Posted on by John Williams

Monster Black Holes Lurk at the Edge of Time

The reddish object in this infrared image is ULASJ1234+0907, located about 11 billion light-years from Earth. The red color comes from vast amounts of dust, which absorbs bluer light, and obscures the supermassive black hole from view in visible wavelengths. Credit: image created using data from UKIDSS and the Wide-field Infrared Survey Explorer (WISE) observatory.

As if staring toward the edge of the Universe weren’t fascinating enough, scientists at the University of Cambridge say they see enormous, rapidly growing supermassive black holes barely detectable near the edge of time.

Thick dust shrouds the monster black holes but they emit vast amounts of radiation through violent interactions and collisions with their host galaxies making them visible in the infrared part of the electromagnetic spectrum. The team published their results in the journal Monthly Notices of the Royal Astronomical Society.

The most remote object in the study lies at a whopping 11 billion light-years from Earth. Ancient light from the supermassive black hole, named ULASJ1234+0907 and located toward the constellation of Virgo, the Maiden, has traveled (at almost 10 trillion kilometers, or 6 million million miles, per year) across the cosmos for nearly the estimated age of the Universe. The monster black hole is more than 10 billion times the mass of our Sun and 10,000 times more massive than the black hole embedded in the Milky Way Galaxy; making it one of the most massive black holes ever seen. And it’s not alone. Researchers say that there may be as many as 400 giants black holes in the tiny sliver of the Universe that we can observe.

“These results could have a significant impact on studies of supermassive black holes” said Dr Manda Banerji, lead author of the paper, in a press release. “Most black holes of this kind are seen through the matter they drag in. As the neighbouring material spirals in towards the black holes, it heats up. Astronomers are able to see this radiation and observe these systems.”

The team from Cambridge used infrared surveys being carried out on the UK Infrared Telescope (UKIRT) to peer through the dust and locate the giant black holes for the first time.

“These results are particularly exciting because they show that our new infrared surveys are finding super massive black holes that are invisible in optical surveys,” says Richard McMahon, co-author of the study. “These new quasars are important because we may be catching them as they are being fed through collisions with other galaxies. Observations with the new Atacama Large Millimeter Array (ALMA) telescope in Chile will allow us to directly test this picture by detecting the microwave frequency radiation emitted by the vast amounts of gas in the colliding galaxies.”

Huge black holes are known to reside at the centers of all galaxies. Astronomers predict the most massive of these cosmic phenomena grow through violent collisions with other galaxies. Galactic interactions trigger star formation which provides more fuel for black holes to devour. And it’s during this process that thick layers of dust hide the munching black holes.

“Although these black holes have been studied for some time,” says Banergi, “the new results indicate that some of the most massive ones may have so far been hidden from our view. The newly discovered black holes, devouring the equivalent of several hundred Suns every year, will shed light on the physical processes governing the growth of all supermassive black holes.”

Astronomers compare the extreme case of ULASJ1234+0907 with the relatively nearby and well-studied Markarian 231. Markarian 231, found just 600 million light-years away, appears to have recently undergone a violent collision with another galaxy producing an example of a dusty, growing black hole in the local Universe. By contrast, the more extreme example of ULASJ1234+0907, shows scientists that conditions in the early Universe were more turbulent and inhospitable than today.

Source: Royal Astronomical Society

Image Credit: Markarian 231, an example of a galaxy with a dusty rapidly growing supermassive black hole located 600 million light years from Earth. The bright source at the center of the galaxy marks the black hole while rings of gas and dust can be seen around it as well as “tidal tails” left over from a recent impact with another galaxy. Courtesy of NASA/ESA Hubble Space Telescope.

