WMAP Year Two Data?

[antoniseb]

Originally posted by folkhemmet1@May 14 2005, 05:47 PM
How much is the temperature data supposed to improve over four years? Also, since it is the same spacecraft, where is the improvement coming from?

These are all very good questions, and I make the rash assumption that whatever data they are getting will work like the telescope images that improve resolution when images are overlaid on each other because it provides better signal to noise ratio by making the noise blend together into a more average gray, while the signal stands taller above the noise.

Thus, it would be my hope that eight years of data would improve the signal to noise by a factor of about 2.8. Will this be enough to save the mission? Who knows? My overall hope is that we learn something, and like you, I am really irritated that they aren't coming out with the honest story of what the trouble is (forcing me to guess).

[folkhemmet]

I found some evidence that the next WMAP data release will contain not just second year data, but also third year data. Unfortunately, there is no evidence for when it will be released (surprised). LOL.

Spergel discussed what is the maximal "l" (orbital angular momentum) that we can detect with various available tools:

WMAP, 1 year: l=300
WMAP, 6 years: l=600 (those six years are already planned; they are preparing the final report on the 3rd year of WMAP, and David said that people should not be impatient because an imperfect report would not help the community)
PLANCK: l=1500
IDEAL: l=2000 (this is the realistic maximum we can ever get)

quote is from URL http://motls.blogspot.com/

Based on Motl's summary, Spergel seems to be optimistic about the future of cosmology. A more pessimistic tone from Spergel, the lead theoretician on the WMAP team, on my view, would suggest that systematic errors are dimming the previously espoused bright future of "precision cosmology." This got me thinking that the new data, when it comes out, in combination with other types of cosmological measurements should be a non-neglible improvement over the first year data. I am interested in the formation of the first stars, the nature of dark energy, and the search for the topology of the universe.

[Greg]

I do not understand why they would keep the data secret. Even publishing a null result is still significant since it tells us something. I can only guess in a negative fashion that something about the year two data may call into question some of the conclusions that they have already made. If the year two data didn't make them look bad in some way then why would they not have published it? It look like a bias is involved here in some way. Any way I look at it, it makes me suspicious of their motives and therefore instills doubt about the conclusions they have published and will publish in the future.

[Zahl]

Could the reason behind this delay be that the WMAP team has discovered that the large angular size polarization data has a preferred direction towards Virgo?

There have been several studies exploring the strange alignment of the dipole, quadrupole and octopole WMAP 1-year data, most recently by Schwarz, Starkman, Huterer and Copi, who confirmed earlier findings and reported that the alignment is exceedingly unlikely (arXiv:astro-ph/0403353 and 0311430) and that the normal vectors of the quadrupole and the octopole point towards Virgo. Starkman called these findings "seriously troubling". Read his plain language recap here. This has been explained away by Bennett & Co as "cosmic variance", ie. random chance, but in view of Hinshaw's quoted comment earlier in this thread that "making sense of this data [large angular size polarization data] has turned out to be much more challenging than we anticipated" and the fact that other researchers have found similar alignment in Quasar polarization independent of WMAP (arXiv:astro-ph/0301530 and 0501043), this explanation as well as references to systematic errors seem insufficient.

If the large angular size polarization of new WMAP data really shows a preferred direction, then the cosmic variance argument can't deal with the probabilities any longer and the independent quasar polarization data with similar anomalies make the systematic errors argument highly implausible. CBI and other ground based projects deal with the small angular size polarization and don't shed light on this puzzle.

[GOURDHEAD]

If the large angular size polarization of new WMAP data really shows a preferred direction, then the cosmic variance argument can't deal with the probabilities any longer and the independent quasar polarization data with similar anomalies make the systematic errors argument highly implausible.

From the linked article:

This is because to properly compare, one should first subtract from the
quadrupole the piece caused by the motion of the solar system through the universe .

Now the mosasaurs are performing a ballet in the swimming pool!! We neither can nor have observed enough of the physical universe to know this motion independently of the CMBR.

[antoniseb]

Originally posted by GOURDHEAD@May 19 2005, 12:58 PM
Now the mosasaurs are performing a ballet in the swimming pool!! We neither can nor have observed enough of the physical universe to know this motion independently of the CMBR.

