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Posts Tagged ‘gravitational microlensing’

Astronomers ‘Unscramble’ Einstein Ring To Reveal Most Detailed View Ever Of Star Formation In The Distant Universe


Credit: ALMA (NRAO/ESO/NAOJ)/Y. Tamura (The University of Tokyo)/Mark Swinbank (Durham University)

Credit: ALMA (NRAO/ESO/NAOJ)/Y. Tamura (The University of Tokyo)/Mark Swinbank (Durham University)

ALMA’s Long Baseline Campaign produced spectacular images of the distant, gravitationally lensed galaxy called HATLAS J090311.6+003906, otherwise known as SDP.81. New analyses of these images reveal details never before seen in a galaxy so remote, including phenomenally massive yet concentrated clumps of star-forming material.

The ALMA observations of SDP.81, made at the end of 2014, were enabled by a cosmic effect known as gravitational lensing. A large galaxy nestled between SDP.81 and ALMA is acting as a lens, magnifying the more distant galaxy’s light and warping it into a near-perfect example of a phenomenon known as an Einstein Ring.

In the months following these observations, at least seven groups of scientists have independently analyzed the ALMA data on SDP.81. This flurry of research papers has divulged unprecedented information about the galaxy, including details about its structure, contents, motion, and other physical characteristics.

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Mapping Dark Matter, 4.5 Billion light Years Away


Credit: ESA/Hubble, NASA, HST Frontier Fields

Credit: ESA/Hubble, NASA, HST Frontier Fields

Using the NASA/ESA Hubble Space Telescope, an international team of astronomers have mapped the mass within a galaxy cluster more precisely than ever before. Created using observations from Hubble’s Frontier Fields observing programme, the map shows the amount and distribution of mass within MCS J0416.1–2403, a massive galaxy cluster found to be 160 trillion times the mass of the Sun.

The detail in this ‘mass map’ was made possible thanks to the unprecedented depth of data provided by new Hubble observations, and the cosmic phenomenon known as strong gravitational lensing. The team, led by Dr Mathilde Jauzac of Durham University in the UK and the Astrophysics & Cosmology Research Unit in South Africa, publish their results in the journal Monthly Notices of the Royal Astronomical Society.

Measuring the amount and distribution of mass within distant objects in the Universe can be very difficult. A trick often used by astronomers is to explore the contents of large clusters of galaxies by studying the gravitational effects they have on the light from very distant objects beyond them. This is one of the main goals of Hubble’s Frontier Fields, an ambitious observing programme scanning six different galaxy clusters — including MCS J0416.1–2403.

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Hubble Shows Farthest Lensing Galaxy Yields Clues To Early Universe


Credit: NASA, ESA, K.-V. Tran (Texas A&M University), and K. Wong (Academia Sinica Institute of Astronomy & Astrophysics)

Credit: NASA, ESA, K.-V. Tran (Texas A&M University), and K. Wong (Academia Sinica Institute of Astronomy & Astrophysics)

Astronomers using NASA’s Hubble Space Telescope have unexpectedly discovered the most distant cosmic magnifying glass, produced by a monster elliptical galaxy. Seen here as it looked 9.6 billion years ago, this monster elliptical galaxy breaks the previous record holder by 200 million years. These “lensing” galaxies are so massive that their gravity bends, magnifies, and distorts light from objects behind them, a phenomenon called gravitational lensing.

The object behind the cosmic lens is a tiny spiral galaxy undergoing a rapid burst of star formation. Its light has taken 10.7 billion years to arrive here. Seeing this chance alignment at such a great distance from Earth is a rare find.

Locating more of these distant lensing galaxies will offer insight into how young galaxies in the early universe built themselves up into the massive dark-matter-dominated galaxies of today. Dark matter cannot be seen, but it accounts for the bulk of the universe’s matter.