Posted on by Nancy Atkinson

Early Galaxy Found from the Cosmic ‘Dark Ages’

In the big image at left, the many galaxies of a massive cluster called MACS J1149+2223 dominate the scene. Gravitational lensing by the giant cluster brightened the light from the newfound galaxy, known as MACS 1149-JD, some 15 times. At upper right, a partial zoom-in shows MACS 1149-JD in more detail, and a deeper zoom appears to the lower right. Image credit: NASA/ESA/STScI/JHU

Take a close look at the pixelated red spot on the lower right portion of the image above, as it might be the oldest thing humanity has ever seen. This is a galaxy from the very early days of the Universe, and the light from the primordial galaxy traveled approximately 13.2 billion light-years before reaching the Spitzer and Hubble space telescopes. The telescopes — and the astronomers using them — had a little help from a gravitational lens effect to be able to see such a faint and distant object, which was shining way back when our Universe was just 500 million years old.

“This galaxy is the most distant object we have ever observed with high confidence,” said Wei Zheng, a principal research scientist in the department of physics and astronomy at Johns Hopkins University in Baltimore who is lead author of a new paper appearing in Nature. “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.”

This ancient and distant galaxy comes from an important time in the Universe’s history — one which astronomers know little about – the early part of the epoch of reionization, when the Universe began to move from the so-called 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 a window onto the deepest, most remote epochs of cosmic history.

“In essence, during the epoch of reionization, the lights came on in the universe,” said paper co-author Leonidas Moustakas, from JPL.

Because both the Hubble and Spitzer telescopes were used in this observation, this newfound galaxy, named MACS 1149-JD, was imaged in five different wavebands. As part of the Cluster Lensing And Supernova Survey with Hubble Program, the Hubble Space Telescope registered the newly described, far-flung galaxy in four visible and infrared wavelength bands. Spitzer measured it in a fifth, longer-wavelength infrared band, placing the discovery on firmer ground.

Objects at these extreme distances are mostly beyond the detection sensitivity of today’s largest telescopes. To catch sight of these early, distant galaxies, astronomers rely on gravitational lensing, where the gravity of foreground objects warps and magnifies the light from background objects. A massive galaxy cluster situated between our galaxy and MACS 1149-JD magnified the newfound galaxy’s light, brightening the remote object some 15 times and bringing it into view.

Astronomers use redshift to describe cosmic distances, and the ancient but newly-found galaxy has a redshift, of 9.6. The term redshift refers to how much an object’s light has shifted into longer wavelengths as a result of the expansion of the universe.

Based on the Hubble and Spitzer observations, astronomers think the distant galaxy was less than 200 million years old when it was viewed. It also is small and compact, containing only about 1 percent of the Milky Way’s mass. According to leading cosmological theories, the first galaxies indeed should have started out tiny. They then progressively merged, eventually accumulating into the sizable galaxies of the more modern universe.

The epoch of reionization refers to the period in the history of the Universe during which the predominantly neutral intergalactic medium was ionized by the emergence of the first luminous sources, and these first galaxies likely played the dominant role in lighting up the Universe. By studying reionization, astronomers can learn about the process of structure formation in the Universe, and find the evolutionary links between the smooth matter distribution at early times revealed by cosmic microwave background studies, and the highly structured Universe of galaxies and clusters of galaxies at redshifts of 6 and below.

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.

The paper is available here (pdf document).

Source: JPL

Posted on by John Williams

Holy Galaxify Batman! Galaxy Zoo Allows Users to Put Their Name in Big Lights

If you’re going to put your name in lights, you might as well go big; REALLY big. And with millions of galaxies forming all sorts of shapes including letters, numbers and punctuation, GalaxyZoo has created a way for you to do just that.

More than 250,000 people, sorting through about a million images, have taken part in the Galaxy Zoo project since its launch in 2007. “Their findings have ranged from the scientifically exciting to the weird and wonderful,” says the Galaxy Zoo team. And among the weird, the Zooites – that’s what project volunteers call themselves – have found an alphabet of galaxies.

The new “font,” available for anyone to use, is a way to thank all the Zooites for their hard work. But now a new challenge awaits.

