Exploring the X-ray Universe: XMM-Newton Studies Dark Energy

[wolram]

ranyart.

yes i have read the cyclic universe theories, the most
prominent feature is the avoidance of the singularity
and a new way of accounting for the apparent over abundance
of energy.

 

[wolram]

http://www.nature.com/nsu/030609/030609-7.html
Alternative proposed to dark energy's cosmic doomsday.
---------------------------------------------------------------

The destruction begins, say Robert Caldwell of Dartmouth College in New Hampshire, USA, and his coworkers2, about a billion years before it ultimately ends in a Big Rip. First, gravity loses its grip at cosmic scales, allowing clusters of galaxies to drift apart.

Sixty million years before doomsday, our own galaxy, the Milky Way, fractures as stars slip from each other's grasp. A few months before the end, planetary systems like the solar system will be dismembered, and 30 minutes before the Big Rip, the planets and stars themselves disintegrate.

In the split-second before the end, atoms and molecules are torn apart, then the particles that constitute them. Finally, space itself flies open.

All of this is driven, the argument goes, by something known as phantom energy, which fills all of space. The density of phantom energy increases with time, like a bomb that grows ever bigger.

 

[marcus]

Originally posted by wolram
http://www.nature.com/nsu/030609/030609-7.html
...All of this is driven, the argument goes, by something known as phantom energy, which fills all of space. The density of phantom energy increases with time, like a bomb that grows ever bigger.

this is different from the usual picture
what people ordinarily assume for dark energy is
a constant energy density
(often called "cosmological constant" or Lambda)

it does not increase with time
and it does not eventually rip things apart that are gravitationally bound entities (like galaxy or solar system or planet)

nobody knows that the Lambda is actually constant----the evidence has been mounting that it is constant, some reported here at PF, but
nothing conclusive

since no one can say that it is constant, people are free to imagine other scenarios like "phantom energy" which increases over time and has dramatic effects.

I think it's fair to say there is LESS reason to take phantom energy seriously than there is reason to assume the ordinary constant dark energy but that's not to say people should be discouraged from constructing these alternative scenarios

 

[Vast]

Originally posted by ranyart
Any later developing lifeforms would be looking back at this moment as the dawn of Universe, no contraction needed, its a perceptional 'Bounce'!

The usual cosmic model is that of a universe beginning in a cosmic singularity, therefore it seems reasonable to assume a multi universe scenario each beginning in the same manner.

But I think this is off topic to dark energy.

 

[wolram]

NEREID, mentioned the SNOWMASS BOOK, this is new to me its at
http://supernova.lbl.gov/~evlinder/sci.html.
i think its interesting and informative.
thanks NEREID.

 

[hellfire]

some questions

May be I am asking a little bit too late here, but here are some basic questions for my understanding of the observations done by A. Blanchard:

1. I read that this is an X-ray observation of the intergalactic medium in far clusters. In the press release it is written that in old clusters ‘there are more X-rays than today’. What does this mean? Does this mean that old clusters ‘in past’ were more distributed throughout space than today and that they went a gravitational collapse since then (so that some of them grouped into a single cluster and therefore the X-ray emission is received from a narrower region)?

2. It is also argued in the press release, that, if dark energy were existent, it would impede the gravitational collapse of clusters leaving them unchanged from ‘the past’ up to now. But, what is meant with ‘past’? Usually, it is postulated that clusters formed due to gravitational collapse (bottom-up model). Therefore the dark energy (if existent) must be dominating or influencing this process in a later point of time after the actual collapse (otherwise they would not be formed). When is this epoch to be located in time?

3. What is the relation between X-ray intensity and mass? I remember have read somewhere that additionally to mass estimations done according to observations of dynamics and application of the virial theorem, there is the possibiltiy of mass estimations of clusters according to X-ray observations.

Thanks. Regards.

 

[meteor]

I can't opine about this paper because I haven't read it still
"A model of holografic dark energy"
http://arxiv.org/abs/hep-th/0403127
But it seemed to me that the denomination "holographic dark energy" is at least curious, no?

