Spiral galaxies seen edge-on often show dark lanes of interstellar dust blocking light from the galaxy's stars, as in this image of the galaxy NGC 4565 from the Sloan Digital Sky Survey (SDSS-II).

Intergalactic Dust Could Be Messing Up Observations, Calculations

Article Updated: 24 Dec , 2015

by

[/caption]

“Just like household dust, cosmic dust can be a nuisance,” said astronomer Ryan Scranton of the University of California, Davis. Scranton is part of a team of researchers from the Sloan Digital Sky Survey that have been analyzing the colors of distant quasars whose light passes in the vicinity of foreground galaxies on its way to the Earth. What they found is that the vast expanses of intergalactic space appear to be filled with a haze of tiny, smoke-like “dust” particles that dim the light from distant objects and subtly change their colors. “Galaxies contain lots of dust, most of it formed in the outer regions of dying stars,” said team leader Brice Ménard of the Canadian Institute for Theoretical Astrophysics. “The surprise is that we are seeing dust hundreds of thousands of light-years outside of the galaxies, in intergalactic space.”

An implication of this finding means that since most distant supernovae are seen through some haze, our current estimates of their distances may be affected.

Dust grains block blue light more effectively than red light. “We see this when the sun sets: light rays pass through a thicker layer of the atmosphere,” said Scranton, “absorbing more and more blue light, causing the sun to appear reddened. We find similar reddening of quasars from intergalactic dust, and this reddening extends up to ten times beyond the apparent edges of the galaxies themselves.”

The team analyzed the colors of about 100,000 distant quasars located behind 20 million galaxies, using images from SDSS-II. “Putting together and analyzing this huge dataset required cutting-edge ideas from computer science and statistics,” said team member Gordon Richards of Drexel University. “Averaging over so many objects allowed us to measure an effect that is much too small to see in any individual quasar.”

Supernova explosions and “winds” from massive stars drive gas out of some galaxies, Ménard explained, and this gas may carry dust with it. Alternatively, the dust may be pushed directly by starlight.

“Our findings now provide a reference point for theoretical studies,” said Ménard.

Intergalactic dust could also affect planned cosmological experiments that use supernovae to investigate the nature of “dark energy,” a mysterious cosmic component responsible for the acceleration of the expansion of the universe.

Intergalactic dust doesn’t remove the need for dark energy to explain current supernova data, Ménard explained, but it may complicate the interpretation of future high-precision distance measurements. “These experiments are very ambitious in their goals,” said Ménard, “and subtle effects matter.”

The new findings are reported in a paper titled “Measuring the galaxy-mass and galaxy-dust correlations through magnification and reddening,” submitted to the journal Monthly Notices of the Royal Astronomical Society, and posted today on the web site arXiv.org.

Source: Sloan Digital Sky Survey


Sort by:   newest | oldest | most voted
garrafa
Member
garrafa
February 26, 2009 3:02 PM

I’m not an astronomer and I know I’m going far here, so please someone clarify it to me: could this mean that redshift is caused by intergalactic dust and that maybe the universe is not expanding at all?

Jack
Guest
Jack
February 26, 2009 3:22 PM

It certainly screwed up your spellchecker, re calculCations…!!!

Damn that intergalactic dust!!!

Ethan Siegel
Guest
February 26, 2009 3:39 PM

No way, Fst. The dust is going to have subtle effects only, it doesn’t change any of the conclusions people have drawn about cosmology, redshift, or dark energy.

I’m just posting here to avoid alarmism; this is an extremely minor correction to measurements.

