Shining light on elusive dark matter

Apr 04, 2013
Space Station after AMS-02 installation.

The antimatter hunter AMS-02 on the International Space Station is searching for the missing pieces of our Universe. The project's first results published yesterday are hinting at a new phenomenon and revealing more about the invisible 'dark matter'.

AMS-02, the Alpha , consists of seven instruments that monitor cosmic rays from space. Unprotected by Earth's atmosphere the instruments receive a constant barrage of high-. As these particles pass through AMS-02, the instruments record their speed, energy and direction.

AMS-02 testing at ESTEC.

The project is one of the largest scientific collaborations of all time involving 56 institutes from 16 countries. The instrument was tested at ESA's technical facility ESTEC in the Netherlands before being shipped to the US for launch on . As part of his DAMA mission, ESA astronaut Roberto Vittori controlled the Shuttle's that transferred the 6918 kg instrument to the in 2011.

Scientists have collected data on over 400 000 electrons together with their antimatter twins, the positrons. Data released today show how the ratio of positrons compared to electrons passing through AMS-02 changes depending on their energy, confirming data from previous instruments.

The findings hint at a new phenomenon but it is unknown whether the positron ratio comes from colliding with each other or from pulsating stars in our galaxy that produce antimatter.

New cosmic recipe.

Shine a torch in a completely dark room, and you will see only what the torch illuminates. That does not mean that the room around you does not exist. Similarly we know dark matter exists but have never observed it directly.

ESA's Planck satellite refined our knowledge of what makes up our Universe, showing last month that it is made of 26.8% dark matter. AMS-02 and the operators controlling it are working day and night to investigate the individual particles that make up dark matter.

Despite recording over 30 billion cosmic rays since AMS-2 was installed on the International Space Station in 2011, the findings presented today are based on only 10% of the readings the instrument will deliver over its lifetime.

This video is not supported by your browser at this time.
Building AMS-02: 16 years in three minutes. Credit: Widlab

Scientists are confident that AMS-02 will deliver the data needed to solve the riddle of where the changes in positron ratio come from in the near future.

"Over the coming months, AMS will be able to tell us conclusively whether these are a signal for dark matter, or whether they have some other origin." says Professor Samuel Ting, the project's lead investigator.

Explore further: Image: Chandra's view of the Tycho Supernova remnant

add to favorites email to friend print save as pdf

Related Stories

AMS is ready to discover the particle universe

May 20, 2011

(PhysOrg.com) -- The largest and most complex scientific instrument yet to be fitted to the International Space Station was installed today. Taken into space by the Space Shuttle, the Alpha Magnetic Spectrometer ...

Alpha Magnetic Spectrometer arrives at launch site

Aug 26, 2010

(PhysOrg.com) -- One of the most complex space scientific instruments ever built, the Alpha Magnetic Spectrometer (AMS-02) arrived at the Kennedy Space Center in Florida, escorted by astronauts who will fly ...

New Endeavour for an MIT experiment

May 25, 2011

Space Shuttle Endeavour’s final mission, launched May 16, has successfully delivered MIT researchers’ Alpha Magnetic Spectrometer (AMS) — an instrument designed to use the unique environment ...

Recommended for you

Image: Chandra's view of the Tycho Supernova remnant

Jul 25, 2014

More than four centuries after Danish astronomer Tycho Brahe first observed the supernova that bears his name, the supernova remnant it created is now a bright source of X-rays. The supersonic expansion of ...

Satellite galaxies put astronomers in a spin

Jul 24, 2014

An international team of researchers, led by astronomers at the Observatoire Astronomique de Strasbourg (CNRS/Université de Strasbourg), has studied 380 galaxies and shown that their small satellite galaxies almost always ...

Video: The diversity of habitable zones and the planets

Jul 24, 2014

The field of exoplanets has rapidly expanded from the exclusivity of exoplanet detection to include exoplanet characterization. A key step towards this characterization is the determination of which planets occupy the Habitable ...

