Bose-Einstein-condensed scalar field dark matter and the gravitational wave background from inflation: New cosmological constraints and its detectability by LIGO

NASA Astrophysics Data System (ADS)

Li, Bohua; Shapiro, Paul R.; Rindler-Daller, Tanja

2017-09-01

We consider an alternative to weakly interacting massive particle (WIMP) cold dark matter (CDM)—ultralight bosonic dark matter (m ≳10-22 eV /c2) described by a complex scalar field (SFDM) with a global U (1 ) symmetry—for which the comoving particle number density or charge density is conserved after particle production during standard reheating. We allow for a repulsive self-interaction. In a Λ SFDM universe, SFDM starts out relativistic, evolving from stiff (w =1 ) to radiation-like (w =1 /3 ), before becoming nonrelativistic at late times (w =0 ). Thus, before the familiar radiation-dominated era, there is an earlier era of stiff-SFDM domination. During both the stiff-SFDM-dominated and radiation-dominated eras, the expansion rate is higher than in Λ CDM . The SFDM particle mass m and quartic self-interaction coupling strength λ are therefore constrained by cosmological observables, particularly Neff, the effective number of neutrino species during big bang nucleosynthesis, and zeq, the redshift of matter-radiation equality. Furthermore, since the stochastic gravitational-wave background (SGWB) from inflation is amplified during the stiff-SFDM-dominated era, it can contribute a radiation-like component large enough to affect these observables by further boosting the expansion rate after the stiff era ends. Remarkably, this same amplification makes detection of the SGWB possible at high frequencies by current laser interferometer experiments, e.g., aLIGO/Virgo and LISA. For SFDM particle parameters that satisfy these cosmological constraints, the amplified SGWB is detectable by LIGO for a broad range of reheat temperatures Treheat, for values of the tensor-to-scalar ratio r currently allowed by cosmic microwave background polarization measurements. For a given r and λ /(m c2)2, the marginally allowed Λ SFDM model for each Treheat has the smallest m that satisfies the cosmological constraints, and maximizes the present SGWB energy density for that

Measuring the 2D baryon acoustic oscillation signal of galaxies in WiggleZ: cosmological constraints

PubMed Central

Hinton, Samuel R.; Kazin, Eyal; Davis, Tamara M.; Blake, Chris; Brough, Sarah; Colless, Matthew; Couch, Warrick J.; Drinkwater, Michael J.; Glazebrook, Karl; Jurek, Russell J.; Parkinson, David; Pimbblet, Kevin A.; Poole, Gregory B.; Pracy, Michael; Woods, David

2016-01-01

We present results from the 2D anisotropic baryon acoustic oscillation (BAO) signal present in the final data set from the WiggleZ Dark Energy Survey. We analyse the WiggleZ data in two ways: first using the full shape of the 2D correlation function and secondly focusing only on the position of the BAO peak in the reconstructed data set. When fitting for the full shape of the 2D correlation function we use a multipole expansion to compare with theory. When we use the reconstructed data we marginalize over the shape and just measure the position of the BAO peak, analysing the data in wedges separating the signal along the line of sight from that parallel to the line of sight. We verify our method with mock data and find the results to be free of bias or systematic offsets. We also redo the pre-reconstruction angle-averaged (1D) WiggleZ BAO analysis with an improved covariance and present an updated result. The final results are presented in the form of Ωc h2, H(z), and DA(z) for three redshift bins with effective redshifts z = 0.44, 0.60, and 0.73. Within these bins and methodologies, we recover constraints between 5 and 22 per cent error. Our cosmological constraints are consistent with flat ΛCDM cosmology and agree with results from the Baryon Oscillation Spectroscopic Survey. PMID:28066154

Measuring the 2D baryon acoustic oscillation signal of galaxies in WiggleZ: cosmological constraints.

PubMed

Hinton, Samuel R; Kazin, Eyal; Davis, Tamara M; Blake, Chris; Brough, Sarah; Colless, Matthew; Couch, Warrick J; Drinkwater, Michael J; Glazebrook, Karl; Jurek, Russell J; Parkinson, David; Pimbblet, Kevin A; Poole, Gregory B; Pracy, Michael; Woods, David

2017-02-01

We present results from the 2D anisotropic baryon acoustic oscillation (BAO) signal present in the final data set from the WiggleZ Dark Energy Survey. We analyse the WiggleZ data in two ways: first using the full shape of the 2D correlation function and secondly focusing only on the position of the BAO peak in the reconstructed data set. When fitting for the full shape of the 2D correlation function we use a multipole expansion to compare with theory. When we use the reconstructed data we marginalize over the shape and just measure the position of the BAO peak, analysing the data in wedges separating the signal along the line of sight from that parallel to the line of sight. We verify our method with mock data and find the results to be free of bias or systematic offsets. We also redo the pre-reconstruction angle-averaged (1D) WiggleZ BAO analysis with an improved covariance and present an updated result. The final results are presented in the form of Ω c   h 2 , H ( z ), and D A ( z ) for three redshift bins with effective redshifts z = 0.44, 0.60, and 0.73. Within these bins and methodologies, we recover constraints between 5 and 22 per cent error. Our cosmological constraints are consistent with flat ΛCDM cosmology and agree with results from the Baryon Oscillation Spectroscopic Survey.

Measuring the 2D baryon acoustic oscillation signal of galaxies in WiggleZ: cosmological constraints

NASA Astrophysics Data System (ADS)

Hinton, Samuel R.; Kazin, Eyal; Davis, Tamara M.; Blake, Chris; Brough, Sarah; Colless, Matthew; Couch, Warrick J.; Drinkwater, Michael J.; Glazebrook, Karl; Jurek, Russell J.; Parkinson, David; Pimbblet, Kevin A.; Poole, Gregory B.; Pracy, Michael; Woods, David

2017-02-01

We present results from the 2D anisotropic baryon acoustic oscillation (BAO) signal present in the final data set from the WiggleZ Dark Energy Survey. We analyse the WiggleZ data in two ways: first using the full shape of the 2D correlation function and secondly focusing only on the position of the BAO peak in the reconstructed data set. When fitting for the full shape of the 2D correlation function we use a multipole expansion to compare with theory. When we use the reconstructed data we marginalize over the shape and just measure the position of the BAO peak, analysing the data in wedges separating the signal along the line of sight from that parallel to the line of sight. We verify our method with mock data and find the results to be free of bias or systematic offsets. We also redo the pre-reconstruction angle-averaged (1D) WiggleZ BAO analysis with an improved covariance and present an updated result. The final results are presented in the form of Ωc h2, H(z), and DA(z) for three redshift bins with effective redshifts z = 0.44, 0.60, and 0.73. Within these bins and methodologies, we recover constraints between 5 and 22 per cent error. Our cosmological constraints are consistent with flat ΛCDM cosmology and agree with results from the Baryon Oscillation Spectroscopic Survey.

Correlations Between the Cosmic X-Ray and Microwave Backgrounds: Constraints on a Cosmological Constant

NASA Technical Reports Server (NTRS)

Boughn, S. P.; Crittenden, R. G.; Turok, N. G.

1998-01-01

In universes with significant curvature or cosmological constant, cosmic microwave background (CMB) anisotropies are created very recently via the Rees-Sciama or integrated Sachs-Wolfe effects. This causes the CMB anisotropies to become partially correlated with the local matter density (z less than 4). We examine the prospects of using the hard (2- 10 keV) X-ray background as a probe of the local density and the measured correlation between the HEAO1 A2 X-ray survey and the 4-year COBE-DMR map to obtain a constraint on the cosmological constant. The 95% confidence level upper limit on the cosmological constant is OMega(sub Lambda) less than or equal to 0.5, assuming that the observed fluctuations in the X-ray map result entirely from large scale structure. (This would also imply that the X-rays trace matter with a bias factor of b(sub x) approx. = 5.6 Omega(sub m, sup 0.53)). This bound is weakened considerably if a large portion of the X-ray fluctuations arise from Poisson noise from unresolved sources. For example, if one assumes that the X-ray bias is b(sub x) = 2, then the 95% confidence level upper limit is weaker, Omega(sub Lambda) less than or equal to 0.7. More stringent limits should be attainable with data from the next generation of CMB and X-ray background maps.

Right-handed neutrino dark matter in the classically conformal U(1 ) ' extended standard model

NASA Astrophysics Data System (ADS)

Oda, Satsuki; Okada, Nobuchika; Takahashi, Dai-suke

2017-11-01

We consider the dark matter (DM) scenario in the context of the classically conformal U(1 ) ' extended standard model (SM), with three right-handed neutrinos (RHNs) and the U(1 ) ' Higgs field. The model is free from all of the U(1 ) ' gauge and gravitational anomalies in the presence of the three RHNs. We introduce a Z2 parity in the model, under which an odd parity is assigned to one RHN, while all of the other particles are assigned to be Z2 even, and hence the Z2-odd RHN serves as a DM candidate. In this model, the U(1 ) ' gauge symmetry is radiatively broken through the Coleman-Weinberg mechanism, by which the electroweak symmetry breaking is triggered. There are three free parameters in our model—the U(1 ) ' charge of the SM Higgs doublet (xH ), the new U(1 ) ' gauge coupling (gX ), and the U(1 ) ' gauge boson (Z') mass (mZ')—which are severely constrained in order to solve the electroweak vacuum instability problem, and satisfy the LHC Run-2 bounds from the search for the Z' boson resonance. In addition to these constraints, we investigate the RHN DM physics. Because of the nature of classical conformality, we find that a RHN DM pair mainly annihilates into the SM particles through Z' boson exchange. This is the so-called Z'-portal DM scenario. Combining the electroweak vacuum stability condition, the LHC Run-2 bounds, and the cosmological constraint from the observed DM relic density, we find that all constraints work together to narrow the allowed parameter regions and, in particular, exclude mZ'≲3.5 TeV . For the obtained allowed regions, we calculate the spin-independent cross section of the RHN DM with nucleons. We find that the resultant cross section is well below the current experimental upper bounds.

Using cross correlations to calibrate lensing source redshift distributions: Improving cosmological constraints from upcoming weak lensing surveys

DOE Office of Scientific and Technical Information (OSTI.GOV)

De Putter, Roland; Doré, Olivier; Das, Sudeep

2014-01-10

Cross correlations between the galaxy number density in a lensing source sample and that in an overlapping spectroscopic sample can in principle be used to calibrate the lensing source redshift distribution. In this paper, we study in detail to what extent this cross-correlation method can mitigate the loss of cosmological information in upcoming weak lensing surveys (combined with a cosmic microwave background prior) due to lack of knowledge of the source distribution. We consider a scenario where photometric redshifts are available and find that, unless the photometric redshift distribution p(z {sub ph}|z) is calibrated very accurately a priori (bias andmore » scatter known to ∼0.002 for, e.g., EUCLID), the additional constraint on p(z {sub ph}|z) from the cross-correlation technique to a large extent restores the cosmological information originally lost due to the uncertainty in dn/dz(z). Considering only the gain in photo-z accuracy and not the additional cosmological information, enhancements of the dark energy figure of merit of up to a factor of four (40) can be achieved for a SuMIRe-like (EUCLID-like) combination of lensing and redshift surveys, where SuMIRe stands for Subaru Measurement of Images and Redshifts). However, the success of the method is strongly sensitive to our knowledge of the galaxy bias evolution in the source sample and we find that a percent level bias prior is needed to optimize the gains from the cross-correlation method (i.e., to approach the cosmology constraints attainable if the bias was known exactly).« less

Observational constraints on loop quantum cosmology.

PubMed

Bojowald, Martin; Calcagni, Gianluca; Tsujikawa, Shinji

2011-11-18

In the inflationary scenario of loop quantum cosmology in the presence of inverse-volume corrections, we give analytic formulas for the power spectra of scalar and tensor perturbations convenient to compare with observations. Since inverse-volume corrections can provide strong contributions to the running spectral indices, inclusion of terms higher than the second-order runnings in the power spectra is crucially important. Using the recent data of cosmic microwave background and other cosmological experiments, we place bounds on the quantum corrections.

Cosmology based on f(R) gravity admits 1 eV sterile neutrinos.

PubMed

Motohashi, Hayato; Starobinsky, Alexei A; Yokoyama, Jun'ichi

2013-03-22

It is shown that the tension between recent neutrino oscillation experiments, favoring sterile neutrinos with masses of the order of 1 eV, and cosmological data which impose stringent constraints on neutrino masses from the free streaming suppression of density fluctuations, can be resolved in models of the present accelerated expansion of the Universe based on f(R) gravity.

Plasma constraints on the cosmological abundance of magnetic monopoles and the origin of cosmic magnetic fields

NASA Astrophysics Data System (ADS)

Medvedev, Mikhail V.; Loeb, Abraham

2017-06-01

Existing theoretical and observational constraints on the abundance of magnetic monopoles are limited. Here we demonstrate that an ensemble of monopoles forms a plasma whose properties are well determined and whose collective effects place new tight constraints on the cosmological abundance of monopoles. In particular, the existence of micro-Gauss magnetic fields in galaxy clusters and radio relics implies that the scales of these structures are below the Debye screening length, thus setting an upper limit on the cosmological density parameter of monopoles, ΩM lesssim 3 × 10-4, which precludes them from being the dark matter. Future detection of Gpc-scale coherent magnetic fields could improve this limit by a few orders of magnitude. In addition, we predict the existence of magnetic Langmuir waves and turbulence which may appear on the sky as ``zebra patterns'' of an alternating magnetic field with k·B ≠ 0. We also show that magnetic monopole Langmuir turbulence excited near the accretion shock of galaxy clusters may be an efficient mechanism for generating the observed intracluster magnetic fields.

Constraints on universe models with cosmological constant from cosmic microwave background anisotropy

NASA Astrophysics Data System (ADS)

Sugiyama, Naoshi; Gouda, Naoteru; Sasaki, Misao

1990-12-01

Thorough numerical calculations of the fluctuations in the cosmic microwave background radiation using the gage-invariant formalism are carried out for various cosmological models with the cosmological constant. It is shown that a spatially flat cold dark matter-dominated universe of Omega(0) = 0.1 to about 0.4 and H(0) = 50 to about 100 km/s per Mpc with adiabatic perturbations has the possibility of giving the final answer to cosmological puzzles. It is also found that the introduction of the cosmological constant may revive pure baryonic universe models.

Cosmological constraints from galaxy clustering in the presence of massive neutrinos

NASA Astrophysics Data System (ADS)

Zennaro, M.; Bel, J.; Dossett, J.; Carbone, C.; Guzzo, L.