Astrofiend
Member
Astrofiend
February 26, 2009 3:52 PM
“# Fst Says: February 26th, 2009 at 3:02 pm I’m not an astronomer and I know I’m going far here, so please someone clarify it to me: could this mean that redshift is caused by intergalactic dust and that maybe the universe is not expanding at all?” >>>No – this is a separate effect. Redshift and ‘reddening’ are two different things. Note that there is a theory flying about that states that redshift could be caused by interstellar gas and dust, but almost no astronomer or physicist believes it – it has major problems apparently. Anyway – back to the original question. This reddening that the article speaks about is essentially why we see sunsets as red –… Read more »
lotusface
Member
lotusface
February 26, 2009 3:58 PM

These are the subtleties that will clue us in to the real nature of the universe, we have been almost correct in our observations of the place. When we find the difference between the environment inside & outside of the heliosphere there will be additional minor corrections and likewise with the milky way locale. I know in my bones that the “supernatural” ideas some have will be explained by subtle discoveries like this(way down the timeline).

robbi
Guest
robbi
February 26, 2009 4:00 PM
Fst- I’m not an astronomer either, but the ‘general’ distance to close to distant galaxy are correct enough for ‘general amateur astronomers-too many indicators out there says our Universe is expanding, one is if the Universe is ‘static’ or not expanding is, ALL the light from distant galaxies should’ve brighten up our Universe far more than what we see, and our ‘night’ sky would not be so dark! What this feed is about is, ‘fine tuning’ of our Universes’ expansion and recently found/theorized data from distant Supernova Type 1A that our Universe is accelerating the expansion, the acceleration is real and forever took the heat off Cosmologist and general Astronomers why the previous rate of expansion and age… Read more »
Total Science
Member
February 26, 2009 6:19 PM

Well I guess that would explain the myopia and scotoma of mainstream science.

Dave
Guest
Dave
February 26, 2009 6:30 PM
#Fst: Im no astronomer either, but i think the evidence for the expanding universe is seen in the spectral lines in the light from different galaxies ( absorption lines from various elements like hydrogen etc)…the lines themselves are shifted to the red, and more so the farther away the galaxy in question is…all the dust would do is attenuate the light at various colours, but the spectral lines would not be shifted…the shift is due to the expanding universe having something like a Doppler effect on the lines due to space itself getting bigger while the light in question is on the way to us…..any experts on here care to clarify? #oilsmastery: huh? What you mentioned doesnt explain… Read more »
Steven C
Guest
Steven C
February 26, 2009 8:23 PM
Well, as with all things big and small … theories are based on observed phenomena. Many theories that seemed to explain the observed phenomena later proved to be “fantasy”. As observations accumulate, some theories fade because no amount of “fine-tuning” of the theory permits the observed phenomena to be satisfactorily explained. The origin of the Moon is as good an example as there is. When I was in School, the universally accepted theory said that the moon was thrown out of a rapidly spinning young earth – the division theory. Only in the mid to late 1980’s did scientific community embrace and shift to the glancing impact of a planet sized object as the theory of choice —… Read more »
robbi
Guest
robbi
February 26, 2009 9:14 PM
Steven C Says-In the late 50s’ I was a child and wonder why looking at a map, S.America was a perfect fit with Africa-everyone saw that, so I asked the teacher why does S.America,Africa and so many other areas looks as if they all fit to another, I was told the it’s all a coincidence and the mountains are a shrinking effect, I had a heated discussion with the teacher and said why doesn’t the whole Earth look like a prune- well I had to see the principal lol. Coninental drifting was fully published by Alfred Wegener in 1912,but convention scientist and geologist at the time and later called him a nutcase and worst. It wasn’t until the… Read more »
robbi
Guest
robbi
February 26, 2009 10:57 PM
Steven C Says-There are 2 strange things that makes my thinking about the Comets and the Solar Wind kinda hazy-=I was near Perth ,Austrailia in Jan-Feb07 on vacation there and thru New Zealand. I saw Comet McNaught-it was brighter than Comet Hale-Bopp, the brilliant tail as seen even with the naked eyes and then a 25x125mm binoculars had the most oddly quick changing tail that show brilliant lanes far frome the nucleus that Solar Wind alone can not cause, because the changes were so quick and startling, I checked if there was auroras increased sighting, none. Than Comet Holmes. it was so far from the Sun and yet became bright enough to see with the naked eye in… Read more »
robbi
Guest
robbi
February 27, 2009 2:25 AM
Steven C Says- Interesting when you said about the divsion theory about Earth-Moon system as in the late 50s’ it was the Sun pulling enough mass from out molten Earth that created the Moon-and the void was the Pacific Ocean which of course before Drifting Continent was finally accepted by scientist and Geologist . In the late 60s to about 2000 when wine,woman, family and song messed up my mind, I finally got back to get my own large ‘scope with the ‘puter control etc. and retired at age 55 in late 2006. In the late 70s’ I was asking my young sons what the teacher said how the Moon was created, most students had already said a… Read more »
Aodhhan
Member
Aodhhan
February 27, 2009 5:25 AM
Never amazed by the amount of misinformation given by people who know just enough about astronomy to be dangerous. To address the redshift question/problem. In a very simple way. Long wavelengths appear red. The longer the wave is, the darker and more rich the red color appears. Short wavelengths appear blue. The shorter and more compact, the deeper and more rich the blue color. Think of a slinky, and imagine the coils as light waves. As distance increases between the two ends of the slinky, the wave lengths become greater, and the slinky would turn redder. Increase the distance more, and wavelength increases, and the red light becomes richer. If you compacted the slinky, the distance between the… Read more »
Chris
Guest
Chris
February 27, 2009 6:37 AM