User comments : 30

Adjust slider to filter visible comments by rank

Display comments: newest first

Pkunk_
2.3 / 5 (3) Apr 04, 2013
Aren't positrons also emitted by the atmosphere itself during thunderstorms ? How much would atmospheric events skew the results ?

Do any biological or electrical processes on the ISS release positrons ? Considering 6-8 humans are staying on the ISS and their electronic paraphernalia.
panorama
not rated yet Apr 04, 2013
Still not as elusive as Robert Denby...
eachus
4.7 / 5 (3) Apr 04, 2013
Aren't positrons also emitted by the atmosphere itself during thunderstorms ? How much would atmospheric events skew the results ?


The positrons that AMS is looking at are very high energy beasts. They can get this strong if accelerated after they are formed, but otherwise they must come from some exotic source. What they are expecting is that some of the high-energy positrons come from collisions of cosmic rays with dark matter. If so the positrons may include a "signature" of the collision that created them.

Why look at these electrons and positrons? They effectively sample the entire flight time of a cosmic ray so even very rare collisions will show up.
Maggnus
5 / 5 (2) Apr 04, 2013
What they are expecting is that some of the high-energy positrons come from collisions of cosmic rays with dark matter.


Actually, I believe they are expecting to find evidence of collision between dark matter particles, not DM being struck by `regular` matter.
Porgie
1 / 5 (3) Apr 04, 2013
Pkunk is right. There is no dark matter. We just have yet to discover the rest of the matter out there. Its a good theory, but incorrect.
Fleetfoot
5 / 5 (4) Apr 05, 2013
Aren't positrons also emitted by the atmosphere itself during thunderstorms? How much would atmospheric events skew the results?


There's much more information in this release:

http://press.web....periment

The key part is "The positron to electron ratio shows no anisotropy indicating the energetic positrons are not coming from a preferred direction in space.". Those coming from Earth would be easily identified. You might also expect more to be coming from the galactic plane if other stars produced them, the dark matter halo surrounds the galaxy so a near isotropic result is a good indication that they are on the right track. As the article says, a rapid cutoff in the spectrum will be the key observation but looking at the graph, that's going to be nearer 1TeV, 3 times the highest energy AMS-02 can detect.
ValeriaT
1 / 5 (2) Apr 05, 2013
Pkunk is right. There is no dark matter.
Dark matter is an observational fact - a phenomenological artifact. I can be composed of space-time curvature at small (particle) or large scales (field) or both. If unsure, consider the both, says the AWT.
vidyunmaya
1 / 5 (3) Apr 05, 2013
Sub: Knowledge base-Cosmology -Best of Brains Trust
The shaded Universe concept helps to unravel the mystery of the Dark matter-Lead kindly Light gets integrated with Tamosoma Jyothir-Gamyam- Milky way Sensex will show Human being Sensitive index.Plasma Occupies the shape of the body- UPE model- 1991- IEEE-ICOPS
See Space Time Energy-Curvature etc need orientation-
http://www.scribd...del-2003
Change in Concept will help next dimensional Knowledge base.search Origins-Space Cosmology Vedas Interlinks
ValeriaT
1 / 5 (2) Apr 05, 2013
Dark matter detected in orbit? Not so fast, scientists say The more energetic the positrons, the more massive their "parent" dark matter particles must be. They look at the positrons in higher and higher energy brackets, waiting for the populations to suddenly drop off. That drop-off point would mark the maximum possible mass of the dark matter particles. "That would be the smoking gun for a dark matter annihilation signal," said Gaitskell. "Unfortunately, with this current result there is no indication of that." So - in contrary to PO article above - the AMS finding makes the presence of dark matter particles doubtful, rather than confirms it.. We should realize, the more expensive the experiment is, the higher political pressure exists for presentation of at least some finding, which would justify this investments...
Fleetfoot
2.3 / 5 (3) Apr 06, 2013
We should realize, the more expensive the experiment is, the higher political pressure exists for presentation of at least some finding, which would justify this investments...