2018-06-01

The clustering ratio is defined as the ratio between the correlation function and the variance of the smoothed overdensity field. In Λ cold dark matter (ΛCDM) cosmologies without massive neutrinos, it has already been proven to be independent of bias and redshift space distortions on a range of linear scales. It therefore can provide us with a direct comparison of predictions (for matter in real space) against measurements (from galaxies in redshift space). In this paper we first extend the applicability of such properties to cosmologies that account for massive neutrinos, by performing tests against simulated data. We then investigate the constraining power of the clustering ratio on cosmological parameters such as the total neutrino mass and the equation of state of dark energy. We analyse the joint posterior distribution of the parameters that satisfy both measurements of the galaxy clustering ratio in the SDSS-DR12, and the angular power spectra of cosmic microwave background temperature and polarization anisotropies measured by the Planck satellite. We find the clustering ratio to be very sensitive to the CDM density parameter, but less sensitive to the total neutrino mass. We also forecast the constraining power the clustering ratio will achieve, predicting the amplitude of its errors with a Euclid-like galaxy survey. First we compute parameter forecasts using the Planck covariance matrix alone, then we add information from the clustering ratio. We find a significant improvement on the constraint of all considered parameters, and in particular an improvement of 40 per cent for the CDM density and 14 per cent for the total neutrino mass.

KiDS-450: the tomographic weak lensing power spectrum and constraints on cosmological parameters

NASA Astrophysics Data System (ADS)

Köhlinger, F.; Viola, M.; Joachimi, B.; Hoekstra, H.; van Uitert, E.; Hildebrandt, H.; Choi, A.; Erben, T.; Heymans, C.; Joudaki, S.; Klaes, D.; Kuijken, K.; Merten, J.; Miller, L.; Schneider, P.; Valentijn, E. A.

2017-11-01

We present measurements of the weak gravitational lensing shear power spectrum based on 450 ° ^2 of imaging data from the Kilo Degree Survey. We employ a quadratic estimator in two and three redshift bins and extract band powers of redshift autocorrelation and cross-correlation spectra in the multipole range 76 ≤ ℓ ≤ 1310. The cosmological interpretation of the measured shear power spectra is performed in a Bayesian framework assuming a ΛCDM model with spatially flat geometry, while accounting for small residual uncertainties in the shear calibration and redshift distributions as well as marginalizing over intrinsic alignments, baryon feedback and an excess-noise power model. Moreover, massive neutrinos are included in the modelling. The cosmological main result is expressed in terms of the parameter combination S_8 ≡ σ _8 √{Ω_m/0.3} yielding S8 = 0.651 ± 0.058 (three z-bins), confirming the recently reported tension in this parameter with constraints from Planck at 3.2σ (three z-bins). We cross-check the results of the three z-bin analysis with the weaker constraints from the two z-bin analysis and find them to be consistent. The high-level data products of this analysis, such as the band power measurements, covariance matrices, redshift distributions and likelihood evaluation chains are available at http://kids.strw.leidenuniv.nl.

Constraints on cosmological parameters from the analysis of the cosmic lens all sky survey radio-selected gravitational lens statistics.

PubMed

Chae, K-H; Biggs, A D; Blandford, R D; Browne, I W A; De Bruyn, A G; Fassnacht, C D; Helbig, P; Jackson, N J; King, L J; Koopmans, L V E; Mao, S; Marlow, D R; McKean, J P; Myers, S T; Norbury, M; Pearson, T J; Phillips, P M; Readhead, A C S; Rusin, D; Sykes, C M; Wilkinson, P N; Xanthopoulos, E; York, T

2002-10-07

We derive constraints on cosmological parameters and the properties of the lensing galaxies from gravitational lens statistics based on the final Cosmic Lens All Sky Survey data. For a flat universe with a classical cosmological constant, we find that the present matter fraction of the critical density is Omega(m)=0.31(+0.27)(-0.14) (68%)+0.12-0.10 (syst). For a flat universe with a constant equation of state for dark energy w=p(x)(pressure)/rho(x)(energy density), we find w<-0.55(+0.18)(-0.11) (68%).

Plasma Constraints on the Cosmological Abundance of Magnetic Monopoles and the Origin of Cosmic Magnetic Fields

NASA Astrophysics Data System (ADS)

Medvedev, Mikhail; Loeb, Abraham

2017-10-01

Existing theoretical and observational constraints on the abundance of magnetic monopoles are limited. Here we demonstrate that an ensemble of monopoles forms a plasma whose properties are well determined and whose collective effects place new tight constraints on the cosmological abundance of monopoles. In particular, the existence of micro-Gauss magnetic fields in galaxy clusters and radio relics implies that the scales of these structures are below the Debye screening length, thus setting an upper limit on the cosmological density parameter of monopoles, ΩM <= 3 ×10-4 , which precludes them from being the dark matter. Future detection of Gpc-scale coherent magnetic fields could improve this limit by a few orders of magnitude. In addition, we predict the existence of magnetic Langmuir waves and turbulence which may appear on the sky as ``zebra patterns'' of an alternating magnetic field with k . B ≠ 0 . We also show that magnetic monopole Langmuir turbulence excited near the accretion shock of galaxy clusters may be an efficient mechanism for generating the observed intracluster magnetic fields. The authors acknowledge DOE partial support via Grant DE-SC0016368.

Plasma constraints on the cosmological abundance of magnetic monopoles and the origin of cosmic magnetic fields

DOE Office of Scientific and Technical Information (OSTI.GOV)

Medvedev, Mikhail V.; Loeb, Abraham, E-mail: mmedvedev@cfa.harvard.edu, E-mail: aloeb@cfa.harvard.edu

Existing theoretical and observational constraints on the abundance of magnetic monopoles are limited. Here we demonstrate that an ensemble of monopoles forms a plasma whose properties are well determined and whose collective effects place new tight constraints on the cosmological abundance of monopoles. In particular, the existence of micro-Gauss magnetic fields in galaxy clusters and radio relics implies that the scales of these structures are below the Debye screening length, thus setting an upper limit on the cosmological density parameter of monopoles, Ω {sub M} {sub ∼<} {sub 3} {sub ×} {sub 10}{sup −4}, which precludes them from being themore » dark matter. Future detection of Gpc-scale coherent magnetic fields could improve this limit by a few orders of magnitude. In addition, we predict the existence of magnetic Langmuir waves and turbulence which may appear on the sky as ''zebra patterns'' of an alternating magnetic field with k·B ≠ 0. We also show that magnetic monopole Langmuir turbulence excited near the accretion shock of galaxy clusters may be an efficient mechanism for generating the observed intracluster magnetic fields.« less

Introduction to big bang nucleosynthesis and modern cosmology

NASA Astrophysics Data System (ADS)

Mathews, Grant J.; Kusakabe, Motohiko; Kajino, Toshitaka

Primordial nucleosynthesis remains as one of the pillars of modern cosmology. It is the testing ground upon which many cosmological models must ultimately rest. It is our only probe of the universe during the important radiation-dominated epoch in the first few minutes of cosmic expansion. This paper reviews the basic equations of space-time, cosmology, and big bang nucleosynthesis. We also summarize the current state of observational constraints on primordial abundances along with the key nuclear reactions and their uncertainties. We summarize which nuclear measurements are most crucial during the big bang. We also review various cosmological models and their constraints. In particular, we analyze the constraints that big bang nucleosynthesis places upon the possible time variation of fundamental constants, along with constraints on the nature and origin of dark matter and dark energy, long-lived supersymmetric particles, gravity waves, and the primordial magnetic field.

Cosmological origin of anomalous radio background

NASA Astrophysics Data System (ADS)

Cline, James M.; Vincent, Aaron C.

2013-02-01

The ARCADE 2 collaboration has reported a significant excess in the isotropic radio background, whose homogeneity cannot be reconciled with clustered sources. This suggests a cosmological origin prior to structure formation. We investigate several potential mechanisms and show that injection of relativistic electrons through late decays of a metastable particle can give rise to the observed excess radio spectrum through synchrotron emission. However, constraints from the cosmic microwave background (CMB) anisotropy, on injection of charged particles and on the primordial magnetic field, present a challenge. The simplest scenario is with a gtrsim9 GeV particle decaying into e+e- at a redshift of z ~ 5, in a magnetic field of ~ 5μG, which exceeds the CMB B-field constraints, unless the field was generated after decoupling. Decays into exotic millicharged particles can alleviate this tension, if they emit synchroton radiation in conjunction with a sufficiently large background magnetic field of a dark U(1)' gauge field.

Cosmological applications of singular hypersurfaces in general relativity

NASA Astrophysics Data System (ADS)

Laguna-Castillo, Pablo

Three applications to cosmology of surface layers, based on Israel's formalism of singular hypersurfaces and thin shells in general relativity, are presented. Einstein's field equations are analyzed in the presence of a bubble nucleated in vacuum phase transitions within the context of the old inflationary universe scenario. The evolution of a bubble with vanishing surface energy density is studied. It is found that such bubbles lead to a worm-hole matching. Next, the observable four-dimensional universe is considered as a singular hypersurface of discontinuity embedded in a five-dimensional Kaluza-Klein cosmology. It is possible to rewrite the projected five-dimensional Einstein equations on the surface layer in a similar way to the four-dimensional Robertson-Walker cosmology equations. Next, a model is described for an infinite-length, straight U(1) cosmic string as a cylindrical, singular shell enclosing a region of false vacuum. A set of equations is introduced which are required to develop a three-dimensional computer code whose purpose is to study the process of intercommuting cosmic strings with the inclusion of gravitational effects. The outcome is evolution and constraint equations for the gravitational, scalar and gauge field of two initially separated, perpendicular, cosmic strings.

Constraint on energy-momentum squared gravity from neutron stars and its cosmological implications

NASA Astrophysics Data System (ADS)

Akarsu, Özgür; Barrow, John D.; ćıkıntoǧlu, Sercan; Ekşi, K. Yavuz; Katırcı, Nihan

2018-06-01

Deviations from the predictions of general relativity due to energy-momentum squared gravity (EMSG) are expected to become pronounced in the high density cores of neutron stars. We derive the hydrostatic equilibrium equations in EMSG and solve them numerically to obtain the neutron star mass-radius relations for four different realistic equations of state. We use the existing observational measurements of the masses and radii of neutron stars to constrain the free parameter, α , that characterizes the coupling between matter and spacetime in EMSG. We show that -10-38 cm3/erg <α <+10-37 cm3/erg . Under this constraint, we discuss what contributions EMSG can provide to the physics of neutron stars, in particular, their relevance to the so called hyperon puzzle in neutron stars. We also discuss how EMSG alters the dynamics of the early universe from the predictions of the standard cosmological model. We show that EMSG leaves the standard cosmology safely unaltered back to t ˜10-4 seconds at which the energy density of the universe is ˜1034 erg cm-3 .

Observational Constraints on the Nature of the Dark Energy: First Cosmological Results From the ESSENCE Supernova Survey

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wood-Vasey, W.Michael; Miknaitis, G.; Stubbs, C.W.

We present constraints on the dark energy equation-of-state parameter, w = P/({rho}c{sup 2}), using 60 Type Ia supernovae (SNe Ia) from the ESSENCE supernova survey. We derive a set of constraints on the nature of the dark energy assuming a flat Universe. By including constraints on ({Omega}{sub M}, w) from baryon acoustic oscillations, we obtain a value for a static equation-of-state parameter w = -1.05{sub -0.12}{sup +0.13} (stat 1{sigma}) {+-} 0.13 (sys) and {Omega}{sub M} = 0.274{sub -0.020}{sup +0.033} (stat 1{sigma}) with a best-fit {chi}{sup 2}/DoF of 0.96. These results are consistent with those reported by the Super-Nova Legacy Surveymore » in a similar program measuring supernova distances and redshifts. We evaluate sources of systematic error that afflict supernova observations and present Monte Carlo simulations that explore these effects. Currently, the largest systematic currently with the potential to affect our measurements is the treatment of extinction due to dust in the supernova host galaxies. Combining our set of ESSENCE SNe Ia with the SuperNova Legacy Survey SNe Ia, we obtain a joint constraint of w = -1.07{sub -0.09}{sup +0.09} (stat 1{sigma}) {+-} 0.13 (sys), {Omega}{sub M} = 0.267{sub -0.018}{sup +0.028} (stat 1{sigma}) with a best-fit {chi}{sup 2}/DoF of 0.91. The current SNe Ia data are fully consistent with a cosmological constant.« less

Cosmological Parameters From Pre-Planck CMB Measurements: A 2017 Update

NASA Technical Reports Server (NTRS)

Calabrese, Erminia; Hlolzek, Renee A.; Bond, J. Richard; Devlin, Mark J.; Dunkley, Joanna; Halpern, Mark; Hincks, Adam D.; Irwin, Kent D.; Kosowsky, Arthur; Moodley, Kavilan;

Precision cosmology from X-ray AGN clustering

NASA Astrophysics Data System (ADS)

Basilakos, Spyros; Plionis, Manolis

2009-11-01

We place tight constraints on the main cosmological parameters of spatially flat cosmological models by using the recent angular clustering results of XMM-Newton soft (0.5-2keV) X-ray sources, which have a redshift distribution with a median of z ~ 1. Performing a standard likelihood procedure, assuming a constant in comoving coordinates active galactic nuclei (AGN) clustering evolution, the AGN bias evolution model of Basilakos, Plionis & Ragone-Figueroa and the Wilkinson Microwave Anisotropy Probe5 value of σ8, we find stringent simultaneous constraints in the (Ωm, w) plane, with Ωm = 0.26 +/- 0.05, w = -0.93+0.11-0.19.

Cosmological Constraint on Brans-Dicke Theory

NASA Astrophysics Data System (ADS)

Chen, Xuelei; Wu, Fengquan

We develop the covariant formalism of the cosmological perturbation theory for the Brans-Dicke gravity, and use it to calculate the cosmic microwave background (CMB) anisotropy and large scale structure (LSS) power spectrum. We introduce a new parameter ζ which is related to the Brans-Dicke parameter ζ = ln(1/ω + 1), and use the Markov-Chain Monte Carlo (MCMC) method to explore the parameter space. Using the latest CMB data published by WMAP, ACBAR, CBI, Boomerang teams, and the LSS data from the SDSS survey DR4, we find that the the 2σ (95.5%) bound on ζ is about |ζ| > 10-2, or |ω| > 102, the precise limit depends somewhat on the prior used.

Cosmology and particle physics

NASA Technical Reports Server (NTRS)

Turner, Michael S.

1988-01-01

The interplay between cosmology and elementary particle physics is discussed. The standard cosmology is reviewed, concentrating on primordial nucleosynthesis and discussing how the standard cosmology has been used to place constraints on the properties of various particles. Baryogenesis is discussed, showing how a scenario in which the B-, C-, and CP-violating interactions in GUTs provide a dynamical explanation for the predominance of matter over antimatter and for the present baryon-to-photon ratio. It is shown how the very early dynamical evolution of a very weakly coupled scalar field which is initially displaced from the minimum of its potential may explain a handful of very fundamental cosmological facts which are not explained by the standard cosmology.