 

[wolram]

http://arxiv.org/PS_cache/astro-ph/pdf/0204/0204500.pdf


by HELLFIRE.
1. I read that this is an X-ray observation of the intergalactic medium in far clusters. In the press release it is written that in old clusters ‘there are more X-rays than today’. What does this mean? Does this mean that old clusters ‘in past’ were more distributed throughout space than today and that they went a gravitational collapse since then (so that some of them grouped into a single cluster and therefore the X-ray emission is received from a narrower region)?
---------------------------------------------------------------------
the above url is over 170 pages long and is comprehensive.
i haven't been able to confirm that old clusters are more
x ray active, maybe NEREID or other PF members can answer
your questions, in the meantime i will read the posted article.

 

[wolram]

the subject of X ray emissions from early-type galaxies seems
to be very wide, from the posted url----------
studies of large sample of early type galaxies are suggestive that
the X-ray structure of these systems is mostly determined by
the gravitational potential well produced by large amounts of
dark matter rather than by thermal mechanisms.
---------------------------------------------------------------------
cD galaxies are galaxies with a nucleus of a very luminous
elliptical embedded in an extended amorphous halo of low surface
brightness, "this galaxy type may have been formed by collision".
---------------------------------------------------------------------
some early type galaxies that have hot (1KeV) interstellar
medium trapped by the galaxy potential well whose emission is
due to thermal processes.
---------------------------------------------------------------------
i haven't read all the article yet but i think you will find it
very infomative.

 

[wolram]

posted by METEOR.

But it seemed to me that the denomination "holographic dark energy" is at least curious, no?
----------------------------------------------------------------
yes it is, if it wasn't for the Hubble scale problem this theory
might be better than others.

 

[hellfire]

Thanks wolram, it looks a bit intimidating... but I will try to take a look. Anyway, it would be great if someone could answer shortly my questions.

 

[marcus]

Originally posted by hellfire
Thanks wolram, it looks a bit intimidating... but I will try to take a look. Anyway, it would be great if someone could answer shortly my questions.

hello hellfire, I remember enjoying your discussions before and I would like to try later today to answer, if no one gets to it earlier. I may not be able to because am supposed to be away for part of the day.

I think we already found the relevant technical paper by Blanchard
and posted, discussing this business of more dark matter and less (or zero) dark energy. IIRC he needs to assume a lower Hubble parameter to make all the numbers add up.

It will take me a while to reconstruct his argument. Maybe you already have and can explain it.

 

[marcus]

hellfire, it turns out there was some discussion in this very thread!
what I was remembering was on the first page of this thread. this link may be the one to the technical article that corresponds to the
wide-audience account you mentioned.

Originally posted by marcus
Alain Blanchard must be the most important dissident to the
"concordance" cosmology picture. the leader of the opposition.

his most recent preprint in arxiv is
http://arxiv.org/astro-ph/0402297

I'm not sure but I think
the article you pointed to in Astronomy magazine
by Amanda Jefter (dated 23 December 2003) refers
to earlier articles of Blanchard

mainly this one
http://arxiv.org/astro-ph/0304237

but also this 3-pager
http://arxiv.org/astro-ph/0311626

Nereid may have responded to the gist of what
is in these articles in another thread. I forget which.
Or I may have. I don't think Blanchard's case is strong
enough yet to start bringing more people over to his side
but he certainly bears watching. If he continues to
assemble evidence of much more dark matter then
he could start a shift of opinion.

I think the argument here is between dark matter and dark energy.

the concordance model says that familiar types of matter total around 4 or 5 percent of the average density in space

but that leaves 96 percent to account for

the "concordance" estimate is that it is split 73 d.energy plus
23 d.matter

Blanchard's main message, if I understand it, is to give much more importance to dark matter and less to dark energy.

he may also favor a lower value than 71 for the Hubble parameter
and consequently a lower overall density (so that the observed amount of ordinary matter would play a larger role)
...

I looked back at an earlier thread and found another blanchard link
http://arxiv.org/abs/astro-ph/0311381

 

[marcus]

hello again,
I'm copying your post so we have your questions in front of us. If we are lucky we will be able to put your questions together with the links to Blanchard's papers and recall how his arguments go, and respond to your questions. Or you will beat me to it and figure out
Blanchard's reasoning yourself.

Originally posted by hellfire
May be I am asking a little bit too late here, but here are some basic questions for my understanding of the observations done by A. Blanchard:

1. I read that this is an X-ray observation of the intergalactic medium in far clusters. In the press release it is written that in old clusters ‘there are more X-rays than today’. What does this mean? Does this mean that old clusters ‘in past’ were more distributed throughout space than today and that they went a gravitational collapse since then (so that some of them grouped into a single cluster and therefore the X-ray emission is received from a narrower region)?

