WMAP - Second Release |
WMAP - Second Release |
Mar 19 2006, 05:43 AM
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#31
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Newbie Group: Members Posts: 5 Joined: 19-March 06 Member No.: 714 |
Thanks for the kind words, folks. I was very interested to hear what the new results would be; I know a few people on WMAP, and I worked briefly on COBE before it. The results appear to conflict on some level with Bradley Schaeffer's work on using gamma-ray bursts to determine the cosmological (maybe not so) constant. I love a new field of astronomy! It's always really exciting to watch as new ideas unfold.
-------------------- The Bad Astronomer
http://www.badastronomy.com |
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Mar 20 2006, 03:58 PM
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#32
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Member Group: Members Posts: 562 Joined: 29-March 05 Member No.: 221 |
Thanks for the kind words, folks. I was very interested to hear what the new results would be; I know a few people on WMAP, and I worked briefly on COBE before it. The results appear to conflict on some level with Bradley Schaeffer's work on using gamma-ray bursts to determine the cosmological (maybe not so) constant. I love a new field of astronomy! It's always really exciting to watch as new ideas unfold. Hello Phil, welcome to the Board. Been a fan of your site for some time now. |
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Mar 20 2006, 04:28 PM
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#33
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Senior Member Group: Members Posts: 3419 Joined: 9-February 04 From: Minneapolis, MN, USA Member No.: 15 |
Yes -- welcome, Phil! I think you might enjoy hanging around here -- the signal-to-noise ratio is remarkably high for such internet fora. You will be a very welcome addition to the place!
-the other Doug -------------------- “The trouble ain't that there is too many fools, but that the lightning ain't distributed right.” -Mark Twain
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Mar 20 2006, 10:12 PM
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#34
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Senior Member Group: Members Posts: 2454 Joined: 8-July 05 From: NGC 5907 Member No.: 430 |
Paper: astro-ph/0603449
Date: Sun, 19 Mar 2006 18:35:44 GMT (1021kb) Title: Wilkinson Microwave Anisotropy Probe (WMAP) Three Year Results: Implications for Cosmology Authors: D. N. Spergel, R. Bean, O. Dore', M. R. Nolta, C. L. Bennett, G. Hinshaw, N. Jarosik, E. Komatsu, L. Page, H. V. Peiris, L. Verde, C. Barnes, M. Halpern, R. S. Hill, A. Kogut, M. Limon, S. S. Meyer, N. Odegard, G. S. Tucker, J. L. Weiland, E. Wollack, E. L. Wright Comments: 89 pages, 28 figures, submitted to ApJ \\ A simple cosmological model with only six parameters (matter density, Omega_m h^2, baryon density, Omega_b h^2, Hubble Constant, H_0, amplitude of fluctuations, sigma_8, optical depth, tau, and a slope for the scalar perturbation spectrum, n_s) fits not only the three year WMAP temperature and polarization data, but also small scale CMB data, light element abundances, large-scale structure observations, and the supernova luminosity/distance relationship. Using WMAP data only, the best fit values for cosmological parameters for the power-law flat LCDM model are (Omega_m h^2, Omega_b h^2, h, n_s, tau, sigma_8) = (0.127+0.007-0.013, 0.0223+0.0007-0.0009, 0.73 +- 0.03, 0.951+0.015-0.019, 0.09 +- 0.03, 0.74+0.05-0.06). The three year data dramatically shrink the allowed volume in this six-dimensional parameter space. Assuming that the primordial fluctuations are adiabatic with a power law spectrum, the WMAP data_alone_ require dark matter, and a spectral index that is significantly less than the Harrison-Zel'dovich-Peebles scale-invariant spectrum (n_s=1,r=0). Models that suppress large-scale power through a running spectral index or a large-scale cut-off in the power spectrum are a slightly better fit to the WMAP and small scale CMB data than the power-law LCDM model (Delta chi^2 = 3) The combination of WMAP and other astronomical data yields significant constraints on the geometry of the universe, the equation of state of the dark energy, the gravitational wave energy density, and neutrino properties. Consistent with the predictions of simple inflationary theories, we detect no significant deviations from Gaussianity in the CMB maps. \\ ( http://arXiv.org/abs/astro-ph/0603449 , 1022kb) ------------------------------------------------------------------------------ \\ Paper: astro-ph/0603450 Date: Fri, 17 Mar 