astronomer Michael West of the Maria Mitchell Observatory, who was not part of the discovery team. "Many astronomers are eagerly waiting to get their hands on the data!"

Unfortunately, the gravitational lens effect also distorts the ancient galaxies like a "fun house mirror," West says. "Imagine you could only see someone's distorted face in a circus fun house mirror and had to draw a picture of what that person really looks like without being able to see them directly."

Fortunately, astronomers can estimate the amount of distortion produced by the gravitational lensing and reconstruct an image of the distant galaxies and their properties.

For now, the picture painted by these images is one of an early universe where star production ramped up and galaxies grew larger and larger over the first four billion years of the universe.

When it comes to seeing early stars, Glikman says, "we have to be careful the tip of the iceberg really looks like the base of the iceberg." But these early galaxies "are really good indicators of what was going on early in the universe."


Why can we still see 10 billion year old galaxies? - Astronomy




Hyperactive galaxies roam early Universe
DR EMILY BALDWIN
ASTRONOMY NOW
Posted: August 06, 2009

Astronomers have measured the motions of stars for the first time in a very distant galaxy, speeding around its host at twice the speed of our Sun through the Milky Way.

The speeding stars may help astronomers understand how such compact galaxies form so early in the Universe and then evolve into the galaxies we see in today's 13.7 billion year old Universe.

This illustration compares the Milky Way with a compact galaxy in the early Universe. Image: NASA, ESA, and A. Feild (STScI).

"This galaxy is very small, but the stars are whizzing around as if they were in a giant galaxy that we would find closer to us and not so far back in time," says Pieter van Dokkum, professor of astronomy and physics at Yale University. The stars are clocking up speeds of over 1.6 million kilometres per hour.

Van Dokkum and colleagues used data from the Hubble Space Telescope to confirm the size of the galaxy, and the eight metre Gemini South telescope in Chile to collect enough light to determine the motions of the stars. These near-infrared spectroscopic observations of galaxy 1255-0 spanned 29 hours to allow the faint light to be collected.

"By looking at this galaxy we are able to look back in time and see what galaxies looked like in the distant past when the Universe was very young," says team member Mariska Kriek of Princeton University. Galaxy 1255-0 was born when the Universe was just three billion years old.

The team hope that the results will shed light on how such compact, massive galaxies form, and why they are not seen in today's local Universe. "One possibility is that we are looking at what will eventually be the dense central region of a very large galaxy," says Marijn Franx of Leiden University. "The centre of big galaxies may have formed first, presumably together with the giant black holes that we know exist in today's large galaxies that we see nearby."

The next step will be to capture these galaxies in the process of forming, such as with Hubble's new Wide Field Camera 3. "The ancestors of these extreme galaxies should have quite spectacular properties as they probably formed a huge amount of stars, in addition to a massive black hole, in a relatively short amount of time," says van Dokkum.

Recent work revealed that the oldest most luminous galaxies in the early Universe are also very compact, yet exhibit masses similar to those of today's elliptical galaxies. The most massive galaxies we see in the local Universe which have a mass similar to 1255-0 are typically five times larger than a young compact galaxy, so understanding how galaxies grew so much in the past 10 billion years is a key piece of evidence in eventually solving this puzzle.

The results of this study are presented in the August 6 issue of the journal Nature, along with a companion paper in the Astrophysical Journal.


Space news: Astronomers spot 10 billion-year-old planetary system using NASA satellite

Link copied

The NASA Tess launched to find planets outside our solar system

When you subscribe we will use the information you provide to send you these newsletters. Sometimes they'll include recommendations for other related newsletters or services we offer. Our Privacy Notice explains more about how we use your data, and your rights. You can unsubscribe at any time.

A star 280 light-years from Earth called TOI-561 is one of the oldest stars in the Milky Way. The star formed 10 billion years ago, and has a mass which is roughly 80 percent that of the Sun. Astronomers using NASA's Transiting Exoplanet Survey Satellite (TESS) have discovered that the star has three planets orbiting it.

Related articles

TESS is capable of studying the mass, size, density and orbit of a large cohort of small planets, including a sample of rocky planets in the habitable zones of their host stars.

The satellite works by searching for telltale brightness dips potentially indicating planetary transits - the passages of orbiting worlds across their parent stars&rsquo faces.

By studying the star using TESS, researchers were able to spot three planets orbiting the star.

One such planet is a super-Earth - a large rocky world which has similar features to our planet.

Space news: Astronomers spot 10 billion-year-old planetary system using NASA satellite (Image: Adam Makarenko / W.M. Keck Observatory.)

A star 280 light-years from Earth called TOI-561 is one of the oldest stars in the Milky Way (Image: GETTY)

The super-Earth, however, is so close to the star that it just takes 0.44 Earth days to complete an orbit.

