a significant gravitational lensing bias in high-redshift galaxy samples

a member has just made me aware of a news piece that is in my area
Aggie Man has posted a link to the news that

a significant gravitational lensing bias in high-redshift galaxy samples

the tittle

Gravitational Lensing: Cosmic Magnifying Lenses Distort View of Distant Galaxies

a picture



link to news
does not explain the massive nature of the announcement

gravataional lensing may increse red shift
this is huge in the terms of understanding the nature and age of the universe
and has implecations on understanding what we are really looking at when we look into deep space

"In this sense, the very distant universe is like a house of mirrors that you visit at the State Fair -- there may be fewer direct lines-of-sight to a very distant object, and their images may reach us more often via a gravitationally-bent path. What you see is not what you've got!''

the potential for further Discoveries following this one is huge

We show that gravitational lensing by foreground galaxies will lead to a higher number of galaxies to be counted at redshifts z>8-10. This number may be boosted significantly, by as much as an order of magnitude. If there existed only three galaxies above the detection threshold at redshifts z>10 in the Hubble field-of-view without the presence of lensing, the bias from gravitational lensing may make as many as 10-30 of them visible in the Hubble images," explains Windhorst

with the new designs for telescopes we could very likley learn a vast amount of information on the size and location of the galaxies and objects in our universe.

this is the first time i have heard of red shift being attributed to gravity lenses from someone else
here is my thread on a universe full of lense shaped bubbles (theory) posted on 18-11-2010 @ 11:42 AM
www.abovetopsecret.com...

the idea that lenses can be transitioned and shift wavelength and amplitude is also discussed here
spherical speed of transition (theory),
posted on 24-11-2010 @ 11:15 AM
www.abovetopsecret.com...

i am not claiming these discoveries as mine but that some of my theorys have been shown to have merit is cause to celebrate for me as it shows im on the right track


the fact that lenses are shifting light down in frequency is one of my favourite theorys
as is the posability of a gravatational microscoping effect from these very same lenses
gravatational microscoping theory posted on 22-11-2010 @ 04:47 PM
www.abovetopsecret.com...

thanks to aggie man for remembering my posts and bringing this news to my u2u
having a drink of the good stuff now

XPLodER

the "standard candle" or the objects we use for distence calculations has had some refinments to do with red and blue shifts being created by supernova gasses escaping from their core

Even when astronomers correct for this effect, their measurements still show some scatter, which leads to inaccuracies when calculating distances and therefore the effects of dark energy. Studies looking for ways to make more accurate corrections have had limited success until now.

"We've been looking for this sort of 'second-order effect' for nearly two decades," said Foley.

Foley discovered that after correcting for how quickly Type Ia supernovae faded, they show a distinct relationship between the speed of their ejected material and their color: the faster ones are slightly redder and the slower ones are bluer.

here we have the "medium" (hot gasses and plasma) traveling at diferent speeds creating a red or blue shift to the observer.
this goes to show that the "medium density" of the gass around a star can effect shifts of light either up or down in colour/frequency

this is an important observation
IMHO

xploder

up to 20 % of the observable galaxies may be lensed

Although ESA did not have funds for FOCAL, Maccone continues to write actively about the mission in papers and books. He’ll also be fascinated to see how the subject is being discussed at the American Astronomical Society’s 217th annual meeting, which concludes today. A team led by Stuart Wyithe (University of Melbourne) has made the case in a presentation and related paper in Nature that as many as 20 percent of the most distant galaxies we can detect appear brighter than they actually are, meaning that lensing has gone from a curious effect to a significant factor in evaluating galaxy surveys to make sure they are accurate.

source

up to 20% of the backround galaxies are an image representation of much further away galaxies "lensed" onto a closer surface on a gravitational lense alowing us to see them with our telescopes
the galaxies are many time more luminous than they would be without this effect and proberly would not be seen without the gravatational lense effect.

xploder

Originally posted by XPLodER
gravataional lensing may increse red shift

This is like saying if you're too far to see the people on the beach, and you buy a telescope so you can see the people on the beach, then the telescope increases the number of people on the beach.

No, it doesn't, it only increases the number of people you can see, the number of people didn't change.