Right, We assume that all of the measured dipole difference of the CMBR is a result of this motion. If there really IS some objective zero velocity, and a real sinusoidal dipole temperature difference, we will never know it.

BTW, Hi Zahl, welcome to the Universe Today forum. We have a mixture of professionals, amateurs, and younger students. It is very nice to have a new person on board with a good understanding of some of the more technical aspects of CMB measurements. I have to say that I was unfamilar with the science behind your post, and would appreciate a pointer to an explanation if possible. I saw this paper this morning:
http://www.arxiv.org/PS_cache/astro-ph/pdf...505/0505357.pdf

Is this related in some way to what you are trying to say? (I don't understand how quasars are related to CMB polarization). Also, were you implying that the quadrapole and octopole moments pointing to Virgo suggests a connection to the center of our supercluster?

[Zahl]

If the large angular size polarization of new WMAP data really shows a preferred direction, then the cosmic variance argument can't deal with the probabilities any longer and the independent quasar polarization data with similar anomalies make the systematic errors argument highly implausible.

From the linked article:

This is because to properly compare, one should first subtract from the
quadrupole the piece caused by the motion of the solar system through the universe .

Now the mosasaurs are performing a ballet in the swimming pool!! We neither can nor have observed enough of the physical universe to know this motion independently of the CMBR.

I'm not sure what your point is. The dipole contributes a small signature to the quadrupole and this residual must be removed if we want to examine the clean quadrupole. The highly improbable alignment between the two is there even if this removal is not done, but it gets stronger when we look at the cleaned signal. But the quadrupole-octopole alignment and all the other alignment anomalies (that were not predicted and are still not explained by the standard model) are there regardless of our interpretation of the dipole. If you are referring to the cosmic variance argument, then the question is how much non-gaussianity can you deal with in a (presumedly) random gaussian isotropic sky before you start to consider than something is wrong.

[Zahl]

antoniseb:

Right, We assume that all of the measured dipole difference of the CMBR is a result of this motion. If there really IS some objective zero velocity, and a real sinusoidal dipole temperature difference, we will never know it.

Some of it is due to the Earth moving about the Sun.

I have to say that I was unfamilar with the science behind your post, and would appreciate a pointer to an explanation if possible.

If you are referring to possible explanations for the apparently unrelated alignment anomalies, then a good case is made in "The Virgo Alignment Puzzle in Propagation of Radiation on Cosmological Scales" by Ralston and Jain, available from Arxiv (0311430). They push the idea that the phenomena might be definitive signatures of scalar field Dark Energy. Chapter 4.3 "Mechanisms" is a nice semi-technical summary of their ideas.

I saw this paper this morning:
http://www.arxiv.org/PS_cache/astro-...05/0505357.pdf

Is this related in some way to what you are trying to say?

Faraday rotation (Polarization plane rotation in a magnetic field) depends on many things, including the wavelength of the propagating signal (the rotation decreases with increasing frequency), and is assumed to be of minor importance as far as CMB is concerned, but if the Virgo Cluster and/or the Local Supercluster have significant magnetic fields, then it could be at least part of the explanation.

(I don't understand how quasars are related to CMB polarization).

Not the quasars themselves, but their radiation could be affected during propagation by a previously unknown process. This same process might also explain the CMB anomalies.

Also, were you implying that the quadrapole and octopole moments pointing to Virgo suggests a connection to the center of our supercluster?

It is very intriguing that the dipole, quadrupole, octopole and distant radio/optical signals from quasars and galaxies at high redshift all have a same preferred direction and of all places it happens to be the Virgo cluster, the huge mass center in our local universe. This is diametrically opposed to the standard model prediction that the large angular scales should show random gaussian isotropy and it puts most inflation theories into jeopardy. I'm suggesting that the WMAP team has found the same anomaly in the large angular size CMB polarization data and as Hinshaw put it, have so far not been able to "make sense" of it.

PS. Thanks for the warm welcome.

[folkhemmet]

Zahl said:
"It is very intriguing that the dipole, quadrupole, octopole and distant radio/optical signals from quasars and galaxies at high redshift all have a same preferred direction and of all places it happens to be the Virgo cluster, the huge mass center in our local universe. This is diametrically opposed to the standard model prediction that the large angular scales should show random gaussian isotropy and it puts most inflation theories into jeopardy. I'm suggesting that the WMAP team has found the same anomaly in the large angular size CMB polarization data and as Hinshaw put it, have so far not been able to "make sense" of it."