2. It is also argued in the press release, that, if dark energy were existent, it would impede the gravitational collapse of clusters leaving them unchanged from ‘the past’ up to now. But, what is meant with ‘past’? Usually, it is postulated that clusters formed due to gravitational collapse (bottom-up model). Therefore the dark energy (if existent) must be dominating or influencing this process in a later point of time after the actual collapse (otherwise they would not be formed). When is this epoch to be located in time?

3. What is the relation between X-ray intensity and mass? I remember have read somewhere that additionally to mass estimations done according to observations of dynamics and application of the virial theorem, there is the possibiltiy of mass estimations of clusters according to X-ray observations.

Thanks. Regards.

 

[wolram]

http://www.astro.ucla.edu/~wright/cosmolog.htm

2 Feb 2004 - A group led by Prof. Tom Shanks of the University of Durham, UK, has suggested that the Sunyaev-Zeldovich effect may have significantly affected the WMAP results on the anisotropy of the cosmic microwave background. However, the S-Z effect goes through zero at 220 GHz and the ARCHEOPS balloon-borne CMB experiment which observes at 143 and 217 GHz sees the same map and angular power spectrum as WMAP. The fact that ARCHEOPS agrees with WMAP within -4.4+/-2.8% in the amplitude of the first acoustic peak means that the S-Z effect has very little influence on the WMAP results. So this was another scientific theory that, like the dodecahedral Universe, was already disproven by the time the authors sent out their press release.
-----------------------------------------------------------------------
the S-Z effect has been used in many arguments in cosmology
NWs view is that it is immaterial regarding WMAP data.
but others are taking advantage of this effect to define
the parameters of galaxies.

 

[wolram]

http://www.sciencedaily.com/releases/2002/04/020422073037.htm



By comparing the X-ray emission and the Sunyaev-Zeldovich effect, Mohr can study even faint, high-redshift galaxy clusters that are currently inaccessible by other means. Such measurements, correlating galaxy cluster redshift distribution, structure and spatial distribution, should determine the equation of state of dark energy and, therefore, help define the essence of dark energy.

 

[wolram]

. What is the relation between X-ray intensity and mass? I remember have read somewhere that additionally to mass estimations done according to observations of dynamics and application of the virial theorem, there is the possibiltiy of mass estimations of clusters according to X-ray observations.
---------------------------------------------------------------------
http://www.astro.su.se/~ostlin/ColMag/Source/colMag_clusters.html

The image here shows a view of the core of the Virgo cluster in the X-ray waveband and illustrates the structure of the hot, gravitationally-bound gas in the cluster's potential well. This potential well is sufficiently deep that the gas between the galaxies within the cluster is compressed and heated to high enough temperature that emits radiation at X-ray wavelengths. Images of this X-ray radiation illustrate the very extended potential well of the cluster, which contains two major peaks, associated with sub-groups of galaxies within the cluster. Nevertheless, the X-ray image still appears much smoother than the distribution of the individual galaxies. Moreover, the temperature and the distribution of the X-ray gas can be used to estimate the mass of the cluster (assuming that the hot X-ray gas behaves as an ideal gas) and in all cases this has been found to significantly exceed the mass contained within the galaxies. These observations are one of the strongest pieces of evidence for dark matter on large scales in the Universe. Observing at X-ray wavelengths requires the use satellites to get above the absorption from the Earth's atmosphere, which is opaque in the X-ray band.

 

[wolram]

2. It is also argued in the press release, that, if dark energy were existent, it would impede the gravitational collapse of clusters leaving them unchanged from ‘the past’ up to now. But, what is meant with ‘past’? Usually, it is postulated that clusters formed due to gravitational collapse (bottom-up model). Therefore the dark energy (if existent) must be dominating or influencing this process in a later point of time after the actual collapse (otherwise they would not be formed). When is this epoch to be located in time?
--------------------------------------------------------------------
according to first paper on this thread, 5 billion YRS ago.

 

[wolram]

after reading all these papers the main stream view seems
to hold true, we used to have a nice quiet universe until
AE came along and spoilt it, now we have a suicidal one full
of DARK ENERGY that is pushing us to oblivion, it seems that
everything in nature gets recycled except nature itself,
life after the BIG RIP seems implausible without some kind of
divine intervention, so on a cosmological time scale its
BIG BANG count to---------------- its all over by by.
it maybe philosophical but i canot think that our universe
is a use once and throw away item, I'm sure that main stream
science will be found incorrect, and that universes dont
die they just get recycled.