A New Approach for Obtaining Cosmological Constraints from Type Ia Supernovae using Approximate Bayesian Computation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jennings, Elise; Wolf, Rachel; Sako, Masao

2016-11-09

Cosmological parameter estimation techniques that robustly account for systematic measurement uncertainties will be crucial for the next generation of cosmological surveys. We present a new analysis method, superABC, for obtaining cosmological constraints from Type Ia supernova (SN Ia) light curves using Approximate Bayesian Computation (ABC) without any likelihood assumptions. The ABC method works by using a forward model simulation of the data where systematic uncertainties can be simulated and marginalized over. A key feature of the method presented here is the use of two distinct metrics, the `Tripp' and `Light Curve' metrics, which allow us to compare the simulated data to the observed data set. The Tripp metric takes as input the parameters of models fit to each light curve with the SALT-II method, whereas the Light Curve metric uses the measured fluxes directly without model fitting. We apply the superABC sampler to a simulated data set ofmore » $$\\sim$$1000 SNe corresponding to the first season of the Dark Energy Survey Supernova Program. Varying $$\\Omega_m, w_0, \\alpha$$ and $$\\beta$$ and a magnitude offset parameter, with no systematics we obtain $$\\Delta(w_0) = w_0^{\\rm true} - w_0^{\\rm best \\, fit} = -0.036\\pm0.109$$ (a $$\\sim11$$% 1$$\\sigma$$ uncertainty) using the Tripp metric and $$\\Delta(w_0) = -0.055\\pm0.068$$ (a $$\\sim7$$% 1$$\\sigma$$ uncertainty) using the Light Curve metric. Including 1% calibration uncertainties in four passbands, adding 4 more parameters, we obtain $$\\Delta(w_0) = -0.062\\pm0.132$$ (a $$\\sim14$$% 1$$\\sigma$$ uncertainty) using the Tripp metric. Overall we find a $17$% increase in the uncertainty on $$w_0$$ with systematics compared to without. We contrast this with a MCMC approach where systematic effects are approximately included. We find that the MCMC method slightly underestimates the impact of calibration uncertainties for this simulated data set.« less

Hořava Gravity in the Effective Field Theory formalism: From cosmology to observational constraints

NASA Astrophysics Data System (ADS)

Frusciante, Noemi; Raveri, Marco; Vernieri, Daniele; Hu, Bin; Silvestri, Alessandra

2016-09-01

We consider Hořava gravity within the framework of the effective field theory (EFT) of dark energy and modified gravity. We work out a complete mapping of the theory into the EFT language for an action including all the operators which are relevant for linear perturbations with up to sixth order spatial derivatives. We then employ an updated version of the EFTCAMB/EFTCosmoMC package to study the cosmology of the low-energy limit of Hořava gravity and place constraints on its parameters using several cosmological data sets. In particular we use cosmic microwave background (CMB) temperature-temperature and lensing power spectra by Planck 2013, WMAP low- ℓ polarization spectra, WiggleZ galaxy power spectrum, local Hubble measurements, Supernovae data from SNLS, SDSS and HST and the baryon acoustic oscillations measurements from BOSS, SDSS and 6dFGS. We get improved upper bounds, with respect to those from Big Bang Nucleosynthesis, on the deviation of the cosmological gravitational constant from the local Newtonian one. At the level of the background phenomenology, we find a relevant rescaling of the Hubble rate at all epoch, which has a strong impact on the cosmological observables; at the level of perturbations, we discuss in details all the relevant effects on the observables and find that in general the quasi-static approximation is not safe to describe the evolution of perturbations. Overall we find that the effects of the modifications induced by the low-energy Hořava gravity action are quite dramatic and current data place tight bounds on the theory parameters.

Constraints on Cosmological Parameters from the Angular Power Spectrum of a Combined 2500 deg$^2$ SPT-SZ and Planck Gravitational Lensing Map

DOE PAGES

Simard, G.; et al.

2018-06-20

We report constraints on cosmological parameters from the angular power spectrum of a cosmic microwave background (CMB) gravitational lensing potential map created using temperature data from 2500 degmore » $^2$ of South Pole Telescope (SPT) data supplemented with data from Planck in the same sky region, with the statistical power in the combined map primarily from the SPT data. We fit the corresponding lensing angular power spectrum to a model including cold dark matter and a cosmological constant ($$\\Lambda$$CDM), and to models with single-parameter extensions to $$\\Lambda$$CDM. We find constraints that are comparable to and consistent with constraints found using the full-sky Planck CMB lensing data. Specifically, we find $$\\sigma_8 \\Omega_{\\rm m}^{0.25}=0.598 \\pm 0.024$$ from the lensing data alone with relatively weak priors placed on the other $$\\Lambda$$CDM parameters. In combination with primary CMB data from Planck, we explore single-parameter extensions to the $$\\Lambda$$CDM model. We find $$\\Omega_k = -0.012^{+0.021}_{-0.023}$$ or $$M_{\

Constraints on Cosmological Parameters from the Angular Power Spectrum of a Combined 2500 deg$^2$ SPT-SZ and Planck Gravitational Lensing Map

DOE Office of Scientific and Technical Information (OSTI.GOV)

Simard, G.; et al.

We report constraints on cosmological parameters from the angular power spectrum of a cosmic microwave background (CMB) gravitational lensing potential map created using temperature data from 2500 degmore » $^2$ of South Pole Telescope (SPT) data supplemented with data from Planck in the same sky region, with the statistical power in the combined map primarily from the SPT data. We fit the corresponding lensing angular power spectrum to a model including cold dark matter and a cosmological constant ($$\\Lambda$$CDM), and to models with single-parameter extensions to $$\\Lambda$$CDM. We find constraints that are comparable to and consistent with constraints found using the full-sky Planck CMB lensing data. Specifically, we find $$\\sigma_8 \\Omega_{\\rm m}^{0.25}=0.598 \\pm 0.024$$ from the lensing data alone with relatively weak priors placed on the other $$\\Lambda$$CDM parameters. In combination with primary CMB data from Planck, we explore single-parameter extensions to the $$\\Lambda$$CDM model. We find $$\\Omega_k = -0.012^{+0.021}_{-0.023}$$ or $$M_{\

The ΩDE-ΩM Plane in Dark Energy Cosmology

NASA Astrophysics Data System (ADS)

Qiang, Yuan; Zhang, Tong-Jie

The dark energy cosmology with the equation of state w=const. is considered in this paper. The ΩDE-ΩM plane has been used to study the present state and expansion history of the universe. Through the mathematical analysis, we give the theoretical constraint of cosmological parameters. Together with some observations such as the transition redshift from deceleration to acceleration, more precise constraint on cosmological parameters can be acquired.

Seeking sterile neutrinos in Finslerian cosmology

NASA Astrophysics Data System (ADS)

Wang, Deng; Meng, Xin-He

2017-11-01

For the first time, to search for sterile neutrinos in the framework of Finler geometry, we constrain four cosmological models using the most stringent constraint we can provide so far. We find that the Finslerian massless sterile neutrino model can, respectively, give a better cosmological fit to data and alleviate the current H_0 tension more effectively than the other three models. For the Finslerian massless sterile neutrino model, we obtain the constraint N_eff=3.237^{+0.092}_{-0.185}, which is consistent with Δ N_eff > 0 at the 1.03σ confidence level (CL). This gives a very weak hint of massless sterile neutrinos and may imply the non-existence of massless sterile neutrinos in the Finslerian cosmological setting. For the Finslerian massive sterile neutrino model, we obtain the constraints N_eff=3.143^{+0.064}_{-0.066}, which favors Δ N_eff > 0 at the 1.47σ CL, and m_{ν , sterile}^eff < 0.121 eV at the 2σ CL which is much tighter than the Planck results. This very tight restriction appears to indicate the massive sterile neutrinos are also non-existent in the Finslerian scenarios. Consequently, one may conclude that the sterile neutrinos are possibly non-existent in the Finslerian universe. Our results are compatible with the recent results of the neutrino oscillation experiments implemented by the Daya Bay and MINOS collaborations and the cosmic ray one carried out by the IceCube collaboration.

Emergent cosmology revisited

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bag, Satadru; Sahni, Varun; Shtanov, Yuri

We explore the possibility of emergent cosmology using the effective potential formalism. We discover new models of emergent cosmology which satisfy the constraints posed by the cosmic microwave background (CMB). We demonstrate that, within the framework of modified gravity, the emergent scenario can arise in a universe which is spatially open/closed. By contrast, in general relativity (GR) emergent cosmology arises from a spatially closed past-eternal Einstein Static Universe (ESU). In GR the ESU is unstable, which creates fine tuning problems for emergent cosmology. However, modified gravity models including Braneworld models, Loop Quantum Cosmology (LQC) and Asymptotically Free Gravity result inmore » a stable ESU. Consequently, in these models emergent cosmology arises from a larger class of initial conditions including those in which the universe eternally oscillates about the ESU fixed point. We demonstrate that such an oscillating universe is necessarily accompanied by graviton production. For a large region in parameter space graviton production is enhanced through a parametric resonance, casting serious doubts as to whether this emergent scenario can be past-eternal.« less

Cosmology with photometric weak lensing surveys: Constraints with redshift tomography of convergence peaks and moments

NASA Astrophysics Data System (ADS)

Petri, Andrea; May, Morgan; Haiman, Zoltán

2016-09-01

Weak gravitational lensing is becoming a mature technique for constraining cosmological parameters, and future surveys will be able to constrain the dark energy equation of state w . When analyzing galaxy surveys, redshift information has proven to be a valuable addition to angular shear correlations. We forecast parameter constraints on the triplet (Ωm,w ,σ8) for a LSST-like photometric galaxy survey, using tomography of the shear-shear power spectrum, convergence peak counts and higher convergence moments. We find that redshift tomography with the power spectrum reduces the area of the 1 σ confidence interval in (Ωm,w ) space by a factor of 8 with respect to the case of the single highest redshift bin. We also find that adding non-Gaussian information from the peak counts and higher-order moments of the convergence field and its spatial derivatives further reduces the constrained area in (Ωm,w ) by factors of 3 and 4, respectively. When we add cosmic microwave background parameter priors from Planck to our analysis, tomography improves power spectrum constraints by a factor of 3. Adding moments yields an improvement by an additional factor of 2, and adding both moments and peaks improves by almost a factor of 3 over power spectrum tomography alone. We evaluate the effect of uncorrected systematic photometric redshift errors on the parameter constraints. We find that different statistics lead to different bias directions in parameter space, suggesting the possibility of eliminating this bias via self-calibration.

Addressing Beyond Standard Model physics using cosmology

NASA Astrophysics Data System (ADS)

Ghalsasi, Akshay

We have consensus models for both particle physics (i.e. standard model) and cosmology (i.e. LambdaCDM). Given certain assumptions about the initial conditions of the universe, the marriage of the standard model (SM) of particle physics and LambdaCDM cosmology has been phenomenally successful in describing the universe we live in. However it is quite clear that all is not well. The three biggest problems that the SM faces today are baryogenesis, dark matter and dark energy. These problems, along with the problem of neutrino masses, indicate the existence of physics beyond SM. Evidence of baryogenesis, dark matter and dark energy all comes from astrophysical and cosmological observations. Cosmology also provides the best (model dependent) constraints on neutrino masses. In this thesis I will try address the following problems 1) Addressing the origin of dark energy (DE) using non-standard neutrino cosmology and exploring the effects of the non-standard neutrino cosmology on terrestrial and cosmological experiments. 2) Addressing the matter anti-matter asymmetry of the universe.

The Complete Light-curve Sample of Spectroscopically Confirmed SNe Ia from Pan-STARRS1 and Cosmological Constraints from the Combined Pantheon Sample

NASA Astrophysics Data System (ADS)

Scolnic, D. M.; Jones, D. O.; Rest, A.; Pan, Y. C.; Chornock, R.; Foley, R. J.; Huber, M. E.; Kessler, R.; Narayan, G.; Riess, A. G.; Rodney, S.; Berger, E.; Brout, D. J.; Challis, P. J.; Drout, M.; Finkbeiner, D.; Lunnan, R.; Kirshner, R. P.; Sanders, N. E.; Schlafly, E.; Smartt, S.; Stubbs, C. W.; Tonry, J.; Wood-Vasey, W. M.; Foley, M.; Hand, J.; Johnson, E.; Burgett, W. S.; Chambers, K. C.; Draper, P. W.; Hodapp, K. W.; Kaiser, N.; Kudritzki, R. P.; Magnier, E. A.; Metcalfe, N.; Bresolin, F.; Gall, E.; Kotak, R.; McCrum, M.; Smith, K. W.

2018-06-01

We present optical light curves, redshifts, and classifications for 365 spectroscopically confirmed Type Ia supernovae (SNe Ia) discovered by the Pan-STARRS1 (PS1) Medium Deep Survey. We detail improvements to the PS1 SN photometry, astrometry, and calibration that reduce the systematic uncertainties in the PS1 SN Ia distances. We combine the subset of 279 PS1 SNe Ia (0.03 < z < 0.68) with useful distance estimates of SNe Ia from the Sloan Digital Sky Survey (SDSS), SNLS, and various low-z and Hubble Space Telescope samples to form the largest combined sample of SNe Ia, consisting of a total of 1048 SNe Ia in the range of 0.01 < z < 2.3, which we call the “Pantheon Sample.” When combining Planck 2015 cosmic microwave background (CMB) measurements with the Pantheon SN sample, we find {{{Ω }}}m=0.307+/- 0.012 and w=-1.026+/- 0.041 for the wCDM model. When the SN and CMB constraints are combined with constraints from BAO and local H 0 measurements, the analysis yields the most precise measurement of dark energy to date: {w}0=-1.007+/- 0.089 and {w}a=-0.222+/- 0.407 for the {w}0{w}aCDM model. Tension with a cosmological constant previously seen in an analysis of PS1 and low-z SNe has diminished after an increase of 2× in the statistics of the PS1 sample, improved calibration and photometry, and stricter light-curve quality cuts. We find that the systematic uncertainties in our measurements of dark energy are almost as large as the statistical uncertainties, primarily due to limitations of modeling the low-redshift sample. This must be addressed for future progress in using SNe Ia to measure dark energy.

Gravitational baryogenesis in DGP brane cosmology

NASA Astrophysics Data System (ADS)

Atazadeh, K.

2018-06-01

We consider the imbalance of matter and antimatter by using a gravitational baryogenesis mechanism in the background of Dvali-Gabadadze-Porrati (DGP) brane cosmology. By taking into account a flat Friedmann-Lemaître-Robertson-Walker (FLRW) metric in the DGP brane model, we find that for a radiation dominated universe, w=1/3, the ratio of baryon number density to entropy from the gravitational baryogenesis is not zero, contrary to ordinary general relativity. Also, we study the ratio of baryon number density to entropy against the observational constraints in DGP cosmology.

Axion cosmology

NASA Astrophysics Data System (ADS)

Marsh, David J. E.

