The Coma galaxy cluster is unique among known clusters because it contains two giant elliptical galaxies at its center. And recent news shows that this cluster may have other features we don’t see elsewhere.

Galaxy clusters, collections of galaxies bound together by gravity, occur throughout the Universe, and as clusters go, the Coma cluster is one of the largest. It contains over 1,000 galaxies, with more to be identified!

All these galaxies reside inside a giant cloud of hot, energetic gas. Astronomers using NASA’s Chandra X-ray Observatory and ESA’s XMM-Newton to observe Coma discovered huge arms of hot gas over half a million light years long.

Using the speed of sound in hot gas and the gas arms’ length, astronomers calculated the gas to be over 300 million years old! Oddly, the gas in the Coma cluster has a smooth profile, without the lumpiness astronomers expect to see in an active galactic environment. Usually galactic mergers generate significant turbulence that stirs up local gas, but this cluster seems to exist in a relatively calm environment.

This new finding, published in the journal Science, offers insight into how the Coma cluster grew from the mergers of smaller groups of galaxies. As the galaxy groups move through space, head wind strips their gas away, which later forms the giant gas arms we see now.

The multimillion-degree X-ray emission shows that the arms appear to be connected to galaxies far from Coma’s center. At least one of these arms also appears to be connected to a larger structure 1.5 million light years away. It seems that Coma’s tentacles reach for into the cosmos.

Clues hidden in the gas will tell us more about this one-of-a-kind cluster, so stay tuned!

Alyssa Keimach is an astronomy and astrophysics student at the University of Michigan and interns for the Morrison Planetarium.

Image: NASA/CXC/MPE/J.Sanders et al, Optical: SDSS

The newest cosmic mystery: four distinct high-energy flashes! (Is the Universe trying to get our attention?) Astronomers are calling them Fast Radio Bursts, but we have yet to determine their origins.

Radio astronomers detected the first burst about six years ago, but it seemed so strange that many people thought it was a fluke. Dan Thornton, a PhD student at England’s University of Manchester and Australia’s Commonwealth Scientific and Industrial Research Organization, decided to investigate. He spent the next six years looking for these strange flashes.

So far Thornton and his team have found four radio bursts. Astonishingly, the flashes—taken from only a small section of the sky—indicate that there should be one of these signals going off every ten seconds.

“The bursts last only a tenth of the blink of an eye,” explained Max-Planck Institute Director and Manchester professor, Michael Kramer. “With current telescopes we need to be lucky to look at the right spot at the right time. But if we could view the sky with ‘radio eyes’ there would be flashes going off all over the sky every day.”

Astronomers have ruled out terrestrial sources for the Fast Radio Bursts and the origins in the high galactic latitudes suggest that they originate from beyond the Milky Way.

The brightness and distance of the mysterious flashes also hint that they originated when the Universe was about half its current age. “They have come such a long way that by the time they reach the Earth, the Parkes telescope would have to operate for one million years to collect enough to have the equivalent energy of a flying mosquito,” said Thornton.

Co-author Professor Matthew Bailes, from the Swinburne University of Technology in Melbourne, Australia, thinks that burst energies indicate that they come from events involving relativistic objects—maybe even from a type of neutron star called a magnetar. “Magnetars can give off more energy in a millisecond than our Sun does in 300,000 years and are a leading candidate for the burst.”

Astronomers have a lot more research to do before we can solve the radio burst puzzle, but the findings may also help crack some other astronomical mysteries. “We are still not sure about what makes up the space between galaxies, so we will be able to use these radio bursts like probes in order to understand more about some of the missing matter in the Universe,” said Ben Stappers, from Manchester’s School of Physics and Astronomy.

So these Fast Radio Bursts could even speed up cosmic discovery!

Alyssa Keimach is an astronomy and astrophysics student at the University of Michigan and interns for the Morrison Planetarium.

Image: Diceman Stephen West

We have peered far into the Universe and vastly expanded our knowledge of distant realms. But interestingly enough, we are still refining our understanding of our own place within our galaxy, the Milky Way. Research into this question follows in the footsteps of many great names in astronomy: from Herschel to Hubble, and from Kapteyn to Kant, generations of astronomers helped to establish our understanding of our place in space.