 

[hellfire]

Excellent, thanks again wolram for the references and also marcus for your efforts. After reading again the article (I think I misinterpreted something) and the references I consider all my questions answered:

Regarding the epoch of start of domination of the cosmological constant (5 billion years ago), I have to apologize since I did not read the article referred in the first post of this thread.

The third question (x-ray / mass relation) seams to be clear with:

This potential well is sufficiently deep that the gas between the galaxies within the cluster is compressed and heated to high enough temperature that emits radiation at X-ray wavelengths.

And this fits with the claim of Blanchard, that they found fewer x-rays than today: potential wells are postulated to be deeper today, which is an argument against the cosmological constant.

Regards.

 

[hellfire]

in the press release in the second link of the thread:

http://www.esa.int/sci_mediacentre/...html?release=54

it is in fact written that

They seem to give out more X-rays than today.

According to the quote in the previous post, this would imply that potential wells were more deep in the past, which fits with the cosmological constant hypothesis and contradicts Blanchards own thesis.

Any help?

Regards.

 

[wolram]

HELLFIRE.

may i refer you to NED Wrights website ref (Hubble parameter)
http://www.bright.net/~mrf/App9.html
blanchard is arguing that more DARK MATTER exists in the
universe than others theories, which could require an
adjustment to the H-P=71, as the H-P has been refined over
the years it now seems almost unshakable, the BIG problem
with cosmology seems to be that numbers can be manipulated
to fit a pet theory, i guess we will have to wait for the
data from new satellite missions to see what amount of
dark matter, dark energy is out there.
i was hopping that MARCUS or NEREID would jump in as they
are easier to understand and much better qualified than me.

 

[wolram]

HELLFIRE.
i have found this link in ref to to your question, have a
look ,i have not read it all yet so maybe you can tell me
if it helps.
http://www-xray.ast.cam.ac.uk/~jss/research/mnr_5510.pdf

 

[marcus]

Originally posted by wolram
... would jump in as they
are easier to understand and much better qualified than me.

the more explaining you do on PF the easier to understand
you get

6 months ago you only asked one-line questions
and the more questions you asked the better they got
now you elucidate and the more you
practice the better it gets
(hellfire and Nereid may have noticed, why should I jump in?)

today is Greg B's 21 birthday
what shall we say to him on this occasion
except that we see that the PF he has built
seems now and then to be good for something
beyond simple recreation

 

[wolram]

well to start i think GREG Bs built a world leading science
forum that everyone should be proud of, but MARCUS i value
your contributions as you know i am a minnow in this sea
of whales, i am stuck on the variance of x-ray luminosity
in clusters over time, intuitively i would say that it would
decrease, but the clusters may be evolving gravitationally
or could be acquiring mass, the last post in this thread is
the closest i have come to finding an answer.

 

[hellfire]

wolram, regarding your last reference: I have been reading some references and I think the process of cooling of the intra cluster gas is not relevant in this case. Cooling refers to the loss of energy due to the x-ray emissions (which are generated due to thermal bremsstrahlung) and its characteristic time is of the scale (or usually longer than) the Hubble time for most of the clusters. It is therefore usualy not considered for time evolution of the luminosity. As far as I understood, Blanchard also does not consider the cooling effect for his main argumentation.

My impression now is that x-ray emission depends not only on the potential well, but on a function called density contrast. This is the quotient of the main density of the cluster (density perturbation) and the energy density of the universe at the time where the cluster gets virialized (more or less stability of the gravitationally bound system is reached).

In general, it is the number of clusters of a given virial mass, which depends on the density contrast, but, since there is a postulated relation between luminosity and virial mass, also the emission of x-rays should depend on the density contrast.

Blanchard claims to have found more x-rays than today. I thought this implies deeper potential wells (in contradiction with Blanchards own thesis) but it seams that this is not the case due to the dependence on the density contrast function.

Due to the relation between density and radius the cosmological constant enters the density contrast function making use of the Friedmann equation. I am not able now to make any qualitative statement about the relations. As you see I just think now I have found the right equations, but I am still far from understanding properly the effect of evolution of luminosity.