2006 19:34:46 GMT (2546kb) Title: Three Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations: Polarization Analysis Authors: L. Page, G. Hinshaw, E. Komatsu, M. R. Nolta, D. N. Spergel, C. L. Bennett, C. Barnes, R. Bean, O. Dore', M. Halpern, R. S. Hill, N. Jarosik, A. Kogut, M. Limon, S. S. Meyer, N. Odegard, H. V. Peiris, G. S. Tucker, L. Verde, J. L. Weiland, E. Wollack, E. L. Wright Comments: 46 pages, 28 figures, submitted to ApJ \\ The Wilkinson Microwave Anisotropy Probe WMAP has mapped the entire sky in five frequency bands between 23 and 94 GHz with polarization sensitive radiometers. We present three-year full-sky maps of the polarization and analyze them for foreground emission and cosmological implications. These observations open up a new window for understanding the universe. WMAP observes significant levels of polarized foreground emission due to both Galactic synchrotron radiation and thermal dust emission. The least contaminated channel is at 61 GHz. Informed by a model of the Galactic foreground emission, we subtract the foreground emission from the maps. In the foreground corrected maps, for l=2-6, we detect l(l+1) C_l^{EE} / (2 pi) = 0.086 +-0.029 microkelvin^2. This is interpreted as the result of rescattering of the CMB by free electrons released during reionization and corresponds to an optical depth of tau = 0.09 +- 0.03. We see no evidence for B-modes, limiting them to l(l+1) C_l^{BB} / (2 pi) = -0.04 +- 0.03 microkelvin^2. We find that the limit from the polarization signals alone is r<2.2 (95% CL) corresponding to a limit on the cosmic density of gravitational waves of Omega_{GW}h^2 < 5 times 10^{-12}. From the full WMAP analysis, we find r<0.55 (95% CL) corresponding to a limit of Omega_{GW}h^2 < 10^{-12} (95% CL). \\ ( http://arXiv.org/abs/astro-ph/0603450 , 2546kb) ------------------------------------------------------------------------------ \\ Paper: astro-ph/0603451 Date: Fri, 17 Mar 2006 19:47:49 GMT (2480kb) Title: Three-Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations: Temperature Analysis Authors: G. Hinshaw, M. R. Nolta, C. L. Bennett, R. Bean, O. Dore', M. R. Greason, M. Halpern, R. S. Hill, N. Jarosik, A. Kogut, E. Komatsu, M. Limon, N. Odegard, S. S. Meyer, L. Page, H. V. Peiris, D. N. Spergel, G. S. Tucker, L. Verde, J. L. Weiland, E. Wollack, E. L. Wright Comments: 93 pages, 24 figures, submitted to ApJ \\ We present new full-sky temperature maps in five frequency bands from 23 to 94 GHz, based on the first three years of the WMAP sky survey. The new maps, which are consistent with the first-year maps and more sensitive, incorporate improvements in data processing made possible by the additional years of data and by a more complete analysis of the polarization signal. These include refinements in the gain calibration and beam response models. We employ two forms of multi-frequency analysis to separate astrophysical foreground signals from the CMB, each of which improves on our first-year analyses. First, we form an improved 'Internal Linear Combination' map, based solely on WMAP data, by adding a bias correction step and by quantifying residual uncertainties in the resulting map. Second, we fit and subtract new spatial templates that trace Galactic emission; in particular, we now use low-frequency WMAP data to trace synchrotron emission. The WMAP point source catalog is updated to include 115 new sources. We derive the angular power spectrum of the temperature anisotropy using a hybrid approach that combines a maximum likelihood estimate at low l (large angular scales) with a quadratic cross-power estimate for l>10. Our best estimate of the CMB power spectrum is derived by averaging cross-power spectra from 153 statistically independent channel pairs. The combined spectrum is cosmic variance limited to l=400, and the signal-to-noise ratio per l-mode exceeds unity up to l=850. The first two acoustic peaks are seen at l=220.7 +- 0.7 and l=531.3 +- 3.5, respectively, while the first two troughs are seen at l=412.8 +- 1.9 and l=674.6 +- 12.1, respectively. The rise to the third peak is unambiguous; when the WMAP data are combined with higher resolution CMB measurements, the existence of a third acoustic peak is well established. \\ ( http://arXiv.org/abs/astro-ph/0603451 , 2310kb) ------------------------------------------------------------------------------ \\ Paper: astro-ph/0603452 Date: Fri, 17 Mar 2006 19:44:11 GMT (2127kb) Title: Three-Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations: Beam Profiles, Data Processing, Radiometer Characterization and Systematic Error Limits Authors: N. Jarosik, C. Barnes, M. R. Greason, R. S. Hill, M. R. Nolta, N. Odegard, J. L. Weiland, R. Bean, C. L. Bennett, O. Dore', M. Halpern, G. Hinshaw, A. Kogut, E. Komatsu, M. Limon, S. S. Meyer, L. Page, D. N. Spergel, G. S. Tucker, E. Wollack, E. L. Wright Comments: 49 pages, 13 figures, submitted to ApJ \\ The WMAP satellite has now completed 3 years of observations of the cosmic microwave background radiation. The 3-year data products include several sets of full sky maps of the Stokes I, Q and U parameters in 5 frequency bands, spanning 23 to 94 GHz, and supporting items, such as beam window functions and noise covariance matrices. The processing used to produce the current sky maps and supporting products represents a significant advancement over the first year analysis, and is described herein. Improvements to the pointing reconstruction, radiometer gain modeling, window function determination and radiometer spectral noise parametrization are presented. A detailed description of the updated data processing that produces maximum likelihood sky map estimates is presented, along with the methods used to produce reduced resolution maps and corresponding noise covariance matrices. Finally two methods used to evaluate the noise of the full resolution sky maps are presented along with several representative year-to-year null tests, demonstrating that sky maps produced from data from different observational epochs are consistent. \\ ( http://arXiv.org/abs/astro-ph/0603452 , 2127kb) -------------------- "After having some business dealings with men, I am occasionally chagrined,
and feel as if I had done some wrong, and it is hard to forget the ugly circumstance. I see that such intercourse long continued would make one thoroughly prosaic, hard, and coarse. But the longest intercourse with Nature, though in her rudest moods, does not thus harden and make coarse. A hard, sensible man whom we liken to a rock is indeed much harder than a rock. From hard, coarse, insensible men with whom I have no sympathy, I go to commune with the rocks, whose hearts are comparatively soft." - Henry David Thoreau, November 15, 1853 |
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Mar 20 2006, 11:09 PM
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#35
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Member Group: Members Posts: 624 Joined: 10-August 05 Member No.: 460 |
Paper: astro-ph/0603449 Date: Sun, 19 Mar 2006 18:35:44 GMT (1021kb) Title: Wilkinson Microwave Anisotropy Probe (WMAP) Three Year Results: Implications for Cosmology Authors: D. N. Spergel, R. Bean, O. Dore', M. R. Nolta, C. L. Bennett, G. Hinshaw, N. Jarosik, E. Komatsu, L. Page, H. V. Peiris, L. Verde, C. Barnes, M. Halpern, R. S. Hill, A. Kogut, M. Limon, S. S. Meyer, N. Odegard, G. S. Tucker, J. L. Weiland, E. Wollack, E. L. Wright Comments: 89 pages, 28 figures, submitted to ApJ \\ A simple cosmological model with only six parameters (matter density, Omega_m h^2, baryon density, Omega_b h^2, Hubble Constant, H_0, amplitude of fluctuations, sigma_8, optical depth, tau, and a slope for the scalar perturbation spectrum, n_s) fits not only the three year WMAP temperature and polarization data, but also small scale CMB data, light element abundances, large-scale structure observations, and the supernova luminosity/distance relationship. I will have eternal heartburn over this pronouncement: Relegating baryonic matter to 4% of the effective mass of the universe is a hollow victory. At one time I worked with a chemist who was trying to use X-ray flourecence to quantify the ingredients in a mixture. The counts at the wavelengths-of-interest were only ~ 102% of the background. One day I left one of the main ingredients (11%) completely out of the mix, and the assay still reported a value of 4.5%. Useless. Taken in this context, using six parameters to draw a line connecting five or six dots at one end of the curve does not seem too difficult, and is even less revealing. Padding is padding, whether it is made out of goose down or dark stuff. |
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Mar 21 2006, 08:24 AM
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#36
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Senior Member Group: Members Posts: 1870 Joined: 20-February 05 Member No.: 174 |
I keep waiting for deviations from the standard model to show up in the microwave background images. The SZ (I can't spell it out) effect of superclusters on photons traversing the cluster while the universe expands is one such "feature" superimposed on the background. Other most interesting things that could show up are edges/creases in the background caused by cosmic string. Also possible are "none-of-the-above" unexpected features.