At that rate, there would be more than two years on the super-Earth, called TOI-561b, for a regular day on Earth.

Study co-author Dr Stephen Kane, a planetary astrophysicist at the University of California, Riverside, said: &ldquoFor every day you&rsquore on Earth, this planet orbits its star twice.

&ldquoPart of the reason for the short orbit is the planet&rsquos proximity to its star, which also creates incredible heat.

The TESS satellite (Image: NASA)

Related articles

&ldquoIts estimated average surface temperature is over 1,727 degrees Celsius (2,000 degrees Kelvin) - much too toasty to host life as we know it today, though it may once have been possible.&rdquo

TOI-561b is 3.2 times the size of Earth but has a similar mass which indicated its rocky composition.

Dr Kane continued: &ldquoWe calculated its density to be the same as our planet.

&ldquoThis is surprising because you&rsquod expect the density to be higher. This is consistent with the notion that the planet is extremely old.&rdquo

Hubble Telescope in numbers (Image: EXPRESS)

University of Hawaii postdoctoral researcher Lauren Weiss added: &ldquoTOI-561b is one of the oldest rocky planets yet discovered.

&ldquoIts existence shows that the Universe has been forming rocky planets almost since its inception 14 billion years ago.&rdquo

The planetary system, in general, is poor in metal, which is likely to do with the age of the star.

TOI-561 belongs to a population of stars called Galactic thick disk stars.

Ms Weiss said: &ldquoStars in this region are chemically distinct, with fewer heavy elements such as iron or magnesium that are associated with planet building."

Earth facts and figure (Image: EXPRESS)

Trending

However, the star is extremely bright, which allowed the astronomers to see the super-Earth as well as the farther out smaller planets.

They orbit their host star once every 10.8 and 16.3 days.

The researchers said in their paper published in the Astronomical Journal: &ldquoThanks to the bright host star, this multiplanet system is amenable to atmospheric follow-up with space-based telescopes.

&ldquoTOI-561b is expected to be a good eclipse target, while planets TOI-561c and d are promising targets for transmission spectroscopy.

&ldquoComparative atmospheric properties for the planets in this very metal-poor system would provide a unique test for planet formation scenarios.&rdquo


13-Billion-Year-Old Galaxy Protocluster Found

Using the Subaru, Keck, and Gemini telescopes, astronomers have discovered a young cluster of galaxies in the early Universe. Named z66OD, the protocluster contains at least 12 huge galaxies and is 13 billion light-years away. It is the earliest galaxy protocluster ever observed, meaning such large-scale structures were around very early in the Universe’s existence.

The z66OD protocluster: the blue shading shows the calculated extent of the protocluster, and the bluer color indicates higher density of galaxies in the protocluster the red objects in zoom-in figures are the 12 galaxies found in it. Image credit: NAOJ / Harikane et al.

“Tracing the formation of the largest structures in the Universe, and the galaxies inside them, is the new frontier in extragalactic astronomy,” said Imperial College London’s Dr. Dave Clements, co-author of the study.

“This result pushes that frontier back still further, and provides some hints as to the processes behind protocluster galaxy formation.”

The Subaru Telescope had previously spotted a giant gaseous nebula called Himiko in the region, and the closer inspection revealed Himiko is a massive galaxy, accompanied by 11 other complete galaxies.

“A protocluster is a rare and special system with an extremely high density, and not easy to find,” said lead author Dr. Yuichi Harikane, an astronomer at the National Astronomical Observatory of Japan (NAOJ).

“To overcome this problem, we used the wide field of view of the Subaru Telescope to map a large area of the sky and look for protoclusters.”

In the map of the Universe made by the Subaru Telescope, the researchers first discovered a candidate of a protocluster in a location where galaxies were 15 times more concentrated than expected.

They conducted follow-up observations using the Keck and Gemini telescopes and confirmed the z66OD protocluster.

In the Subaru map, they also spotted another protocluster, named z57OD, which contains at least 44 galaxies and resides some 12.7 billion light-years away from Earth.

Furthermore, the team discovered that the number of stars forming inside the z66OD protocluster is five times larger than other galaxies with similar masses in the same period of the Universe.

“We believe this is because of the large amount of gas in the system, a crucial ingredient for star formation, and eventually, galaxy formation,” the scientists said.

They were also surprised to discover that the massive Himiko galaxy was not in the center of the z66OD protocluster, but on the edge, around 500 million light-years away from the center.

“It is still not understood why Himiko is not located in the center of z66OD,” said study co-author Dr. Masami Ouchi, from the NAOJ and the University of Tokyo.

“This result will be a key to understanding the connection between galaxy clusters and massive galaxies.”

The discovery is reported in a paper in the Astrophysical Journal.