Imagine, if you will, trying to take a picture of the United States from somewhere close to the center of it. (That’s right. Lots of corn fields.) You would have no way to observe the entire country at the same time. Astronomers face a similar challenge in observing our home galaxy: we live within the disc of the Milky Way, a long way from the center (about 7,600 parsecs or 25,000 light years) and only a small distance from the middle of the plane (27 parsecs or close to 88 light years), with thick lanes of gas and dust blocking our view. We can see other more distant galaxies and have discovered many shapes and types, so comparing ourselves to them can help us determine the approximate shape and layout of the Milky Way.

Dr. Alyssa Goodman and her team recently realized that a dark cool cloud dubbed “Nessie” in the constellation Ara might have some secrets to tell about the Milky Way. We have seen similar features in other spiral galaxies: slightly denser tubes of material that define long spiral arms. By studying this “bone” of our galaxy, we may soon be able to refine our map of home to an even greater degree. We reside just far enough from the plane of the Milky Way’s disc that we could perhaps one day find the rest of these bones and create an even better layout of our place in space.

This concept and more appear in Goodman’s Authorea paper, currently in development now for later publication. Amazingly, you can to read the paper online while the authors finalize it! Talk about science in action…

Josh Roberts is a program presenter and astronomer at the California Academy of Sciences. He also contributes content to Morrison Planetarium productions.

Image: NASA/JPL-Caltech/R. Hurt (SSC/Caltech)

Earth’s neighborhood just got a little larger.

Astronomers thought that Earth was located on a spur of an arm of the Milky Way… until data from the Very Long Baseline Array telescopes suggested that we could be located closer to the center.

While it’s simple to observe a bird’s-eye view of other galaxies, models of the Milky Way are inaccurate due to Earth’s limited vantage point. We are attempting to measure an entire galaxy using only Earth’s narrow perspective, and at the center of our galaxy is a large bulge, blocking about half of the Milky Way from view.

To make the best model possible, astronomers use a technique called parallax. Measurements are taken from locations on either side of the sun to give multiple perspectives of our location in the sky. Then, astronomers use trigonometry to calculate where we might reside in comparison to distant objects.

At the center of the Milky Way is a supermassive black hole, whose gravitational pull is capable of keeping 200–400 billion stars in orbit around the galaxy. Measurements from NASA’s Spitzer Space Telescope revealed that these stars are oriented in two arms that spiral around the black hole.

“Based on both the distances and the space motions we measured, our Local Arm is not a spur,” said Alberto Sanna, a postdoctoral fellow with the Max-Planck Institute for Radio Astronomy (MPIFR). “It is a major structure, maybe a branch of the Perseus Arm, or possibly an independent arm segment.”

Sanna and his colleagues presented their research this week at the American Astronomical Society meeting, held in Indiana.

Astronomers are creating increasingly accurate models of the Milky Way and every new finding tells us more about the entire universe.

Alyssa Keimach is an astronomy and astrophysics student at the University of Michigan and interns for the Morrison Planetarium.

Image: NASA

I’m not going to get into exoplanet announcements such as this one or this one from yesterday morning’s meeting (as one attendee tweeted in summary, “There’s more exoplanets than you can shake an exostick at.”). We have ten press conferences scheduled, and three of them revolve around (pun intended) exoplanet discoveries. So I’ll plan for an exoplanet wrap-up toward the end of the conference.

Instead, I’d like to talk about the work of a few of those spiffy space-based telescopes—yes, the ever-popular Hubble Space Telescope, but also Chandra X-Ray Observatory and a new mission known as NuSTAR.

A grand effort known as the Hubble Ultra Deep Field (HUDF) has imaged the same, small, seemingly-dull part of the sky repeatedly at numerous, finely-tuned wavelengths of light, revealing distant galaxies that reside farther than just about anything we can see. Looking out into space means looking back into time, so the HUDF reveals an important epoch in the history of the Universe.

