First Observed Evidence of Galactic Wind Phenomenon

Research led by Johns Hopkins University scientists has found new persuasive evidence that could help solve a longstanding mystery in astrophysics. A paper published in the Monthly Notices of the Royal Astronomical Society, finds evidence supporting the argument that intense radiation and galaxy-scale winds emitted by quasars heats up clouds of dust and gas preventing material from cooling and forming more dense clouds, and eventually stars.

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“I would argue that this is the first convincing observational evidence of the presence of quasar feedback,” said Tobias Marriage, an assistant professor in the university’s Henry A. Rowland Department of Physics and Astronomy.

cosmic microwave background

Specifically, investigators looked at information on 17,468 galaxies and found a tracer of energy when high-energy electrons disturb the Cosmic Microwave Background. This phenomenon is known as the Sunyaev-Zel’dovich Effect. The phenomenon, named for two Russian physicists who predicted it nearly 50 years ago.

Information gathered in the Sloan Digital Sky Survey by an optical telescope at the Apache Point Observatory in New Mexico was used to find the quasars. Thermal energy and evidence of the SZ Effect were found using information from the Atacama Cosmology Telescope, an instrument designed to study the CMB that stands in the Atacama Desert in northern Chile. To focus on the dust, investigators used data from the SPIRE, or Spectral and Photometric Imaging Receiver, on the Herschel Space Observatory.

Astronomers Report Most ‘Outrageously’ Luminous Galaxies Ever Observed

Astronomers at the University of Massachusetts Amherst report that they have observed the most luminous galaxies ever seen in the Universe, objects so bright that established descriptors such as “ultra-” and “hyper-luminous” used to describe previously brightest known galaxies don’t even come close. Lead author and undergraduate Kevin Harrington says, “We’ve taken to calling them ‘outrageously luminous’ among ourselves, because there is no scientific term to apply.”

astronomers

Details appear in the current early online edition of Monthly Notices of the Royal Astronomical Society.

Harrington is a senior undergraduate in astronomy professor Min Yun’s group, which uses the 50-meter diameter Large Millimeter Telescope (LMT), the largest, most sensitive single-aperture instrument in the world for studying star formation. It is operated jointly by UMass Amherst and Mexico’s Instituto Nacional de Astrofísica, Óptica y Electrónica and is located on the summit of Sierra Negra, a 15,000-foot extinct volcano in the central state of Puebla, a companion peak to Mexico’s highest mountain.

Yun, Harrington and colleagues also used the latest generation of satellite telescope and a cosmology experiment on the NASA/ESA collaboration Planck satellite that detects the glow of the Big Bang and microwave background for this work. They estimate that the newly observed galaxies they identified are about 10 billion years old and were formed only about 4 billion years after the Big Bang.

Harrington explains that in categorizing luminous sources, astronomers call an infrared galaxy “ultra-luminous” when it has a rating of about 1 trillion solar luminosities, and that rises to about 10 trillion solar luminosities at the “hyper-luminous” level. Beyond that, for the 100 trillion solar luminosities range of the new objects, “we don’t even have a name,” he says.

Yun adds, “The galaxies we found were not predicted by theory to exist; they’re too big and too bright, so no one really looked for them before.” Discovering them will help astronomers understand more about the early Universe. “Knowing that they really do exist and how much they have grown in the first 4 billion years since the Big Bang helps us estimate how much material was there for them to work with. Their existence teaches us about the process of collecting matter and of galaxy formation. They suggest that this process is more complex than many people thought.”

The newly observed galaxies are not as large as they appear, the researchers point out. Follow-up studies suggest that their extreme brightness arises from a phenomenon called gravitational lensing that magnifies light passing near massive objects, as predicted by Einstein’s general relativity. As a result, from Earth they look about 10 times brighter than they really are. Even so, they are impressive, Yun says.

