universe – A Darker View

Primordial Galaxy Discovered, First of Its Kind

MACS1423-z7p64 galaxy — Graphic illustration of how MACS1423-z7p64 was detected via gravitational lensing with NASA’s Hubble Space Telescope and confirmed by W. M. Keck Observatory’s MOSFIRE. Credit: NASA/W. M. Keck Observatory/A. Hoag/M. Bradac

Seven years of meticulous observing have resulted in a cosmic discovery that comes from an era dating back 13.1 billion years, giving scientists a detailed glimpse of what may have happened just after the Big Bang.

Using the world-class W. M. Keck Observatory on Maunakea, Hawaii, an international team of astronomers from the United States, Australia, and Europe has confirmed the existence of one of the most distant galaxies in the universe.

To characterize the faint galaxy, the discovery team, led by Austin Hoag, a University of California, Davis physics graduate student, used MOSFIRE, the most in-demand instrument on the 10-meter Keck I telescope.

What makes this galaxy extraordinary is that it is ordinary. It is thought to be a common galaxy at that distance and age of the universe. However, such galaxies would normally be too faint to detect. The astronomers used a method called gravitational lensing to magnify the galaxy so they could study it.

“Most objects that we’ve seen at that distance are extremely bright, and probably rare compared to other galaxies,” said Hoag. “We think this galaxy is much more representative of other galaxies of its time.”

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Astronomers Measure Universe Expansion, Get Hints of ‘New Physics’

W. M. Keck Observatory press release…

Astronomers have just made a new measurement of the Hubble constant, the rate at which the universe is expanding, and it doesn’t quite line up with a different estimate of the same number. That discrepancy could hint at “new physics” beyond the standard model of cosmology, according to the team, which includes physicists from the University of California, Davis, that made the observation.

Lensed Quasar HE0435-1223 — The image of this quasar is split into four by a massive galaxy acting as a gravitational lens. Image credit: Sherry Suyu, European Space Agency/Hubble Space Telescope/NASA

The Hubble constant allows astronomers to measure the scale and age of the universe and measure the distance to the most remote objects we can see, said Chris Fassnacht, a physics professor at UC Davis and a member of the international H0LiCOW (H0 Lenses in COSMOGRAIL’s Wellspring) collaboration, which carried out the work.

Led by Sherry Suyu at the Max Planck Institute for Astrophysics in Germany, the H0LICOW team used the NASA/ESA Hubble Space Telescope and other space- and Earth-based telescopes, including the Keck telescopes in Hawaii, to observe three galaxies and arrive at an independent measurement of the Hubble constant. Eduard Rusu, a postdoctoral researcher at UC Davis, is first author on one of five papers describing the work, due to be published in the Monthly Notices of the Royal Astronomical Society.

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Shattering the Silence

It has been over three months since the protest began. Three months of standoff with the protesters who would not see another telescope built on Mauna Kea.

Mauna Kea Observing — My 18″ telescope Deep violet set up under the stars at the MKVIS.

It has been my habit over the last eight years to spend a night under the stars, high on the mountain, each time the new Moon arrives. On the nights when there is no moonlight the sky is dark, truly dark. The stars shine undiminished, the universe is open to be explored. I have used binoculars, small telescopes, cameras, or simply my eyes.

It is with my handmade 18 inch telescope that I can truly gaze into the depths of space. This simple device of plywood and glass allows me to see galaxies millions of light years into the past. With this telescope I have seen hundreds of galaxies, giving me a glimpse of the indescribable vastness of space.

Often I would set up in the patio right at the Mauna Kea Visitor Information Station. The first couple hours spent talking with visitors, showing them the wonders our universe has to offer. After the VIS closes the visitors depart, driven back to their hotels by the cold mountain air. I have a heavy winter jacket, ski-pants, a thermos of hot tea, everything I need to be comfortable under the night sky. I would have the rest of the night to myself, just me, the mountain and the stars.