Starting today, the Galaxy Zoo now has more than 250,000 new images of galaxies, most of which have never been seen by humans…. and the GZ team really wants them to be seen by humans!

But first, the reward:

Galaxy Zoo team member Dr. Steven Bamford, of the University of Nottingham, created the website at http://www.mygalaxies.co.uk allowing users to create a message in stars.

“We’d like to thank all those that have taken part in Galaxy Zoo in the past five years. Humans are better than computers at pattern recognition tasks like this, and we couldn’t have got so far without everyone’s help,” says Galaxy Zoo principal investigator Dr. Chris Lintott from the University of Oxford, in a press release. “Now we’ve got a new challenge, and we’d like to encourage volunteers old and new to get involved. You don’t have to be an expert — in fact we’ve found not being an expert tends to make you better at this task. There are too many images for us to inspect ourselves, but by asking hundreds of thousands of people to help us we can find out what’s lurking in the data.”

New images available at the Galaxy Zoo website come from large surveys with NASA‘s Hubble Space Telescope as well as ground-based imagery from the Sloan Digital Sky Survey.

“The two sources of data work together perfectly: the new images from Sloan give us our most detailed view of the local universe, while the CANDELS survey from the Hubble telescope allows us to look deeper into the universe’s past than ever before,” says Astronomer and Galaxy Zoo team member Kevin Schawinski from ETH Zurich in Switzerland.

Team members are quick to point out, however, that the quirky nature of the galactic alphabet is not the focus of Galaxy Zoo. Finding unusual galaxies that resemble animals and letters help scientists learn about galaxy interactions as well as the formation and evolution of the biggest structures in the Universe.

Image Credit: Sloan Digital Sky Survey, NASA Hubble Space Telescope and Galaxy Zoo

 

About the author:John Williams is owner of TerraZoom, a Colorado-based web development shop specializing in web mapping and online image zooms. He also writes the award-winning blog, StarryCritters, an interactive site devoted to looking at images from NASA’s Great Observatories and other sources in a different way. A former contributing editor for Final Frontier, his work has appeared in the Planetary Society Blog, Air & Space Smithsonian, Astronomy, Earth, MX Developer’s Journal, The Kansas City Star and many other newspapers and magazines.

Posted on by Nancy Atkinson

Win a Hubble Photograph, Now Through September 16

We all hate to see the summer end (coming soon in the northern hemisphere) but before the September equinox arrives, the HubbleSite team is making the most of the last few days of summer by giving away copies of a few iconic images taken by the venerable Hubble Space Telescope. The End-of-Summer Hubble Picture Giveaway is a random drawing accessible via HubbleSite’s Facebook page. Three winners per day, selected randomly from Sept. 4-16 will receive one 16×20 print of one of three images: Mystic Mountain (as seen below), The Helix Nebula, or Barred Spiral Galaxy NGC 1300.

HubbleSite runs these drawings periodically on its Facebook page, but for readers of Universe Today, they are we’re offering an extra chance to win for users who enter a promo code in the appropriate field!

The code for Universe Today readers is UNIVTDAY.

So check out HubbleSite’s Facebook page, and also check out the HubbleSite website, chock full of all the images taken by HST.

So, enter every day — and don’t forget you can enter twice a day by using the special code for UT readers.

Thanks to the HubbleSite Facebook team!

Hubble’s ‘Mystic Mountain’ shows a mountain of dust and gas rising in the Carina Nebula. The top of a three-light-year tall pillar of cool hydrogen is being worn away by the radiation of nearby stars, while stars within the pillar unleash jets of gas that stream from the peaks. Credit: NASA, ESA, and M. Livio and the Hubble 20th Anniversary Team (STScI)

Posted on by John Williams

Hubble’s Hidden Treasures Unveiled

A quick check of Hubble’s gallery shows just 1,300 images; however more than raw 700,000 images reside in a vast archive with hundreds of potentially jaw-dropping astronomical scenes just waiting to be uncovered. That was the idea behind the European Space Agency’s international contest called Hubble’s Hidden Treasures. And now with the hard work of amateur astronomers and more than 3,000 submissions, some of Hubble’s incredible celestial treasures are revealed.