I doubt further WMAP data will be able to shed more light (no pun intended) on these large scale anomalies. The signal-to-noise ratio should improve as more full-sky scans are completed, but we have to remember that we are dealing with the same telescope, with the same angular resolution, and with the same detector sensitivity; thus, the Law of Diminishing Returns will eventually come into play. It will probably take an even sharper satellite, such as the Planck surveyor, to crack open these anomalies. Or perhaps observations are just ahead of theory.

Even so, how important are these anomalies? What bearing do they have on our ability to constrain the curvature, Hubble constant, and other basic cosmological parameters. Afterall, each of these basic parameters predate inflation. Furthermore, I agree with Greg--that is, I also think they should tell us what the results of their analysis are even if the results are somewhat mysterious. They are stewards of public money and we have a right to know what is going on. What will history say of the WMAP satellite and of the team's careers if they abstain from releasing the data?

BTW, has anybody considered emailing Ned Wright about this thread's topic? He has a great cosmology tutorial and he is a member of the WMAP team.

Peace be with all of you....

[Zahl]

folkhemmet1:

I doubt further WMAP data will be able to shed more light (no pun intended) on these large scale anomalies. The signal-to-noise ratio should improve as more full-sky scans are completed, but we have to remember that we are dealing with the same telescope, with the same angular resolution, and with the same detector sensitivity; thus, the Law of Diminishing Returns will eventually come into play.

The full sky polarization maps and the EE power spectrum is precisely the data we are waiting for. They were not included in the 1-year data release and will be first time releases. Without such data it is impossible to say what WMAP's final word on these anomalies will be. It is also interesting to see if the previously identified anomalies will strengthen or weaken when the signal to noise ratio improves.

Even so, how important are these anomalies? What bearing do they have on our ability to constrain the curvature, Hubble constant, and other basic cosmological parameters. Afterall, each of these basic parameters predate inflation.

If the anomalies are caused by dominating local foregrounds, it is difficult to imagine that they have zero impact on small angular scale data and the values of various parameters. How will the TT power spectrum peak heigths and other features change when the foregrounds are removed? Is the low height of the second peak related to these anomalies? Such a scenario would be problematic in many ways. If on the other hand Ralston and Jain are on the right track and the anomalies have something to do with dark energy, they would open a whole new window to investigate it.

Furthermore, I agree with Greg--that is, I also think they should tell us what the results of their analysis are even if the results are somewhat mysterious. They are stewards of public money and we have a right to know what is going on. What will history say of the WMAP satellite and of the team's careers if they abstain from releasing the data?

Coming up with mysterious data and no answers would seem incompetent. I don't think they will release anything until they think they have the answers, even if it will take years. But the more time passes without releases, the more it starts to look like from the outside that something is seriously wrong.

[wstevenbrown]

http://arxiv.org/astro-ph/0506036

Licia Verde is back, with some rather broad hints. S

[Duane]

Hmm, yep looks like we can expect something from them shortly. I don't imagine it will have that much info just yet though.

[antoniseb]

Originally posted by wstevenbrown@Jun 3 2005, 08:04 PM
Licia Verde is back, with some rather broad hints.

This is an interesting paper... I enjoyed the part near the end where the discussed what could be achieved by an ideal CMB experiment. This really laid out a lot of what the WMAP team is struggling with. Don't expect really precise results.

[folkhemmet]

Antoniseb said:

This really laid out a lot of what the WMAP team is struggling with. Don't expect really precise results.

Yes, Hiranya Peiris and Licia Verde (both members of the WMAP team) submitted a paper on polarization last night. The paper underscores the difficulty researchers are going to face trying to find the signiture (or lack thereof) of inflationary gravity waves in the CMB. Having said that, the paper didn't offer us any hints about how hard the E-mode polarization signal will be to tease out. Actually, the E-mode polarization has already been found by several ground based CMB experiments, and as Verde et al says in the paper,

The primordial B-mode anisotropy, if it exists, is at least an order of magnitude smaller than the E-mode polarization.