Aodhhan,

How can we now be certain that there is no dust between us and some arbitrary far-distant object? If it took us this long to come to the realization that there is some dust in intergalactic space nearby, isn’t it possible that there is even more accumulated dust the further away we look? In other words, how can we possibly discount the possibility that we’re seeing something “clearly” without the effect of dust when we’ve been seeing this (allegedly) small dust effect the entire time?

ND
Guest
ND
February 27, 2009 7:15 AM

Aodhhan,

I think you’re confusing reddening and redshifting. They’re different phenomenon. redshifting is a measure of how far spectral lines have shifted because of the speed of the object along the line of sight, regardless of how much reddening may occur. Reddening is basically like looking through a reddish filter.

jerry
Guest
jerry
February 27, 2009 7:35 AM

The study throws a major wrench in the supernova cosmological studies. Specifically, relativistic reddening IS difficult to discern from dust reddening.

In the current supernova distance determinations, there is little reddening budget assigned to dust; and this lack of dust in the supernova sample is statistically inconsistent with the amount of dust implied from this general study.

collin
Guest
collin
February 27, 2009 9:27 AM
Distance does not stretch wavelengths, velocity does. It’s the same concept of hearing a fire engine speed away from you and the siren drops in pitch. If the fire enging was stationary, the pitch would be the same whether it was 5 feet away from you or 100 feet away. My problem is this…I can’t seem to reconsile the difference between the *appearance* of reddened and redshifted light. How would we know which is which? The perception of red is just the wavelength of light that hits our lenses so what would be the difference of light that came in at red wavelengths due to redshifting or reddening? I guess I might argue that this dust phenomenon, while… Read more »
Aodhhan
Member
Aodhhan
February 27, 2009 10:02 AM

ND, No I’m not confused at all. Reddening is throwing off the accuracy of redshift measurement. How about that? smile

Chris, could be a can of worms. I’m going to hold off for a bit to see what sort of consistencies (or lack of), distortion, etc turn up with further study.

Another question; is there any “magnified” affect of this reddening when observing far away galaxies via gravitational lensing.

jerry
Guest
jerry
February 27, 2009 10:06 AM
Dust ‘reddening’ is not consistent at all wavelengths, whereas doppler redshift is; so within margins of error, you can compare the attenuation in different spectral ranges and differentiate between doppler redshift and dust reddening. At very high velocities; general relativity causes a ‘reddening’ effect in addition to the doppler shift in the frequency bands. Supernova researchers have concluded, or at least assumed, that most of the reddening they observe is due to relativistic effects, not dust. It is a degenerative problem, in that if you assume or conclude there is substantial dust reddening, then you also must presuppose that the most distant supernova events are much brighter and/or much closer than current distance estimates. The difference is substantial:… Read more »
Aodhhan
Member
Aodhhan
February 27, 2009 10:07 AM

Collin, you have it all wrong. If what you said was the case (since the speed of light is constant) there would be no redshifting. I would have also spent a lot of my career wasting time.

Please study more about the doppler affect.

wpDiscuz