What Drives Universe’s Expansion?

Astronomy experiments could soon test an idea developed by Albert Einstein almost exactly a century ago, scientists say.

Tests using advanced technology could resolve a longstanding puzzle over what is driving the accelerated expansion of the Universe.

Researchers have long sought to determine how the Universe’s accelerated expansion is being driven. Calculations in a new study could help to explain whether dark energy- as required by Einstein’s theory of general relativity — or a revised theory of gravity are responsible.

Einstein’s theory, which describes gravity as distortions of space and time, included a mathematical element known as a Cosmological Constant. Einstein originally introduced it to explain a static universe, but discarded his mathematical factor as a blunder after it was discovered that our Universe is expanding.

Research carried out two decades ago, however, showed that this expansion is accelerating, which suggests that Einstein’s Constant may still have a part to play in accounting for dark energy. Without dark energy, the acceleration implies a failure of Einstein’s theory of gravity across the largest distances in our Universe.

Scientists from the University of Edinburgh have discovered that the puzzle could be resolved by determining the speed of gravity in the cosmos from a study of gravitational waves -space-time ripples propagating through the universe.

The researchers’ calculations show that if gravitational waves are found to travel at the speed of light, this would rule out alternative gravity theories, with no dark energy, in support of Einstein’s Cosmological Constant. If however, their speed differs from that of light, then Einstein’s theory must be revised.

Such an experiment could be carried out by the Laser Interferometer Gravitational-Wave Observatory (LIGO) in the US, whose twin detectors, 2000 miles apart, directly detected gravitational waves for the first time in 2015.

Experiments at the facilities planned for this year could resolve the question in time for the 100th anniversary of Einstein’s Constant.

The study, published in Physics Letters B, was supported by the UK Science Technology Facilities Council, the Swiss National Science Foundation, and the Portuguese Foundation of Science and Technology.

Dr Lucas Lombriser, of the University of Edinburgh’s School of Physics and Astronomy, said: “Recent direct gravitational wave detection has opened up a new observational window to our Universe. Our results give an impression of how this will guide us in solving one of the most fundamental problems in physics.”

Ancient Signals From The Early Universe

For the first time, theoretical physicists from the University of Basel have calculated the signal of specific gravitational wave sources that emerged fractions of a second after the Big Bang. The source of the signal is a long-lost cosmological phenomenon called “oscillon.” The journal Physical Review Letters has published the results.

Although Albert Einstein had already predicted the existence of gravitational waves, their existence was not actually proven until fall 2015, when highly sensitive detectors received the waves formed during the merging of two black holes. Gravitational waves are different from all other known waves. As they travel through the universe, they shrink and stretch the space-time continuum; in other words, they distort the geometry of space itself. Although all accelerating masses emit gravitational waves, these can only be measured when the mass is extremely large, as is the case with black holes or supernovas.

Gravitational waves transport information from the Big Bang

However, gravitational waves not only provide information on major astrophysical events of this kind but also offer an insight into the formation of the universe itself. In order to learn more about this stage of the universe, Prof. Stefan Antusch and his team from the Department of Physics at the University of Basel are conducting research into what is known as the stochastic background of gravitational waves. This background consists of gravitational waves from a large number of sources that overlap with one another, together yielding a broad spectrum of frequencies. The Basel-based physicists calculate predicted frequency ranges and intensities for the waves, which can then be tested in experiments.

A highly compressed universe

Shortly after the Big Bang, the universe we see today was still very small, dense, and hot. “Picture something about the size of a football,” Antusch explains. The whole universe was compressed into this very small space, and it was extremely turbulent. Modern cosmology assumes that at that time the universe was dominated by a particle known as the inflaton and its associated field.

Oscillons generate a powerful signal

The inflaton underwent intensive fluctuations, which had special properties. They formed clumps, for example, causing them to oscillate in localized regions of space. These regions are referred to as oscillons and can be imagined as standing waves. “Although the oscillons have long since ceased to exist, the gravitational waves they emitted are omnipresent — and we can use them to look further into the past than ever before,” says Antusch.

Using numerical simulations, the theoretical physicist and his team were able to calculate the shape of the oscillon’s signal, which was emitted just fractions of a second after the Big Bang. It appears as a pronounced peak in the otherwise rather broad spectrum of gravitational waves. “We would not have thought before our calculations that oscillons could produce such a strong signal at a specific frequency,” Antusch explains. Now, in a second step, experimental physicists must actually prove the signal’s existence using detectors.million years.”