So, the gist of that paper, in my opinion, is that it will be a while before we can legitimately search for the B-mode polarization. It says little about the E-mode signal. WMAP is supposed to have the E-mode signal mapped across the full-sky for the next data release. Still, there is no indication when we'll see those E-mode sky maps or the new temperature data combined with a host of other improved astronomical measurements (SDSS galaxy power spectrum).

[antoniseb]

Originally posted by folkhemmet1@Jun 3 2005, 09:22 PM
it will be a while before we can legitimately search for the B-mode polarization

Yes, and if they had this as their goal before publishing, they set they goals too high.
I'm guessing from what this paper says that even the Planck mission will have a great deal of difficulty finding a solid B-mode signal.

[folkhemmet]

Antoniseb,

I don't think most cosmologists expect WMAP or even Planck to detect the B-mode polarization. Figure 3 in the Verde et al paper is pretty informative; it shows the strengths of the E and B mode polarization relative not only to each other but also relative to various sources of foreground contamination. It looks as though a firm detection of the B-mode polarization will indeed require a satellite beyond Planck. However, given the info in Figure 3 plus the CBI, DASI, and CAPMAP solid detections of the E-mode polarization, I just don't see why WMAP hasn't released new data yet? Has anybody tried emailing them lately?

Below is a good description of the E-mode polarization from http://calvin.phys.columbia.edu/group_web/.../ebexterms.html

E-mode Polarization
"E-mode, or curl-free, polarization of the CMB resulted from Thomson scattering of the CMB photons off of electrons in an anisotropic velocity field; the anisotropic velocity field was generated by quadrupolar fluctuations in density, and thus temperature, at the surface of last scattering. Detections of E-mode polarization can divulge information about the matter anisotropies at the surface of last scattering. Additionally, the E-mode data, and the cross-correlation between the E-mode and temperature data, will contribute to a more precise calculation of various cosmological parameters such as Ωdm, Ωb, and ΩΛ."

[Zahl]

If someone is going to e-mail them, ask them to deny that there is a directional anomaly in the large angular scale polarization data on the Virgo axis. This would help stem rumours and speculations that are sure escalate as time passes and the WMAP team refuses to comment and release anything.

[antoniseb]

Originally posted by Zahl@Jun 4 2005, 01:03 PM
If someone is going to e-mail them, ask them to deny that there is a directional anomaly in the large angular scale polarization data on the Virgo axis.

You can do that yourself. Let us know what they say. Personally, if you are talking about the dipole along that axis, That would simply be a sign that our cluster is moving toward (or away from) Virgo relative to the overall expansion. I don't think that really requires much explanation.

[Zahl]

Originally posted by antoniseb+Jun 4 2005, 01:34 PM--></div><table border='0' align='center' width='95%' cellpadding='3' cellspacing='1'><tr><td>QUOTE (antoniseb &#064; Jun 4 2005, 01:34 PM)</td></tr><tr><td id='QUOTE'><!--QuoteBegin-Zahl@Jun 4 2005, 01:03 PM
If someone is going to e-mail them, ask them to deny that there is a directional anomaly in the large angular scale polarization data on the Virgo axis.

You can do that yourself. Let us know what they say. Personally, if you are talking about the dipole along that axis, That would simply be a sign that our cluster is moving toward (or away from) Virgo relative to the overall expansion. I don&#39;t think that really requires much explanation.[/b][/quote]
Have those ubiquitous alternative theorists finally managed to convert you, antoniseb? There is no mechanism in standard physics to produce a full sky preferred direction (eg. a strong polarization plane rotation along this axis that falls off at increasing angles from it) in the polarization data through observer&#39;s motion.

It is interesting that Verde et al make it clear in the linked paper that "Our assumptions about foregrounds contamination are based on information coming from much lower or higher frequencies than the CMB window" and not from any insight of inside WMAP data analysis.

[antoniseb]

Originally posted by Zahl@Jun 6 2005, 09:36 PM
There is no mechanism in standard physics to produce a full sky preferred direction (eg. a strong polarization plane rotation along this axis that falls off at increasing angles from it) in the polarization data through observer&#39;s motion.

Sorry Zahl, I misunderstood you. I didn&#39;t think you were talking about a dipole in the polarization. I thought you were talking about a dipole in the overall temperature of the CMB.