2016-07-01

Axions comprise a broad class of particles that can play a major role in explaining the unknown aspects of cosmology. They are also well-motivated within high energy physics, appearing in theories related to CP-violation in the standard model, supersymmetric theories, and theories with extra-dimensions, including string theory, and so axion cosmology offers us a unique view onto these theories. I review the motivation and models for axions in particle physics and string theory. I then present a comprehensive and pedagogical view on the cosmology and astrophysics of axion-like particles, starting from inflation and progressing via BBN, the CMB, reionization and structure formation, up to the present-day Universe. Topics covered include: axion dark matter (DM); direct and indirect detection of axions, reviewing existing and future experiments; axions as dark radiation; axions and the cosmological constant problem; decays of heavy axions; axions and stellar astrophysics; black hole superradiance; axions and astrophysical magnetic fields; axion inflation, and axion DM as an indirect probe of inflation. A major focus is on the population of ultralight axions created via vacuum realignment, and its role as a DM candidate with distinctive phenomenology. Cosmological observations place robust constraints on the axion mass and relic density in this scenario, and I review where such constraints come from. I next cover aspects of galaxy formation with axion DM, and ways this can be used to further search for evidence of axions. An absolute lower bound on DM particle mass is established. It is ma > 10-24eV from linear observables, extending to ma ≳ 10-22eV from non-linear observables, and has the potential to reach ma ≳ 10-18eV in the future. These bounds are weaker if the axion is not all of the DM, giving rise to limits on the relic density at low mass. This leads to the exciting possibility that the effects of axion DM on structure formation could one day be detected

HICOSMO: cosmology with a complete sample of galaxy clusters - II. Cosmological results

NASA Astrophysics Data System (ADS)

Schellenberger, G.; Reiprich, T. H.

2017-10-01

The X-ray bright, hot gas in the potential well of a galaxy cluster enables systematic X-ray studies of samples of galaxy clusters to constrain cosmological parameters. HIFLUGCS consists of the 64 X-ray brightest galaxy clusters in the Universe, building up a local sample. Here, we utilize this sample to determine, for the first time, individual hydrostatic mass estimates for all the clusters of the sample and, by making use of the completeness of the sample, we quantify constraints on the two interesting cosmological parameters, Ωm and σ8. We apply our total hydrostatic and gas mass estimates from the X-ray analysis to a Bayesian cosmological likelihood analysis and leave several parameters free to be constrained. We find Ωm = 0.30 ± 0.01 and σ8 = 0.79 ± 0.03 (statistical uncertainties, 68 per cent credibility level) using our default analysis strategy combining both a mass function analysis and the gas mass fraction results. The main sources of biases that we correct here are (1) the influence of galaxy groups (incompleteness in parent samples and differing behaviour of the Lx-M relation), (2) the hydrostatic mass bias, (3) the extrapolation of the total mass (comparing various methods), (4) the theoretical halo mass function and (5) other physical effects (non-negligible neutrino mass). We find that galaxy groups introduce a strong bias, since their number density seems to be over predicted by the halo mass function. On the other hand, incorporating baryonic effects does not result in a significant change in the constraints. The total (uncorrected) systematic uncertainties (∼20 per cent) clearly dominate the statistical uncertainties on cosmological parameters for our sample.

Cosmology based on f(R) gravity with O(1) eV sterile neutrino

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chudaykin, Anton S.; Gorbunov, Dmitry S.; Starobinsky, Alexei A.

2015-05-01

We address the cosmological role of an additional O(1) eV sterile neutrino in modified gravity models. We confront the present cosmological data with predictions of the FLRW cosmological model based on a variant of f(R) modified gravity proposed by one of the authors previously. This viable cosmological model which deviation from general relativity with a cosmological constant Λ decreases as R{sup −2n} for large, but not too large values of the Ricci scalar R (while no Λ is introduced by hand at small R) provides an alternative explanation of present dark energy and the accelerated expansion of the Universe (themore » case n=2 is considered in the paper). Various up-to-date cosmological data sets exploited include measurements of the cosmic microwave background (CMB) anisotropy, the CMB lensing potential, the baryon acoustic oscillations (BAO), the cluster mass function and the Hubble constant. We find that the CMB+BAO constraints strongly restrict the sum of neutrino masses from above. This excludes values of the model parameter λ∼ 1 for which distinctive cosmological features of the model are mostly pronounced as compared to the ΛCDM model, since then free streaming damping of perturbations due to neutrino rest masses is not sufficient to compensate their extra growth occurring in f(R) modified gravity. Thus, in the gravity sector we obtain λ>8.2 (2σ) with the account of systematic uncertainties in galaxy cluster mass function measurements and λ>9.4 (2σ) without them. At the same time in the latter case we find for the sterile neutrino mass 0.47 eV < m{sub ν, sterile} < 1 eV (2σ) assuming that the sterile neutrinos are thermalized and the active neutrinos are massless, not significantly larger than in the standard ΛCDM with the same data set: 0.45 eV < m{sub ν, sterile} < 0.92 eV (2σ). However, a possible discovery of a sterile neutrino with the mass m{sub ν, sterile} ≈ 1.5 eV motivated by various anomalies in neutrino

KiDS-450: cosmological constraints from weak-lensing peak statistics - II: Inference from shear peaks using N-body simulations

NASA Astrophysics Data System (ADS)

Martinet, Nicolas; Schneider, Peter; Hildebrandt, Hendrik; Shan, HuanYuan; Asgari, Marika; Dietrich, Jörg P.; Harnois-Déraps, Joachim; Erben, Thomas; Grado, Aniello; Heymans, Catherine; Hoekstra, Henk; Klaes, Dominik; Kuijken, Konrad; Merten, Julian; Nakajima, Reiko

2018-02-01

We study the statistics of peaks in a weak-lensing reconstructed mass map of the first 450 deg2 of the Kilo Degree Survey (KiDS-450). The map is computed with aperture masses directly applied to the shear field with an NFW-like compensated filter. We compare the peak statistics in the observations with that of simulations for various cosmologies to constrain the cosmological parameter S_8 = σ _8 √{Ω _m/0.3}, which probes the (Ωm, σ8) plane perpendicularly to its main degeneracy. We estimate S8 = 0.750 ± 0.059, using peaks in the signal-to-noise range 0 ≤ S/N ≤ 4, and accounting for various systematics, such as multiplicative shear bias, mean redshift bias, baryon feedback, intrinsic alignment, and shear-position coupling. These constraints are ˜ 25 per cent tighter than the constraints from the high significance peaks alone (3 ≤ S/N ≤ 4) which typically trace single-massive haloes. This demonstrates the gain of information from low-S/N peaks. However, we find that including S/N < 0 peaks does not add further information. Our results are in good agreement with the tomographic shear two-point correlation function measurement in KiDS-450. Combining shear peaks with non-tomographic measurements of the shear two-point correlation functions yields a ˜20 per cent improvement in the uncertainty on S8 compared to the shear two-point correlation functions alone, highlighting the great potential of peaks as a cosmological probe.

The covariant entropy conjecture and concordance cosmological models

NASA Astrophysics Data System (ADS)

He, Song; Zhang, Hongbao

2008-10-01

Recently a covariant entropy conjecture has been proposed for dynamical horizons. We apply this conjecture to concordance cosmological models, namely, those cosmological models filled with perfect fluids, in the presence of a positive cosmological constant. As a result, we find that this conjecture has a severe constraint power. Not only does this conjecture rule out those cosmological models disfavored by the anthropic principle, but also it imposes an upper bound 10-60 on the cosmological constant for our own universe, which thus provides an alternative macroscopic perspective for understanding the long-standing cosmological constant problem.

Estimate of the cosmological bispectrum from the MAXIMA-1 cosmic microwave background map.

PubMed

Santos, M G; Balbi, A; Borrill, J; Ferreira, P G; Hanany, S; Jaffe, A H; Lee, A T; Magueijo, J; Rabii, B; Richards, P L; Smoot, G F; Stompor, R; Winant, C D; Wu, J H P

2002-06-17

We use the measurement of the cosmic microwave background taken during the MAXIMA-1 flight to estimate the bispectrum of cosmological perturbations. We propose an estimator for the bispectrum that is appropriate in the flat sky approximation, apply it to the MAXIMA-1 data, and evaluate errors using bootstrap methods. We compare the estimated value with what would be expected if the sky signal were Gaussian and find that it is indeed consistent, with a chi(2) per degree of freedom of approximately unity. This measurement places constraints on models of inflation.

Constraints on moduli cosmology from the production of dark matter and baryon isocurvature fluctuations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lemoine, Martin; Martin, Jerome; Yokoyama, Jun'ichi

2009-12-15

We set constraints on moduli cosmology from the production of dark matter - radiation and baryon -radiation isocurvature fluctuations through modulus decay, assuming the modulus remains light during inflation. We find that the moduli problem becomes worse at the perturbative level as a significant part of the parameter space m{sub {sigma}} (modulus mass) - {sigma}{sub inf} (modulus vacuum expectation value at the end of inflation) is constrained by the nonobservation of significant isocurvature fluctuations. We discuss in detail the evolution of the modulus vacuum expectation value and perturbations, in particular, the consequences of Hubble scale corrections to the modulus potential,more » and the stochastic motion of the modulus during inflation. We show, in particular, that a high modulus mass scale m{sub {sigma}} > or approx. 100 TeV, which allows the modulus to evade big bang nucleosynthesis constraints is strongly constrained at the perturbative level. We find that generically, solving the moduli problem requires the inflationary scale to be much smaller than 10{sup 13} GeV.« less

Hybrid Inflation: Multi-field Dynamics and Cosmological Constraints

NASA Astrophysics Data System (ADS)

Clesse, Sébastien

2011-09-01

The dynamics of hybrid models is usually approximated by the evolution of a scalar field slowly rolling along a nearly flat valley. Inflation ends with a waterfall phase, due to a tachyonic instability. This final phase is usually assumed to be nearly instantaneous. In this thesis, we go beyond these approximations and analyze the exact 2-field dynamics of hybrid models. Several effects are put in evidence: 1) the possible slow-roll violations along the valley induce the non existence of inflation at small field values. Provided super-planckian fields, the scalar spectrum of the original model is red, in agreement with observations. 2) The initial field values are not fine-tuned along the valley but also occupy a considerable part of the field space exterior to it. They form a structure with fractal boundaries. Using bayesian methods, their distribution in the whole parameter space is studied. Natural bounds on the potential parameters are derived. 3) For the original model, inflation is found to continue for more than 60 e-folds along waterfall trajectories in some part of the parameter space. The scalar power spectrum of adiabatic perturbations is modified and is generically red, possibly in agreement with CMB observations. Topological defects are conveniently stretched outside the observable Universe. 4) The analysis of the initial conditions is extended to the case of a closed Universe, in which the initial singularity is replaced by a classical bounce. In the third part of the thesis, we study how the present CMB constraints on the cosmological parameters could be ameliorated with the observation of the 21cm cosmic background, by future giant radio-telescopes. Forecasts are determined for a characteristic Fast Fourier Transform Telescope, by using both Fisher matrix and MCMC methods.

Solar system constraints on disformal gravity theories

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ip, Hiu Yan; Schmidt, Fabian; Sakstein, Jeremy, E-mail: iphys@mpa-garching.mpg.de, E-mail: jeremy.sakstein@port.ac.uk, E-mail: fabians@mpa-garching.mpg.de

Disformal theories of gravity are scalar-tensor theories where the scalar couples derivatively to matter via the Jordan frame metric. These models have recently attracted interest in the cosmological context since they admit accelerating solutions. We derive the solution for a static isolated mass in generic disformal gravity theories and transform it into the parameterised post-Newtonian form. This allows us to investigate constraints placed on such theories by local tests of gravity. The tightest constraints come from preferred-frame effects due to the motion of the Solar System with respect to the evolving cosmological background field. The constraints we obtain improve uponmore » the previous solar system constraints by two orders of magnitude, and constrain the scale of the disformal coupling for generic models to ℳ ∼> 100 eV. These constraints render all disformal effects irrelevant for cosmology.« less

Cosmology with photometric weak lensing surveys: Constraints with redshift tomography of convergence peaks and moments

DOE PAGES

Petri, Andrea; May, Morgan; Haiman, Zoltán

2016-09-30

Weak gravitational lensing is becoming a mature technique for constraining cosmological parameters, and future surveys will be able to constrain the dark energy equation of state w. When analyzing galaxy surveys, redshift information has proven to be a valuable addition to angular shear correlations. We forecast parameter constraints on the triplet (Ω m,w,σ 8) for a LSST-like photometric galaxy survey, using tomography of the shear-shear power spectrum, convergence peak counts and higher convergence moments. Here we find that redshift tomography with the power spectrum reduces the area of the 1σ confidence interval in (Ω m,w) space by a factor ofmore » 8 with respect to the case of the single highest redshift bin. We also find that adding non-Gaussian information from the peak counts and higher-order moments of the convergence field and its spatial derivatives further reduces the constrained area in (Ω m,w) by factors of 3 and 4, respectively. When we add cosmic microwave background parameter priors from Planck to our analysis, tomography improves power spectrum constraints by a factor of 3. Adding moments yields an improvement by an additional factor of 2, and adding both moments and peaks improves by almost a factor of 3 over power spectrum tomography alone. We evaluate the effect of uncorrected systematic photometric redshift errors on the parameter constraints. In conclusion, we find that different statistics lead to different bias directions in parameter space, suggesting the possibility of eliminating this bias via self-calibration.« less

Effects of self-calibration of intrinsic alignment on cosmological parameter constraints from future cosmic shear surveys

NASA Astrophysics Data System (ADS)

Yao, Ji; Ishak, Mustapha; Lin, Weikang; Troxel, Michael

2017-10-01

Intrinsic alignments (IA) of galaxies have been recognized as one of the most serious contaminants to weak lensing. These systematics need to be isolated and mitigated in order for ongoing and future lensing surveys to reach their full potential. The IA self-calibration (SC) method was shown in previous studies to be able to reduce the GI contamination by up to a factor of 10 for the 2-point and 3-point correlations. The SC method does not require the assumption of an IA model in its working and can extract the GI signal from the same photo-z survey offering the possibility to test and understand structure formation scenarios and their relationship to IA models. In this paper, we study the effects of the IA SC mitigation method on the precision and accuracy of cosmological parameter constraints from future cosmic shear surveys LSST, WFIRST and Euclid. We perform analytical and numerical calculations to estimate the loss of precision and the residual bias in the best fit cosmological parameters after the self-calibration is performed. We take into account uncertainties from photometric redshifts and the galaxy bias. We find that the confidence contours are slightly inflated from applying the SC method itself while a significant increase is due to the inclusion of the photo-z uncertainties. The bias of cosmological parameters is reduced from several-σ, when IA is not corrected for, to below 1-σ after SC is applied. These numbers are comparable to those resulting from applying the method of marginalizing over IA model parameters despite the fact that the two methods operate very differently. We conclude that implementing the SC for these future cosmic-shear surveys will not only allow one to efficiently mitigate the GI contaminant but also help to understand their modeling and link to structure formation.