“The response was impressive, with almost 3000 submissions,” the ESA said in a press release. “More than a thousand of these images were fully processed: a difficult and time-consuming task. We’ve already started featuring the best of these in our Hubble Picture of the Week series.”

The top 10 images selected in the Hubble Hidden Treasures basic imaging category. Top row: NGC 6300 by Brian Campbell, V* PV Cephei by Alexey Romashin, IRAS 14568-6304 by Luca Limatola, NGC 1579 by Kathlyn Smith, B 1608+656 by Adam Kill Bottom row: NGC 4490 by Kathy van Pelt, NGC 6153 by Ralf Schoofs, NGC 6153 by Matej Novak, NGC 7814 by Gavrila Alexandru, NGC 7026 by Linda Morgan-O’Connor

Credit: NASA & ESA

Judges ranked images from two categories, an image processing category and basic image searching category. Judges sifted through 1189 entries in the image processing category; a painstaking process of finding promising data and creating an attractive image using professional imaging software. But even if contestants didn’t have the technical know-how to create large mosaics and combine color filters, they could find stunning images in the Hubble archive using using simple online tools. The ESA received more than 1600 entries in this category.

“Every week, we search the archive for hidden treasures, process the scientific data into attractive images and publish them as the Hubble Picture of the Week,” says the ESA on their Hidden Treasures website. “But the archive is so vast that nobody really knows the full extent of what Hubble has observed.”

Josh Lake of the United States won with this awesome image of NGC 1763, part of the N11 star-forming region of the Large Magellanic Cloud.

First place in the processed category, which asked contestants to find promising data within the archive and process that scene into an attractive image, went to Josh Lake, from the United States. The image, which won the public vote, narrowly edged out other images. Lake produced a bold two-color image that is not in natural colors but contrasts light from glowing hydrogen and nitrogen. In natural colors, the two glowing gasses produce almost indistinguishable shades of red. Lake’s image separates them out into red and blue offering a dramatic view of the structure.

Messier 77 produced by Andre van der Hoeven, of the Netherlands came in a close second.

Andre van der Hoeven of the Netherlands came in a close second. The jury noted the impressive nature of Messier 77 in the image as well as the processing which combines several datasets from separate instruments to create the amazing image.

“This was my hardest job until now,” van der Hoeven says on the Flickr page. “Combining the different datasets to get equal colors was really hard. M77 was not fully covered by one dataset, so I had to combine channels of the WFPC2 with different wavelengths and tune the colors to get them to fit. But the result is in my opinion quite astonishing.”

We are as surprised as him that this image had not been released before.

Judy Schmidt of the United States entered this image of XZ Tauri, a new star lighting up a nearby cloud of gas and dust. She entered several images into the contest.

Third place went to an interesting image of XZ Tauri, a newborn star spraying gas into its surroundings as well as lighting up a nearby cloud of gas. The panel said it was a challenging dataset to process because Hubble captured only two colors in the region. “Nevertheless, the end result is an attractive image, and an unusual object that we would never have found without her help,” the panel said.

Revealing the challenge of many Hubble mosaics, the jury was impressed with the technical achievement Renaud Houdinet showed in putting together this ambitious view. He called this “The Great Mosaic Disaster in Chamaeleon. “Sometimes, things don’t turn out as they ought,” Houdinet admits on the Flickr description. Chamaeleon 1 is a large nebula near the south celestial pole and was not covered in one single Hubble image.

Robert Gendler took fifth place with an image of spiral galaxy Messier 96. You may know Gendler’s work as his version of Hubble’s image of NGC 3190 is the default image on the desktop of new Apple computers.

