'Cosmic mirages' confirm accelerated cosmic expansion

Apr 11, 2012
Figure 1 Image of SDSSJ1226-0006, a new gravitationally lensed quasar discovered in this survey. The quasar image in the original image of the Sloan Digital Sky Survey (SDSS), which has been used for the actual survey to identify gravitational lensing, looks only slightly extended, but the Hubble Space Telescope (HST) image clearly exhibits two distinct quasar images (white) as well as a massive galaxy in between the quasar images (orange) that produces gravitational lensing.

(Phys.org) -- An international team of researchers led by Masamune Oguri at Kavli IPMU and Naohisa Inada at Nara National College of Technology conduced an unprecedented survey of gravitationally lensed quasars, and used it to measure the expansion history of the universe. The result provides strong evidence that the expansion of the universe is accelerating. There were several observations that suggested the accelerated cosmic expansion, including distant supernovae for which the 2011 Nobel Prize in Physics was awarded. The team's result confirms the accelerated cosmic expansion using a completely different approach, which strengthens the case for dark energy. This result will be published in The Astronomical Journal.

Quasars are very luminous objects powered by of gas into at the centers of distant galaxies. A quasar is typically located far away. ", a phenomenon that a is split into two or more images due to the gravity of a massive foreground object." Toshifumi Futamase, Professor at University says, "Prof. Oguri is a leading young researcher in the research field of gravitational lensing. He leads the test of the presence of dark energy using gravitational lensing. The great advantage of this research is much higher statistical significance, which is made possible by a large sample of in the SDSS." The phenomenon of gravitational lensing, often called as "Cosmic Mirage", was first discovered in 1979, and since then more than 100 gravitationally lensed quasars have been reported.

An international team of researchers led by Masamune Oguri, Assistant Professor at the Kavli Institute for the Physics and Mathematics of the Universe (Kavli IPMU), and Naohisa Inada, Lecturer at Nara National College of Technology, conducted a large survey to search for gravitationally lensed quasars in the massive data sets of the Sloan Digital Sky Survey (SDSS). Over almost 10 years of careful examinations of 100,000 quasars, the team successfully discovered nearly 50 new gravitationally lensed quasars in total, significantly increased a sample of cosmic mirages (Figure 1).

Figure 2 Illustration of the gravitational lensing measurement of the cosmic expansion speed. The accelerated expansion increases the distance to the quasar, giving rise to higher chance of having a massive galaxy very close to the light path to produce gravitational lensing.

The frequency of gravitational lensing, which can be measured by counting the number of gravitationally lensed quasars within a given quasar catalog, allows one to infer the expansion speed of the universe, because the accelerated expansion increases the distance to each quasar and therefore enhances the chance of gravitational lensing (Figure 2).

The team measured the probability of gravitational lensing among distant quasars to be about 0.05 percent, which was then compared with detailed theoretical calculations to extract information on the expansion hisotry. The result indicates that the is indeed accelerating, which suggests that the universe must be filled with mysterious energy component called dark energy.

"The accelerated is one of the central problems in modern cosmology", Oguri says, "In 2011, the was awarded to the discovery of the accelerated expansion of the universe using observations of distant supernovae. A caution is that this method using supernovae is built on several assumptions, and therefore independent checks of the result are important in order to draw any robust conclusion. Our new result using gravitational lensing not only provides additional strong evidence for the accelerated cosmic expansion, but also is useful for accurate measurements of the expansion speed, which is essential for investigating the nature of dark energy."

Careful comparisons with other cosmological observation led to the conclusion that dark energy behaves almost like Einstein's cosmological constant. "Statistical method on gravitationally lensed quasars have been known to be sensitive to the expansion history of the universe,"  Masashi Chiba, Professor at Tohoku University, says,"therefore actively studied by Japanese researchers in the 1990s. Observations of gravitational lensing at that time already hinted the presence of dark energy, but both due to the small sample size and large uncertainty in the theoretical modeling of lensing rates the result was not widely accepted. This research conducted a enormous survey of gravitationally lensed quasars and adopted much more sophisticated theoretical calculations to build a very convincing case for the accelerated cosmic expansion."