Cosmological parameter constraints from galaxy-galaxy lensing and galaxy clustering with the SDSS DR7

NASA Astrophysics Data System (ADS)

Mandelbaum, Rachel; Slosar, Anže; Baldauf, Tobias; Seljak, Uroš; Hirata, Christopher M.; Nakajima, Reiko; Reyes, Reinabelle; Smith, Robert E.

2013-06-01

Recent studies have shown that the cross-correlation coefficient between galaxies and dark matter is very close to unity on scales outside a few virial radii of galaxy haloes, independent of the details of how galaxies populate dark matter haloes. This finding makes it possible to determine the dark matter clustering from measurements of galaxy-galaxy weak lensing and galaxy clustering. We present new cosmological parameter constraints based on large-scale measurements of spectroscopic galaxy samples from the Sloan Digital Sky Survey (SDSS) data release 7. We generalize the approach of Baldauf et al. to remove small-scale information (below 2 and 4 h-1 Mpc for lensing and clustering measurements, respectively), where the cross-correlation coefficient differs from unity. We derive constraints for three galaxy samples covering 7131 deg2, containing 69 150, 62 150 and 35 088 galaxies with mean redshifts of 0.11, 0.28 and 0.40. We clearly detect scale-dependent galaxy bias for the more luminous galaxy samples, at a level consistent with theoretical expectations. When we vary both σ8 and Ωm (and marginalize over non-linear galaxy bias) in a flat Λ cold dark matter model, the best-constrained quantity is σ8(Ωm/0.25)0.57 = 0.80 ± 0.05 (1σ, stat. + sys.), where statistical and systematic errors (photometric redshift and shear calibration) have comparable contributions, and we have fixed ns = 0.96 and h = 0.7. These strong constraints on the matter clustering suggest that this method is competitive with cosmic shear in current data, while having very complementary and in some ways less serious systematics. We therefore expect that this method will play a prominent role in future weak lensing surveys. When we combine these data with Wilkinson Microwave Anisotropy Probe 7-year (WMAP7) cosmic microwave background (CMB) data, constraints on σ8, Ωm, H0, wde and ∑mν become 30-80 per cent tighter than with CMB data alone, since our data break several parameter

Cosmological implications of primordial black holes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Luis Bernal, José; Bellomo, Nicola; Raccanelli, Alvise

The possibility that a relevant fraction of the dark matter might be comprised of Primordial Black Holes (PBHs) has been seriously reconsidered after LIGO's detection of a ∼ 30 M {sub ⊙} binary black holes merger. Despite the strong interest in the model, there is a lack of studies on possible cosmological implications and effects on cosmological parameters inference. We investigate correlations with the other standard cosmological parameters using cosmic microwave background observations, finding significant degeneracies, especially with the tilt of the primordial power spectrum and the sound horizon at radiation drag. However, these degeneracies can be greatly reduced withmore » the inclusion of small scale polarization data. We also explore if PBHs as dark matter in simple extensions of the standard ΛCDM cosmological model induces extra degeneracies, especially between the additional parameters and the PBH's ones. Finally, we present cosmic microwave background constraints on the fraction of dark matter in PBHs, not only for monochromatic PBH mass distributions but also for popular extended mass distributions. Our results show that extended mass distribution's constraints are tighter, but also that a considerable amount of constraining power comes from the high-ℓ polarization data. Moreover, we constrain the shape of such mass distributions in terms of the correspondent constraints on the PBH mass fraction.« less

Observational constraints on cosmological models with Chaplygin gas and quadratic equation of state

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sharov, G.S., E-mail: german.sharov@mail.ru

Observational manifestations of accelerated expansion of the universe, in particular, recent data for Type Ia supernovae, baryon acoustic oscillations, for the Hubble parameter H ( z ) and cosmic microwave background constraints are described with different cosmological models. We compare the ΛCDM, the models with generalized and modified Chaplygin gas and the model with quadratic equation of state. For these models we estimate optimal model parameters and their permissible errors with different approaches to calculation of sound horizon scale r {sub s} ( z {sub d} ). Among the considered models the best value of χ{sup 2} is achieved formore » the model with quadratic equation of state, but it has 2 additional parameters in comparison with the ΛCDM and therefore is not favored by the Akaike information criterion.« less

Measuring Cosmological Parameters with Photometrically Classified Pan-STARRS Supernovae

NASA Astrophysics Data System (ADS)

Jones, David; Scolnic, Daniel; Riess, Adam; Rest, Armin; Kirshner, Robert; Berger, Edo; Kessler, Rick; Pan, Yen-Chen; Foley, Ryan; Chornock, Ryan; Ortega, Carolyn; Challis, Peter; Burgett, William; Chambers, Kenneth; Draper, Peter; Flewelling, Heather; Huber, Mark; Kaiser, Nick; Kudritzki, Rolf; Metcalfe, Nigel; Tonry, John; Wainscoat, Richard J.; Waters, Chris; Gall, E. E. E.; Kotak, Rubina; McCrum, Matt; Smartt, Stephen; Smith, Ken

2018-01-01

We use nearly 1,200 supernovae (SNe) from Pan-STARRS and ~200 low-z (z < 0.1) SNe Ia to measure cosmological parameters. Though most of these SNe lack spectroscopic classifications, in a previous paper we demonstrated that photometrically classified SNe can still be used to infer unbiased cosmological parameters by using a Bayesian methodology that marginalizes over core-collapse (CC) SN contamination. Our sample contains nearly twice as many SNe as the largest previous compilation of SNe Ia. Combining SNe with Cosmic Microwave Background (CMB) constraints from the Planck satellite, we measure the dark energy equation of state parameter w to be -0.986±0.058 (stat+sys). If we allow w to evolve with redshift as w(a) = w0 + wa(1-a), we find w0 = -0.923±0.148 and wa = -0.404±0.797. These results are consistent with measurements of cosmological parameters from the JLA and from a new analysis of 1049 spectroscopically confirmed SNe Ia (Scolnic et al. 2017). We try four different photometric classification priors for Pan-STARRS SNe and two alternate ways of modeling the CC SN contamination, finding that none of these variants gives a w that differs by more than 1% from the baseline measurement. The systematic uncertainty on w due to marginalizing over the CC SN contamination, σwCC = 0.019, is approximately equal to the photometric calibration uncertainty and is lower than the systematic uncertainty in the SN\\,Ia dispersion model (σwdisp = 0.024). Our data provide one of the best current constraints on w, demonstrating that samples with ~5% CC SN contamination can give competitive cosmological constraints when the contaminating distribution is marginalized over in a Bayesian framework.

Constraints on Cosmology and Gravity from the Dynamics of Voids.

PubMed

Hamaus, Nico; Pisani, Alice; Sutter, P M; Lavaux, Guilhem; Escoffier, Stéphanie; Wandelt, Benjamin D; Weller, Jochen

2016-08-26

The Universe is mostly composed of large and relatively empty domains known as cosmic voids, whereas its matter content is predominantly distributed along their boundaries. The remaining material inside them, either dark or luminous matter, is attracted to these boundaries and causes voids to expand faster and to grow emptier over time. Using the distribution of galaxies centered on voids identified in the Sloan Digital Sky Survey and adopting minimal assumptions on the statistical motion of these galaxies, we constrain the average matter content Ω_{m}=0.281±0.031 in the Universe today, as well as the linear growth rate of structure f/b=0.417±0.089 at median redshift z[over ¯]=0.57, where b is the galaxy bias (68% C.L.). These values originate from a percent-level measurement of the anisotropic distortion in the void-galaxy cross-correlation function, ϵ=1.003±0.012, and are robust to consistency tests with bootstraps of the data and simulated mock catalogs within an additional systematic uncertainty of half that size. They surpass (and are complementary to) existing constraints by unlocking cosmological information on smaller scales through an accurate model of nonlinear clustering and dynamics in void environments. As such, our analysis furnishes a powerful probe of deviations from Einstein's general relativity in the low-density regime which has largely remained untested so far. We find no evidence for such deviations in the data at hand.

Inner space/outer space - The interface between cosmology and particle physics

NASA Astrophysics Data System (ADS)

Kolb, Edward W.; Turner, Michael S.; Lindley, David; Olive, Keith; Seckel, David

A collection of papers covering the synthesis between particle physics and cosmology is presented. The general topics addressed include: standard models of particle physics and cosmology; microwave background radiation; origin and evolution of large-scale structure; inflation; massive magnetic monopoles; supersymmetry, supergravity, and quantum gravity; cosmological constraints on particle physics; Kaluza-Klein cosmology; and future directions and connections in particle physics and cosmology.

KiDS-450 + 2dFLenS: Cosmological parameter constraints from weak gravitational lensing tomography and overlapping redshift-space galaxy clustering

NASA Astrophysics Data System (ADS)

Joudaki, Shahab; Blake, Chris; Johnson, Andrew; Amon, Alexandra; Asgari, Marika; Choi, Ami; Erben, Thomas; Glazebrook, Karl; Harnois-Déraps, Joachim; Heymans, Catherine; Hildebrandt, Hendrik; Hoekstra, Henk; Klaes, Dominik; Kuijken, Konrad; Lidman, Chris; Mead, Alexander; Miller, Lance; Parkinson, David; Poole, Gregory B.; Schneider, Peter; Viola, Massimo; Wolf, Christian

2018-03-01

We perform a combined analysis of cosmic shear tomography, galaxy-galaxy lensing tomography, and redshift-space multipole power spectra (monopole and quadrupole) using 450 deg2 of imaging data by the Kilo Degree Survey (KiDS-450) overlapping with two spectroscopic surveys: the 2-degree Field Lensing Survey (2dFLenS) and the Baryon Oscillation Spectroscopic Survey (BOSS). We restrict the galaxy-galaxy lensing and multipole power spectrum measurements to the overlapping regions with KiDS, and self-consistently compute the full covariance between the different observables using a large suite of N-body simulations. We methodically analyse different combinations of the observables, finding that the galaxy-galaxy lensing measurements are particularly useful in improving the constraint on the intrinsic alignment amplitude, while the multipole power spectra are useful in tightening the constraints along the lensing degeneracy direction. The fully combined constraint on S_8 ≡ σ _8 √{Ω _m/0.3}=0.742± 0.035, which is an improvement by 20 per cent compared to KiDS alone, corresponds to a 2.6σ discordance with Planck, and is not significantly affected by fitting to a more conservative set of scales. Given the tightening of the parameter space, we are unable to resolve the discordance with an extended cosmology that is simultaneously favoured in a model selection sense, including the sum of neutrino masses, curvature, evolving dark energy and modified gravity. The complementarity of our observables allows for constraints on modified gravity degrees of freedom that are not simultaneously bounded with either probe alone, and up to a factor of three improvement in the S8 constraint in the extended cosmology compared to KiDS alone.

Cosmology with CLASS

NASA Astrophysics Data System (ADS)

Watts, Duncan; CLASS Collaboration

2018-01-01

The Cosmology Large Angular Scale Surveyor (CLASS) will use large-scale measurements of the polarized cosmic microwave background (CMB) to constrain the physics of inflation, reionization, and massive neutrinos. The experiment is designed to characterize the largest scales, which are inaccessible to most ground-based experiments, and remove Galactic foregrounds from the CMB maps. In this dissertation talk, I present simulations of CLASS data and demonstrate their ability to constrain the simplest single-field models of inflation and to reduce the uncertainty of the optical depth to reionization, τ, to near the cosmic variance limit, significantly improving on current constraints. These constraints will bring a qualitative shift in our understanding of standard ΛCDM cosmology. In particular, CLASS's measurement of τ breaks cosmological parameter degeneracies. Probes of large scale structure (LSS) test the effect of neutrino free-streaming at small scales, which depends on the mass of the neutrinos. CLASS's τ measurement, when combined with next-generation LSS and BAO measurements, will enable a 4σ detection of neutrino mass, compared with 2σ without CLASS data.. I will also briefly discuss the CLASS experiment's measurements of circular polarization of the CMB and the implications of the first-such near-all-sky map.

Late time cosmological phase transitions 1: Particle physics models and cosmic evolution

NASA Technical Reports Server (NTRS)

Frieman, Joshua A.; Hill, Christopher T.; Watkins, Richard

1991-01-01

We described a natural particle physics basis for late-time phase transitions in the universe. Such a transition can seed the formation of large-scale structure while leaving a minimal imprint upon the microwave background anisotropy. The key ingredient is an ultra-light pseudo-Nambu-Goldstone boson with an astronomically large (O(kpc-Mpc)) Compton wavelength. We analyze the cosmological signatures of and constraints upon a wide class of scenarios which do not involve domain walls. In addition to seeding structure, coherent ultra-light bosons may also provide unclustered dark matter in a spatially flat universe, omega sub phi approx. = 1.

Cosmological tests of modified gravity.

PubMed

Koyama, Kazuya

2016-04-01

We review recent progress in the construction of modified gravity models as alternatives to dark energy as well as the development of cosmological tests of gravity. Einstein's theory of general relativity (GR) has been tested accurately within the local universe i.e. the Solar System, but this leaves the possibility open that it is not a good description of gravity at the largest scales in the Universe. This being said, the standard model of cosmology assumes GR on all scales. In 1998, astronomers made the surprising discovery that the expansion of the Universe is accelerating, not slowing down. This late-time acceleration of the Universe has become the most challenging problem in theoretical physics. Within the framework of GR, the acceleration would originate from an unknown dark energy. Alternatively, it could be that there is no dark energy and GR itself is in error on cosmological scales. In this review, we first give an overview of recent developments in modified gravity theories including f(R) gravity, braneworld gravity, Horndeski theory and massive/bigravity theory. We then focus on common properties these models share, such as screening mechanisms they use to evade the stringent Solar System tests. Once armed with a theoretical knowledge of modified gravity models, we move on to discuss how we can test modifications of gravity on cosmological scales. We present tests of gravity using linear cosmological perturbations and review the latest constraints on deviations from the standard [Formula: see text]CDM model. Since screening mechanisms leave distinct signatures in the non-linear structure formation, we also review novel astrophysical tests of gravity using clusters, dwarf galaxies and stars. The last decade has seen a number of new constraints placed on gravity from astrophysical to cosmological scales. Thanks to on-going and future surveys, cosmological tests of gravity will enjoy another, possibly even more, exciting ten years.

Cosmology with orthogonal nilpotent superfields

NASA Astrophysics Data System (ADS)

Ferrara, Sergio; Kallosh, Renata; Thaler, Jesse

2016-02-01

We study the application of a supersymmetric model with two constrained supermultiplets to inflationary cosmology. The first superfield S is a stabilizer chiral superfield satisfying a nilpotency condition of degree 2, S2=0 . The second superfield Φ is the inflaton chiral superfield, which can be combined into a real superfield B ≡1/2 i (Φ -Φ ¯ ) . The real superfield B is orthogonal to S , S B =0 , and satisfies a nilpotency condition of degree 3, B3=0 . We show that these constraints remove from the spectrum the complex scalar sgoldstino, the real scalar inflaton partner (i.e. the "sinflaton"), and the fermionic inflatino. The corresponding supergravity model with de Sitter vacua describes a graviton, a massive gravitino, and one real scalar inflaton, with both the goldstino and inflatino being absent in unitary gauge. We also discuss relaxed superfield constraints where S2=0 and S Φ ¯ is chiral, which removes the sgoldstino and inflatino, but leaves the sinflaton in the spectrum. The cosmological model building in both of these inflatino-less models offers some advantages over existing constructions.