The data from Planck will push the sensativity further toward being able to detect such exotic things, if they're out there. |
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Mar 21 2006, 08:54 PM
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#37
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Member Group: Members Posts: 624 Joined: 10-August 05 Member No.: 460 |
There are clearly are large number of cyclotronic features 'out there', each with the potential to perturb and contribute to the general microwave spectra. We know too little to accept the optomistic projections of the WMAP team without a healthy dose of skepticism.
There is also the issue of local contamination, statistically extracted from the first year WMAP. I'm not looking forward to plowing through all these papers, figuring out if and how they have addressed this. |
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Mar 22 2006, 04:54 PM
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#38
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Senior Member Group: Members Posts: 2454 Joined: 8-July 05 From: NGC 5907 Member No.: 430 |
Paper: astro-ph/0603539
Date: Mon, 20 Mar 2006 19:47:01 GMT (97kb) Title: Inflation models after WMAP year three Authors: Laila Alabidi and David H. Lyth Comments: 4 pages \\ The survey of models in astro-ph/0510441 is updated. For the first time, a large fraction of the models are ruled out at more than $3\sigma$. \\ ( http://arXiv.org/abs/astro-ph/0603539 , 97kb) ------------------------------------------------------------------------------ \\ Paper: astro-ph/0508383 replaced with revised version Sun, 19 Mar 2006 18:26:23 GMT (282kb) Title: A blind estimation of the power spectrum of CMB anisotropy from WMAP Authors: Rajib Saha (IUCAA, IIT Kanpur), Pankaj Jain (IIT Kanpur) and Tarun Souradeep (IUCAA) Comments: 5 pages, 3 figures, (trimmed to 4 pages) Matches WMAP team estimate exactly. The small excess is shown to be consistent with a significantly tempered residual power from unresolved point sources, simulations include foreground contamination, Suppl. details at: http://meghnad.iucaa.ernet.in/~tarun/sup0508383 Report-no: IUCAA-34/2005 \\ ( http://arXiv.org/abs/astro-ph/0508383 , 282kb) -------------------- "After having some business dealings with men, I am occasionally chagrined,
and feel as if I had done some wrong, and it is hard to forget the ugly circumstance. I see that such intercourse long continued would make one thoroughly prosaic, hard, and coarse. But the longest intercourse with Nature, though in her rudest moods, does not thus harden and make coarse. A hard, sensible man whom we liken to a rock is indeed much harder than a rock. From hard, coarse, insensible men with whom I have no sympathy, I go to commune with the rocks, whose hearts are comparatively soft." - Henry David Thoreau, November 15, 1853 |
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Mar 23 2006, 04:03 PM
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#39
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Senior Member Group: Members Posts: 2454 Joined: 8-July 05 From: NGC 5907 Member No.: 430 |
Paper: astro-ph/0603589
Date: Wed, 22 Mar 2006 20:38:09 GMT (9kb) Title: Limits on SUSY GUTs and Defects Formation in Hybrid Inflationary Models with Three-Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations Authors: Aur\'elien A. Fraisse (Princeton University) Comments: 10 pages, 2 tables \\ We confront the predicted effects of hybrid inflationary models on the Cosmic Microwave Background (CMB) with three years of Wilkinson Microwave Anisotropy Probe (WMAP) observations. Using model selection, we compare the ability of a simple flat power-law LCDM model to describe the data to hybrid inflationary models involving global or local cosmic strings, or global textures. We find that it is statistically impossible to distinguish between these models: they all give a similar description of the data, the maximum ratio of the various evidences involved being never higher than e^{0.1 \pm 0.5}. We then derive the maximum contribution that topological defects can make to the CMB, and place an upper bound on the possible value of cosmic strings tension of G\mu \leq 2.1 \times 10^{-7} (68% CL). Finally, we give the corresponding constraints on the strings and D-strings masses, as well as limits on the D- and F-term coupling constants (\kappa and \lambda) and mass scales (M and \sqrt{\xi}). \\ ( http://arXiv.org/abs/astro-ph/0603589 , 9kb) -------------------- "After having some business dealings with men, I am occasionally chagrined,