“When you look more than 9 billion years ago in the early universe, you don’t expect to find this type of galaxy-galaxy lensing at all,” explained lead researcher Kim-Vy Tran of Texas A&M University in College Station. “It’s very difficult to see an alignment between two galaxies in the early universe.”

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Hubble Astronomers Use Supernovae To Gauge Power Of Cosmic Lenses


Distant exploding stars observed by NASA’s Hubble Space Telescope are providing astronomers with a powerful tool to determine the strength of naturally-occurring “cosmic lenses” that are used to magnify objects in the remote universe.

Two teams of astronomers, working independently, observed three such exploding stars, called supernovae. Their light was amplified by the immense gravity of massive galaxy clusters in the foreground — a phenomenon called gravitational lensing. Astronomers use the gravitational lensing effect to search for distant objects that might otherwise be too faint to see, even with today’s largest telescopes.

“We have found supernovae that can be used like an eye chart for each lensing cluster,” explained Saurabh Jha of Rutgers University in Piscataway, N.J., a member of the Cluster Lensing and Supernova survey with Hubble (CLASH) team. “Because we can estimate the intrinsic brightness of the supernovae, we can measure the magnification of the lens.”

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‘Upside-Down Planet’ Reveals New Method For Studying Binary Star Systems


Simulation. Credit: NASA

Simulation. Credit: NASA

What looked at first like a sort of upside-down planet has instead revealed a new method for studying binary star systems, discovered by a University of Washington student astronomer.

Working with UW astronomer Eric Agol, doctoral student Ethan Kruse has confirmed the first “self-lensing” binary star system — one in which the mass of the closer star can be measured by how powerfully it magnifies light from its more distant companion star. Though our sun stands alone, about 40 percent of similar stars are in binary (two-star) or multi-star systems, orbiting their companions in a gravitational dance.

Kruse’s discovery confirms an astronomer’s prediction in 1973, based on stellar evolution models of the time, that such a system should be possible. A paper by Kruse and Agol was published in the April 18 edition of Science.

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Faraway Moon Or Faint Star? Possible Exomoon Found


Titan, Europa, Io and Phobos are just a few members of our solar system’s pantheon of moons. Are there are other moons out there, orbiting planets beyond our sun?

NASA-funded researchers have spotted the first signs of an “exomoon,” and though they say it’s impossible to confirm its presence, the finding is a tantalizing first step toward locating others. The discovery was made by watching a chance encounter of objects in our galaxy, which can be witnessed only once.

“We won’t have a chance to observe the exomoon candidate again,” said David Bennett of the University of Notre Dame, Ind., lead author of a new paper on the findings appearing in the Astrophysical Journal. “But we can expect more unexpected finds like this.”

The international study is led by the joint Japan-New Zealand-American Microlensing Observations in Astrophysics (MOA) and the Probing Lensing Anomalies NETwork (PLANET) programs, using telescopes in New Zealand and Tasmania. Their technique, called gravitational microlensing, takes advantage of chance alignments between stars. When a foreground star passes between us and a more distant star, the closer star can act like a magnifying glass to focus and brighten the light of the more distant one. These brightening events usually last about a month.

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NASA Hubble Team Finds Monster “El Gordo” Galaxy Cluster Bigger Than Thought


Image Credit: NASA, ESA, and J. Jee (University of California, Davis)

Image Credit: NASA, ESA, and J. Jee (University of California, Davis)

NASA’s Hubble Space Telescope has weighed the largest known galaxy cluster in the distant universe, catalogued as ACT-CL J0102-4915, and found it definitely lives up to its nickname — El Gordo (Spanish for “the fat one”).

By measuring how much the cluster’s gravity warps images of galaxies in the distant background, a team of astronomers has calculated the cluster’s mass to be as much as 3 million billion times the mass of our sun. Hubble data show the galaxy cluster, which is 9.7 billion light-years away from Earth, is roughly 43 percent more massive than earlier estimates.