Perhaps we should look at the science instead. Figure 4 in this paper shows the state of knowledge prior to this mission:

http://arxiv.org/...72v1.pdf

The results go up to ~40 GeV and there is just a hint of an upturn. This is the current result:

http://press.web....ure2.jpg

It is obvious that there is a clear peak above the slowly falling background starting around 10GeV.

From your article: "Ting noted. 'With a little – or maybe a lot – more data, we should be able to solve this problem,' he said."

Unlikely, the peak will fall but whether it is sharp or gentle is above the range of the detector. What this experiment has SUCCEEDED in doing is telling us where the drop is, something that wasn't known from the AMS-01 results in the paper above.
ValeriaT
1 / 5 (2) Apr 06, 2013
the peak will fall but whether it is sharp or gentle is above the range of the detector
At first it's not statistically significant, at second "it could also mean that positrons caused by pulsars – rotating neutron stars that hurl radiation into space – are drowning out any dark matter signal", even if such a signal would exist. At third such a cut-off in electron-positron ratio could be caused with annihilation of positrons with atom nuclei which do undoubtedly exist in ionosphere. There are too many alternative explanations viable trough Occam razor, that the existence of WIMPS (which weren't observed at any other experiments including LHC) remains doubtful. I'm forced to judge all these experiments together.
Fleetfoot
3.7 / 5 (3) Apr 06, 2013
the peak will fall but whether it is sharp or gentle is above the range of the detector
At first it's not statistically significant


The error bars are shown the signal is much higher so you are wrong on that.

second "it could also mean that positrons caused by pulsars – rotating neutron stars that hurl radiation into space – are drowning out any dark matter signal"


That's what I said, the slope of the roll-off will determine which we are seeing but it is out of the range of AMS-03.

third such a cut-off in electron-positron ratio could be caused with annihilation of positrons with atom nuclei which do undoubtedly exist in ionosphere.


Last I heard the International Space Station is above the ionosphere. If not, DUCK!

I'm forced to judge all these experiments together.


First you need to learn how to read a graph with error bars, you will be in no position to judge any experiment until you learn the maths.
ValeriaT
1 / 5 (2) Apr 06, 2013
you will be in no position to judge any experiment until you learn the maths
It's like to say to Galileo: "Well, the order of Venus phases apparently doesn't fit our excellent geocentric model - but until you cannot present any math, you should shut up - we are doing enough money with our horoscopes".
Fleetfoot
4.2 / 5 (5) Apr 06, 2013
At first it's not statistically significant
you will be in no position to judge any experiment until you learn the maths
It's like to say to Galileo ....


Galileo wasn't commenting on whether a graph showing error bars was "statistically significant". It is blatantly obvious from the graph that the peak IS statistically significant relative to the descending background on the left side so you are trying to comment on things you clearly don't understand.

What is producing the peak, dark matter or pulsars, is another question entirely.
jsdarkdestruction
5 / 5 (3) Apr 06, 2013
We should realize, the more expensive the experiment is, the higher political pressure exists for presentation of at least some finding, which would justify this investments...

You should realize that a finding of nothing is still a finding and justifies the expense too. if it turns out to be pulsars or something other than dark matter...great, at least we'd know and can move forward with our understanding a little clearer.
ValeriaT
1 / 5 (2) Apr 06, 2013
that a finding of nothing is still a finding and justifies the expense too
Only when more advanced theories which predict the null outcome aren't ignored. Technically we could spend all money in search of pink panther at Pluto with such an approach and nobody would feel responsible for it. The contemporary physicists don't search for explanation of phenomena - they're looking for confirmation of their theories at the first line. Which is wrong and biased approach, especially when applied systematically. So far all searches for WIMPS has failed (LHC, DAMA/LIBRA, CRESST, EDELWEISS, CDMS, XENON, PICASSO) and the supersymmetry is ad-hoced approach, which has no support in experimental physics, so we should look at the alternative explanations first. The opposite approach is mainstream version of crackpotism.
Q-Star
2.3 / 5 (6) Apr 06, 2013
The contemporary physicists don't search for explanation of phenomena - they're looking for confirmation of their theories at the first line.