"Studies of dark energy (cosmological constant) were popular in Japan already in the early 1990s, largely because of pioneering work by Prof. Fukugita, Principal Investigator at Kavli IPMU and a co-author of this paper.", says Yasushi Suto, Professor at University of Tokyo, "This survey of gravitationally lensed quasars was initiated and organized by Profs. Oguri and Inada, who were graduate students when the survey started, within the large international SDSS collaboration, and they led the team to success. This result is important in that it confirms the presence of dark energy independently from the observation of supernovae."

Detailed properties of dark energy are planned to be explored in the SuMIRe project, an international survey project led by Kavli IPMU using the Subaru telescope. Suto says, "This result demonstrates that Japanese theoretical and observational cosmologists will play an essential role in the SuMIRe project." Chiba also says, "This result creates big momentum for the survey of the cosmic by the SuMIRe project."

Explore further: Image: Multicoloured view of supernova remnant

More information: The Astronomical Journal, "The Sloan Digital Sky Survey Quasar Lens Search. VI. Constraints on Dark Energy and the Evolution of Massive Galaxies," Masamune Oguri, Naohisa Inada et al. Preprint: arxiv.org/abs/1203.1088

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kevinrtrs
1.1 / 5 (15) Apr 11, 2012
I am really beginning to like the name given to this unknown and invisible "dark energy".
Seems like scientists are encountering a ghost in the machine - only they cannot call it that, even if it fits the description!

A question I have to ask in my ignorance, in the light of the following statement:
he result indicates that the expansion of the universe is indeed accelerating, which suggests that the universe must be filled with mysterious energy component called dark energy.
Is the universe STILL expanding at an accelerated rate or are we just observing the expansion that occurred in the past? How does one distinguish between the two options? Perhaps someone can enlighten me on this issue.
Shootist
3.9 / 5 (7) Apr 11, 2012
Seems like scientists are encountering a ghost in the machine - only they cannot call it that, even if it fits the description!


Accelerating expansion is seen and measured. How is this a 'ghost'?

At the largest scales in the cosmos, there are billion ly wide voids, surrounded by filaments of matter. The mass congregates, further curving space-time by its presence, creating, if you will a deep trench surrounding the Voids. This is what is seen at scales of 6-8 GLy.

I'll go (way) out on a limb with what I think is a most elegant solution: Space-time has negative curvature in the presence of mass. The assumption is space-time is flat (no curvature) in the absence of mass. What if, at the largest scales (say 2*10^9 Ly), when mass has moved beyond some limit, space-time has a slightly positive curvature in the absence of mass?

Results in constantly accelerating expansion, with no new energy to be described.
HannesAlfven
1.6 / 5 (14) Apr 11, 2012
Does it make any sense to claim a higher confidence in an inference, when competing inferences are simply ignored and de-funded, and no real effort goes into seeking out or investigating alternatives? Confidence based upon intentional ignorance is hardly something worth getting excited about. Exploring alternatives is not "inefficient". Arp was not "wasting telescope time"; he was coming up with additional evidence for the very inference which could compete with this one, and the astronomical community just watched it all happen, and all nodded their heads when statistics were used to disqualify him.

Statistics seem to be a popular way to undermine threatening ideas in the scientific community. They were also used against Gerrit Verschuur's claims that dozens of WMAP hotspots could be correlated with local HI filaments. Interestingly, statistics were also used in an attempt to discredit allegations that PhD programs are taking too long to complete.
mcausal
5 / 5 (2) Apr 11, 2012
Is the universe STILL expanding at an accelerated rate or are we just observing the expansion that occurred in the past?


Since we observe more distant objects (billions of lightyears away - older) to have a lower expansion rate than what we observe locally (present) we deduce accelerating expansion.
brodix
1 / 5 (2) Apr 11, 2012
mcausal,
As I understood it originally, it was that the expansion was not decelerating at the rate assumed by theory. The most distant galaxies are presumably accelerating away at close to the speed of light, so the closer galaxies are not going faster than that.