There actually is a change in redshift near the intervening galaxies but it's cancel So gravitational lensing may only increases the number of red shifted objects we see, not the number of objects, and the red shift itself is changed and then changed back in the lens before it gets to us, so it's unchanged.

Originally posted by Arbitrageur

Originally posted by XPLodER
gravataional lensing may increse red shift

This is like saying if you're too far to see the people on the beach, and you buy a telescope so you can see the people on the beach, then the telescope increases the number of people on the beach.

No, it doesn't, it only increases the number of people you can see, the number of people didn't change.

There actually is a change in redshift near the intervening galaxies but it's cancel So gravitational lensing may only increases the number of red shifted objects we see, not the number of objects, and the red shift itself is changed and then changed back in the lens before it gets to us, so it's unchanged.

when we veiw the universe and we see red shift we asume a masive distence
in this instence the fore ground gravitational lenses are increasing the red shift and increseing the luminosity of the perceived galaxies or stellar objects
what this means is
when we look through alot of fore ground objects we are more likley to see red shifted objects as the light has been "bent" or shifted by the gravitational distortion and when you consider that up to 20% of the objects may be red shifted by fore ground gravitational distortions this has huge implecations on the survey of galaxies and their distences calculated from shifted values and we are talking about 20% of the red shifted galaxies
and their distences to us

another point to note is the fact that as observers we need to account for the red shift when it comes from gravitational sources as to not get incorrect distence calculations

if galaxies can be red shifted by lensing
is the red shift an acurite measure of speed? considering we dont know if any galaxy is being lensed as we observe it?

and if red shift is proportional to distence is that lensed distence? or distence to the observer?
or the non lensed distence? because if 20% of red shifted objects are getting lensed then alot of the shifts we see could be simply lensed of other lenses

xploder

Originally posted by XPLodER
in this instence the fore ground gravitational lenses are increasing the red shift

No, that's wrong.

What makes you think that?

The light is blueshifted when it enters the gravitational field, but when it leaves the gravitational field, it is redshifted so it's only changing back to the same redshift it had before it entered the gravitational field.

See the diagram at about 3 minutes in this video:

reply to post by Arbitrageur

The light is blueshifted when it enters the gravitational field, but when it leaves the gravitational field, it is redshifted so it's only changing back to the same redshift it had before it entered the gravitational field.

Although ESA did not have funds for FOCAL, Maccone continues to write actively about the mission in papers and books. He’ll also be fascinated to see how the subject is being discussed at the American Astronomical Society’s 217th annual meeting, which concludes today. A team led by Stuart Wyithe (University of Melbourne) has made the case in a presentation and related paper in Nature that as many as 20 percent of the most distant galaxies we can detect appear brighter than they actually are, meaning that lensing has gone from a curious effect to a significant factor in evaluating galaxy surveys to make sure they are accurate.

source

We show that gravitational lensing by foreground galaxies will lead to a higher number of galaxies to be counted at redshifts z>8-10. This number may be boosted significantly, by as much as an order of magnitude. If there existed only three galaxies above the detection threshold at redshifts z>10 in the Hubble field-of-view without the presence of lensing, the bias from gravitational lensing may make as many as 10-30 of them visible in the Hubble images. In this sense, the very distant universe is like a house of mirrors that you visit at the State Fair — there may be fewer direct lines-of-sight to a very distant object, and their images may reach us more often via a gravitationally-bent path. What you see is not what you’ve got!”

and from a post in this thread

Even when astronomers correct for this effect, their measurements still show some scatter, which leads to inaccuracies when calculating distances and therefore the effects of dark energy. Studies looking for ways to make more accurate corrections have had limited success until now.

"We've been looking for this sort of 'second-order effect' for nearly two decades," said Foley.

Foley discovered that after correcting for how quickly Type Ia supernovae faded, they show a distinct relationship between the speed of their ejected material and their color: the faster ones are slightly redder and the slower ones are bluer.

so to recap upto 20% of the known universe may be being "lensed"
that is upto 1/5 of the observable universe being lensed

the most important bit

a significant gravitational lensing bias in high-redshift galaxy samples

that the higher the red shift the more likely it is to be lensed= direct relationship between redshift and lensing
xploder

reply to post by Arbitrageur


the recent nasa documentation about the changes to cepheids

This image layout illustrates how NASA's Spitzer Space Telescope was able to show that a "standard candle" used to measure cosmological distances is shrinking -- a finding that affects precise measurements of the age, size and expansion rate of our universe. Image credit: NASA/JPL-Caltech/Iowa State
› Full image and caption PASADENA, Calif. -- Astronomers have turned up the first direct proof that "standard candles" used to illuminate the size of the universe, termed Cepheids, shrink in mass, making them not quite as standard as once thought. The findings, made with NASA's Spitzer Space Telescope, will help astronomers make even more precise measurements of the size, age and expansion rate of our universe.