Top image caption: Top ten images selected in the Hubble Hidden Treasures image processing competition. Top row: NGC 1763 by Josh Lake, M 77 by Andre van der Hoeven, XZ Tauri by Judy Schmidt, Chamaeleon I by Renaud Houdinet, M 96 by Robert Gendler. Bottom row: SNR 0519-69 by Claude Cornen, PK 111-2.1 by Josh Barrington, NGC 1501 by kyokugaisha1, Abell 68 by Nick Rose, IC 10 by Nikolaus Sulzenauer. Credit: NASA & ESA

Links:

About the Author: John Williams is owner of TerraZoom, a Colorado-based web development shop specializing in web mapping and online image zooms. He also writes the award-winning blog, StarryCritters, an interactive site devoted to looking at images from NASA’s Great Observatories and other sources in a different way. A former contributing editor for Final Frontier, his work has appeared in the Planetary Society Blog, Air & Space Smithsonian, Astronomy, Earth, MX Developer’s Journal, The Kansas City Star and many other newspapers and magazines.

Posted on by Nancy Atkinson

Star Clusters on a Clandestine Collision Course

Astronomers originally thought that just one massive star cluster shone brightly in a huge star forming region of the Tarantula Nebula, also known as 30 Doradus. But closer analysis using data from the Hubble Space Telescope shows that it is actually two different clusters that are just starting to collide and merge. A team of astronomers led by Elena Sabbi of the Space Telescope Science Institute noticed that different stars in the same region were of different ages, by at least one million years. Besides the age differences, the scientists also noticed two distinct regions, with one having the elongated “look” of a merging cluster.

“Stars are supposed to form in clusters,” said Sabbi, “but there are many young stars outside 30 Doradus that could not have formed where they are; they may have been ejected at very high velocity from 30 Doradus itself.”


Sabbi and her team were initially looking for runaway stars — fast-moving stars that have been kicked out of their stellar nurseries where they first formed.

But they noticed something unusual about the cluster when looking at the distribution of the low-mass stars detected by Hubble. It is not spherical, as was expected, but has features somewhat similar to the shape of two merging galaxies where their shapes are elongated by the tidal pull of gravity.

Some models predict that giant gas clouds out of which star clusters form may fragment into smaller pieces. Once these small pieces precipitate stars, they might then interact and merge to become a bigger system. This interaction is what Sabbi and her team think they are observing in 30 Doradus.

There are also an unusually large number of runaway, high-velocity stars around 30 Doradus, and after looking more closely at the clusters, the astronomers believe that these runaway stars were expelled from the core of 30 Doradus as the result of the dynamical interactions between the two star clusters. These interactions are very common during a process called core collapse, in which more-massive stars sink to the center of a cluster by dynamical interactions with lower-mass stars. When many massive stars have reached the core, the core becomes unstable and these massive stars start ejecting each other from the cluster.

The big cluster R136 in the center of the 30 Doradus region is too young to have already experienced a core collapse. However, since in smaller systems the core collapse is much faster, the large number of runaway stars that has been found in the 30 Doradus region can be better explained if a small cluster has merged into R136.

The entire 30 Doradus complex has been an active star-forming region for 25 million years, and it is currently unknown how much longer this region can continue creating new stars. Smaller systems that merge into larger ones could help to explain the origin of some of the largest known star clusters, Sabbi and her team said.

Follow-up studies will look at the area in more detail and on a larger scale to see if any more clusters might be interacting with the ones observed. In particular the infrared sensitivity of NASA’s planned James Webb Space Telescope (JWST) will allow astronomers to look deep into the regions of the Tarantula Nebula that are obscured in visible-light photographs. In these areas cooler and dimmer stars are hidden from view inside cocoons of dust. Webb will better reveal the underlying population of stars in the nebula.