Gravitational lensing of a distant galaxy by another galaxy is quite rare, he adds, so finding as many as eight potential lensed objects as part of this investigation “is another potentially important discovery.” Harrington points out that discovering gravitational lensing is already like finding a needle in a haystack, because it requires a precise alignment from viewing on Earth. “On top of that, finding lensed sources this bright is as rare as finding the hole in the needle in the haystack.”

They also conducted analyses to show that the galaxies’ brightness is most likely due solely to their amazingly high rate of star formation. “The Milky Way produces a few solar masses of stars per year, and these objects look like they forming one star every hour,” Yun says. Harrington adds, “We still don’t know how many tens to hundreds of solar masses of gas can be converted into stars so efficiently in these objects, and studying these objects might help us to find out.”

For this work, the team used data from the most powerful international facilities available today to achieve these discoveries, the Planck Surveyor, the Herschel, and the LMT. As Yun explains, the all-sky coverage of the Planck is the only way to find these rare but exceptional objects, but the much higher resolutions of the Herschel and the LMT are needed to pinpoint their exact locations.

He suggests, “If the Planck says there’s an object of interest in Boston, the Herschel and LMT have the precision to say that the object is on which table in a particular bar next to Fenway Park.” With this information, another LMT instrument called “Redshift Search Receiver” can be deployed to determine how far away and how old these galaxies are and how much gas they contain to sustain their extreme luminosities.

One other aspect of this project is extraordinary, Yun says. “For an undergrad to do this kind of study is really impressive. In 15 years of teaching, I have seen only a few undergraduates who pushed a project to the point of publishing in a major journal article such as this. Kevin deserves a lot of credit for this work.”

For his part, Harrington, who will graduate in May with a double major in astronomy and neuroscience, says he plans to start his doctoral work in September at Germany’s Max Planck Institute for Astronomy and the University of Bonn, continuing this research on galaxy evolution.

This work was supported by the National Science Foundation, the UMass Amherst Commonwealth Honors College Research Fellowship and Honors Grants, and The William Bannick Student Travel Grant, without which Harrington’s two trips to the remote telescope in Mexico would not have been possible, Yun says.

New Finding Indicates Humans in Ireland 12,500 Years Ago

For decades, the earliest evidence of human life in Ireland dated from 8,000 BC. But radiocarbon dating of a bear’s knee bone indicated it had been butchered by a human in about 10,500 BC – some 12,500 years ago and far earlier than the previous date.

ireland palaeolithic period caves

“This find adds a new chapter to the human history of Ireland,” said Marion Dowd, an archaeologist at the Institute of Technology Sligo who made the discovery along with Ruth Carden, a research associate with the National Museum of Ireland.

The knee bone, which is marked by cuts from a sharp tool, was one of thousands of bones first found in 1903 in a cave in County Clare on the west coast of Ireland.

It was stored in the National Museum of Ireland since the 1920s, until Carden and Dowd re-examined it and applied for funding to have it radiocarbon dated – a technique developed in the 1940s – by Queen’s University Belfast.

The team sent a second sample to the University of Oxford to double-check the result. Both tests indicated the bear had been cut up by a human about 12,500 years ago.

The new date means there was human activity in Ireland in the Stone Age or Palaeolithic period, whereas previously, scientists only had evidence of humans in Ireland in the later Mesolithic period.

“Archaeologists have been searching for the Irish Palaeolithic since the 19th century, and now, finally, the first piece of the jigsaw has been revealed,” Dowd said.

Three experts further confirmed that the cut marks on the bone had been made when the bone was fresh, confirming they dated from the same time as the bone.

The results were revealed in a paper published in the journal Quaternary Science Reviews.

As well as pushing back the date of human history in Ireland, the find may have important implications for zoology, as scientists have not previously considered that humans could have influenced extinctions of species in Ireland so long ago.

“From a zoological point of view, this is very exciting,” Carden said. “This paper should generate a lot of discussion within the zoological research world and it’s time to start thinking outside the box… or even dismantling it entirely!”

The National Museum of Ireland noted that approximately two million more specimens are held in its collections and could reveal more secrets.