Anyway, it would be great if somebody could confirm or correct me.

These are the references I used:
http://arxiv.org/astro-ph/9611085
http://nedwww.ipac.caltech.edu/level5/March02/Sarazin/Sarazin_contents.html
http://nedwww.ipac.caltech.edu/level5/Sept02/Padmanabhan/Pad_contents.html

Regards.

 

[Nereid]

Originally posted by marcus
the more explaining you do on PF the easier to understand
you get

6 months ago you only asked one-line questions
and the more questions you asked the better they got
now you elucidate and the more you
practice the better it gets
(hellfire and Nereid may have noticed, why should I jump in?)

today is Greg B's 21 birthday
what shall we say to him on this occasion
except that we see that the PF he has built
seems now and then to be good for something
beyond simple recreation

This thread is roaring along so quickly, it's scary I've started to reply to some post or other here several times, only to find, upon reading more of the thread, that some other aspect needs to be covered (or has already been covered). Whew, what a ride!

Someone may have commented on this already (yes, I've been in the slow class several times), but Peacock's paper on large scale structure and cosmology may be quite interesting to several readers (see if you can ignore the equations wolfram, and get an idea of the logic; you may also pick up a thing or two about some of those puzzling parameters which you read in other papers, e.g. 'tilt', 'bias', 'tensors').

 

[marcus]

I've been distracted from this thread by other (local off-web) activity and also swamped by the complexity of the issues. I need to find a suitable tutorial and an up-to-date review article that surveys how things stand at present and how the various investigations into dark energy are going.

Right now I am convinced that several of you other posters (hellfire, wolram, Nereid) are ahead of me and I need to catch up.

This morning over coffee I looked at Sahni's review article
"Dark Matter and Dark Energy"
http://arxiv.org./astro-ph/0403324

You can tell its meant as a review article because it has 190 references in its bibliography

You can tell its meant to be understandable to a wider audience because it doesn't explain very much in detail.

It is the sort of thing that OUGHT to help, but instead of helping integrate, it zaps my understanding by showing me that the jigsaw puzzle has 1000 pieces rather than the 100 or so I expected. I should be grateful to Nature for being so complex? Is this a sign something really interesting will emerge? Or is this just the wrong review article to try to read? Maybe there is a better one

 

[marcus]

Varun Sahni's Figure 1 is a graphic undeniable demonstration of the existence of dark matter:
the rotation curve for M33 keeps going up!

"It is interesting that the total mass of an individual
galaxy is still somewhat of an unknown quantity since a turnaround to the v ~ r^−1/2 law at large radii has not been convincingly observed." (page 4)

Can this be true? They have not even seen where the rotation curve
stops increasing and begins to decline? The situation is more confusing than I thought.



In the most basic entry-level details of the picture, there are unexpected signals. here is some more on page 4:

"An important difference between the distribution of dark matter in galaxies and clusters needs to be emphasised: whereas dark matter appears to increase with distance in galaxies, in clusters exactly the reverse is true, the dark matter distribution actually decreases with distance..."

so clusters of galaxies have a central concentration of DM but individual galaxies do not-----their DM is spread out an order of magnitude more than their visible matter. And he emphasizes this aspect by giving a little evidence:

"...Indeed, for certain dwarfs (such as DD0154) the rotation curve has been measured to almost 15 optical length scales indicating that the dark matter surrounding this object is extremely spread out (see also figure 1).

A foreground cluster, on the other hand, acts as a gravitational lens which focuses the light from background objects such as galaxies and QSO’s thereby allowing us to determine the depth of the cluster potential well. Observations of strong lensing by clusters indicate
that dark matter is strongly concentrated in central regions with a projected mass of 10¹³ − 10¹⁴ solar masses being contained within 0.2 - 0.3 Mpc of the central region. As we shall see later, this observation may prove to be problematic for alternatives to the dark matter hypothesis such as the Modified Newtonian..."

Then there is the business of the Xray-emitting gas. Varun Sahni says that even the visible matter in clusters of galaxies is not what I thought it was. It is not stars, he says, most of the mass of visible matter in a cluster is in the form of Xray-emitting gas!

"The mass-to-light ratio in clusters can be as large as M/L = 300M_sol/L_sol. However since most of the mass in clusters is in the form of hot, x-ray emitting intracluster gas, the extent of dark matter in these objects is estimated to be M/M_lum = 20, where M_lum is the total mass in luminous matter including stars and gas."