Sorry Zeph, that one is right over my head. How can ya explain the phenomena without looking for confirmation of your explanation?

Of course, to the Zephyr, the reality of the explanation is of little consequence as long as he gets a forum to explain his intuitive view of the phenomena. (If ya have trouble with that,,, it means that ya the explanation is more important than the truth.)

Zephyr, I say this in kindness, ya should forgo science and apply yourself to art. With art the only reality ya need confront is your own, your view is the only one that matters. In science ya have to be able to be consistent and be constrained by nature.
ValeriaT
1 / 5 (2) Apr 06, 2013
How can ya explain the phenomena without looking for confirmation of your explanation?
You can tell me, how string theory can exist fifty years without confirmation... I'm proposing the ways, in which my ideas can be confirmed all the time. For example my last post here ("such a scattering is quite common at the water surface....Note that for certain wavelength the red shift effect disappears and it's subsequently replaced with blue shift and positive violation of inverse square law)" contains just three links to experimental/observational confirmations.
ValeriaT
1 / 5 (2) Apr 06, 2013
Note that at least three significant bloggers (1, 2, 3) are openly skeptical to interpretation of AMS-2 results as a finding of dark matter. All these bloggers are professional physicists, two of them are string theorists. Whereas the dark matter is mentioned 9 times in the CERN press release, supersymmetry twice.

"There's absolutely no way that measurements of the positron spectrum may give us a reliable evidence for dark matter: not now, and not anytime soon. We simply have no robust way of telling a dark matter signal from a boring astrophysics background in that channel, because we don't know the shape nor the normalization of the background."

This is just the example, in which the mainstream science manipulates publics.
ValeriaT
1 / 5 (2) Apr 06, 2013
For comparison, this is how the same finding is interpreted in popular scientific press (and with naive kids at reddit in its consequence). Everyone is believing this lie, because he has no chance to verify it. Maybe we aren't religious society like at the medieval times - but the propaganda is spreading with the same efficiency, like the teaching of Holy Church at the Galileo era, because the layman people are using to trust the science.
Fleetfoot
3 / 5 (2) Apr 07, 2013
You should realize that a finding of nothing is still a finding and justifies the expense too. ..


The point is though that they didn't find nothing, they found and measured a large peak that had never been seen before with what looks like better than 10 sigma accuracy. Val just hasn't the faintest idea how to read a graph and uses the term "statistically significant" because he sees other people say it and thinks he'll look smart if he slips it in somewhere. Typically, he used it on a result that is vastly more statistically significant than those which were accepted as the discovery claim for the Higgs boson (the usual 5 sigma).
Fleetfoot
3 / 5 (2) Apr 07, 2013
Note that at least three significant bloggers (http://www.math.c...?p=5736) are openly skeptical to interpretation of AMS-2 results as a finding of dark matter. All these bloggers are professional physicists, ...


Yes, and the original release from the AMS team said the same thing, only by looking at the slope of the roll-off which is above the detector range can they find out whether this is dark matter or not.

This is just the example, in which the mainstream science manipulates publics.


No, this is yet another example of where the popular press tries to grab headlines by claiming something which the scientists were careful to point out was not true. They from past experience how it would be manipulated and tried to prevent it but the press ignored them to gain a quick buck.
ValeriaT
1 / 5 (2) Apr 07, 2013
That drop-off point would mark the maximum possible mass of the dark matter particles.

"That would be the smoking gun for a dark matter annihilation signal," said Gaitskell. "Unfortunately, with this current result there is no indication of that."


Briefly speaking, no drop-off point can be recognized in current data. This is how the drop-off point is supposed to look. What is observed instead is statistically insignificant trend on the AMS graph (which could be explained in dozens alternative ways). Everything else is just a data fishing and it doesn't belong into science.
Fleetfoot
3 / 5 (2) Apr 07, 2013
For example my last post http://phys.org/n...ble.html ("such a scattering is quite common at the water surface....