On the other hand, there is a mechanism that COULD potentially under special circumstances produce a preferred polarization direction for SOME photon energies (though probably not the CMB frequencies) and that would be if the Sun were near the edge of a diffuse dust cloud, so that there was much more dust in one direction than another. I understand that we ARE at the edge of such a cloud.

[folkhemmet]

I think the Virgo anomalies may just be a coincidence. For example, one could look for all kinds of reasons why the moon just happens to be the right size and the right distance from the earth to cause eclipses. Most planetary systems probably lack such a configuration, but just because our solar system has this fortuitous configuration, should we from this conclude that somehow the laws of physics are invalid? Similarly, the Virgo alignment may be strange, but does that mean we should discount the basic physics upon which the CMB rests, especially when you consider that the latest ground-based polarization measurements confirm that CMB photons had to be generated at Z~1000.

Don&#39;t get me wrong. I believe alternatives should be pursued and authority in science and politics should be challenged--that is how progress comes about. BUT with respect to cosmology (still labeled in some dictionaries as a branch of metaphysics), I would really like to believe that even if we don&#39;t know the whole picture, at least we now have a foundation: Hot Big Bang/LCDM.

PEace...

[folkhemmet]

Antoniseb,

I found some evidence for when the data may be released.

Ripples cause cosmic doubts over inflation
30 April 2005
RIPPLES in the faint afterglow of the big bang do not seem to be scattered as randomly as expected. This casts doubt on the theory of inflation, a cornerstone of modern cosmology.

According to the theory, space expanded violently a split second after the big bang. That ought to mean that the properties of hot and cold spots in the microwave background left over from the big bang should follow a Gaussian distribution, because the spots would have started off as random quantum fluctuations.

But when David Larson and Benjamin Wandelt of the University of Illinois at Urbana-Champaign looked at data from NASA&#39;s Wilkinson Microwave Anisotropy Probe (WMAP), they found a subtle but statistically significant deviation from a Gaussian distribution.

The pattern could turn out to be a glitch in WMAP&#39;s instruments. But if it is a real feature of the early universe, then its origin is a complete mystery, says Wandelt. He cannot even speculate at what process could have caused these deviations. The second year&#39;s worth of WMAP data, which may be released this summer, should help to clarify this tentative result.

From issue 2497 of New Scientist magazine, 30 April 2005, page 19

Not to be pessimistic, but we should remember that there have been hints before as to when the data was supposed to be released and it hasn&#39;t yet materialized. I wonder how the newscientist people would know that the data may be released this summer? Anyway, I suggest that those of us writing in this thread should email WMAP to ask whether or not the data really is coming out this summer, like the article above suggests.

[antoniseb]

Originally posted by folkhemmet1@Jun 8 2005, 02:12 PM
which may be released this summer

That&#39;s a good spot, thanks. I&#39;m guessing that NS gave their estimate based on yet another vague "weeks rather than months" kind of answer as to when. I note that the story says *may* be released. They don&#39;t know.

I do agree with you that we should message the WMAP team again. I haven&#39;t personally tried to communicate with them since November/December 2004.

[John L]

Originally posted by folkhemmet1 says
For example, one could look for all kinds of reasons why the moon just happens to be the right size and the right distance from the earth to cause eclipses.

You do know that the Moon has been receeding from the Earth since its creation, that in the past the Moon covered much more than the Sun during a full eclipse, and in the future, as it receeds further from the Earth, that full eclipses will no longer occur.

And I recommend that EVERYONE of you write to them. I harassed them a few weeks back, and really did write to my Congressman, but it didn&#39;t seem to have much of an effect. If we all did then maybe we&#39;d get some better answers than "keep waiting."

[folkhemmet]

JohnL,

I agree. If we all emailed them at the same time, more or less within a day or two, then that might have some impact. When I email them I am going to say to them (i) when is the second year data coming out, and (ii) if they were wrong about some of the conclusions reached in the first data release that is still progress. Intellectually brilliant people are sometimes wrong. Plus, why should we have to wait for answers from a European satellite when our taxes dollars went to fund a spacecraft designed to take more than just a year of data? It really is hard to believe at this juncture that WMAP has actually been extended beyond the original four years.

[antoniseb]

phooey, I just composed and mailed an email to my Congressman, and it bounced off the house&#39;s mail server.