Yuichi Harikane et al. 2019. SILVERRUSH. VIII. Spectroscopic Identifications of Early Large-scale Structures with Protoclusters over 200 Mpc at z

6–7: Strong Associations of Dusty Star-forming Galaxies. ApJ 883, 142 doi: 10.3847/1538-4357/ab2cd5


Four new galaxy clusters discovered 10 billion light years from Earth

Three (false) colour Herschel images of the clumps identified by Planck. Blue, green and red represent infrared light at successively longer wavelengths, of 250μm, 350μm and 500μm respectively. The green circle indicates the size of the Planck beam at the position of the source, which Herschel was able to resolve in far greater detail. Credit: D. Clements / ESA / NASA

(Phys.org) —Four unknown galaxy clusters each potentially containing thousands of individual galaxies have been discovered some 10 billion light years from Earth.

An international team of astronomers, led by Imperial College London, used a new way of combining data from the two European Space Agency satellites, Planck and Herschel, to identify more distant galaxy clusters than has previously been possible. The researchers believe up to 2000 further clusters could be identified using this technique, helping to build a more detailed timeline of how clusters are formed.

Galaxy clusters are the most massive objects in the universe, containing hundreds to thousands of galaxies, bound together by gravity. While astronomers have identified many nearby clusters, they need to go further back in time to understand how these structures are formed. This means finding clusters at greater distances from the Earth.

The light from the most distant of the four new clusters identified by the team has taken over 10 billion years to reach us. This means the researchers are seeing what the cluster looked like when the universe was just three billion years old.

Lead researcher Dr David Clements, from the Department of Physics at Imperial College London, explains: "Although we're able to see individual galaxies that go further back in time, up to now, the most distant clusters found by astronomers date back to when the universe was 4.5 billion years old. This equates to around nine billion light years away. Our new approach has already found a cluster in existence much earlier than that, and we believe it has the potential to go even further."

The clusters can be identified at such distances because they contain galaxies in which huge amounts of dust and gas are being formed into stars. This process emits light that can be picked up by the satellite surveys.

Galaxies are divided into two types: elliptical galaxies that have many stars, but little dust and gas and spiral galaxies like our own, the Milky Way, which contain lots of dust and gas. Most clusters in the universe today are dominated by giant elliptical galaxies in which the dust and gas has already been formed into stars.

"What we believe we are seeing in these distant clusters are giant elliptical galaxies in the process of being formed," says Dr Clements.

Observations were recorded by the Spectral and Photometric Imaging Receiver (SPIRE) instrument as part of Herschel Multi-tiered Extragalactic Survey (HerMES). Seb Oliver, Head of the HerMES survey said: "The fantastic thing about Herschel-SPIRE is that we are able to scan very large areas of the sky with sufficient sensitivity and image sharpness that we can find these rare and exotic things. This result from Dr. Clements is exactly the kind of thing we were hoping to find with the HerMES survey"

The researchers are among the first to combine data from two satellites that ended their operations last year: the Planck satellite, which scanned the whole sky, and the Herschel satellite, which surveyed certain sections in greater detail. The researchers used Planck data to find sources of far-infrared emission in areas covered by the Herschel satellite, then cross referenced with Herschel data to look at these sources more closely. Of sixteen sources identified by the researchers, most were confirmed as single, nearby galaxies that were already known. However, four were shown by Herschel to be formed of multiple, fainter sources, indicating previously unknown galaxy clusters.

The team then used additional existing data and new observations to estimate the distance of these clusters from Earth and to determine which of the galaxies within them were forming stars. The researchers are now looking to identify more galaxy clusters using this technique, with the aim of looking further back in time to the earliest stage of cluster formation.

The research involved scientists from the UK, Spain, USA, Canada, Italy and South Africa. It is published in the Monthly Notices of the Royal Astronomical Society and was part funded by the Science and Technology Facilities Research Council and the UK Space Agency.


Hubble Deep Field galaxies

Looking at what information I can get on the HDF galaxies, project scientists date some of them at more than 10 billion years old. How long was it supposed to take to form these galaxies? What is the timeline on galaxy formation after the big bang? If the Universe is only 12 to 15 billion years old, can these galaxies really be 10 or more billion years old. Wouldn't it have taken billions of years for them to have developed to their current state, which we see as 10 billion years ago according to their distance? Do these galaxies jive with current theories of the age of the universe? What indicators are there in a galaxy that can lead us to its age? Trees have rings, what do galaxies have?

#2 markf

I think they're still working out how galaxies form. I'm not sure on the current thinking as far as that goes.

But dating is based on red-shift generally. How much to the "red" the light has shifted helps point them to the age of the light source.

#3 Doug Phillipson

But the age of the light source isn't the age of the galaxy. It's just the length of time it took the light to get to us. What we see is the object as it was 10 or more billion years ago, which at the time was quite well formed and probably already billions of years old.