and feel as if I had done some wrong, and it is hard to forget the ugly circumstance. I see that such intercourse long continued would make one thoroughly prosaic, hard, and coarse. But the longest intercourse with Nature, though in her rudest moods, does not thus harden and make coarse. A hard, sensible man whom we liken to a rock is indeed much harder than a rock. From hard, coarse, insensible men with whom I have no sympathy, I go to commune with the rocks, whose hearts are comparatively soft." - Henry David Thoreau, November 15, 1853 |
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Mar 29 2006, 04:16 PM
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#40
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Senior Member Group: Members Posts: 2454 Joined: 8-July 05 From: NGC 5907 Member No.: 430 |
Astrophysics, abstract
astro-ph/0603753 From: Antony Lewis [view email] Date: Tue, 28 Mar 2006 20:07:14 GMT (111kb) Observational constraints and cosmological parameters Authors: Antony Lewis Comments: Contribution to Rencontres de Moriond: Contents and Structures of the Universe, March 18-25, 2006, La Thuile I discuss the extraction of cosmological parameter constraints from the recent WMAP 3-year data, both on its own and in combination with other data. The large degeneracies in the first year data can be largely broken with the third year data, giving much better parameter constraints from WMAP alone. The polarization constraint on the optical depth is crucial to obtain the main results, including n_s < 1 in basic six-parameter models. Almost identical constraints can also be obtained using only temperature data with a prior on the optical depth. I discuss the modelling of secondaries when extracting parameter constraints, and show that the effect of CMB lensing is about as important as SZ and slightly increases the inferred value of the spectral index. Constraints on correlated matter isocurvature modes are not radically better than before, and the data is consistent with a purely adiabatic spectrum. Combining WMAP 3-year data with data from the Lyman-alpha forest suggests somewhat higher values for sigma_8 than from WMAP alone, and there is no significant evidence for running of the spectral index. http://arxiv.org/abs/astro-ph/0603753 -------------------- "After having some business dealings with men, I am occasionally chagrined,
and feel as if I had done some wrong, and it is hard to forget the ugly circumstance. I see that such intercourse long continued would make one thoroughly prosaic, hard, and coarse. But the longest intercourse with Nature, though in her rudest moods, does not thus harden and make coarse. A hard, sensible man whom we liken to a rock is indeed much harder than a rock. From hard, coarse, insensible men with whom I have no sympathy, I go to commune with the rocks, whose hearts are comparatively soft." - Henry David Thoreau, November 15, 1853 |
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Mar 30 2006, 02:35 PM
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#41
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Senior Member Group: Members Posts: 2454 Joined: 8-July 05 From: NGC 5907 Member No.: 430 |
Astrophysics, abstract
astro-ph/0603662 From: Lung-Yih Chiang [view email] Date (v1): Fri, 24 Mar 2006 09:44:34 GMT (87kb) Date (revised v2): Sun, 26 Mar 2006 19:37:27 GMT (88kb) Date (revised v3): Tue, 28 Mar 2006 19:24:24 GMT (88kb) Testing Gaussian random hypothesis with the cosmic microwave background temperature anisotropies in the three-year WMAP data Authors: Lung-Yih Chiang (1), Pavel D. Naselsky (1), Peter Coles (2) ((1) Niels Bohr Institute, (2) Nottingham University) Comments: submitted to ApJL, some corrections on the curves of Fig.5 and 6. The curves and extrema locations are shifted by 180 degs, but the statistics are unchanged We test the hypothesis that the temperature of the cosmic microwave background is consistent with a Gaussian random field defined on the celestial sphere, using de-biased internal linear combination (DILC) map produced from the 3-year WMAP data. We test the phases for spherical harmonic modes with l <= 10 (which should be the cleanest) for their uniformity, randomness, and correlation