Dwarf Star 200 Light Years Away Contains Life’s Building Blocks

Many scientists believe the Earth was dry when it first formed, and that the building blocks for life on our planet — carbon, nitrogen and water — appeared only later as a result of collisions with other objects in our solar system that had those elements.

Today, a UCLA-led team of scientists reports that it has discovered the existence of a white dwarf star whose atmosphere is rich in carbon and nitrogen, as well as in oxygen and hydrogen, the components of water. The white dwarf is approximately 200 light years from Earth and is located in the constellation Boötes.

Benjamin Zuckerman, a co-author of the research and a UCLA professor of astronomy, said the study presents evidence that the planetary system associated with the white dwarf contains materials that are the basic building blocks for life. And although the study focused on this particular star — known as WD 1425+540 — the fact that its planetary system shares characteristics with our solar system strongly suggests that other planetary systems would also.

“The findings indicate that some of life’s important preconditions are common in the universe,” Zuckerman said.

The scientists report that a minor planet in the planetary system was orbiting around the white dwarf, and its trajectory was somehow altered, perhaps by the gravitational pull of a planet in the same system. That change caused the minor planet to travel very close to the white dwarf, where the star’s strong gravitational field ripped the minor planet apart into gas and dust. Those remnants went into orbit around the white dwarf — much like the rings around Saturn, Zuckerman said — before eventually spiraling onto the star itself, bringing with them the building blocks for life.

The researchers think these events occurred relatively recently, perhaps in the past 100,000 years or so, said Edward Young, another co-author of the study and a UCLA professor of geochemistry and cosmochemistry. They estimate that approximately 30 percent of the minor planet’s mass was water and other ices, and approximately 70 percent was rocky material.

The research suggests that the minor planet is the first of what are likely many such analogs to objects in our solar system’s Kuiper belt. The Kuiper belt is an enormous cluster of small bodies like comets and minor planets located in the outer reaches of our solar system, beyond Neptune. Astronomers have long wondered whether other planetary systems have bodies with properties similar to those in the Kuiper belt, and the new study appears to confirm for the first time that one such body exists.

White dwarf stars are dense, burned-out remnants of normal stars. Their strong gravitational pull causes elements like carbon, oxygen and nitrogen to sink out of their atmospheres and into their interiors, where they cannot be detected by telescopes.

The research, published in the Astrophysical Journal Letters, describes how WD 1425+540 came to obtain carbon, nitrogen, oxygen and hydrogen. This is the first time a white dwarf with nitrogen has been discovered, and one of only a few known examples of white dwarfs that have been impacted by a rocky body that was rich in water ice.

“If there is water in Kuiper belt-like objects around other stars, as there now appears to be, then when rocky planets form they need not contain life’s ingredients,” said Siyi Xu, the study’s lead author, a postdoctoral scholar at the European Southern Observatory in Germany who earned her doctorate at UCLA.

“Now we’re seeing in a planetary system outside our solar system that there are minor planets where water, nitrogen and carbon are present in abundance, as in our solar system’s Kuiper belt,” Xu said. “If Earth obtained its water, nitrogen and carbon from the impact of such objects, then rocky planets in other planetary systems could also obtain their water, nitrogen and carbon this way.”

A rocky planet that forms relatively close to its star would likely be dry, Young said.

“We would like to know whether in other planetary systems Kuiper belts exist with large quantities of water that could be added to otherwise dry planets,” he said. “Our research suggests this is likely.”

According to Zuckerman, the study doesn’t settle the question of whether life in the universe is common.

“First you need an Earth-like world in its size, mass and at the proper distance from a star like our sun,” he said, adding that astronomers still haven’t found a planet that matches those criteria.

The researchers observed WD 1425+540 with the Keck Telescope in 2008 and 2014, and with the Hubble Space Telescope in 2014. They analyzed the chemical composition of its atmosphere using an instrument called a spectrometer, which breaks light into wavelengths. Spectrometers can be tuned to the wavelengths at which scientists know a given element emits and absorbs light; scientists can then determine the element’s presence by whether it emits or absorbs light of certain characteristic wavelengths. In the new study, the researchers saw the elements in the white dwarf’s atmosphere because they absorbed some of the background light from the white dwarf.