Scattering doesn't match observation, your speculation is proven false.

Note that for certain wavelength the red shift effect disappears ..


The article you linked is about BAO and says nothing about red shift at all.

replaced with blue shift


The Pioneer signal is nothing more than the Doppler effect from the recoil of waste heat.

and positive violation of inverse square law


The article you linked is about background radio emissions and completely unrelated to the inverse square law.

contains just three links to experimental/observational confirmations.


One is by a clueless crank posting on out of date information, the other two are completely unrelated to anything you said and only prove you have no clue about the topics being discussed.
Fleetfoot
3 / 5 (2) Apr 07, 2013
...said Gaitskell. "Unfortunately, with this current result there is no indication of that."


Briefly speaking, no drop-off point can be recognized in current data.


ROFL, nice pun. That graph is of a power company's voltage output.

Everything else is just a data fishing and it doesn't belong into science.


You are the only one fishing, you even quoted what the article said, let's see it again:

"with this current result there is no indication of that."


You haven't twigged it yet, have you? The peak is above the range of the present detector so their going to have to build one that goes up to ~2TeV to resolve the question. That's another decade's employment for someone ;-)
ValeriaT
1 / 5 (2) Apr 07, 2013
The Pioneer signal is nothing more than the Doppler effect from the recoil of waste heat
IMO it's mostly manifestation of blue shift in microwave spectrum. The deceleration curve of Pioneer space-probe doesn't fit the decay curve of plutonium, which is heat source there. But apparently too many people (including you) want the opposite..;-)
The article you linked is about background radio emissions and completely unrelated to the inverse square law
Background radio emissions don't exist in the universe. They're always related to some distant sources - and the scientists expected six-times lower emissions, than those which they measured.
That's another decade's employment for someone
I don't think, without cold fusion someone will find another multiple billions of dollars for another magnetic spectrometer in foreseeable future.
Fleetfoot
3 / 5 (2) Apr 07, 2013
The deceleration curve of Pioneer space-probe doesn't fit the decay curve of plutonium, which is heat source there.


They managed to recover older data and over the extended time, the decay did fit, you are just out of touch.

The article you linked is about background radio emissions and completely unrelated to the inverse square law
Background radio emissions don't exist in the universe. They're always related to some distant sources ..

That's why they are called "background".

the scientists expected six-times lower emissions, than those which they measured.


Right, so whatever the sources are, they are brighter than expected or perhaps closer, still nothing about inverse square.

I don't think .. someone will find another multiple billions of dollars for another magnetic spectrometer in foreseeable future.


Sadly you might be right, but the success of this experiment means the LHC group now know what mass range to search.
ValeriaT
1 / 5 (2) Apr 07, 2013
they are brighter than expected or perhaps closer, still nothing about inverse square
Because you're not smart enough for to realize, why they're considered brighter or closer at all? If you don't understand something, it doesn't mean, no logic is there...
Fleetfoot
3 / 5 (2) Apr 07, 2013
they are brighter than expected or perhaps closer, still nothing about inverse square
Because you're not smart enough for to realize, why they're considered brighter or closer at all? If you don't understand something, it doesn't mean, no logic is there...


Since the article says nothing about the sources, their brightness or their distances, nothing in it suggests anything about a failure of the inverse square law. Any such implication is nothing more than your personal fantasy. None of the articles you cited had any relevance to what you were claiming.
eachus
5 / 5 (1) Apr 12, 2013
Actually, I believe they are expecting to find evidence of collision between dark matter particles, not DM being struck by `regular` matter.


Depends who you ask. ;-) Either would be new physics. The hypothesis that DM particles can decay when they collide requires that DM is its own antiparticle. (Majorana particles.) Cosmic rays recoiling from DM (via a weak or strong nuclear force channel), to me better satisfies Occam's Razor.

In the end, of course, the data will decide--it is amazing how many beautiful theories are destroyed by ugly facts.