If this is true it will take a bit of getting used to.
the U has right amount of energy density to make it flat
and most of that energy isn't matter, it is DE
but there is some matter
however most of the matter isn't visible it is DM
on the other hand there is some visible matter
but (before you get too comfortable with that, notice that)
the visible matter is mostly not stars it is visible by
its Xrays because the great bulk of it is Xray-emitting gas.

I had accepted the idea that only 4 percent of the U was
ordinary baryonic matter and I decided to be content with that,
but I thought it at least was stars. Now I find that the
4 percent is mostly Xray-emitting gas. Bah. I shall write the
editors of Nature and threaten to cancel my subscription if
they cannot abide by the rules of ordinary decency

 

[marcus]

Something almost funny in Varun Sahni's review article.
the speed of the Earth relative to galactic center varies, being 7 percent faster in the summer than in the winter

so the Earth should bump into more dark matter in the summer

a controversy has arisen because a research group called DAMA
claims to have detected this bumping
with an annual variation just as predicted:
more bumping in the summer

but regretfully it must be said that not a single other research group has been able to reproduce this result

the controversy and lack of confirmation does not deter Sahni from including this in his review and he also has a nice little picture of the Earth going around the sun to explain why the speed varies by 7 percent----Figure 3 on page 8

 

[wolram]

thanks STINGRAY.
it seems that the properties of these early type galaxies
are Dependant on the potential energy of dark matter rather
than any barionic mechanisms, i am catching up your last
post helped lots.
thanks for link NEREID your observation on the speed of
this thread just hit me, i think i spent all my fuel to
early and now have to coast, but that will be enjoyable
as i have lots to read.

 

[wolram]

by MARCUS.
Something almost funny in Varun Sahni's review article.
the speed of the Earth relative to galactic center varies, being 7 percent faster in the summer than in the winter

this is a strange comment.

 

[marcus]

Originally posted by wolram
by MARCUS.
...this is a strange comment.

Pax wolram. :-)

One research group has detected us plowing through dark matter
ever since 1996
but no other group is able to sense this happening.

 

[Nereid]

Originally posted by marcus I've been distracted from this thread by other (local off-web) activity and also swamped by the complexity of the issues. I need to find a suitable tutorial and an up-to-date review article that surveys how things stand at present and how the various investigations into dark energy are going.

Right now I am convinced that several of you other posters (hellfire, wolram, Nereid) are ahead of me and I need to catch up.

This morning over coffee I looked at Sahni's review article
"Dark Matter and Dark Energy"
http://arxiv.org./astro-ph/0403324

You can tell its meant as a review article because it has 190 references in its bibliography

You can tell its meant to be understandable to a wider audience because it doesn't explain very much in detail.

It is the sort of thing that OUGHT to help, but instead of helping integrate, it zaps my understanding by showing me that the jigsaw puzzle has 1000 pieces rather than the 100 or so I expected. I should be grateful to Nature for being so complex? Is this a sign something really interesting will emerge? Or is this just the wrong review article to try to read? Maybe there is a better one

This is, IMHO, a good review! Of course, it could have been longer (there's always more you want to know ).

AND it has the figure that I was trying to find for a previous post! It's figure 11, on page 33.

Originally posted by marcus
Can this be true? They have not even seen where the rotation curve stops increasing and begins to decline? The situation is more confusing than I thought.

Er, yes, it's true. But it's not a problem, because the mass in clusters is constrained by other estimates, and what are clusters but many galaxies (including 'dark' ones) and 'some' IGM?

Originally posted by marcus Then there is the business of the Xray-emitting gas. [a.k.a. IGM] Varun Sahni says that even the visible matter in clusters of galaxies is not what I thought it was. It is not stars, he says, most of the mass of visible matter in a cluster is in the form of Xray-emitting gas!

Omigosh! hock! Shorror! Lends a whole new meaning to the phrase 'scum of the universe', doesn't it?

 

[Nereid]

Originally posted by marcus
One research group has detected us plowing through dark matter ever since 1996 but no other group is able to sense this happening.

So maybe those researchers found something else in 1996?

Anyway, won't it be nice when we detect some real, honest-to-Hoyle neutralinos, binos, winos, higgsinos, axions, Wimpzillas, axinos, or gravitinos?