Planet’s Atmospheric Oxygen Rose Through Glaciers

A University of Wyoming researcher contributed to a paper that determined a “Snowball Earth” event actually took place 100 million years earlier than previously projected, and a rise in the planet’s oxidation resulted from a number of different continents — including what is now Wyoming — that were once connected.

“Isotopic dating of the Ongeluk large igneous province, South Africa, revealed that the first Paleoproterozoic global glaciation and the first significant step change in atmospheric oxygenation likely occurred between 2,460 and 2,426 million years ago, approximately 100 million years earlier than previous estimates,” says Kevin Chamberlain, a UW research professor in the Department of Geology and Geophysics. “And the rise of atmospheric oxygen was not monotonic but, instead, was characterized by significant oscillations before irreversible oxygenation of the atmosphere 2,250 million years ago.”

Chamberlain is the second author of a paper, titled “Timing and Tempo of the Great Oxidation Event,” which appears in the Proceedings of the National Academy of Sciences (PNAS).

Ashley Gumsley, a doctoral student at Lund University in Lund, Sweden, is the paper’s lead author. Other contributors were from the Geological Survey of Canada in Ottawa; Swedish Museum of Natural History; University of Johannesburg, South Africa; and the University of California-Riverside.

The research relates to a period in Earth’s history about 2.45 billion years ago, when climate swung so extremely that the polar ice caps extended to the equator and Earth was a snowball, and the atmosphere was largely isolated from the hydrosphere, Chamberlain says. Recovery from this Snowball Earth led to the first and largest, rapid rise in oxygen content in the atmosphere, known as the Great Oxygenation Event (GOE), setting the stage for the dominance of aerobic life, he says.

A later, and better known, Snowball Earth period occurred at about 700 million years ago, and led to multicellular life in the Cambrian period, Chamberlain says. The events show there was not one event, but an oscillation of oxygen over time that led to Earth’s conditions today.

“So, both Snowball Earth periods had extreme impacts on the development of life,” he says. “It helps us understand the evolution of Earth and Earth’s atmosphere, and evolution of life, for that matter.”

Chamberlain’s contribution focuses on igneous rocks exposed in South Africa that record the existence of equatorial glaciers and contain chemical indicators for the rise of atmospheric oxygen. Chamberlain’s in situ method to determine the age of the rocks does not require removing baddeleyite crystals from the rock. This process allows for analysis of key samples with smaller crystals than previously allowed. Using a mass spectrometer, the age of the rocks is determined by measuring the buildup of lead from the radioactive decay of uranium, he says.

“The basic story had been worked out earlier by others, but our results have significantly refined the timing and duration of the ‘event,’ which is more of a transition actually,” Chamberlain explains. “With all the discussion of climate change in the present day, understanding how Earth responded and the effects on the atmosphere in the past may help us predict the future.”

Chamberlain points to a Wyoming connection in this research. From paleomagnetic data, many of the continents, at the time, including the basement rocks of Wyoming, were all connected into a single, large continent and situated near the equator. Other continents connected included parts of what are now Canada and South Africa. This situation is part of the trigger for the “Snowball Earth” conditions.

“There are glacial deposits exposed in the Medicine Bow Mountains and Sierra Madre that are from this same event,” he says.

These rocks, known as diamictites, have large drop stones that depress very fine-grained mudstone. The large stones dropped from the underside of glacial sheets as they spread out and melted over shallow seas, similar to sediments beneath the Ross sea ice sheet of Antarctica today.

“The fact that these sediments were at the equator at 2.45 billion years ago comes from the paleomagnetic data from associated igneous rocks,” Chamberlain says.

New Study Suggest Dwarf Cluster Formed Milky Way

Using data from the Sloan Digital Sky Survey (SDSS) and various optical telescopes, a team of astronomers has discovered seven distinct groups of dwarf galaxies with just the right starting conditions to eventually merge and form larger galaxies, including spiral galaxies like the Milky Way. This discovery offers compelling evidence that the mature galaxies we see in the universe today were formed when smaller galaxies merged many billions of years ago.