Constraints on cosmological models from strong gravitational lensing systems

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cao, Shuo; Pan, Yu; Zhu, Zong-Hong

Strong lensing has developed into an important astrophysical tool for probing both cosmology and galaxies (their structure, formation, and evolution). Using the gravitational lensing theory and cluster mass distribution model, we try to collect a relatively complete observational data concerning the Hubble constant independent ratio between two angular diameter distances D{sub ds}/D{sub s} from various large systematic gravitational lens surveys and lensing by galaxy clusters combined with X-ray observations, and check the possibility to use it in the future as complementary to other cosmological probes. On one hand, strongly gravitationally lensed quasar-galaxy systems create such a new opportunity by combiningmore » stellar kinematics (central velocity dispersion measurements) with lensing geometry (Einstein radius determination from position of images). We apply such a method to a combined gravitational lens data set including 70 data points from Sloan Lens ACS (SLACS) and Lens Structure and Dynamics survey (LSD). On the other hand, a new sample of 10 lensing galaxy clusters with redshifts ranging from 0.1 to 0.6 carefully selected from strong gravitational lensing systems with both X-ray satellite observations and optical giant luminous arcs, is also used to constrain three dark energy models (ΛCDM, constant w and CPL) under a flat universe assumption. For the full sample (n = 80) and the restricted sample (n = 46) including 36 two-image lenses and 10 strong lensing arcs, we obtain relatively good fitting values of basic cosmological parameters, which generally agree with the results already known in the literature. This results encourages further development of this method and its use on larger samples obtained in the future.« less

Planck 2015 Cosmological results

NASA Astrophysics Data System (ADS)

Tristram, Matthieu

2015-08-01

On behalf of the Planck collaboration, I will present the cosmological results from the 2015 release. The new release now include polarization data from both the LFI and the HFI.I will focus on the impact of the polarization on both the standard LCDM model and its basic extensions. I will compare these constraints with other cosmological probes such as BAO, gravitational lensing and redshift space distortions.LCDM is still a very good fit of the Planck CMB data. The scalar fluctuations are consistent with adiabatic modes.

Relativistic numerical cosmology with silent universes

NASA Astrophysics Data System (ADS)

Bolejko, Krzysztof

2018-01-01

Relativistic numerical cosmology is most often based either on the exact solutions of the Einstein equations, or perturbation theory, or weak-field limit, or the BSSN formalism. The silent universe provides an alternative approach to investigate relativistic evolution of cosmological systems. The silent universe is based on the solution of the Einstein equations in 1  +  3 comoving coordinates with additional constraints imposed. These constraints include: the gravitational field is sourced by dust and cosmological constant only, both rotation and magnetic part of the Weyl tensor vanish, and the shear is diagnosable. This paper describes the code simsilun (free software distributed under the terms of the reposi General Public License), which implements the equations of the silent universe. The paper also discusses applications of the silent universe and it uses the Millennium simulation to set up the initial conditions for the code simsilun. The simulation obtained this way consists of 16 777 216 worldlines, which are evolved from z  =  80 to z  =  0. Initially, the mean evolution (averaged over the whole domain) follows the evolution of the background ΛCDM model. However, once the evolution of cosmic structures becomes nonlinear, the spatial curvature evolves from ΩK =0 to ΩK ≈ 0.1 at the present day. The emergence of the spatial curvature is associated with ΩM and Ω_Λ being smaller by approximately 0.05 compared to the ΛCDM.

Spinfoam cosmology with the proper vertex amplitude

NASA Astrophysics Data System (ADS)

Vilensky, Ilya

2017-11-01

The proper vertex amplitude is derived from the Engle-Pereira-Rovelli-Livine vertex by restricting to a single gravitational sector in order to achieve the correct semi-classical behaviour. We apply the proper vertex to calculate a cosmological transition amplitude that can be viewed as the Hartle-Hawking wavefunction. To perform this calculation we deduce the integral form of the proper vertex and use extended stationary phase methods to estimate the large-volume limit. We show that the resulting amplitude satisfies an operator constraint whose classical analogue is the Hamiltonian constraint of the Friedmann-Robertson-Walker cosmology. We find that the constraint dynamically selects the relevant family of coherent states and demonstrate a similar dynamic selection in standard quantum mechanics. We investigate the effects of dynamical selection on long-range correlations.

Hamiltonian BFV-BRST theory of closed quantum cosmological models

NASA Astrophysics Data System (ADS)

Kamenshchik, A. Yu.; Lyakhovich, S. L.

1997-02-01

We introduce and study a new discrete basis of gravity constraints by making use of harmonic expansion for closed cosmological models. The full set of constraints is split into area-preserving spatial diffeomorphisms, forming closed subalgebra, and Virasoro-like generators. Operational Hamiltonian BFV-BRST quantization is performed in the framework of perturbative expansion in the dimensionless parameter, which is a positive power of the ratio of Planckian volume to the volume of the Universe. For the (N + 1)-dimensional generalization of stationary closed Bianchi-I cosmology the nilpotency condition for the BRST operator is examined in the first quantum approximation. It turns out that a certain relationship between the dimensionality of the space and the spectrum of matter fields emerges from the requirement of quantum consistency of the model.

Hamiltonian BFV-BRST theory of closed quantum cosmological models

NASA Astrophysics Data System (ADS)

Kamenshchik, A. Yu.; Lyakhovich, S. L.

1997-08-01

We introduce and study a new discrete basis of gravity constraints by making use of the harmonic expansion for closed cosmological models. The full set of constraints is split into area-preserving spatial diffeomorphisms, forming a closed subalgebra, and Virasoro-like generators. The operatorial Hamiltonian BFV-BRST quantization is performed in the framework of a perturbative expansion in the dimensionless parameter which is a positive power of the ratio of the Planck volume to the volume of the Universe. For the (N + 1) - dimensional generalization of a stationary closed Bianchi-I cosmology the nilpotency condition for the BRST operator is examined in the first quantum approximation. It turns out that a relationship between the dimensionality of the space and the spectrum of matter fields emerges from the requirement of quantum consistency of the model.

Integrated cosmological probes: Extended analysis

NASA Astrophysics Data System (ADS)

Nicola, Andrina; Refregier, Alexandre; Amara, Adam

2017-04-01

Recent progress in cosmology has relied on combining different cosmological probes. In an earlier work, we implemented an integrated approach to cosmology where the probes are combined into a common framework at the map level. This has the advantage of taking full account of the correlations between the different probes, to provide a stringent test of systematics and of the validity of the cosmological model. We extend this analysis to include not only cosmic microwave background (CMB) temperature, galaxy clustering, and weak lensing from the Sloan Digital Sky Survey (SDSS) but also CMB lensing, weak lensing from Dark Energy Survey Science Verification (DES SV) data, type Ia supernova, and H0 measurements. This yields 12 auto- and cross-power spectra which include the CMB temperature power spectrum, cosmic shear, galaxy clustering, galaxy-galaxy lensing, CMB lensing cross-correlation along with other cross-correlations, as well as background probes. Furthermore, we extend the treatment of systematic uncertainties by studying the impact of intrinsic alignments, baryonic corrections, residual foregrounds in the CMB temperature, and calibration factors for the different power spectra. For Λ CDM , we find results that are consistent with our earlier work. Given our enlarged data set and systematics treatment, this confirms the robustness of our analysis and results. Furthermore, we find that our best-fit cosmological model gives a good fit to all the data we consider with no signs of tensions within our analysis. We also find our constraints to be consistent with those found by the joint analysis of the WMAP9, SPT, and ACT CMB experiments and the KiDS weak lensing survey. Comparing with the Planck Collaboration results, we see a broad agreement, but there are indications of a tension from the marginalized constraints in most pairs of cosmological parameters. Since our analysis includes CMB temperature Planck data at 10 <ℓ<610 , the tension appears to arise between

Inflationary spectra with inverse-volume corrections in loop quantum cosmology and their observational constraints from Planck 2015 data

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhu, Tao; Wang, Anzhong; Wu, Qiang

We first derive the primordial power spectra, spectral indices and runnings of both scalar and tensor perturbations of a flat inflationary universe to the second-order approximations of the slow-roll parameters, in the framework of loop quantum cosmology with the inverse-volume quantum corrections. This represents an extension of our previous work in which the parameter σ was assumed to be an integer, where σ characterizes the quantum corrections and in general can take any of values from the range σ  element of  (0, 6]. Restricting to the first-order approximations of the slow-roll parameters, we find corrections to the results obtained previously inmore » the literature, and point out the causes for such errors. To our best knowledge, these represent the most accurate calculations of scalar and tensor perturbations given so far in the literature. Then, fitting the perturbations to the recently released data by Planck (2015), we obtain the most severe constraints for various values of σ. Using these constraints as our referring point, we discuss whether these quantum gravitational corrections can lead to measurable signatures in the future cosmological observations. We show that, depending on the value of σ, the scale-dependent contributions to the relativistic inflationary spectra due to the inverse-volume corrections could be well within the range of the detectability of the forthcoming generations of experiments, such as the Stage IV experiments.« less

Cosmological implications of different baryon acoustic oscillation data

NASA Astrophysics Data System (ADS)

Wang, Shuang; Hu, YaZhou; Li, Miao

2017-04-01

In this work, we explore the cosmological implications of different baryon acoustic oscillation (BAO) data, including the BAO data extracted by using the spherically averaged one-dimensional galaxy clustering (GC) statistics (hereafter BAO1) and the BAO data obtained by using the anisotropic two-dimensional GC statistics (hereafter BAO2). To make a comparison, we also take into account the case without BAO data (hereafter NO BAO). Firstly, making use of these BAO data, as well as the SNLS3 type Ia supernovae sample and the Planck distance priors data, we give the cosmological constraints of the ΛCDM, the wCDM, and the Chevallier-Polarski-Linder (CPL) model. Then, we discuss the impacts of different BAO data on cosmological consquences, including its effects on parameter space, equation of state (EoS), figure of merit (FoM), deceleration-acceleration transition redshift, Hubble parameter H( z), deceleration parameter q( z), statefinder hierarchy S 3 (1)( z), S 4 (1)( z) and cosmic age t( z). We find that: (1) NO BAO data always give a smallest fractional matter density Ω m0, a largest fractional curvature density Ωk0 and a largest Hubble constant h; in contrast, BAO1 data always give a largest Ω m0, a smallest Ω k0 and a smallest h. (2) For the wCDM and the CPL model, NO BAO data always give a largest EoS w; in contrast, BAO2 data always give a smallest w. (3) Compared with the case of BAO1, BAO2 data always give a slightly larger FoM, and thus can give a cosmological constraint with a slightly better accuracy. (4) The impacts of different BAO data on the cosmic evolution and the comic age are very small, and cannot be distinguished by using various dark energy diagnoses and the cosmic age data.

A fresh look at linear cosmological constraints on a decaying Dark Matter component

NASA Astrophysics Data System (ADS)

Poulin, Vivian; Serpico, Pasquale D.; Lesgourgues, Julien

2016-08-01

We consider a cosmological model in which a fraction fdcdm of the Dark Matter (DM) is allowed to decay in an invisible relativistic component, and compute the resulting constraints on both the decay width (or inverse lifetime) Γdcdm and fdcdm from purely gravitational arguments. We report a full derivation of the Boltzmann hierarchy, correcting a mistake in previous literature, and compute the impact of the decay—as a function of the lifetime—on the CMB and matter power spectra. From CMB only, we obtain that no more than 3.8% of the DM could have decayed in the time between recombination and today (all bounds quoted at 95% CL). We also comment on the important application of this bound to the case where primordial black holes constitute DM, a scenario notoriously difficult to constrain. For lifetimes longer than the age of the Universe, the bounds can be cast as fdcdmΓdcdm < 6.3×10-3 Gyr-1. For the first time, we also checked that degeneracies with massive neutrinos are broken when information from the large scale structure is used. Even secondary effects like CMB lensing suffice to this purpose. Decaying DM models have been invoked to solve a possible tension between low redshift astronomical measurements of σ8 and Ωm and the ones inferred by Planck. We reassess this claim finding that with the most recent BAO, HST and σ8 data extracted from the CFHT survey, the tension is only slightly reduced despite the two additional free parameters. Nonetheless, the existing tension explains why the bound on fdcdmΓdcdm loosens to fdcdmΓdcdm < 15.9×10-3 Gyr-1 when including such additional data. The bound however improves to fdcdmΓdcdm < 5.9 ×10-3 Gyr-1 if only data consistent with the CMB are included. This highlights the importance of establishing whether the tension is due to real physical effects or unaccounted systematics, for settling the reach of achievable constraints on decaying DM.

Planck 2015 results: XIII. Cosmological parameters

DOE PAGES

Ade, P. A. R.; Aghanim, N.; Arnaud, M.; ...