The 30 Doradus Nebula is particularly interesting to astronomers because it is a good example of how star-forming regions in the young universe may have looked. This discovery could help scientists understand the details of cluster formation and how stars formed in the early Universe.

Science Paper by: E. Sabbi, et al. (ApJL, 2012) (PDF document)

Source: HubbleSite

Posted on by Nancy Atkinson

Inspiring Video: The Biological Advantage of Being Awestruck

How many times a week do we use the word “awesome” here on Universe Today? While we haven’t kept track, we admit it’s quite often. We feel privileged to be able to share with you the incredible — yes, awesome — images, videos and stories of our exploration of space. And it turns out, being awestruck could actually be good for us.

“Our ability to awe was biologically selected for us by evolution because it imbues our lives with a sense of cosmic significance that has resulted in a species that works harder not just to survive but to flourish and thrive,” writes filmmaker Jason Silva, who has produced this awesome new video about being awestruck.

Based on three different researcher’s work, Silva’s film highlights how having regular experiences of awe makes us feel good, provides a reason to live and love, spurs us to keep exploring and pushing onward, and provides an “unprecedented expansion of human vision.” The video shows many images from space, especially pictures produced by the Hubble Space Telescope, and Silva told Universe Today that this video is actually dedicated to the HST.

Sit back and enjoy the wonder of being awestruck!

Caption: A firestorm of star birth in the active galaxy Centaurus A. Credit: NASA, ESA, and the Hubble Heritage (STScI/AURA)-ESA/Hubble Collaboration

The Biological Advantage of Being Awestruck – by @Jason_Silva from Jason Silva on Vimeo.

Posted on by John Williams

Hubble Spies Tiny, Ancient ‘Ghost Galaxies’

These Hubble images show the dim, star-starved dwarf galaxy Leo IV. The image at left shows part of the galaxy, outlined by the white rectangular box. The box measures 83 light-years wide by 163 light-years long. The few stars in Leo IV are lost amid neighboring stars and distant galaxies. A close-up view of the background galaxies within the box is shown in the middle image. The image at right shows only the stars in Leo IV. The galaxy, which contains several thousand stars, is composed of sun-like stars, fainter, red dwarf stars, and some red giant stars brighter than the sun. Credit: NASA, ESA, and T. Brown (STScI)

They’re out there; tiny, extremely faint and incredibly ancient dwarf galaxies with so few stars that scientists call them ‘ghost galaxies.’ NASA’s Hubble Space Telescope captured images of three of these small-fry galaxies in hopes of unraveling a mystery 13 billion years in the making.

Astronomers believe these tiny, ghost-like galaxies spotted alongside the Milky Way Galaxy are among the oldest, tiniest and most pristine galaxies in the Universe. Hubble views reveal that their stars share the same birth date. The galaxies all started forming stars more than 13 billions years ago but then abruptly stopped within just one billion years after the Universe was born.

“These galaxies are all ancient and they’re all the same age, so you know something came down like a guillotine and turned off the star formation at the same time in these galaxies,” said Tom Brown of the Space Telescope Science Institute in Baltimore, Md., the study’s leader. “The most likely explanation is reionization.”

Reionization of the Universe began in the first billion years after the Big Bang. During this time, radiation from the first stars knocked electrons off hydrogen atoms, ionizing the hydrogen gas. This process also allowed hydrogen gas to become transparent to ultraviolet light. This same process may also have squashed star-making in dwarf galaxies, such as those in Brown’s study. These galaxies are tiny cousins to star-making dwarf galaxies near the Milky Way. And because of their small size, just 2,000 light-years across, they were not massive enough to shield themselves from the harsh ultraviolet light of the early Universe which stripped away their meager supply of hydrogen gas, leaving them unable to make new stars.

Astronomers proposed many reasons for the lack of stars in these galaxies in addition to the reioniation theory. Some scientists believed internal events such as supernovae blasted away the gas needed to create new stars. Others suggested that the galaxies simply used up their supply of hydrogen gas needed to make stars.