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Scientists Discover Brightest Early Galaxy and Likely First Generation Stars

W. M Keck Observatory press release…

Astronomers using several of the largest telescopes on Earth and space have discovered the brightest galaxy yet found in the early Universe and have strong evidence that examples of the first generation of stars lurk within it. The results have been accepted for publication in The Astrophysical Journal.

Early Galaxy — An artist’s impression of a galaxy in the early universe, credit: David Sobral

The team’s expansive study was made using the 10-meter W. M. Keck Observatory, the 8.2-meter ESO Very Large Telescope and Subaru Telescope, as well as the NASA/ESA Hubble Space Telescope. The team discovered — and confirmed — a number of surprisingly bright very young galaxies.

A team — led by David Sobral from the Institute of Astrophysics and Space Sciences, the Faculty of Sciences of the University of Lisbon in Portugal, and Leiden Observatory in the Netherlands — peered back into the ancient Universe, to the reionization period approximately 800 million years after the Big Bang. Instead of conducting a narrow and deep study of a small area of the sky, the team broadened their scope to produce the widest survey of very distant galaxies ever attempted.

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Scientists Build First Map of Hidden Universe

W. M. Keck Observatory press release…

A team led by astronomers from the Max Planck Institute for Astronomy has created the first three-dimensional map of the ‘adolescent’ Universe, just 3 billion years after the Big Bang. This map, built from data collected from the W. M. Keck Observatory, is millions of light-years across and provides a tantalizing glimpse of large structures in the ‘cosmic web’ – the backbone of cosmic structure.

On the largest scales, matter in the Universe is arranged in a vast network of filamentary structures known as the ‘cosmic web’, its tangled strands spanning hundreds of millions of light-years. Dark matter, which emits no light, forms the backbone of this web, which is also suffused with primordial hydrogen gas left over from the Big Bang. Galaxies like our own Milky Way are embedded inside this web, but fill only a tiny fraction of its volume.

Now a team of astronomers led by Khee-Gan Lee, a post-doc at the Max Planck Institute for Astronomy, has created a map of hydrogen absorption revealing a three-dimensional section of the universe 11 billions light years away – the first time the cosmic web has been mapped at such a vast distance. Since observing to such immense distances is also looking back in time, the map reveals the early stages of cosmic structure formation when the Universe was only a quarter of its current age, during an era when the galaxies were undergoing a major ‘growth spurt’.

The map was created by using faint background galaxies as light sources, against which gas could be seen by the characteristic absorption features of hydrogen. The wavelengths of each hydrogen feature showed the presence of gas at a specific distance from us. Combining all of the measurements across the entire field of view allowed the team a tantalizing glimpse of giant filamentary structures extending across millions of light-years, and paves the way for more extensive studies that will reveal not only the structure of the cosmic web, but also details of its function – the ways that pristine gas is funneled along the web into galaxies, providing the raw material for the formation of galaxies, stars, and planets.

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The Rise and Fall of Galactic Cities

JPL Press Release…

In the fable of the town and country mice, the country mouse visits his city-dwelling cousin to discover a world of opulence. In the early cosmos, billions of years ago, galaxies resided in the equivalent of urban or country environments. Those that dwelled in crowded areas called clusters also experienced a kind of opulence, with lots of cold gas, or fuel, for making stars.

Today, however, these galactic metropolises are ghost towns, populated by galaxies that can no longer form stars. How did they get this way and when did the fall of galactic cities occur?

A new study from NASA’s Spitzer Space Telescope finds evidence that these urban galaxies, or those that grew up in clusters, dramatically ceased their star-making ways about 9 billion years ago (our universe is 13.8 billion years old). These galactic metropolises either consumed or lost their fuel. Galaxies in the countryside, by contrast, are still actively forming stars.

“We know the cluster galaxies we see around us today are basically dead, but how did they get that way?” wondered Mark Brodwin of the University of Missouri-Kansas City, lead author of this paper, published in the Astrophysical Journal. “In this study, we addressed this question by observing the last major growth spurt of galaxy clusters, which happened billions of years ago.”

