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Dodelson, S.

Publications and source records attributed to Dodelson, S..

98 records · Page 6
All sourcesNASA NTRSDOE OSTI
DOE OSTI2015

Neutrino physics from the cosmic microwave background and large scale structure

This is a report on the status and prospects of the quantification of neutrino properties through the cosmological neutrino background for the Cosmic Frontier of the Division of Particles and Fields Community Summer Study long-term planning exercise. Experiments planned and underway are prepared to study the cosmological neutrino background in detail via its influence on distance-redshift relations and the growth of structure. The program for the next decade described in this document, including upcoming spectroscopic galaxy surveys eBOSS and DESI and a new Stage-IV CMB polarization experiment CMB-S4, will achieve σ (σmν)(σmν) = 16 meV and σ (Neff)(Neff) = 0.020. Such a mass measurement will produce a high significance detection of non-zero σmνσmν, whose lower bound derived from atmospheric and solar neutrino oscillation data is about 58 meV. If neutrinos have a minimal normal mass hierarchy, this measurement will definitively rule out the inverted neutrino mass hierarchy, shedding light on one of the most puzzling aspects of the Standard Model of particle physics — the origin of mass. This precise a measurement of NeffNeff will allow for high sensitivity to any light and dark degrees of freedom produced in the big bang and a precision test of the standard cosmological model prediction that View the MathML sourceNeff=3.046.

Cosmic microwave background↗
DOE OSTI2014

Inflation physics from the cosmic microwave background and large scale structure

Here, fluctuations in the intensity and polarization of the cosmic microwave background (CMB) and the large-scale distribution of matter in the universe each contain clues about the nature of the earliest moments of time. The next generation of CMB and large-scale structure (LSS) experiments are poised to test the leading paradigm for these earliest moments—the theory of cosmic inflation—and to detect the imprints of the inflationary epoch, thereby dramatically increasing our understanding of fundamental physics and the early universe. A future CMB experiment with sufficient angular resolution and frequency coverage that surveys at least 1% of the sky to a depth of 1 uK-arcmin can deliver a constraint on the tensor-to-scalar ratio that will either result in a 5σ measurement of the energy scale of inflation or rule out all large-field inflation models, even in the presence of foregrounds and the gravitational lensing B -mode signal. LSS experiments, particularly spectroscopic surveys such as the Dark Energy Spectroscopic Instrument, will complement the CMB effort by improving current constraints on running of the spectral index by up to a factor of four, improving constraints on curvature by a factor of ten, and providing non-Gaussianity constraints that are competitive with the current CMB bounds.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2014

Exploiting Cross Correlations and Joint Analyses

In this report, we present a wide variety of ways in which information from multiple probes of dark energy may be combined to obtain additional information not accessible when they are considered separately. Fundamentally, because all major probes are affected by the underlying distribution of matter in the regions studied, there exist covariances between them that can provide information on cosmology. Combining multiple probes allows for more accurate (less contaminated by systematics) and more precise (since there is cosmological information encoded in cross-correlation statistics) measurements of dark energy. The potential of cross-correlation methods is only beginning to be realized. By bringing in information from other wavelengths, the capabilities of the existing probes of dark energy can be enhanced and systematic effects can be mitigated further. We present a mixture of work in progress and suggestions for future scientific efforts. Given the scope of future dark energy experiments, the greatest gains may only be realized with more coordination and cooperation between multiple project teams; we recommend that this interchange should begin sooner, rather than later, to maximize scientific gains.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2014

Constraints on cosmology from the cosmic microwave background power spectrum of the 2500 deg{sup 2} SPT-SZ survey

We explore extensions to the ΛCDM cosmology using measurements of the cosmic microwave background (CMB) from the recent SPT-SZ survey, along with data from WMAP7 and measurements of H {sub 0} and baryon acoustic oscillation (BAO). We check for consistency within ΛCDM between these data sets, and find some tension. The CMB alone gives weak support to physics beyond ΛCDM, due to a slight trend relative to ΛCDM of decreasing power toward smaller angular scales. While it may be due to statistical fluctuation, this trend could also be explained by several extensions. We consider running of the primordial spectral index (dn{sub s} /dln k), as well as two extensions that modify the damping tail power (the primordial helium abundance Y{sub p} and the effective number of neutrino species N {sub eff}) and one that modifies the large-scale power due to the integrated Sachs-Wolfe effect (the sum of neutrino masses ∑m {sub ν}). These extensions have similar observational consequences and are partially degenerate when considered simultaneously. Of the six one-parameter extensions considered, we find CMB to have the largest preference for dn{sub s} /dln k with –0.046 < dn{sub s} /dln k < –0.003 at 95% confidence, which strengthens to a 2.7σ indication of dn{sub s} /dln k < 0 from CMB+BAO+H {sub 0}. Detectable dn{sub s} /dln k ≠ 0 is difficult to explain in the context of single-field, slow-roll inflation models. We find N {sub eff} = 3.62 ± 0.48 for the CMB, which tightens to N {sub eff} = 3.71 ± 0.35 from CMB+BAO+H {sub 0}. Larger values of N {sub eff} relieve the mild tension between CMB, BAO, and H {sub 0}. When the Sunyaev-Zel'dovich selected galaxy cluster abundances (SPT{sub CL}) data are also included, we obtain N {sub eff} = 3.29 ± 0.31. Allowing for ∑m {sub ν} gives a 3.0σ detection of ∑m {sub ν} > 0 from CMB+BAO+H {sub 0} +SPT{sub CL}. The median value is (0.32 ± 0.11) eV, a factor of six above the lower bound set by neutrino oscillation observations. All data sets except H {sub 0} show some preference for massive neutrinos; data combinations including H {sub 0} favor nonzero masses only if BAO data are also included. We also constrain the two-parameter extensions N {sub eff} + ∑m {sub ν} and N {sub eff} + Y{sub p} to explore constraints on additional light species and big bang nucleosynthesis, respectively.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2014

Planning the Future of U.S. Particle Physics (Snowmass 2013): Chapter 4: Cosmic Frontier

These reports present the results of the 2013 Community Summer Study of the APS Division of Particles and Fields ("Snowmass 2013") on the future program of particle physics in the U.S. Chapter 4, on the Cosmic Frontier, discusses the program of research relevant to cosmology and the early universe. This area includes the study of dark matter and the search for its particle nature, the study of dark energy and inflation, and cosmic probes of fundamental symmetries.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
NASA NTRS2000

Dark energy and the cosmic microwave background radiation

We find that current cosmic microwave background anisotropy data strongly constrain the mean spatial curvature of the Universe to be near zero, or, equivalently, the total energy density to be near critical-as predicted by inflation. This result is robust to editing of data sets, and variation of other cosmological parameters (totaling seven, including a cosmological constant). Other lines of argument indicate that the energy density of nonrelativistic matter is much less than critical. Together, these results are evidence, independent of supernovae data, for dark energy in the Universe.

Microwaves↗
NASA NTRS1998

Updates on SuZIE and Python

SuZIE and Python are two mature cosmic microwave background (CMB) anisotropy experiments. In this presentation we preview recent oberservations from both experiments.

Cosmology Cosmic Microwave Background: Observation↗