Morphing the CMB: a technique for interpolating power spectra

Sigurdson, Kris; Scott, D.

doi:10.1016/s1384-1076(00)00007-5

Cited by 5 publications

(4 citation statements)

References 8 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…However, we now speculate on a potential application. With further development, perhaps our analytic understanding of the shifts in the peak locations could be combined with the morphing procedure of Sigurdson (2000), to achieve a highly accurate, very fast, Boltzmann code emulator, improving upon interpolative schemes such as PICO (Fendt & Wandelt 2007).…”

Section: Discussionmentioning

confidence: 99%

Cosmic microwave background acoustic peak locations

Pan

Knox

Mulroe

et al. 2016

Mon. Not. R. Astron. Soc.

View full text Add to dashboard Cite

The Planck collaboration has measured the temperature and polarization of the cosmic microwave background well enough to determine the locations of eight peaks in the temperature (TT) power spectrum, five peaks in the polarization (EE) power spectrum and twelve extrema in the cross (TE) power spectrum. The relative locations of these extrema give a striking, and beautiful, demonstration of what we expect from acoustic oscillations in the plasma; e.g., that EE peaks fall half way between TT peaks. We expect this because the temperature map is predominantly sourced by temperature variations in the last scattering surface, while the polarization map is predominantly sourced by gradients in the velocity field, and the harmonic oscillations have temperature and velocity 90 degrees out of phase. However, there are large differences in expectations for extrema locations from simple analytic models vs. numerical calculations. Here we quantitatively explore the origin of these differences in gravitational potential transients, neutrino free-streaming, the breakdown of tight coupling, the shape of the primordial power spectrum, details of the geometric projection from three to two dimensions, and the thickness of the last scattering surface. We also compare the peak locations determined from Planck measurements to expectations under the ΛCDM model. Taking into account how the peak locations were determined, we find them to be in agreement.

show abstract

Section: Discussionmentioning

confidence: 99%

Cosmic microwave background acoustic peak locations

Pan

Knox

Mulroe

et al. 2016

Mon. Not. R. Astron. Soc.

View full text Add to dashboard Cite

show abstract

“…• The accuracy in Step 2 can probably be further improved by using some form of morphing technique as suggested by Sigurdson & Scott (2000). The basic idea is to interpolate not the power spectrum itself but some cleverly chosen parametrization thereof.…”

Section: Discussionmentioning

confidence: 99%

Current Cosmological Constraints from a 10 Parameter Cosmic Microwave Background Analysis

Tegmark¹,

Zaldarriaga²

2000

ApJ

104

128

View full text Add to dashboard Cite

We compute the constraints on a "standard" 10 parameter cold dark matter (CDM) model from the most recent CMB data and other observations, exploring 30 million discrete models and two continuous parameters. Our parameters are the densities of CDM, baryons, neutrinos, vacuum energy and curvature, the reionization optical depth, and the normalization and tilt for both scalar and tensor fluctuations. Our strongest constraints are on spatial curvature, −0.24 < Ω k < 0.38, and CDM density, h 2 Ω cdm < 0.3, both at 95%. Including SN 1a constraints gives a positive cosmological constant at high significance. We explore the robustness of our results to various assumptions. We find that three different data subsets give qualitatively consistent constraints. Some of the technical issues that have the largest impact are the inclusion of calibration errors, closed models, gravity waves, reionization, nucleosynthesis constraints and 10-dimensional likelihood interpolation.

show abstract

“…It has been proposed that "morphing" techniques borrowed from computer graphics could be used for efficient calculations of CMB spectra [47]. This morphing approach defines certain control points based on special fea- tures of the spectra (such as acoustic peaks and troughs), interpolates between pre-calculated curves to determine where these points would be for a different set of input (e.g.…”

Section: A Strategymentioning

confidence: 99%

Predicted constraints on cosmic string tension from Planck and future CMB polarization measurements

2011

View full text Add to dashboard Cite

We perform a Fisher matrix calculation of the predicted uncertainties on estimates of the cosmic string tension G from upcoming observational data (namely, cosmic microwave background power spectra from the Planck satellite and an idealized future polarization experiment). We employ simulations that are more general than others commonly used in the literature, leaving the mean velocity of strings, correlation length of the string network, and wiggliness (which parametrizes smaller-scale structure along the strings) as free parameters that can be observationally measured. In a new code, STRINGFAST, we implement a method for efficient computation of the C ' spectra induced by a network of strings, which is fast enough to be used in Markov Chain Monte Carlo analyses of future data. Performing a calculation with the string parameters left free results in projected constraints on G that are larger than those obtained by fixing their values a priori, typically by a factor of $2-7. We also find that, if G is equal to the current observational maximum, Planck will be able to make a confident detection of strings. However, if G is 2 orders of magnitude smaller, even a perfect, lensing-free measurement of polarization power spectra will not be able to detect a nonzero string tension at better than 2 confidence.

show abstract

Morphing the CMB: a technique for interpolating power spectra

Cited by 5 publications

References 8 publications

Cosmic microwave background acoustic peak locations

Cosmic microwave background acoustic peak locations

Current Cosmological Constraints from a 10 Parameter Cosmic Microwave Background Analysis

Predicted constraints on cosmic string tension from Planck and future CMB polarization measurements

Contact Info

Product

Resources

About