Standard candles are astronomical objects that make up the rungs of the so-called cosmic distance ladder, a tool for measuring the distances to farther and farther galaxies. The ladder's first rung consists of pulsating stars called Cepheid variables, or Cepheids for short. Measurements of the distances to these stars from Earth are critical in making precise measurements of even more distant objects. Each rung on the ladder depends on the previous one, so without accurate Cepheid measurements, the whole cosmic distance ladder would come unhinged.

Now, new observations from Spitzer show that keeping this ladder secure requires even more careful attention to Cepheids. The telescope's infrared observations of one particular Cepheid provide the first direct evidence that these stars can lose mass—or essentially shrink. This could affect measurements of their distances.

NASA

so with a new "standard candle" measurement we are talking about astrological distences that

This calculation was famously performed by astronomer Edwin Hubble in 1924, leading to the revelation that our galaxy is just one of many in a vast cosmic sea. Cepheids also helped in the discovery that our universe is expanding and galaxies are drifting apart.

thing is the refinment to the luminosity/distence ratios will be altered and this affects distence calculations
the other point to note is if the stella object is being lensed by fore ground objects this further effects the likely red shift bias and this also relates directly to distence.

with these two refinements to our calculations of distence and perspective we are effectivly changing the distence between stars (to our observable position)
and redfining the size and rate of expansion in the universe

remember up to 20% of back round galaxies could be lensed
including the Cepheids we use to "guage" distence

xploder

reply to post by Arbitrageur

Everything crumbles in cosmology studies if you don't start up with the most precise measurements of Cepheids possible," said Pauline Barmby of the University of Western Ontario, Canada, lead author of the follow-up Cepheid study published online Jan. 6 in the Astronomical Journal. "This discovery will allow us to better understand these stars, and use them as ever more precise distance indicators."

xploder

reply to post by Arbitrageur

Dr Mattia Negrello, of the Open University and lead researcher of the study, explained, "Our survey of the sky looks for sources of sub-millimetre light. The big breakthrough is that we have discovered that many of the brightest sources are being magnified by lenses, which means that we no longer have to rely on the rather inefficient methods of finding lenses which are used at visible and radio wavelengths."

the idea is to use the detection of sub millimeter light as an indication of gravatational lensing
if the sub milimeter was the source it would have disapated before interaction with the lense
if it was Infra Red it could have reached the lense and been shifted by the lense into sub milimeter frequencies

like a tourch shining a beam into fog
the sub milimeter light wont penatrate the gas and dust very far
and would only be visable close to the lense because of scattering

Herschel looks at far-infrared light, which is emitted not by stars, but by the gas and dust from which they form. Its panoramic imaging cameras have allowed astronomers to find examples of these lenses by scanning large areas of the sky in far-infrared and sub-millimetre light.

Dr Mattia Negrello, of the Open University and lead researcher of the study, said: "Our survey of the sky looks for sources of sub-millimetre light. The big breakthrough is that we have discovered that many of the brightest sources are being magnified by lenses, which means that we no longer have to rely on the rather inefficient methods of finding lenses which are used at visible and radio wavelengths."

The Herschel-ATLAS images contain thousands of galaxies, most so far away that the light has taken billions of years to reach us. Dr Negrello and his team investigated five surprisingly bright objects in this small patch of sky. Looking at the positions of these bright objects with optical telescopes on the Earth, they found galaxies that would not normally be bright at the far-infrared wavelengths observed by Herschel. This led them to suspect that the galaxies seen in visible light might be gravitational lenses magnifying much more distant galaxies seen by Herschel.

here we have the teams says they find galaies that would not normally be bright at the far infra red wavelengths
being see as sub millimeter or far infra red when observed from a lense.



xploder