“We know that to make a large galaxy, the universe has to bring together many smaller galaxies,” said Sabrina Stierwalt an astronomer with the National Radio Astronomy Observatory (NRAO) and University of Virginia in Charlottesville. “For the first time, we have found examples of the first steps in this process — entire populations of dwarf galaxies that are all bound together in the same general neighborhoods.”

Stierwalt and her team began their search by poring over SDSS data looking for pairs of interacting dwarf galaxies. The astronomers then examined the images to find specific pairs that appeared to be part of even larger assemblages of similar galaxies.

The researchers then used the Magellan telescope in Chile, the Apache Point Observatory in New Mexico, and the Gemini telescope in Hawaii to confirm that the apparent clusters are not just on the same line of sight but are also approximately the same distance from Earth, indicating they are gravitationally bound together.

This discovery of long-sought groups of tiny galaxies is reported online in the journal Nature Astronomy.

“We hope this discovery will enable future studies of groups of dwarf galaxies and offer insights into the formation of galaxies like the Milky Way,” concluded Stierwalt.

BREAKING NEWS: New Discovery of Ancient Tree Rings Indicate Stable Predictable Sunspot Cycle Over 300 Million Years Period

I know your first instinct is to say something like “duh”. I would certainly support you in this analysis. However, setting this obvious notion aside, this new finding does attribute a great amount of credibility to the scientific discipline of cycles; furthermore, it provides a greater comprehension in regards to ‘time-linked’ measurements such as short-term, medium-term  and long-term cycles. Examples would be the 11 year sunspot cycle, the 26,000 year precession cycle, and the Milankovitch or Eccentricity cycle with a 100,000 and 410,000 cycle.

In a new study published in the scientific journal Geology, researchers Ludwig Luthardt, professor at the Natural History Museum in Chemnitz, and Ronald Rößler, professor at Freiberg University of Mining and Technology, describe how they found evidence in ancient tree rings, identifying a solar sunspot cycle that occurred millions of years ago and compared it to recent cycles . “The median tree-ring curve of that period revealed a 10.62 year cycle, the duration of which is almost identical to the modern 11 year solar cycle we see today,” said Luthardt.

Sunspot activity swings between a period known as ‘solar maximum’, at which time an enormous amount of radiation is released through the development of powerful streams of charged particles which is released in various forms such as solar flares, coronal mass ejections, coronal holes, and purging filaments.

When a percentage of these particles penetrate the Earth’s magnetic field and continue into the upper and lower atmosphere, the measured effects are captured in assorted forms of Flora such as tree-rings, lake bottom sediment, and deep ice cores. Such high-resolution records are commonly used for reconstructing climatic variations in the younger geological history.

The team discovered large wooded tree trunks from the early Permian Fossil Forest of Chemnitz, southeast Germany. This region had been covered by lava during a volcanic eruption during the Permian period, offering a historical record of Sun activity. “For the first time we applied dendrochronological methods (tree-ring dating) – to Paleozoic trees in order to recognize annual variations; says Rößler.

The team found that sunspot activity recorded 300 million years ago as reflected in tree ring archived analysis, matches almost identically with today’s caused fluctuations of cosmic radiation input to the atmosphere.


New Study Identifies Distinctive Emission Signatures of Pulsars

In two studies, international teams of astronomers suggest that recent images from NASA’s Chandra X-ray Observatory of two pulsars – Geminga and B0355+54 – may help shine a light on the distinctive emission signatures of pulsars, as well as their often perplexing geometry.

Pulsars are a type of neutron star that are born in supernova explosions when massive stars collapse. Discovered initially by lighthouse-like beams of radio emission, more recent research has found that energetic pulsars also produce beams of high energy gamma rays..

Interestingly, the beams rarely match up, said Bettina Posselt, senior research associate in astronomy and astrophysics, Penn State. The shapes of observed radio and gamma-ray pulses are often quite different and some of the objects show only one type of pulse or the other. These differences have generated debate about the pulsar model.

“It’s not fully understood why there are variations between different pulsars,” said Posselt. “One of the main ideas here is that pulse differences have a lot to do with geometry – and it also depends on how the pulsar’s spin and magnetic axes are oriented with respect to line of sight whether you see certain pulsars or not, as well as how you see them.”