Shootist,

I agree with your theory. When Einstein first proposed the CC, it was to balance gravity. So since gravity is dominant around mass/galaxies, it would make sense this CC is dominant in the voids. Since the light we receive from the distant galaxies must necessarily travel the least disturbed routes, it would mostly pass through these areas of positive curvature. The greater the distance, the more the effect would be compounded, so there is a horizon line where it appears to exceed C. Beyond that it would only be black body radiation, which would explain the background radiation that is observed to be coming from the edges of the visible universe, rather than it being from a Big Bang. Resolving Olber's paradox.
brodix
1 / 5 (3) Apr 11, 2012
Keep in mind that not only is dark energy necessary to resolve discrepancies between observation and Big Bang Theory, but Inflation was the original massive patch to save it.
Shelgeyr
1.4 / 5 (11) Apr 11, 2012
Their confidence level in their assumptions concerning gravitational lensing is unjustifiably high. Even more so, their iterative calculations founded upon those assumptions (which I guess, technically, should be "even less so"...) should be approached with great trepidation.

What passes for "established fact" in Astronomy often wouldn't pass for "idle speculation" in an actual hard science.

"Sometimes I think that Astronomy is not so much a science as a series of scandals." - Halton Arp
DaFranker
1 / 5 (5) Apr 11, 2012
Something to keep in mind about "Dark Energy", kevinrtrs, is that this phenomenon is essentially "We have no idea why we got these measurements, or what's causing what we're seeing, or even if what we're seeing is accurately representing truth, but we'll make up some imaginary energy that has a fun name and try various calculations with it until we have a better idea of what's going on."

Thus, there is currently no way to distinguish fully between the two possibilities that you propose, because we're not even sure *either* of them is correct. The "expansion" we're seeing could, for all we know, be some obscure phenomenon such as gravitational information transmission eating up its own energy over distance causing, at astronomical scales, relativistic delays in gravimetric synchronisation between particles.

"Dark Energy" is just a fun and mysterious way of working with near-complete unknowns.

PS: Apologies about my poor vocabulary/wording. I'm no professional physicist.
julianpenrod
1.7 / 5 (6) Apr 11, 2012
Among other things, again, if they are demonstrating behavior among distantly viewed objects, then they are viewing events from billions and billions of years ago! If they show "acceleration", it's acceleration that occurred then! Their motion is described by all promoting the claim as being "faster than expansion velocities of closer objects". But closer objects are objects viewed nearer to our time, meaning, not as long ago! So, if nearer objects are moving not as swiftly, then the universe has not accelerated, in fact, expansion is occurring more slowly now!
julianpenrod
1.7 / 5 (6) Apr 11, 2012
And those who blieve special relativity have overlooked an important facet, time dilation! Objects moving at great speed are supposed to appear to move more slowly. The "proof" that galaxies are "further away than they are" is that supernove took longer to reach maximum brightness, therefore, "they must be very bright" and the fact they appear dim proves they're further away. But, near the speed of light, a short period of brightening can appear long! They didn't take long to brighten, so they aren't brighter than would be expected!
HannesAlfven
1.7 / 5 (12) Apr 11, 2012
What's most alarming about concepts like dark matter and dark energy is that there exists this widespread assumption that real-world physics can somehow instantiate from these nebulous concepts -- as if all of the theoretical speculations (and there are MANY) up to this point in time are without a doubt correct.

But really, I personally get a strong whiff of fear from this self-imposed tunnel vision. As real-world jobs and livelihoods depend upon these rather unreal concepts not simply being the product of a prior mistake, this society of thinkers naturally gravitates away from theoretical possibilities which inspire that largely subconscious fear.

But, anybody with a little perspective knows that mistakes are necessary for learning and progress in the real world. But, when people double-down on this gamble that there are no mistakes in the framework, over and over again, it is really the hallmark of addictive behavior (but based upon an aversion to the fear of being wrong)
bewertow
3.4 / 5 (5) Apr 11, 2012
Dark energy is most likely just vacuum energy. It isn't that mysterious. The only problem is that current calculations overestimate the energy density.
Tennex
1 / 5 (2) Apr 11, 2012
Dark energy violates standard model of cosmology, in which the Universe should expand with decreasing speed. It supports the dispersive model of the red shift, in which Universe expansion is the result of the light dispersion at vacuum fluctuations in similar way, like at the case of surface ripples, the dispersion of which is nonlinear too.
RealityCheck
1 / 5 (5) Apr 11, 2012
"...allows one to infer the expansion speed of the universe, because the accelerated expansion increases the distance to each quasar and therefore enhances the chance of gravitational lensing."