2016-09-20

single-parameter extension to base ΛCDM we find an upper limit on the tensor-to-scalar ratio of r 0.002< 0.11, consistent with the Planck 2013 results and consistent with the B-mode polarization constraints from a joint analysis of BICEP2, Keck Array, and Planck (BKP) data. Adding the BKP B-mode data to our analysis leads to a tighter constraint of r 0.002 < 0.09 and disfavours inflationarymodels with a V(φ) ∝ φ 2 potential. The addition of Planck polarization data leads to strong constraints on deviations from a purely adiabatic spectrum of fluctuations. We find no evidence for any contribution from isocurvature perturbations or from cosmic defects. Combining Planck data with other astrophysical data, including Type Ia supernovae, the equation of state of dark energy is constrained to w = -1.006 ± 0.045, consistent with the expected value for a cosmological constant. The standard big bang nucleosynthesis predictions for the helium and deuterium abundances for the best-fit Planck base ΛCDM cosmology are in excellent agreement with observations. We also constraints on annihilating dark matter and on possible deviations from the standard recombination history. In neither case do we find no evidence for new physics. The Planck results for base ΛCDM are in good agreement with baryon acoustic oscillation data and with the JLA sample of Type Ia supernovae. However, as in the 2013 analysis, the amplitude of the fluctuation spectrum is found to be higher than inferred from some analyses of rich cluster counts and weak gravitational lensing. We show that these tensions cannot easily be resolved with simple modifications of the base ΛCDM cosmology. Finally, apart from these tensions, the base ΛCDM cosmology provides an excellent description of the Planck CMB observations and many other astrophysical data sets.« less

Planck 2015 results. XIII. Cosmological parameters

NASA Astrophysics Data System (ADS)

Planck Collaboration; Ade, P. A. R.; Aghanim, N.; Arnaud, M.; Ashdown, M.; Aumont, J.; Baccigalupi, C.; Banday, A. J.; Barreiro, R. B.; Bartlett, J. G.; Bartolo, N.; Battaner, E.; Battye, R.; Benabed, K.; Benoît, A.; Benoit-Lévy, A.; Bernard, J.-P.; Bersanelli, M.; Bielewicz, P.; Bock, J. J.; Bonaldi, A.; Bonavera, L.; Bond, J. R.; Borrill, J.; Bouchet, F. R.; Boulanger, F.; Bucher, M.; Burigana, C.; Butler, R. C.; Calabrese, E.; Cardoso, J.-F.; Catalano, A.; Challinor, A.; Chamballu, A.; Chary, R.-R.; Chiang, H. C.; Chluba, J.; Christensen, P. R.; Church, S.; Clements, D. L.; Colombi, S.; Colombo, L. P. L.; Combet, C.; Coulais, A.; Crill, B. P.; Curto, A.; Cuttaia, F.; Danese, L.; Davies, R. D.; Davis, R. J.; de Bernardis, P.; de Rosa, A.; de Zotti, G.; Delabrouille, J.; Désert, F.-X.; Di Valentino, E.; Dickinson, C.; Diego, J. M.; Dolag, K.; Dole, H.; Donzelli, S.; Doré, O.; Douspis, M.; Ducout, A.; Dunkley, J.; Dupac, X.; Efstathiou, G.; Elsner, F.; Enßlin, T. A.; Eriksen, H. K.; Farhang, M.; Fergusson, J.; Finelli, F.; Forni, O.; Frailis, M.; Fraisse, A. A.; Franceschi, E.; Frejsel, A.; Galeotta, S.; Galli, S.; Ganga, K.; Gauthier, C.; Gerbino, M.; Ghosh, T.; Giard, M.; Giraud-Héraud, Y.; Giusarma, E.; Gjerløw, E.; González-Nuevo, J.; Górski, K. M.; Gratton, S.; Gregorio, A.; Gruppuso, A.; Gudmundsson, J. E.; Hamann, J.; Hansen, F. K.; Hanson, D.; Harrison, D. L.; Helou, G.; Henrot-Versillé, S.; Hernández-Monteagudo, C.; Herranz, D.; Hildebrandt, S. R.; Hivon, E.; Hobson, M.; Holmes, W. A.; Hornstrup, A.; Hovest, W.; Huang, Z.; Huffenberger, K. M.; Hurier, G.; Jaffe, A. H.; Jaffe, T. R.; Jones, W. C.; Juvela, M.; Keihänen, E.; Keskitalo, R.; Kisner, T. S.; Kneissl, R.; Knoche, J.; Knox, L.; Kunz, M.; Kurki-Suonio, H.; Lagache, G.; Lähteenmäki, A.; Lamarre, J.-M.; Lasenby, A.; Lattanzi, M.; Lawrence, C. R.; Leahy, J. P.; Leonardi, R.; Lesgourgues, J.; Levrier, F.; Lewis, A.; Liguori, M.; Lilje, P. B.; Linden-Vørnle, M.; López-Caniego, M.; Lubin, P. M.; Macías-Pérez, J. F.; Maggio, G.; Maino, D.; Mandolesi, N.; Mangilli, A.; Marchini, A.; Maris, M.; Martin, P. G.; Martinelli, M.; Martínez-González, E.; Masi, S.; Matarrese, S.; McGehee, P.; Meinhold, P. R.; Melchiorri, A.; Melin, J.-B.; Mendes, L.; Mennella, A.; Migliaccio, M.; Millea, M.; Mitra, S.; Miville-Deschênes, M.-A.; Moneti, A.; Montier, L.; Morgante, G.; Mortlock, D.; Moss, A.; Munshi, D.; Murphy, J. A.; Naselsky, P.; Nati, F.; Natoli, P.; Netterfield, C. B.; Nørgaard-Nielsen, H. U.; Noviello, F.; Novikov, D.; Novikov, I.; Oxborrow, C. A.; Paci, F.; Pagano, L.; Pajot, F.; Paladini, R.; Paoletti, D.; Partridge, B.; Pasian, F.; Patanchon, G.; Pearson, T. J.; Perdereau, O.; Perotto, L.; Perrotta, F.; Pettorino, V.; Piacentini, F.; Piat, M.; Pierpaoli, E.; Pietrobon, D.; Plaszczynski, S.; Pointecouteau, E.; Polenta, G.; Popa, L.; Pratt, G. W.; Prézeau, G.; Prunet, S.; Puget, J.-L.; Rachen, J. P.; Reach, W. T.; Rebolo, R.; Reinecke, M.; Remazeilles, M.; Renault, C.; Renzi, A.; Ristorcelli, I.; Rocha, G.; Rosset, C.; Rossetti, M.; Roudier, G.; Rouillé d'Orfeuil, B.; Rowan-Robinson, M.; Rubiño-Martín, J. A.; Rusholme, B.; Said, N.; Salvatelli, V.; Salvati, L.; Sandri, M.; Santos, D.; Savelainen, M.; Savini, G.; Scott, D.; Seiffert, M. D.; Serra, P.; Shellard, E. P. S.; Spencer, L. D.; Spinelli, M.; Stolyarov, V.; Stompor, R.; Sudiwala, R.; Sunyaev, R.; Sutton, D.; Suur-Uski, A.-S.; Sygnet, J.-F.; Tauber, J. A.; Terenzi, L.; Toffolatti, L.; Tomasi, M.; Tristram, M.; Trombetti, T.; Tucci, M.; Tuovinen, J.; Türler, M.; Umana, G.; Valenziano, L.; Valiviita, J.; Van Tent, F.; Vielva, P.; Villa, F.; Wade, L. A.; Wandelt, B. D.; Wehus, I. K.; White, M.; White, S. D. M.; Wilkinson, A.; Yvon, D.; Zacchei, A.; Zonca, A.

2016-09-01

�CDM we find an upper limit on the tensor-to-scalar ratio of r0.002< 0.11, consistent with the Planck 2013 results and consistent with the B-mode polarization constraints from a joint analysis of BICEP2, Keck Array, and Planck (BKP) data. Adding the BKP B-mode data to our analysis leads to a tighter constraint of r0.002 < 0.09 and disfavours inflationarymodels with a V(φ) ∝ φ2 potential. The addition of Planck polarization data leads to strong constraints on deviations from a purely adiabatic spectrum of fluctuations. We find no evidence for any contribution from isocurvature perturbations or from cosmic defects. Combining Planck data with other astrophysical data, including Type Ia supernovae, the equation of state of dark energy is constrained to w = -1.006 ± 0.045, consistent with the expected value for a cosmological constant. The standard big bang nucleosynthesis predictions for the helium and deuterium abundances for the best-fit Planck base ΛCDM cosmology are in excellent agreement with observations. We also constraints on annihilating dark matter and on possible deviations from the standard recombination history. In neither case do we find no evidence for new physics. The Planck results for base ΛCDM are in good agreement with baryon acoustic oscillation data and with the JLA sample of Type Ia supernovae. However, as in the 2013 analysis, the amplitude of the fluctuation spectrum is found to be higher than inferred from some analyses of rich cluster counts and weak gravitational lensing. We show that these tensions cannot easily be resolved with simple modifications of the base ΛCDM cosmology. Apart from these tensions, the base ΛCDM cosmology provides an excellent description of the Planck CMB observations and many other astrophysical data sets.

Planck 2015 results: XIII. Cosmological parameters

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ade, P. A. R.; Aghanim, N.; Arnaud, M.

single-parameter extension to base ΛCDM we find an upper limit on the tensor-to-scalar ratio of r 0.002< 0.11, consistent with the Planck 2013 results and consistent with the B-mode polarization constraints from a joint analysis of BICEP2, Keck Array, and Planck (BKP) data. Adding the BKP B-mode data to our analysis leads to a tighter constraint of r 0.002 < 0.09 and disfavours inflationarymodels with a V(φ) ∝ φ 2 potential. The addition of Planck polarization data leads to strong constraints on deviations from a purely adiabatic spectrum of fluctuations. We find no evidence for any contribution from isocurvature perturbations or from cosmic defects. Combining Planck data with other astrophysical data, including Type Ia supernovae, the equation of state of dark energy is constrained to w = -1.006 ± 0.045, consistent with the expected value for a cosmological constant. The standard big bang nucleosynthesis predictions for the helium and deuterium abundances for the best-fit Planck base ΛCDM cosmology are in excellent agreement with observations. We also constraints on annihilating dark matter and on possible deviations from the standard recombination history. In neither case do we find no evidence for new physics. The Planck results for base ΛCDM are in good agreement with baryon acoustic oscillation data and with the JLA sample of Type Ia supernovae. However, as in the 2013 analysis, the amplitude of the fluctuation spectrum is found to be higher than inferred from some analyses of rich cluster counts and weak gravitational lensing. We show that these tensions cannot easily be resolved with simple modifications of the base ΛCDM cosmology. Finally, apart from these tensions, the base ΛCDM cosmology provides an excellent description of the Planck CMB observations and many other astrophysical data sets.« less

Anthropic versus cosmological solutions to the coincidence problem

DOE Office of Scientific and Technical Information (OSTI.GOV)

Barreira, A.; Avelino, P. P.; Departamento de Fisica da Faculdade de Ciencias da Universidade do Porto, Rua do Campo Alegre 687, 4169-007 Porto

2011-05-15

In this paper, we investigate possible solutions to the coincidence problem in flat phantom dark-energy models with a constant dark-energy equation of state and quintessence models with a linear scalar field potential. These models are representative of a broader class of cosmological scenarios in which the universe has a finite lifetime. We show that, in the absence of anthropic constraints, including a prior probability for the models inversely proportional to the total lifetime of the universe excludes models very close to the {Lambda} cold dark matter model. This relates a cosmological solution to the coincidence problem with a dynamical dark-energymore » component having an equation-of-state parameter not too close to -1 at the present time. We further show that anthropic constraints, if they are sufficiently stringent, may solve the coincidence problem without the need for dynamical dark energy.« less

Constraints from thermal Sunyaev-Zel'dovich cluster counts and power spectrum combined with CMB

NASA Astrophysics Data System (ADS)

Salvati, Laura; Douspis, Marian; Aghanim, Nabila

2018-06-01

The thermal Sunyaev-Zel'dovich (tSZ) effect is one of the recent probes of cosmology and large-scale structures. We update constraints on cosmological parameters from galaxy clusters observed by the Planck satellite in a first attempt to combine cluster number counts and the power spectrum of hot gas; we used a new value of the optical depth and, at the same time, sampling on cosmological and scaling-relation parameters. We find that in the ΛCDM model, the addition of a tSZ power spectrum provides small improvements with respect to number counts alone, leading to the 68% c.l. constraints Ωm = 0.32 ± 0.02, σ8 = 0.76 ± 0.03, and σ8(Ωm/0.3)1/3 = 0.78 ± 0.03 and lowering the discrepancy with results for cosmic microwave background (CMB) primary anisotropies (updated with the new value of τ) to ≃1.8σ on σ8. We analysed extensions to the standard model, considering the effect of massive neutrinos and varying the equation of state parameter for dark energy. In the first case, we find that the addition of the tSZ power spectrum helps in improving cosmological constraints with respect to number count alone results, leading to the 95% upper limit ∑ mν < 1.88 eV. For the varying dark energy equation of state scenario, we find no important improvements when adding tSZ power spectrum, but still the combination of tSZ probes is able to provide constraints, producing w = -1.0 ± 0.2. In all cosmological scenarios, the mass bias to reconcile CMB and tSZ probes remains low at (1 - b) ≲ 0.67 as compared to estimates from weak lensing and X-ray mass estimate comparisons or numerical simulations.

Current Issues in Cosmology

NASA Astrophysics Data System (ADS)

Pecker, Jean-Claude; Narlikar, Jayant

2011-09-01

Part I. Observational Facts Relating to Discrete Sources: 1. The state of cosmology G. Burbidge; 2. The redshifts of galaxies and QSOs E. M. Burbidge and G. Burbidge; 3. Accretion discs in quasars J. Sulentic; Part II. Observational Facts Relating to Background Radiation: 4. CMB observations and consequences F. Bouchet; 5. Abundances of light nuclei K. Olive; 6. Evidence for an accelerating universe or lack of A. Blanchard; Part III. Standard Cosmology: 7. Cosmology, an overview of the standard model F. Bernardeau; 8. What are the building blocks of our universe? K. C. Wali; Part IV. Large-Scale Structure: 9. Observations of large-scale structure V. de Lapparent; 10. Reconstruction of large-scale peculiar velocity fields R. Mohayaee, B. Tully and U. Frisch; Part V. Alternative Cosmologies: 11. The quasi-steady state cosmology J. V. Narlikar; 12. Evidence for iron whiskers in the universe N. C. Wickramasinghe; 13. Alternatives to dark matter: MOND + Mach D. Roscoe; 14. Anthropic principle in cosmology B. Carter; Part VI. Evidence for Anomalous Redshifts: 15. Anomalous redshifts H. C. Arp; 16. Redshifts of galaxies and QSOs: the problem of redshift periodicities G. Burbidge; 17. Statistics of redshift periodicities W. Napier; 18. Local abnormal redshifts J.-C. Pecker; 19. Gravitational lensing and anomalous redshifts J. Surdej, J.-F. Claeskens and D. Sluse; Panel discussion; General discussion; Concluding remarks.

Anomaly free cosmological perturbations with generalised holonomy correction in loop quantum cosmology

NASA Astrophysics Data System (ADS)

Han, Yu; Liu, Molin

2018-05-01

In the spatially flat case of loop quantum cosmology, the connection is usually replaced by the holonomy in effective theory. In this paper, instead of the standard scheme, we use a generalised, undetermined function to represent the holonomy and by using the approach of anomaly free constraint algebra we fix all the counter terms in the constraints and find the restriction in the form of , then we derive the gauge-invariant equations of motion of the scalar, tensor and vector perturbations and study the inflationary power spectra with generalised holonomy correction.

On the physical Hilbert space of loop quantum cosmology

DOE Office of Scientific and Technical Information (OSTI.GOV)

Noui, Karim; Perez, Alejandro; Vandersloot, Kevin

2005-02-15

In this paper we present a model of Riemannian loop quantum cosmology with a self-adjoint quantum scalar constraint. The physical Hilbert space is constructed using refined algebraic quantization. When matter is included in the form of a cosmological constant, the model is exactly solvable and we show explicitly that the physical Hilbert space is separable, consisting of a single physical state. We extend the model to the Lorentzian sector and discuss important implications for standard loop quantum cosmology.