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Creationist Astronomy

Astronomy is a science where human timescales become insignificant. It seems like everything we are watching takes millions or even billions of years to occur. To be sure, there are a few things that happen quickly, like supernovae, but those events are the exceptions. Everywhere we look we see the stately dance of stars and galaxies, the formation of worlds. The dance is spread across distances and times so vast that even those who study the universe have difficulty comprehending the sheer immensity involved. Stars and planets take hundreds of thousands of years to form, a galaxy collision may go on for millions of years.

M6 The Butterfly Cluster — M6, the Butterfly Cluster

And yet there is a significant portion of our fellow citizens who insist that the universe is only a few thousand years old. I encounter this belief all too often, a dogged insistence that everything was created just a few thousand years ago. There are variations on the theme, with differing numbers, but these beliefs generally accept that our universe and the Earth were formed within the last ten thousand years. Never mind we have literally mountains of evidence to the contrary, when that evidence clashes with worldviews instilled since birth by a religion and parents, a discouraging number of people ignore reality and cling to what they were taught. To admit otherwise would open up too many other dearly held beliefs to questioning, a truly uncomfortable challenge.

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Astronomers Go Infrared to Map Brightest Galaxies in Universe

W. M. Keck Observatory press release…

A group of astronomers from the University of Hawaii at Manoa, the U.S. Mainland, Canada, and Europe recently used the twin telescopes of the W. M. Keck Observatory on Mauna Kea, Hawaii, to conduct a census of the brightest, but until now unseen, galaxies in the distant Universe, bringing astronomers one step closer to understanding how galaxies form and evolve.

Looking Back — A 3D projection of almost 300 galaxies in the census in the same part of the sky.

These galaxies glow so brightly at infrared wavelengths that they would outshine our own Milky Way by hundreds, maybe thousands, of times. They are forming stars so quickly that between 100 and 500 new stars are born in each galaxy every year, and have been coined “starbursts” by astronomers.

While it’s not clear what gives these galaxies their intense luminosity, it could be the result of a collision between two spiral-type galaxies, similar to the Milky Way and Andromeda Galaxies. Or they could be in a particularly gas-rich region of space, where galaxies form stars quickly due to constant bombardment from gas and dust.

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Light-years, Light-minutes and Light-seconds

To quote Douglas Adams… “Space is big. You just won’t believe how vastly, hugely, mind-bogglingly big it is.”

We are accustomed to using miles or kilometers when considering distance. These are the distances that we experience in our everyday lives. Driving to work or the supermarket, we do not travel very far compared to the distances faced by those who study the stars. Those wanting to discuss distances beyond our little planet, the distances to the stars and galaxies face a quandary… The universe is just too big, when using these familiar units the number of zeros become impractical and the numbers cease to be convenient, or even understandable. To express distances in the cosmos, astronomers just need a bigger tape measure.

The Andromeda Galaxy, 2.5 million light years away

When expressing distances among the stars we turn to the same phenomena we use to observe the stars, starlight itself. We know that light travels fast, covering huge distances very quickly. Light, just another form of electromagnetic energy, is a universal constant across the universe, how far it travels in a given time is a convenient standard by which to measure the universe.

In a few minutes light travels across our solar system, in a few years it can reach the nearby stars. Thus a distance unit that makes sense in astronomy… The light-year, the distance light travels in a single year. With this we have a convenient unit of distance, one that links the concepts of distance and time. A simple bit of math converts the light-year into familiar units… 9.45 trillion kilometers or 5.86 trillion miles.

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Keck Lecture – Dr. Brian Siana

On Thursday, May 10, 2012, Keck Observatory hosted a live webcast of an astronomy talk by Dr. Brian Siana of the University of California at Riverside. Below is the recording of that talk, which was delivered to a live audience at the Kahilu Theatre in Kamuela-Waimea, Hawaii.

The first galaxies had an extraordinary impact on the young universe. Their ultraviolet light destroyed nearly all of the atoms in the cosmos. This process, called reionization, had severe consequences for galaxies trying to form thereafter. Unfortunately, we have no idea how it happened. In galaxies today ultraviolet light cannot escape, so the first galaxies must have been very different from those we see today. Dr. Siana will describe the quest to detect these first galaxies and their impact on the early universe.