with those of the foreground templates. The phases themselves are consistent with a uniform distribution, but not for l <= 5, and the differences between phases are not consistent with uniformity. For l=3 and l=6, the phases of the CMB maps cross-correlate with the foregrounds, suggestion the presence of residual contamination in the DLC map even on these large scales. We also use a one-dimensional Fourier representation to assemble a_lm into the \Delta T_l(\phi) for each l mode, and test the positions of the resulting maxima and minima for consistency with uniformity randomness on the unit circle. The results show significant departures at the 0.5% level, with the one-dimensional peaks being concentrated around \phi=180 degs. This strongly significant alignment with the Galactic meridian, together with the cross-correlation of DILC phases with the foreground maps, strongly suggests that even the lowest spherical harmonic modes in the map are significantly contaminated with foreground radiation. http://arxiv.org/abs/astro-ph/0603662 Astrophysics, abstract astro-ph/0603690 From: Enrique Gaztanaga [view email] Date: Mon, 27 Mar 2006 20:57:14 GMT (131kb) Cross-correlation of WMAP 3rd year and the SDSS DR4 galaxy survey: new evidence for Dark Energy Authors: A.Cabre, E.Gaztanaga, M.Manera, P.Fosalba, F.Castander (IEEC/CSIC) Comments: 5 pages, 5 figures, submitted to MNRAS Letter We cross-correlate the third-year WMAP data with galaxy samples extracted from the SDSS DR4 covering 13% of the sky, increasing by a factor of 3.7 the volume sampled in previous analyses. The new measurements confirm a positive cross-correlation with higher significance (total signal-to-noise of about 4.7). The correlation as a function of angular scale is well fitted by the integrated Sachs-Wolfe (ISW) effect for LCDM flat FRW models with a cosmological constant (w=-1). The combined analysis of different samples gives Omega_L=0.75-0.80 (68% Confidence Level, CL) or 0.70-0.82 (95% CL). We find that the best fit Omega_L decreases from 0.82 to 0.75 (95% CL) when we increase the median redshift of the galaxy sample from z~0.3 to z~0.5. The quick drop of the measured signal with z is too fast for the LCDM cosmology. The data can be better reconciled with a model with an effective dark energy equation of state w<-1.5. Such phantom cosmology reduces by up to ~20% the amplitude of the lower multipoles of the CMB temperature anisotropies with respect the w=-1 prediction, which also brings the models closer to the observations. http://arxiv.org/abs/astro-ph/0603690 Astrophysics, abstract astro-ph/0603782 From: Qing-Guo Huang [view email] Date: Wed, 29 Mar 2006 07:33:11 GMT (49kb) Running Spectral Index in Noncommutative Inflation and WMAP Three Year Results Authors: Qing-Guo Huang, Miao Li Comments: 11 pages, 2 figures, harvmac A model independent analysis shows that the running of the spectral index of the three year WMAP results can be nicely realized in noncommutative inflation. We also re-examine some concrete noncommutative inflation models. We find that a large tensor-scalar ratio is required, corresponding to a low number of e-folds before the end of inflation in some simple models. http://arxiv.org/abs/astro-ph/0603782 -------------------- "After having some business dealings with men, I am occasionally chagrined,
and feel as if I had done some wrong, and it is hard to forget the ugly circumstance. I see that such intercourse long continued would make one thoroughly prosaic, hard, and coarse. But the longest intercourse with Nature, though in her rudest moods, does not thus harden and make coarse. A hard, sensible man whom we liken to a rock is indeed much harder than a rock. From hard, coarse, insensible men with whom I have no sympathy, I go to commune with the rocks, whose hearts are comparatively soft." - Henry David Thoreau, November 15, 1853 |
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Mar 31 2006, 03:08 PM
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#42
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Senior Member Group: Members Posts: 2454 Joined: 8-July 05 From: NGC 5907 Member No.: 430 |
Paper: astro-ph/0603830