Chandra’s images are giving the astronomers a closer than ever look at the distinctive geometry of the charged particle winds radiating in X-ray and other wavelengths from the objects, according to Posselt. Pulsars rhythmically rotate as they rocket through space at speeds reaching hundreds of kilometers a second. Pulsar wind nebulae (PWN) are produced when the energetic particles streaming from pulsars shoot along the stars’ magnetic fields, form tori – donut-shaped rings – around the pulsar’s equatorial plane, and jet along the spin axis, often sweeping back into long tails as the pulsars’ quickly cut through the interstellar medium.

“This is one of the nicest results of our larger study of pulsar wind nebulae,” said Roger W. Romani, professor of physics at Stanford University and principal investigator of the Chandra PWN project. “By making the 3-D structure of these winds visible, we have shown how one can trace back to the plasma injected by the pulsar at the center. Chandra’s fantastic X-ray acuity was essential for this study, so we are happy that it was possible to get the deep exposures that made these faint structures visible.”

A spectacular PWN is seen around the Geminga pulsar. Geminga – one of the closest pulsars at only 800 light years away from Earth – has three unusual tails, said Posselt. The streams of particles spewing out of the alleged poles of Geminga – or lateral tails – stretch out for more than half a light year, longer than 1,000 times the distance between the Sun and Pluto. Another shorter tail also emanates from the pulsar.

The astronomers said that a much different PWN picture is seen in the X-ray image of another pulsar called B0355+54, which is about 3,300 light years away from Earth. The tail of this pulsar has a cap of emission, followed by a narrow double tail that extends almost five light years away from the star.

While Geminga shows pulses in the gamma ray spectrum, but is radio quiet, B0355+54 is one of the brightest radio pulsars, but fails to show gamma rays.

“The tails seem to tell us why that is,” said Posselt, adding that the pulsars’ spin axis and magnetic axis orientations influence what emissions are seen on Earth.

According to Posselt, Geminga may have magnetic poles quite close to the top and bottom of the object, and nearly aligned spin poles, much like Earth. One of the magnetic poles of B0355+54 could directly face the Earth. Because the radio emission occurs near the site of the magnetic poles, the radio waves may point along the direction of the jets, she said. Gamma-ray emission, on the other hand, is produced at higher altitudes in a larger region, allowing the respective pulses to sweep larger areas of the sky.

“For Geminga, we view the bright gamma ray pulses and the edge of the pulsar wind nebula torus, but the radio beams near the jets point off to the sides and remain unseen,” Posselt said.

The strongly bent lateral tails offer the astronomers clues to the geometry of the pulsar, which could be compared to either jet contrails soaring into space, or to a bow shock similar to the shockwave created by a bullet as it is shot through the air.

Oleg Kargaltsev, assistant professor of physics, George Washington University, who worked on the study on B0355+54, said that the orientation of B0355+54 plays a role in how astronomers see the pulsar, as well. The study is available online in arXiv.

“For B0355+54, a jet points nearly at us so we detect the bright radio pulses while most of the gamma-ray emission is directed in the plane of the sky and misses the Earth,” said Kargaltsev. “This implies that the pulsar’s spin axis direction is close to our line-of-sight direction and that the pulsar is moving nearly perpendicularly to its spin axis.”

Noel Klingler, a graduate research assistant in physics, George Washington University, and lead author of the B0355+54 paper, added that the angles between the three vectors – the spin axis, the line-of-sight, and the velocity – are different for different pulsars, thus affecting the appearances of their nebulae.

“In particular, it may be tricky to detect a PWN from a pulsar moving close to the line-of-sight and having a small angle between the spin axis and our line-of-sight,” said Klingler.

In the bow-shock interpretation of the Geminga X-ray data, Geminga’s two long tails and their unusual spectrum may suggest that the particles are accelerated to nearly the speed of light through a process called Fermi acceleration. The Fermi acceleration takes place at the intersection of a pulsar wind and the interstellar material, according to the researchers, who report their findings on Geminga in the current issue of Astrophysical Journal.

Although different interpretations remain on the table for Geminga’s geometry, Posselt said that Chandra’s images of the pulsar are helping astrophysicists use pulsars as particle physics laboratories. Studying the objects gives astrophysicists a chance to investigate particle physics in conditions that would be impossible to replicate in a particle accelerator on earth.

“In both scenarios, Geminga provides exciting new constraints on the acceleration physics in pulsar wind nebulae and their interaction with the surrounding interstellar matter,” she said.