It turns out the Universe in its youth went through an unusual phase when most of the hydrogen in deep space was in the form of molecules, with no net electrical charge… By the time the Universe reached the age of about 800 million years, however, most of the hydrogen had become ionized, which is to say broken down into electrons and protons (both of which have electrical charge). But it takes energy to ionize hydrogen, so where did that energy come from?

This is the kind of puzzle that keeps astronomers busy (and employed) for decades. Since 2004, astronomers have refined and extended the HUDF observations to eke out more information about this epoch, and the most recent observations have allowed scientists to reach some well-founded, long-sought conclusions.

We know that young galaxies would emit radiation that could ionize the Universe, but can they produce enough radiation to light up the “Cosmic Dawn,” as it’s sometimes called? Astronomers love to come up with more exotic theories, such as the annihilation of dark matter, to explain things like this, but are such puzzling processes required?

Turns out they aren’t. Galaxies can do the job on their own. That’s not the sexiest answer, but it should ultimately feel quite satisfying: the Universe behaves in a way that we understand and can predict. But it took a remarkable amount of sleuthing to come up with this relatively mundane response.

First off, we tally up the galaxies we see, and we estimate how much radiation they would emit. And the first surprise? Small, faint (the researchers like to call ’em “feeble”) galaxies make a significant contribution to the total energy output, and the large, luminous can’t do the job on their own.

Turns out that the currently-observed population of galaxies does not produce enough radiation to ionize all that intergalactic hydrogen. Bummer. But we know that we’re not seeing all the galaxies! We can detect only the brightest ones at these great distances, and the HUDF team’s work suggests that an earlier generation of galaxies existed before the ones we’re seeing. So how can we estimate the energy contribution from what we’re not seeing directly?

The team of astronomers undertook the challenge of tallying the luminous galaxies versus the number of feeble galaxies, and projecting those estimates back in time. Based on HUDF and other observations from, for example, the Wilkinson Microwave Anisotropy Probe (WMAP), we can determine when stars and galaxies started lighting up the Universe, so when the team added up all the light from all the galaxies they estimated to have existed over that time… Bingo! Just enough light energy to ionize the Universe’s hydrogen.

All this work actually pushed Hubble to its limits. And it promises many more discoveries from the James Webb Space Telescope, due to launch in 2018, which will peer back farther in time to see earlier generations of galaxies.

Hubble isn’t alone out there, and x-ray astronomy in particular benefits from having telescopes in space. Stephen S. Murray from Johns Hopkins gave a review of “50 Years of X-Ray Astronomy,” describing remarkable successes in the field. From 1962 to 1999, x-ray astronomy has experienced an increase in sensitivity of 10 billion! (And Murray noted that it took astronomers 400 years to achieve that kind of gain in optical sensitivity…) That kind of revolutionary change has led to spectacular discoveries related to some of the most exotic objects in astronomy—including black holes, pulsars, and supernovae.

An impressive video from Chandra shows a curlicue jet streaming from the pulsar at the center of the Vela Supernova Remnant. This complex structure provides a nifty puzzle for astronomers to describe its origin.

And the recently-launched Nuclear Spectroscopic Telescope Array (NuSTAR), one of the least expensive missions ever launched by NASA, has released its first images. The pair of telescopes spotted two bright, energetic sources of x-rays in the galaxy IC 342—capturing black holes in the process of “feeding” (as NuSTAR team leader Fiona Harrison puts it).

Stay tuned for more spacy stuff the rest of the week…

NuSTAR image courtesy of CalTech

The galaxy, dubbed with the melodic name MACS 1149-JD, was spotted using  the combined power of NASA’s Spitzer and Hubble space telescopes as well as the phenomenon of gravitational lensing – using the gravity of nearer massive galaxies to bend and magnify the light of more distant ones behind them, which would otherwise remain invisible.

Small and compact, the galaxy appears to contain the equivalent of only about 1 percent of the Milky Way’s mass. The galaxy is quite young, only about 200 million years old, but we see it far back in time, when the Universe was quite young. (Imagine looking at an old photograph of your great grandparents: an old image showing a perhaps quite young couple.)  Light from the young galaxy captured by the orbiting observatories shone forth when the 13.7-billion-year-old Universe was just 500 million years old.