Date: Thu, 30 Mar 2006 20:46:40 GMT (8kb) Title: Coleman-Weinberg Potential In Good Agreement With WMAP Authors: Q. Shafi and V. N. Senoguz Comments: 6 pages, 1 table Report-no: BA-06-12 \\ We briefly summarize and update a class of inflationary models from the early eighties based on a quartic (Coleman-Weinberg) potential for a gauge singlet scalar (inflaton) field. For vacuum energy scales comparable to the grand unification scale, the scalar spectral index n_s=0.94-0.96, in very good agreement with the WMAP three year results. The tensor to scalar ratio r<~0.13, while alpha=dn/dlnk is =~-10^-3. An SO(10) version naturally explains the observed baryon asymmetry via non-thermal leptogenesis. \\ ( http://arXiv.org/abs/astro-ph/0603830 , 8kb) Paper: astro-ph/0603817 Date: Thu, 30 Mar 2006 20:24:44 GMT (100kb) Title: Inhomogeneous Big Bang Nucleosynthesis Revisited Authors: J.F. Lara, T. Kajino, G.J. Mathews Comments: 11 pages, 4 figures, accepted for publication in PRD Journal-ref: Phys.Rev. D73 (2006) 083501 \\ We reanalyze the allowed parameters for inhomogeneous big bang nucleosynthesis in light of the WMAP constraints on the baryon-to-photon ratio and a recent measurement which has set the neutron lifetime to be 878.5 +/- 0.7 +/- 0.3 seconds. For a set baryon-to-photon ratio the new lifetime reduces the mass fraction of He4 by 0.0015 but does not significantly change the abundances of other isotopes. This enlarges the region of concordance between He4 and deuterium in the parameter space of the baryon-to-photon ratio and the IBBN distance scale. The Li7 abundance can be brought into concordance with observed He4 and deuterium abundances by using depletion factors as high as 9.3. The WMAP constraints, however, severely limit the allowed comoving (T = 100 GK) inhomogeneity distance scale to (1.3 - 2.6)x10^5 cm. \\ ( http://arXiv.org/abs/astro-ph/0603817 , 100kb) -------------------- "After having some business dealings with men, I am occasionally chagrined,
and feel as if I had done some wrong, and it is hard to forget the ugly circumstance. I see that such intercourse long continued would make one thoroughly prosaic, hard, and coarse. But the longest intercourse with Nature, though in her rudest moods, does not thus harden and make coarse. A hard, sensible man whom we liken to a rock is indeed much harder than a rock. From hard, coarse, insensible men with whom I have no sympathy, I go to commune with the rocks, whose hearts are comparatively soft." - Henry David Thoreau, November 15, 1853 |
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Mar 31 2006, 06:40 PM
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#43
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Member Group: Members Posts: 624 Joined: 10-August 05 Member No.: 460 |
Astrophysics, abstract astro-ph/0603662 From: Lung-Yih Chiang [view email] Date (v1): Fri, 24 Mar 2006 09:44:34 GMT (87kb) Date (revised v2): Sun, 26 Mar 2006 19:37:27 GMT (88kb) Date (revised v3): Tue, 28 Mar 2006 19:24:24 GMT (88kb) Testing Gaussian random hypothesis with the cosmic microwave background temperature anisotropies in the three-year WMAP data Authors: Lung-Yih Chiang (1), Pavel D. Naselsky (1), Peter Coles (2) ((1) Niels Bohr Institute, (2) Nottingham University) ... This strongly significant alignment with the Galactic meridian, together with the cross-correlation of DILC phases with the foreground maps, strongly suggests that even the lowest spherical harmonic modes in the map are significantly contaminated with foreground radiation... Boy! The dogs are all over the new WMAP data - will the WMAP PI's continue to ignore them? Any theory that stuffs all the measureable aspects of the universe into 4% of the interpretive data, and assumes the rest is padding of unknown origin should take a beating. I have reasonable faith in their calculations: Within the 'known' laws of physics, WMAP scientist have created the only viable model. What I do not have faith in is the known laws |
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Apr 4 2006, 04:21 PM
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#44
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Senior Member Group: Members Posts: 2454 Joined: 8-July 05 From: NGC 5907 Member No.: 430 |
Astrophysics, abstract