If that isn't the epitome of circuitous reasoning, then what is? First they assume 'expansion' is what created the distance, then they assume some 'accelerated expansion' created further distance and greater chance of 'line of sight' proximity of intervening lensing galaxies to the quasar light signal, and then they assume that the greater likelihood of such line-of-sight occurrences is due to accelerated expansion!

It probably never enters their presumptive logic circuitous reasoning that the distances to observed quasars may have been what they are all along, and such line-of-sight occurrences would exist irrespective of how those quasars came to be at those distances from us.

The probability of line of sight proximity of intervening lensing galaxies would be the same, irrespective. :)

Tennex
1 / 5 (1) Apr 11, 2012
Apparently, the light is moving in different speed at the different distance from the lens - or the lensing wouldn't be otherwise possible.
PaulRadcliff
1 / 5 (4) Apr 11, 2012
Can you say "guesswork"? How do they know what the frequency of examples of lensing would be with no accelerated expansion? How do they know they've found all of them? This study raises more questions than it answers. It's all a house of cards, built on conjecture upon conjecture. If you look for something hard enough you'll find a way to detect it. The Universe IS an awful big place. We have no real idea how big, but.....
Iourii Gribov
1 / 5 (4) Apr 12, 2012
The DE-mirages disclose hidden Multiverse the Gribov Periodical Multiverse (GPM), solving interrelated DE&DM&SUSY&Higgs problems: Gribov 2012. Dark Matter as Pico-Windows to physically equal Multiverse Worlds with Myriads Civilizations Around Us (in extra dimension). http://www2.hu-be...bov.pdf. The GPM consists of identical periodical matter/antimatter (gravity/antigravity) 3D-Universes - 3D-waveguides with enormous 4D-density ~10000000000 Universes/cm4! The 3D-waveguide thickness Loe~10(-10)cm4 = Compton length of the lightest mass particle - electron. It creates waveguided emergency of the Einsteinian SR & Equivalence Principle - GR & Diracian QM, being the same wave-interference. This explains the DE&DM & flatness & bubbles structure (theoretical DE/(DM + OM) ~74%/26%, near to observations); predicts antigravity in the antimatter - CERN / positronium - Mills lab gravity tests; absence of elementary Sparticles & Higgs bosons.
Torbjorn_Larsson_OM
not rated yet Apr 15, 2012
I am really beginning to like the name given to this unknown and invisible "dark energy".
Seems like scientists are encountering a ghost in the machine - only they cannot call it that, even if it fits the description!


You must really be "ghosted" by black holes or lenses then! They say the same, masses don't always need to interact with light in the obvious way of scattering it or emitting much.

Is the universe STILL expanding at an accelerated rate or are we just observing the expansion that occurred in the past?


Yes, according to standard cosmology models the expansion is accelerating at this era and there is no mechanism stopping it. Cyclical models doesn't fit all the data.
Torbjorn_Larsson_OM
not rated yet Apr 15, 2012
Does it make any sense to claim a higher confidence in an inference, when competing inferences are simply ignored and de-funded, and no real effort goes into seeking out or investigating alternatives?


First, dark energy is, as described in the article, observed by way of expansion and testing of standard cosmology. Science don't do "inferences" outside of hypothesis generation.

That is also the same tests that have managed to reject all the contending hypotheses, from the ones you mention to MOND.

In short, this makes sense and the others didn't.
Torbjorn_Larsson_OM
5 / 5 (1) Apr 15, 2012
Keep in mind that not only is dark energy necessary to resolve discrepancies between observation and Big Bang Theory, but Inflation was the original massive patch to save it.


Yes, those are indeed huge leaps in observability. Cosmology is a great experiment, and we are lucky that standard cosmology allows for these kinds of observations of things that would otherwise remain unobservable until we had gotten other handles on them.

But no "patches", no "place holders", nu "unknowns" (re DaFranker), no "guess work" (re PaulRadcliff), no "mistakes" (re HannesAlfven), those are rookie mistakes: such can't be fitted into theories and have them remain predictive.

And to think that we just 10 years ago had only observed ~ 5 % of the universe content! Well, there were hints, but until the theory no certain observations could be made.

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