[nodem]

Judging from some of the more detailed analysis of CMB anisotropy, the theory of inflation looks like a bust. The WMAP team may be well aware of this and currently have the only detailed data that could offer insights into an alternative theory. It would not be surprising if they sit on this data indefinitely while they see if an alternative theory can be scooped. This may be why they are being so vague about what&#39;s going on, or maybe I&#39;m being sucked into my own conspiracy theory :unsure:

Either way, just because they are using *our* tax money, doesn&#39;t mean that *their* scientific careers will not take precedence... I doubt we will see any results this year (maybe 2/06?) :angry:

[Zahl]

Originally posted by antoniseb+Jun 6 2005, 09:48 PM--></div><table border='0' align='center' width='95%' cellpadding='3' cellspacing='1'><tr><td>QUOTE (antoniseb &#064; Jun 6 2005, 09:48 PM)</td></tr><tr><td id='QUOTE'><!--QuoteBegin-Zahl@Jun 6 2005, 09:36 PM
There is no mechanism in standard physics to produce a full sky preferred direction (eg. a strong polarization plane rotation along this axis that falls off at increasing angles from it) in the polarization data through observer&#39;s motion.

Sorry Zahl, I misunderstood you. I didn&#39;t think you were talking about a dipole in the polarization. I thought you were talking about a dipole in the overall temperature of the CMB.

On the other hand, there is a mechanism that COULD potentially under special circumstances produce a preferred polarization direction for SOME photon energies (though probably not the CMB frequencies) and that would be if the Sun were near the edge of a diffuse dust cloud, so that there was much more dust in one direction than another. I understand that we ARE at the edge of such a cloud.[/b][/quote]
The amount of dust needed to produce a significant polarization asymmetry between hemispheres would be truly immense. But the worst thing is that the already detected temperature asymmetry is hard to explain in terms of foregrounds since it is found to be present at the same amplitude in all the WMAP frequencies and does not seem to decrease significantly with an increasing galaxy cut (papers by Hansen & Eriksen 2004) so multifrequency spectral analysis is useless to clean such a signal.

[folkhemmet]

Nodem said:

Judging from some of the more detailed analysis of CMB anisotropy, the theory of inflation looks like a bust.

I am certainly no expert on cosmology, but I have looked at graphs of the power spectrum as derived from as many types of cosmological measurements as have been done thus far. The curve for this graph agrees with theory on all distance scales except the very largest scales we can observe. It is precisely at these largest scales that the WMAP anomalies were found. Should we abandon all of the other evidence from other cosmological measurements, including high-l CMB e.g. the first acoustic peak at l=220.6 (indicative of a flat universe), supernovae, galaxy clusters, alpha lyman forest, just because the universe isn&#39;t as smooth and random as we thought on these ultra-large scales?

Last but not least, I just emailed the WMAP team today asking them about the newscientist story and if the data is indeed due to be released this summer.

[Zahl]

I think the Virgo anomalies may just be a coincidence.

Hansen&#39;s finding that the optical depth to the surface of last scattering was dramatically different on different hemispheres strongly suggests that there is a similar polarization asymmetry for CMB that is already detected for galaxies and quasars (see earlier posts in this thread) and CMB temperature intensity.

the latest ground-based polarization measurements confirm that CMB photons had to be generated at Z~1000.

This is not true. It has only been confirmed that the E-mode polarization exists (6-sigma detection from DASI), but it is not yet possible to draw any rigorous conclusions. The error bars are simply too big. The CBI team recently acknowledged that while consistent with theory, cosmological parameters can not yet be reliably determined from the polarization signal. And let&#39;s not forget that the ground based projects do not tell anything about the low multipole signal and only observe small patches of the sky.

Detecting and measuring the lensing B-mode signal at predicted levels would be a pretty conclusive proof that the CMB comes from cosmological distances.

Don&#39;t get me wrong. I believe alternatives should be pursued and authority in science and politics should be challenged--that is how progress comes about. BUT with respect to cosmology (still labeled in some dictionaries as a branch of metaphysics), I would really like to believe that even if we don&#39;t know the whole picture, at least we now have a foundation: Hot Big Bang/LCDM.

I don&#39;t know where you got the idea that the Virgo stuff would somehow invalidate the entire BB framework.