astro-ph/0604011 From: Douglas Scott [view email] Date: Sun, 2 Apr 2006 06:36:24 GMT (4kb) Cosmic Conspiracies Authors: Douglas Scott, Ali Frolop Comments: 2 pages The now standard vanilla-flavoured LambdaCDM model has gained further confirmation with the release of the 3-year WMAP data combined with several other cosmological data-sets. As the parameters of this standard model become known with increasing precision, more of its bizarre features become apparent. Here we describe some of the strangest of these ostensible coincidences. In particular we appear to live (within 1sigma) at the precise epoch when the age of the Universe multiplied by the Hubble parameter H_0 t_0 = 1. http://arxiv.org/abs/astro-ph/0604011 Astrophysics, abstract astro-ph/0603859 From: Marcos Cruz [view email] Date: Fri, 31 Mar 2006 19:08:21 GMT (223kb) The non-Gaussian Cold Spot in the 3-year WMAP data Authors: M. Cruz, L. Cayon, E. Martinez-Gonzalez, P. Vielva, J. Jin Comments: 10 pages, 14 figures The non-Gaussian cold spot detected in wavelet space in the WMAP 1-year data, is detected again in the coadded WMAP 3-year data at the same position (b = -57, l = 209) and size in the sky (around 10 degrees). The present analysis is based on several statistical methods: kurtosis, maximum absolute temperature, number of cold pixels below a given threshold, volume and Higher Criticism. All these methods detect deviations from Gaussianity in the 3-year data set at a slightly higher confidence level than in the WMAP 1-year data. These small differences are mainly due to the new foreground reduction technique and not to the reduction of the noise level, which is negligible at the scale of the spot. The probability of finding such a spot in Gaussian simulations is well below 1%. The frequency dependence of the spot is shown to be extremely flat. Galactic foreground emissions are not likely to be responsible for the detected deviation from Gaussianity. http://arxiv.org/abs/astro-ph/0603859 Astrophysics, abstract astro-ph/0603844 From: T Jaffe [view email] Date: Fri, 31 Mar 2006 08:04:16 GMT (371kb) Fast and Efficient Template Fitting of Deterministic Anisotropic Cosmological Models Applied to WMAP Data Authors: T. R. Jaffe, A. J. Banday, H. K. Eriksen, K. M. Gorski, F. K. Hansen Comments: 14 pages, 11 figure, to be published in ApJ We explore methods of fitting templates to cosmic microwave background (CMB) data, and in particular demonstrate the application of the total convolver algorithm as a fast method of performing a search over all possible locations and orientations of the template relative to the sky. This analysis includes investigation of issues such as chance alignments and foreground residuals. We apply these methods to compare Bianchi models of type VII_h to WMAP first year data and confirm the basic result of our 2005 paper. http://arxiv.org/abs/astro-ph/0603844 -------------------- "After having some business dealings with men, I am occasionally chagrined,
and feel as if I had done some wrong, and it is hard to forget the ugly circumstance. I see that such intercourse long continued would make one thoroughly prosaic, hard, and coarse. But the longest intercourse with Nature, though in her rudest moods, does not thus harden and make coarse. A hard, sensible man whom we liken to a rock is indeed much harder than a rock. From hard, coarse, insensible men with whom I have no sympathy, I go to commune with the rocks, whose hearts are comparatively soft." - Henry David Thoreau, November 15, 1853 |
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Apr 4 2006, 06:24 PM
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#45
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Member Group: Members Posts: 624 Joined: 10-August 05 Member No.: 460 |
This is a fun read:
... Authors: Douglas Scott, Ali Frolop http://arxiv.org/PS_cache/astro-ph/pdf/0604/0604011.pdf But in today’s precision cosmology reality, we are forced to explain that the curvature appears to be con- sistent with zero, so you can ignore that non-Euclidean stuff, and that t0 = H−1, even although the expansion rate slowed down for a while and recently speeded up again! This value for H0,t0 is only natural in a completely empty universe, otherwise known as the Milne model [8]. Even string theorists would typically agree that there is empirical evidence for matter in the Universe. I wonder if it is appropriate for such a flippent paper to be in archives, but they make a valid point: Coincidence which were a necessary part of an expanding BB universe should not occur if the expansion rate is variable and/or controlled by a dark matter parameter. Since the stunning coincidences are no longer prior constraints, why do they exist? |
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