MACS 1149-JD existed during an important era when the Universe began to emerge from the cosmic Dark Ages. During this period, the Universe went from a dark, starless expanse to a recognizable cosmos full of galaxies. The discovery of the faint, small galaxy opens up a window into the deepest, remotest periods of cosmic history.

“This galaxy is the most distant object we have ever observed with high confidence,” says Wei Zheng, lead researcher on a paper appearing in Nature this week. “Future work involving this galaxy—as well as others like it that we hope to find—will allow us to study the universe’s earliest objects and how the Dark Ages ended.”

According to leading cosmological theories, the first galaxies should have started out tiny like MACS 1149-JD. They then progressively merged, eventually accumulating into the sizable galaxies of the more modern universe.

These first galaxies likely played the dominant role in the “epoch of reionization,” the event that signaled the demise of the universe’s dark ages. This epoch began about 400,000 years after the Big Bang when neutral hydrogen gas formed from cooling particles. The first luminous stars and their host galaxies emerged a few hundred million years later. The energy released by these earliest galaxies is thought to have caused the neutral hydrogen strewn throughout the Universe to ionize, or lose an electron, a state that the gas has remained in since that time.

Astronomers plan to study the rise of the first stars and galaxies and the epoch of reionization with the successor to both Hubble and Spitzer, NASA’s James Webb Telescope, which is scheduled for launch in 2018. The newly described distant galaxy likely will be a prime target.

Image: NASA/ESA/STScI/JHU

UC Santa Cruz researchers, using Hubble’s powerful Wide Field Planetary Camera 3, have looked 13.2 billion years into the past, discovering a small, compact galaxy of blue stars that existed only 480 million years after the Big Bang.

Creatively named UDFj-39546284, it ranks as the most distant galaxy yet observed. And it is pretty small by galaxy standards—over one hundred such mini-galaxies would fit inside our Milky Way.

Although individual stars can’t be resolved by Hubble, evidence suggests that this is a compact galaxy of hot stars that first started to form 100 to 200 million years earlier in a pocket of dark matter.

How do scientists find these distant, infant galaxies? According to Universe Today,

Astronomers gauge the distance of an object from its redshift, a measure of how much the expansion of space has stretched the light from an object to longer (“redder”) wavelengths.

Nature published the paper describing UDFj-39546284 last week. But astronomers calculate a 20% chance that the distant light is not a galaxy. It will take the pricey James Webb Telescope to confirm its galactic standing. Webb’s infrared vision should provide spectroscopic measurements that can confirm the tremendous distance of the reported object. For now, UDFj-39546284 will have to wait—the telescope won’t launch for at least another three years. But heck, what’s three years compared to 13.2 billion?

Image credit: NASA, ESA, G. Illingworth (University of California, Santa Cruz), R. Bouwens (University of California, Santa Cruz, and Leiden University), and the HUDF09 Team

Here’s how it works: When a large nearby object, such as a galaxy, blocks a distant object, such as another galaxy, gravity from the nearby object causes light to detour around it. But instead of taking a single path, light bends around the object sometimes doubling, sometimes quadrupling, sometimes creating an entire ring of light around the nearby galaxy.

Astrophysicist Phil Marshall explains it quite well using a birthday candle and wine glass stem here.

Using the Hubble Space Telescope and WMAP data, the Stanford team could measure the distances light traveled from a bright, active galaxy to the earth along different paths. For example, if the light quadrupled around the nearby object, the scientists could measure it four times, along four separate paths.

Marshall likens it to four cars taking four different routes between places on opposite sides of a large city, such as Stanford University to Lick Observatory, through or around San Jose. And like automobiles facing traffic snarls, light can encounter delays, too.

By understanding the time it took to travel along each path and the effective speeds involved, researchers could infer not just how far away the galaxy lies but also the overall scale of the universe and some details of its expansion.

Using light bent by gravity, astronomers can measure the Universe—a yardstick billions of light years in length!