The team used Hubble to measure how strongly the mass of the cluster warped space. Hubble’s high resolution allowed measurements of so-called “weak lensing,” where the cluster’s immense gravity subtly distorts space like a funhouse mirror and warps images of background galaxies. The greater the warping, the more mass is locked up in the cluster.

“What I did is basically look at the shapes of the background galaxies that are farther away than the cluster itself,” explained lead author James Jee of the University of California at Davis. “It’s given us an even stronger probability that this is really an amazing system very early in the universe.”

A fraction of this mass is locked up in several hundred galaxies that inhabit the cluster and a larger fraction is in hot gas that fills the entire volume of the cluster. The rest is tied up in dark matter, an invisible form of matter that makes up the bulk of the mass of the universe.

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RX J1131-1231: Chandra & XMM-Newton Provide Direct Measurement Of Distant Black Hole’s Spin


Credit: X-ray: NASA/CXC/Univ of Michigan/R.C.Reis et al; Optical: NASA/STScI

Credit: X-ray: NASA/CXC/Univ of Michigan/R.C.Reis et al; Optical: NASA/STScI

Multiple images of a distant quasar are visible in this combined view from NASA’s Chandra X-ray Observatory and the Hubble Space Telescope. The Chandra data, along with data from ESA’s XMM-Newton, were used to directly measure the spin of the supermassive black hole powering this quasar. This is the most distant black hole where such a measurement has been made, as reported in our press release.

Gravitational lensing by an intervening elliptical galaxy has created four different images of the quasar, shown by the Chandra data in pink. Such lensing, first predicted by Einstein, offers a rare opportunity to study regions close to the black hole in distant quasars, by acting as a natural telescope and magnifying the light from these sources. The Hubble data in red, green and blue shows the elliptical galaxy in the middle of the image, along with other galaxies in the field.

The quasar is known as RX J1131-1231 (RX J1131 for short), located about 6 billion light years from Earth. Using the gravitational lens, a high quality X-ray spectrum – that is, the amount of X-rays seen at different energies – of RX J1131 was obtained.

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Massive Neutrinos Solve A Cosmological Conundrum

February 10, 2014 Leave a comment

Galaxy2-Cropped-445x124_smScientists have solved a major problem with the current standard model of cosmology by combining results from the Planck spacecraft and measurements of gravitational lensing to deduce the mass of ghostly sub-atomic particles called neutrinos.

The team, from the universities of Nottingham and Manchester, used observations of the Big Bang and the curvature of space-time to accurately measure the mass of these elementary particles for the first time.

The recent Planck spacecraft observations of the Cosmic Microwave Background (CMB) – the fading glow of the Big Bang – highlighted a discrepancy between these cosmological results and the predictions from other types of observations.

The CMB is the oldest light in the Universe, and its study has allowed scientists to accurately measure cosmological parameters, such as the amount of matter in the Universe and its age. But an inconsistency arises when large-scale structures of the Universe, such as the distribution of galaxies, are observed.

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NASA’s Fermi Makes First Gamma-ray Study Of A Gravitational Lens

January 7, 2014 Leave a comment

An international team of astronomers, using NASA’s Fermi observatory, has made the first-ever gamma-ray measurements of a gravitational lens, a kind of natural telescope formed when a rare cosmic alignment allows the gravity of a massive object to bend and amplify light from a more distant source.

This accomplishment opens new avenues for research, including a novel way to probe emission regions near supermassive black holes. It may even be possible to find other gravitational lenses with data from the Fermi Gamma-ray Space Telescope.

“We began thinking about the possibility of making this observation a couple of years after Fermi launched, and all of the pieces finally came together in late 2012,” said Teddy Cheung, lead scientist for the finding and an astrophysicist at the Naval Research Laboratory in Washington.

In September 2012, Fermi’s Large Area Telescope (LAT) detected a series of bright gamma-ray flares from a source known as B0218+357, located 4.35 billion light-years from Earth in the direction of a constellation called Triangulum. These powerful flares, in a known gravitational lens system, provided the key to making the lens measurement.

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