“All are available for research and we never know what may emerge,” said Nigel Monaghan, keeper of the natural history division of the National Museum of Ireland.

New Research Reveals Fastest Winds Ever Seen

New research led by astrophysicists at York University has revealed the fastest winds ever seen at ultraviolet wavelengths near a supermassive black hole. The team’s findings were published today in the print edition of the Monthly Notices of the Royal Astronomical Society.

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scienceofcycles.com

Jesse Rogerson, Department of Physics and Astronomy at York University said; “We’re talking wind speeds of 20 per cent the speed of light, which is more than 200 million kilometers an hour. That’s equivalent to a category 77 hurricane – and we have reason to believe that there are quasar winds that are even faster.”

Astronomers have known about the existence of quasar winds since the late 1960s. At least one in four quasars have them. Quasars are the discs of hot gas that form around supermassive black holes at the center of massive galaxies – they are bigger than Earth’s orbit around the Sun and hotter than the surface of the Sun, generating enough light to be seen across the observable universe.

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“Black holes can have a mass that is billions of times larger than the Sun, mostly because they are messy eaters in a way, capturing any material that ventures too close,” says York University Associate Professor Patrick Hall, who is Rogerson’s supervisor. “But as matter spirals toward a black hole, some of it is blown away by the heat and light of the quasar. These are the winds that we are detecting.”

Rogerson and his team used data from a large survey of the sky known as the Sloan Digital Sky Survey to identify new outflows from quasars. After spotting about 300 examples, they selected about 100 for further exploration, collecting data with the Gemini Observatory’s twin telescopes in Hawaii and Chile, in which Canada has a major share.

“We not only confirmed this fastest-ever ultraviolet wind, but also discovered a new wind in the same quasar moving more slowly, at only 140 million kilometers an hour,” says Hall. “We plan to keep watching this quasar to see what happens next.”

Much of this research is aimed at better understanding outflows from quasars and why they happen.

“Quasar winds play an important role in galaxy formation,” says Rogerson. “When galaxies form, these winds fling material outwards and deter the creation of stars. If such winds didn’t exist or were less powerful, we would see far more stars in big galaxies than we actually do.”

Green Comet Approaches Earth

On March 21st, Comet 252P/LINEAR will make a close approach to Earth–only 0.036 AU (5.4 million km) away. This is the fifth closest cometary approach on record and, as a result, the normally dim comet has become an easy target for backyard telescopes. Indeed, it is brightening much faster than expected.

“Comet 252P/LINEAR has surpassed expectations and is now bordering on naked eye visibility for southern observers,” reports Michael Mattiazzo of Swan Hill, Australia. “At the moment it is near magnitude +6,” Observing from Brisbane, Australia, Tom Harradine didn’t even need a telescope to photograph 252P/LINEAR. On March 17th, he caught the green comet (circled) passing by the Tarantula Nebula using just a digital camera.

greencomet_strip

The comet is green because its vaporizing nucleus emits diatomic carbon, C2, a gas which glows green in the near-vacuum of space. The verdant color will become more intense in the nights ahead as 252P/LINEAR approaches Earth.

In recent days, astronomers have realized that Comet 252P/LINEAR might have a companion. A smaller and much dimmer comet named “P/2016 BA14” will buzz Earth even closer than 252P/LINEAR on March 22nd. P/2016 BA14 appears to be a fragment of 252P/LINEAR. Unlike its parent, however, P/2016 BA14 is “pitifully faint” and difficult to observe. Sky and Telescope has the full story.

There is a chance that the comet’s approach could cause a minor meteor shower. According to the International Meteor Organization, “[modeling by forecaster] Mikhail Maslov indicates that there might be a weak episode of faint, very slow meteors (15.5 km/s) on March 28–30 from a radiant near the star μ Leporis.” Little is known about meteors from this comet, so estimates of the meteor rate are very uncertain. Maslov’s models suggest no more than 5 to 10 per hour.