#4 Relativist

#5 markf

But the age of the light source isn't the age of the galaxy. It's just the length of time it took the light to get to us. What we see is the object as it was 10 or more billion years ago, which at the time was quite well formed and probably already billions of years old.

I stand corrected. It's distance, not date. How they date things so far away, no idea.

#6 wilash

#7 matt

- yes, they are dated by redshift
- galaxies are usually dated by their stars stars themselves can be tricky to date (and in those galaxies, there is no way to look at individual stars)
- it's hard to say how old galaxies are, because we have never seen a galaxy age. Most galaxies in our vicinity are "adult" we can't really know what a baby galaxy looks like we might not even tell a baby galaxy from a peculiar type of "regular" one if we saw one.
- galaxies are usually aged by their ratio of stars to dust and gas, and their rate of star formation. Stuff you can infer by spectral examination, on faraway galaxies. It's expected that the older the galaxy, the slower it's gas content and the slower its star formation rate. But then, just like a 20-year old can have a growth spurt, a galaxy can have a burst of star formation, triggered for example by the gravity of another galaxy passing by and shaking things up.

In this case young galaxies do not challenge the Big Bang, but rather our models of how fast the slightly heterogeneous post-Big Bang mix of baryonic matter (read: ordinary matter) gave birth to galaxies to this you can add the chicken-and-egg problem of which came first, stars or galaxies.

Before the HUDF (and a few less widely published images) it was thought that galactic formation had to take at least a couple billion years, and those pictures zooming on the 1-billion year old universe, expected to show proto-galaxies, showed galaxies already up and running.

#8 NewAstronomer

If the Universe is only 12 to 15 billion years old, can these galaxies really be 10 or more billion years old.

Wouldn't it have taken billions of years for them to have developed to their current state, which we see as 10 billion years ago according to their distance?


Astronomers Find Evidence for a Rapid Evolution of Galaxies in the Early Universe

An international team of astronomers -- including the research group of Cornell astronomer Dominik Riechers -- has obtained profound new insight into the nature of galaxies in the early universe and how they formed their stars across cosmic history. The team found that galaxies likely started forming their stars only about 200 million years after the Big Bang and that they were already fairly mature less than one billion years later.

Using large quantities of observing time on the Atacama Large sub/Millimeter Array (ALMA), the research team, dubbed ALPINE (the ALMA Large Program to Investigate C+ at Early Times), looked at 118 galaxies to reach their conclusion that massive galaxies were already much more mature in the early universe than previously expected.

Most galaxies formed when the universe was still very young. (Our own galaxy likely started forming 13.6 billion years ago, in our 13.8 billion-year-old universe.) Galaxies are considered more “mature” than “primordial” when they contain a significant amount of dust and heavy elements, which are considered to be the by-products of dying stars. But galaxies in the early universe have not had much time to build stars yet, so astronomers didn’t expect to see much dust or heavy elements. The ALPINE team, however, found that around 20 percent of the galaxies they studied from this early epoch were already hidden by dust.

The galaxies also appeared more mature than expected because of the diversity in their structures, including the first signs of rotationally supported disks, which may lead to galaxies with a spiral structure such as our Milky Way. Astronomers generally expect that galaxies in the early universe look like more like train wrecks, because they often collide.

The scientists don’t yet fully understand how these galaxies grew up so fast or why some of them already have rotating disks.

Artist's illustration of a dusty, rotating distant galaxy. Credit: B. Saxton NRAO/AUI/NSF, ESO, NASA/STScI NAOJ/Subaru

The ALPINE study was critically enabled by Riechers and his team's initial demonstrations that studies of the star formation properties of faint, very distant galaxies were possible with a telescope as sensitive as ALMA. Riechers’ initial observations were obtained with only about a third of the capabilities that ALMA now offers.

“The ALPINE survey really allowed us to push our initial results to the next level now that ALMA has unfolded its full potential,” said Riechers, assistant professor of astronomy in the College of Arts and Sciences.

Riccardo Pavesi M.S. ’15, Ph.D. ‘19, a member of Riechers’ team, has carried out some of the most detailed studies to date of these early galaxies using ALMA and the Karl G. Jansky Very Large Array.

"It is exciting to see that my involvement in the early planning stages of ALPINE has been so fruitful," said Pavesi. "We now finally know that our initial findings were not a coincidence, but that it rather seems to be the norm for galaxies to mature quite rapidly at these early epochs."

Added Riechers, “The results from ALPINE are fantastic news for a large survey program we have designed for the Fred Young Submillimeter Telescope (FYST, formerly CCAT-prime), which will target the same diagnostic lines across the large-scale structure of the universe." The survey will be carried out with the EoR-Spec spectrometer, which is funded by the National Science Foundation and currently under construction in the Department of Astronomy.