Brown measured the stars’ ages by looking at their brightness and colors. The stellar populations in these fossil galaxies range from a few hundred to a few thousand stars; some sun-like, some red dwarfs and some red stars larger than our Sun. When evidence showed that the stars were indeed ancient, Brown enlisted the help of Hubble’s Advanced Camera for Surveys to burrow deep within six galaxies to determine when they were born. So far, the team has finished analyzing data for three; Hercules, Leo IV and Ursa Major. The galaxies lie between 330,000 light-years to 490,000 light-years. For comparison, Brown compared the galaxies’ stars with those found in M92, a 13 billion-year-old globular cluster located about 26,000 light-years from Earth. He found they are of similar age.

“These are the fossils of the earliest galaxies in the universe,” Brown said. “They haven’t changed in billions of years. These galaxies are unlike most nearby galaxies, which have long star-formation histories.”

Brown’s discovery could help explain the so-called “missing satellite problem.” Astronomers have observed only a few dozen dwarf galaxies around the Milky Way while computer simulations predict thousands should exist. But perhaps they do exist. The Sloan survey found more than a dozen tiny, star-starved galaxies in the Milky Way’s neighborhood while scanning just a portion of the sky. Astronomers think that dozens more ultra-faint galaxies may lurk undetected with the possibility of thousands of even smaller dwarfs containing virtually no stars.

The tiny galaxies may be star-deprived but they still have an abundance of dark matter, the framework upon which galaxies are built. Normal dwarf galaxies near the Milky Way Galaxy contain ten times more dark matter than ordinary visible matter. Brown explains that these tiny galaxies are now islands of mostly dark matter, unseen for billions of years until astronomers began finding them in the Sloan Survey.

Brown’s results appear in the July 1 issue of the Astrophysical Journal Letters.

Image caption 1: These Hubble images show the dim, star-starved dwarf galaxy Leo IV. The image at left shows part of the galaxy, outlined by the white rectangular box. The box measures 83 light-years wide by 163 light-years long. The few stars in Leo IV are lost amid neighboring stars and distant galaxies. A close-up view of the background galaxies within the box is shown in the middle image. The image at right shows only the stars in Leo IV. The galaxy, which contains several thousand stars, is composed of sun-like stars, fainter, red dwarf stars, and some red giant stars brighter than the sun. Credit: NASA, ESA, and T. Brown (STScI)

Image caption 2: These computer simulations show a swarm of dark matter clumps around our Milky Way galaxy. Some of the dark-matter concentrations are massive enough to spark star formation. Thousands of clumps of dark matter coexist with our Milky Way galaxy, shown in the center of the top panel. The green blobs in the middle panel are those dark-matter chunks massive enough to obtain gas from the intergalactic medium and trigger ongoing star formation, eventually creating dwarf galaxies. In the bottom panel, the red blobs are ultra-faint dwarf galaxies that stopped forming stars long ago. Credit: NASA, ESA, and T. Brown and J. Tumlinson (STScI)

Posted on by John Williams

Early Black Holes were Grazers Rather than Glutonous Eaters

Faint quasars powered by black holes. Image credit NASA/ESA/Yale

Black holes powering distant quasars in the early Universe grazed on patches of gas or passing galaxies rather than glutting themselves in dramatic collisions according to new observations from NASA’s Spitzer and Hubble space telescopes.

A black hole doesn’t need much gas to satisfy its hunger and turn into a quasar, says study leader Kevin Schawinski of Yale “There’s more than enough gas within a few light-years from the center of our Milky Way to turn it into a quasar,” Schawinski explained. “It just doesn’t happen. But it could happen if one of those small clouds of gas ran into the black hole. Random motions and stirrings inside the galaxy would channel gas into the black hole. Ten billion years ago, those random motions were more common and there was more gas to go around. Small galaxies also were more abundant and were swallowed up by larger galaxies.”

