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Posts Tagged ‘Gravitational Waves

Dynamical formation signatures of black hole binaries in the first detected mergers by LIGO

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February 10, 2016 at 1:37 pm

Gravitational Waves from a Dark Phase Transition

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Pedro Schwaller
In this work, we show that a large class of models with a composite dark sector undergo a strong first order phase transition in the early Universe, which could lead to a detectable gravitational wave signal.
We summarize the basic conditions for a strong first order phase transition for SU(N) dark sectors with nf flavors, calculate the gravitational wave spectrum and show that, depending on the dark confinement scale, it can be detected at eLISA or in pulsar timing array experiments.
The gravitational wave signal provides a unique test of the gravitational interactions of a dark sector, and we discuss the complementarity with conventional searches for new dark sectors.
The discussion includes the twin Higgs and strongly interacting massive particle models as well as symmetric and asymmetric composite dark matter scenarios.
Read more at http://journals.aps.org/prl/pdf/10.1103/PhysRevLett.115.181101

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October 28, 2015 at 6:32 pm

LIGO Generations – The Film

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Written by physicsgg

March 10, 2015 at 8:42 pm

Posted in COSMOLOGY, RELATIVITY

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Planck: Gravitational waves remain elusive

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Planck_view_of_BICEP2_field_mediumDespite earlier reports of a possible detection, a joint analysis of data from ESA’s Planck satellite and the ground-based BICEP2 and Keck Array experiments has found no conclusive evidence of primordial gravitational waves.

The Universe began about 13.8 billion years ago and evolved from an extremely hot, dense and uniform state to the rich and complex cosmos of galaxies, stars and planets we see today.

An extraordinary source of information about the Universe’s history is the Cosmic Microwave Background, or CMB, the legacy of light emitted only 380 000 years after the Big Bang.

ESA’s Planck satellite observed this background across the whole sky with unprecedented accuracy, and a broad variety of new findings about the early Universe has already been revealed over the past two years. Read the rest of this entry »

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January 30, 2015 at 6:19 pm

The Apollo Missions And The Hunt for Gravitational Waves

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Apollo astronauts left an array of seismometers to study moonquakes. Now astrophysicists are scouring the data for evidence of gravitational waves

apollo111One of the great unanswered questions in science is whether the universe is filled with gravitational waves and if so, whether we can spot them. This question comes directly from Einstein’s theory of general relativity which assumes that the fabric of the cosmos is able to warp, bend and vibrate like a rubber sheet.

The bending and warping effectively causes gravity, the effects of which we can measure in detail. The vibrating is gravitational waves but physicists have yet to see this directly. However, they are hugely confident that gravitational waves must permeate the universe and have spent hundreds of millions of dollars building machines to spot them, so far unsuccessfully.

in recent years, a number of scientists have begun to point out that there may be much cheaper ways of finding gravitational waves. One idea is to study pulsars since the precise signals they send out must “shimmer” when gravitational waves pass by.

Another idea is to look at the Earth itself. The thinking is that it must vibrate like a bell when gravitational waves pass by. So there could be signs of this vibration in the data collected by the global network of sensors set up to measure seismic vibrations around the planet…..
… Read more at medium.com and http://arxiv.org/abs/1409.4680

Written by physicsgg

September 26, 2014 at 12:49 pm

Posted in RELATIVITY, SPACE

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Giant laser observatory makes progress

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Ligo The first generation of Ligo failed to find evidence of gravitational waves

The first generation of Ligo failed to find evidence of gravitational waves

By Maria Dasi Espuig

The Advanced Ligo instrument, a laser “ruler” built to measure the traces of gravitational waves, is progressing at amazing speed, scientists say.

The first generation of Ligo, which ran between 2001 and 2010, saw nothing.

Over the last four years scientists have designed a more sensitive detector that achieved “full lock” in June this year, earlier than planned.

Researchers reported that the new one is already 30% more precise and will start scanning the sky in summer 2015.

Ligo (Laser Interferometer Gravitational-Wave Observatory) operates in two sites in the US, one in Livingston, Louisiana, and another one in Hanford, Washington.

Space ripples

“In June we reached this state that we call ‘locking’, where the entire system is switched on and behaves for a short time, 10 minutes or so, as predicted it should do in science mode,” said Prof Andreas Freise from the School of Physics and Astronomy of the University of Birmingham during the British Science Festival.

Gravitational waves are ripples in the fabric of space and time that propagate across the Universe like sound waves do after an earthquake.

But in this case, the sources of the “tremors” are very energetic events such as supernovas (the explosion of a dying star), fast spinning neutron stars (very dense and compact stars), or the collision of black holes and neutron stars orbiting close to each other. Read the rest of this entry »

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September 12, 2014 at 6:41 pm

Astronomers Hedge on Big Bang Detection Claim

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By DENNIS OVERBYE

A group of astronomers who announced in March that they had detected space-time disturbances — gravity waves — from the beginning of the Big Bang repeated that claim Thursday but conceded that dust from the Milky Way galaxy might have interfered with their observations.

The original announcement, apparently heralding what they said was “a new era” in cosmology, astounded and exhilarated scientists around the world. At a splashy news conference on March 17 at the Harvard-Smithsonian Center for Astrophysics in Cambridge, Mass., the talk quickly turned to multiple universes and Nobel Prizes.

But even as reporters and scientists were gathering there, others convened on Facebook and elsewhere to begin picking apart the findings. What ensued was a rare example of the scientific process — sharp elbows, egos and all — that has played out over the last three months.

If indeed true, the detection of those gravity waves would confirm a theory that the universe began with a violent outward anti-gravitational swoosh known as inflation — a notion that would explain the uniformity of the heavens, among other mysteries, and put physicists in touch with quantum forces that prevailed when the universe was only a trillionth of a trillionth of a second old. The idea once seemed like science fiction, but the astronomers’ findings put it almost tangibly in reach.

As everyone involved said at the time, however, the results needed to be confirmed; it was far too soon to book travel to those other universes.

Now, after weeks of public and private wrangling, discussion and debate with peer reviewers and other astrophysicists, the group, which goes by the name Bicep, has published its official paper in the journal Physical Review Letters. The authors, led by John Kovac of the Harvard-Smithsonian Center for Astrophysics, write that they stand by their original claim — but they also now acknowledge it is possible that dust in the Milky Way galaxy might have interfered with their observations, producing much or even all of their signal. Read the rest of this entry »

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June 19, 2014 at 7:05 pm

Rumours swirl over credibility of big bang ripple find

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bicep2Has the recent discovery of gravitational waves been reduced to dust? Not so fast.

The news that ripples in space-time, called gravitational waves, had been spotted stunned the physics community earlier this year. This week, rumours began swirling that the scientists who reported the find have now admitted to making a mistake. The team missed a key detail in its analysis of galactic dust, the rumours suggest, making it more likely that the signal came from a source other than gravitational waves.

But the team’s response to this claim is unequivocal: “We’ve done no such thing,” says principal investigator John Kovac at Harvard University. The validity of the discovery won’t be known until another group either supports or opposes their finding, which could happen later this year.

In March, the BICEP2 collaboration announced that it had seen an imprint on ancient cosmic light that it says was created by gravitational waves. Those waves are thought to be products of inflation, a period of rapid growth during the first sliver of a second after the big bang. The finding was hailed as a smoking gun for the theory of inflation – and as evidence that theories of a multiverse may be true. Read the rest of this entry »

Written by physicsgg

May 13, 2014 at 9:35 pm