Galactic Cosmic Rays Accelerating to Unprecedented Levels

At the center of the Milky Way, a new discovery reveals for the first time a source of this cosmic radiation at energies never observed before. The center of our galaxy is home to many objects capable of producing cosmic rays of high energy, including, in particular, a supernova remnant, a pulsar wind nebula, and a compact cluster of massive stars.

CREATOR: gd-jpeg v1.0 (using IJG JPEG v62), quality = 75

Today we know that cosmic rays with energies up to approximately 100 teraelectronvolts (TeV) are produced in our galaxy, by objects such as supernova remnants and pulsar wind nebulae. Theoretical arguments and direct measurements of cosmic rays reaching the Earth indicate, however, that the cosmic-ray factories in our galaxy should be able to provide particles up to one petaelectronvolt (PeV) at least. While many multi-TeV accelerators have been discovered in recent years, the search for the sources of the highest energy galactic cosmic rays has, so far, been unsuccessful.

galaxy-center333_mm

However, “the supermassive black hole located at the center of our galaxy Milky Way, called Sgr A*, is the most plausible source of the PeV protons,” says Felix Aharonian (MPIK, Heidelberg and DIAS, Dublin), adding that, “several possible acceleration regions can be considered, either in the immediate vicinity of the black hole, or further away, where a fraction of the material falling into the black hole is ejected back into the environment, thereby initiating the acceleration of particles.”

The (High Energy Stereoscopic System) H.E.S.S. measurement of the gamma-ray emission can be used to infer the spectrum of the protons that have been accelerated by the central black hole – revealing that Sgr A* is very likely accelerating protons to PeV energies. Currently, these protons cannot account for the total flux of cosmic rays detected at the Earth. “If, however, our central black hole was more active in the past,” the scientists argue, “then it could indeed be responsible for the bulk of the galactic cosmic rays that are observed today at the Earth.” If true, this would dramatically influence the century old debate concerning the origin of these enigmatic particles.

BREAKING NEWS: Galactic Cosmic Rays Accelerating to Unprecedented Levels

At the center of the Milky Way, a new discovery reveals for the first time a source of this cosmic radiation at energies never observed before. The center of our galaxy is home to many objects capable of producing cosmic rays of high energy, including, in particular, a supernova remnant, a pulsar wind nebula, and a compact cluster of massive stars.

CREATOR: gd-jpeg v1.0 (using IJG JPEG v62), quality = 75

Today we know that cosmic rays with energies up to approximately 100 teraelectronvolts (TeV) are produced in our galaxy, by objects such as supernova remnants and pulsar wind nebulae. Theoretical arguments and direct measurements of cosmic rays reaching the Earth indicate, however, that the cosmic-ray factories in our galaxy should be able to provide particles up to one petaelectronvolt (PeV) at least. While many multi-TeV accelerators have been discovered in recent years, the search for the sources of the highest energy galactic cosmic rays has, so far, been unsuccessful.

galaxy-center333_mm

However, “the supermassive black hole located at the center of our galaxy Milky Way, called Sgr A*, is the most plausible source of the PeV protons,” says Felix Aharonian (MPIK, Heidelberg and DIAS, Dublin), adding that, “several possible acceleration regions can be considered, either in the immediate vicinity of the black hole, or further away, where a fraction of the material falling into the black hole is ejected back into the environment, thereby initiating the acceleration of particles.”

The (High Energy Stereoscopic System) H.E.S.S. measurement of the gamma-ray emission can be used to infer the spectrum of the protons that have been accelerated by the central black hole – revealing that Sgr A* is very likely accelerating protons to PeV energies. Currently, these protons cannot account for the total flux of cosmic rays detected at the Earth. “If, however, our central black hole was more active in the past,” the scientists argue, “then it could indeed be responsible for the bulk of the galactic cosmic rays that are observed today at the Earth.” If true, this would dramatically influence the century old debate concerning the origin of these enigmatic particles.