Quasars are distant and brilliant galactic powerhouses. These far-off objects are powered by black holes that glut themselves on captured material; this in turn heats the matter to millions of degrees making it super luminous. The brightest quasars reside in galaxies pushed and pulled by mergers and interactions with other galaxies leaving a lot of material to be gobbled up by the super-massive black holes residing in the galactic cores.

Schawinski and his team studied 30 quasars with NASA’s orbiting telescopes Hubble and Spitzer. These quasars, glowing extremely bright in the infrared images (a telltale sign that resident black holes are actively scooping up gas and dust into their gravitational whirlpool) formed during a time of peak black-hole growth between eight and twelve billion years ago. They found 26 of the host galaxies, all about the size of our own Milky Way Galaxy, showed no signs of collisions, such as smashed arms, distorted shapes or long tidal tails. Only one galaxy in the study showed evidence of an interaction. This finding supports evidence that the creation of the most massive black holes in the early Universe was fueled not by dramatic bursts of major mergers but by smaller, long-term events.

“Quasars that are products of galaxy collisions are very bright,” Schawinski said. “The objects we looked at in this study are the more typical quasars. They’re a lot less luminous. The brilliant quasars born of galaxy mergers get all the attention because they are so bright and their host galaxies are so messed up. But the typical bread-and-butter quasars are actually where most of the black-hole growth is happening. They are the norm, and they don’t need the drama of a collision to shine.

“I think it’s a combination of processes, such as random stirring of gas, supernovae blasts, swallowing of small bodies, and streams of gas and stars feeding material into the nucleus,” Schawinski said.

Unfortunately, the process powering the quasars and their black holes lies below the detection of Hubble making them prime targets for the upcoming James Webb Space Telescope, a large infrared orbiting observatory scheduled for launch in 2018.

You can learn more about the images here.

Image caption: These galaxies have so much dust enshrouding them that the brilliant light from their quasars cannot be seen in these images from the NASA/ESA Hubble Space Telescope.

Posted on by Nancy Atkinson

Thierry Legault: One Transit is Not Enough

The transit of the Hubble Space Telescope across the Sun was taken from Queensland, Australia, simultaneously with the 2012 transit of Venus. Credit: Thierry Legault.

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Astrophotographer Thierry Legault had told us he was traveling to Australia for the Transit of Venus, so we knew he had something special planned. But that still didn’t prepare us for the awesomeness of what he has just achieved. During the Transit of Venus, Legault also captured the Hubble Space Telescope moving across the face of the Sun. Not once, but 9 times, during the HST’s transit time of .97 seconds. “Thanks to the continuous shooting mode of the Nikon D4 DSLR running at 10 fps,” Legault said on his website, which shows his new images. Of course, due to the differences in distance from Earth of Hubble vs. Venus, Venus took a lazy 6-plus hours to make its transit. A few giant sunspots also join in the view.

Below see a close-up of the two transits and a look at Legault’s set-up in the Outback of Queensland.

A close-up of Venus and Hubble (tiny black dots just above Venus) transiting the Sun. Credit: Thierry Legault. Used by permission.
Legault's equipment setup for viewing the Venus Transit in Queensland, Australia. Credit: Thierry Legault. Used by permission.

Legault noted that just one of the telescope/camera setups was his. So, he had just one chance of capturing the double transit. And he nailed it.

Here’s the map from CalSky of where the HST transit would be visible, just a thin band across the top of Queensland:

Map from CalSky of the Hubble Transit. Via Thierry Legault.

Legault said he has some more images on the way, including the ring of the atmosphere of Venus around the first contact, images of the transit in H-alpha, and the full ring of Venus 24 hours after the transit, so keep checking his website for more fantastic images.

Congratulations to Thierry Legault for a truly amazing and special capture of the Transit of Venus, something that won’t happen again in our lifetimes. And thanks to Thierry for sharing his images with Universe Today.