Emulating Simulations of Cosmic Dawn for 21 cm Power Spectrum Constraints on Cosmology, Reionization, and X-Ray Heating

NASA Astrophysics Data System (ADS)

Kern, Nicholas S.; Liu, Adrian; Parsons, Aaron R.; Mesinger, Andrei; Greig, Bradley

2017-10-01

Current and upcoming radio interferometric experiments are aiming to make a statistical characterization of the high-redshift 21 cm fluctuation signal spanning the hydrogen reionization and X-ray heating epochs of the universe. However, connecting 21 cm statistics to the underlying physical parameters is complicated by the theoretical challenge of modeling the relevant physics at computational speeds quick enough to enable exploration of the high-dimensional and weakly constrained parameter space. In this work, we use machine learning algorithms to build a fast emulator that can accurately mimic an expensive simulation of the 21 cm signal across a wide parameter space. We embed our emulator within a Markov Chain Monte Carlo framework in order to perform Bayesian parameter constraints over a large number of model parameters, including those that govern the Epoch of Reionization, the Epoch of X-ray Heating, and cosmology. As a worked example, we use our emulator to present an updated parameter constraint forecast for the Hydrogen Epoch of Reionization Array experiment, showing that its characterization of a fiducial 21 cm power spectrum will considerably narrow the allowed parameter space of reionization and heating parameters, and could help strengthen Planck's constraints on {σ }8. We provide both our generalized emulator code and its implementation specifically for 21 cm parameter constraints as publicly available software.

Dynamics of cosmological perturbations and reheating in the anamorphic universe

DOE Office of Scientific and Technical Information (OSTI.GOV)

Graef, L.L.; Ferreira, Elisa G.M.; Brandenberger, Robert

We discuss scalar-tensor realizations of the Anamorphic cosmological scenario recently proposed by Ijjas and Steinhardt [1]. Through an analysis of the dynamics of cosmological perturbations we obtain constraints on the parameters of the model. We also study gravitational Parker particle production in the contracting Anamorphic phase and we compute the fraction between the energy density of created particles at the end of the phase and the background energy density. We find that, as in the case of inflation, a new mechanism is required to reheat the universe.

A numerical relativity scheme for cosmological simulations

NASA Astrophysics Data System (ADS)

Daverio, David; Dirian, Yves; Mitsou, Ermis

2017-12-01

Cosmological simulations involving the fully covariant gravitational dynamics may prove relevant in understanding relativistic/non-linear features and, therefore, in taking better advantage of the upcoming large scale structure survey data. We propose a new 3  +  1 integration scheme for general relativity in the case where the matter sector contains a minimally-coupled perfect fluid field. The original feature is that we completely eliminate the fluid components through the constraint equations, thus remaining with a set of unconstrained evolution equations for the rest of the fields. This procedure does not constrain the lapse function and shift vector, so it holds in arbitrary gauge and also works for arbitrary equation of state. An important advantage of this scheme is that it allows one to define and pass an adaptation of the robustness test to the cosmological context, at least in the case of pressureless perfect fluid matter, which is the relevant one for late-time cosmology.

A cosmological exclusion plot: towards model-independent constraints on modified gravity from current and future growth rate data

DOE Office of Scientific and Technical Information (OSTI.GOV)

Taddei, Laura; Amendola, Luca, E-mail: laura.taddei@fis.unipr.it, E-mail: l.amendola@thphys.uni-heidelberg.de

Most cosmological constraints on modified gravity are obtained assuming that the cosmic evolution was standard ΛCDM in the past and that the present matter density and power spectrum normalization are the same as in a ΛCDM model. Here we examine how the constraints change when these assumptions are lifted. We focus in particular on the parameter Y (also called G{sub eff}) that quantifies the deviation from the Poisson equation. This parameter can be estimated by comparing with the model-independent growth rate quantity fσ{sub 8}(z) obtained through redshift distortions. We reduce the model dependency in evaluating Y by marginalizing over σ{submore » 8} and over the initial conditions, and by absorbing the degenerate parameter Ω{sub m,0} into Y. We use all currently available values of fσ{sub 8}(z). We find that the combination Y-circumflex =YΩ{sub m,0}, assumed constant in the observed redshift range, can be constrained only very weakly by current data, Y-circumflex =0.28{sub −0.23}{sup +0.35} at 68% c.l. We also forecast the precision of a future estimation of Y-circumflex in a Euclid-like redshift survey. We find that the future constraints will reduce substantially the uncertainty, Y-circumflex =0.30{sub −0.09}{sup +0.08} , at 68% c.l., but the relative error on Y-circumflex around the fiducial remains quite high, of the order of 30%. The main reason for these weak constraints is that Y-circumflex is strongly degenerate with the initial conditions, so that large or small values of Y-circumflex are compensated by choosing non-standard initial values of the derivative of the matter density contrast. Finally, we produce a forecast of a cosmological exclusion plot on the Yukawa strength and range parameters, which complements similar plots on laboratory scales but explores scales and epochs reachable only with large-scale galaxy surveys. We find that future data can constrain the Yukawa strength to within 3% of the Newtonian one if the range is around a

Loop quantum gravity simplicity constraint as surface defect in complex Chern-Simons theory

NASA Astrophysics Data System (ADS)

Han, Muxin; Huang, Zichang

2017-05-01

The simplicity constraint is studied in the context of four-dimensional spinfoam models with a cosmological constant. We find that the quantum simplicity constraint is realized as the two-dimensional surface defect in SL (2 ,C ) Chern-Simons theory in the construction of spinfoam amplitudes. By this realization of the simplicity constraint in Chern-Simons theory, we are able to construct the new spinfoam amplitude with a cosmological constant for an arbitrary simplicial complex (with many 4-simplices). The semiclassical asymptotics of the amplitude is shown to correctly reproduce the four-dimensional Einstein-Regge action with a cosmological constant term.

Constraints on the Energy Content of the Universe from a Combination of Galaxy Cluster Observables

NASA Technical Reports Server (NTRS)

Molnar, Sandor M.; Haiman, Zoltan; Birkinshaw, Mark; Mushotzky, Richard F.

2003-01-01

We demonstrate that constraints on cosmological parameters from the distribution of clusters as a function of redshift (dN/dz) are complementary to accurate angular diameter distance (D(sub A)) measurements to clusters, and their combination significantly tightens constraints on the energy density content of the Universe. The number counts can be obtained from X-ray and/or SZ (Sunyaev-Ze'dovich effect) surveys, and the angular diameter distances can be determined from deep observations of the intra-cluster gas using their thermal bremsstrahlung X-ray emission and the SZ effect. We combine constraints from simulated cluster number counts expected from a 12 deg(sup 2) SZ cluster survey and constraints from simulated angular diameter distance measurements based on the X-ray/SZ method assuming a statistical accuracy of 10% in the angular diameter distance determination of 100 clusters with redshifts less than 1.5. We find that Omega(sub m), can be determined within about 25%, Omega(sub lambda) within 20% and w within 16%. We show that combined dN/dz+(sub lambda) constraints can be used to constrain the different energy densities in the Universe even in the presence of a few percent redshift dependent systematic error in D(sub lambda). We also address the question of how best to select clusters of galaxies for accurate diameter distance determinations. We show that the joint dN/dz+ D(lambda) constraints on cosmological parameters for a fixed target accuracy in the energy density parameters are optimized by selecting clusters with redshift upper cut-offs in the range 0.55 approx. less than 1. Subject headings: cosmological parameters - cosmology: theory - galaxies:clusters: general

Redshift drift constraints on holographic dark energy

NASA Astrophysics Data System (ADS)

He, Dong-Ze; Zhang, Jing-Fei; Zhang, Xin

2017-03-01

The Sandage-Loeb (SL) test is a promising method for probing dark energy because it measures the redshift drift in the spectra of Lyman- α forest of distant quasars, covering the "redshift desert" of 2 ≲ z ≲ 5, which is not covered by existing cosmological observations. Therefore, it could provide an important supplement to current cosmological observations. In this paper, we explore the impact of SL test on the precision of cosmological constraints for two typical holographic dark energy models, i.e., the original holographic dark energy (HDE) model and the Ricci holographic dark energy (RDE) model. To avoid data inconsistency, we use the best-fit models based on current combined observational data as the fiducial models to simulate 30 mock SL test data. The results show that SL test can effectively break the existing strong degeneracy between the present-day matter density Ωm0 and the Hubble constant H 0 in other cosmological observations. For the considered two typical dark energy models, not only can a 30-year observation of SL test improve the constraint precision of Ωm0 and h dramatically, but can also enhance the constraint precision of the model parameters c and α significantly.

Searching for sterile neutrinos in dynamical dark energy cosmologies

NASA Astrophysics Data System (ADS)

Feng, Lu; Zhang, Jing-Fei; Zhang, Xin

2018-05-01

We investigate how the dark energy properties change the cosmological limits on sterile neutrino parameters by using recent cosmological observations. We consider the simplest dynamical dark energy models, the wCDM model and the holographic dark energy (HDE) model, to make an analysis. The cosmological observations used in this work include the Planck 2015 CMB temperature and polarization data, the baryon acoustic oscillation data, the type Ia supernova data, the Hubble constant direct measurement data, and the Planck CMB lensing data. We find that, m v,terile ff < 0.2675 eV and Ne f f < 3.5718 for ACDM cosmology, m v,terile ff < 0.5313 eV and Ne f f < 3.5008 for wCDM cosmology, and raffterile < 0.1989 eV and Ne f f < 3.6701 for HDE cosmology, from the constraints of the combination of these data. Thus, without the addition of measurements of growth of structure, only upper limits on both m v,terile ff and Ne f f can be derived, indicating that no evidence of the existence of a sterile neutrino species with eV-scale mass is found in this analysis. Moreover, compared to the ACDM model, in the wCDM model the limit on m v,terile ff becomes much looser, but in the HDE model the limit becomes much tighter. Therefore, the dark energy properties could significantly influence the constraint limits of sterile neutrino parameters.

Neutrino mass priors for cosmology from random matrices

NASA Astrophysics Data System (ADS)

Long, Andrew J.; Raveri, Marco; Hu, Wayne; Dodelson, Scott

2018-02-01

Cosmological measurements of structure are placing increasingly strong constraints on the sum of the neutrino masses, Σ mν, through Bayesian inference. Because these constraints depend on the choice for the prior probability π (Σ mν), we argue that this prior should be motivated by fundamental physical principles rather than the ad hoc choices that are common in the literature. The first step in this direction is to specify the prior directly at the level of the neutrino mass matrix Mν, since this is the parameter appearing in the Lagrangian of the particle physics theory. Thus by specifying a probability distribution over Mν, and by including the known squared mass splittings, we predict a theoretical probability distribution over Σ mν that we interpret as a Bayesian prior probability π (Σ mν). Assuming a basis-invariant probability distribution on Mν, also known as the anarchy hypothesis, we find that π (Σ mν) peaks close to the smallest Σ mν allowed by the measured mass splittings, roughly 0.06 eV (0.1 eV) for normal (inverted) ordering, due to the phenomenon of eigenvalue repulsion in random matrices. We consider three models for neutrino mass generation: Dirac, Majorana, and Majorana via the seesaw mechanism; differences in the predicted priors π (Σ mν) allow for the possibility of having indications about the physical origin of neutrino masses once sufficient experimental sensitivity is achieved. We present fitting functions for π (Σ mν), which provide a simple means for applying these priors to cosmological constraints on the neutrino masses or marginalizing over their impact on other cosmological parameters.

Higgs Physics and Cosmology

NASA Astrophysics Data System (ADS)

Roberts, Alex

2016-08-01

Recently, a new framework for describing the multiverse has been proposed which is based on the principles of quantum mechanics. The framework allows for well-defined predictions, both regarding global properties of the universe and outcomes of particular experiments, according to a single probability formula. This provides complete unification of the eternally inflating multiverse and many worlds in quantum mechanics. We elucidate how cosmological parameters can be calculated in this framework, and study the probability distribution for the value of the cosmological constant. We consider both positive and negative values, and find that the observed value is consistent with the calculated distribution at an order of magnitude level. In particular, in contrast to the case of earlier measure proposals, our framework prefers a positive cosmological constant over a negative one. These results depend only moderately on how we model galaxy formation and life evolution therein. We explore supersymmetric theories in which the Higgs mass is boosted by the non-decoupling D-terms of an extended U(1) X gauge symmetry, defined here to be a general linear combination of hypercharge, baryon number, and lepton number. Crucially, the gauge coupling, gX, is bounded from below to accommodate the Higgs mass, while the quarks and leptons are required by gauge invariance to carry non-zero charge under U(1)X. This induces an irreducible rate, sigmaBR, for pp → X → ll relevant to existing and future resonance searches, and gives rise to higher dimension operators that are stringently constrained by precision electroweak measurements. Combined, these bounds define a maximally allowed region in the space of observables, (sigmaBR, mX), outside of which is excluded by naturalness and experimental limits. If natural supersymmetry utilizes non-decoupling D-terms, then the associated X boson can only be observed within this window, providing a model independent 'litmus test' for this broad

Measuring Dark Energy Properties with Photometrically Classified Pan-STARRS Supernovae. II. Cosmological Parameters

NASA Astrophysics Data System (ADS)

Jones, D. O.; Scolnic, D. M.; Riess, A. G.; Rest, A.; Kirshner, R. P.; Berger, E.; Kessler, R.; Pan, Y.-C.; Foley, R. J.; Chornock, R.; Ortega, C. A.; Challis, P. J.; Burgett, W. S.; Chambers, K. C.; Draper, P. W.; Flewelling, H.; Huber, M. E.; Kaiser, N.; Kudritzki, R.-P.; Metcalfe, N.; Tonry, J.; Wainscoat, R. J.; Waters, C.; Gall, E. E. E.; Kotak, R.; McCrum, M.; Smartt, S. J.; Smith, K. W.

2018-04-01

We use 1169 Pan-STARRS supernovae (SNe) and 195 low-z (z < 0.1) SNe Ia to measure cosmological parameters. Though most Pan-STARRS SNe lack spectroscopic classifications, in a previous paper we demonstrated that photometrically classified SNe can be used to infer unbiased cosmological parameters by using a Bayesian methodology that marginalizes over core-collapse (CC) SN contamination. Our sample contains nearly twice as many SNe as the largest previous SN Ia compilation. Combining SNe with cosmic microwave background (CMB) constraints from Planck, we measure the dark energy equation-of-state parameter w to be ‑0.989 ± 0.057 (stat+sys). If w evolves with redshift as w(a) = w 0 + w a (1 ‑ a), we find w 0 = ‑0.912 ± 0.149 and w a = ‑0.513 ± 0.826. These results are consistent with cosmological parameters from the Joint Light-curve Analysis and the Pantheon sample. We try four different photometric classification priors for Pan-STARRS SNe and two alternate ways of modeling CC SN contamination, finding that no variant gives a w differing by more than 2% from the baseline measurement. The systematic uncertainty on w due to marginalizing over CC SN contamination, {σ }wCC}=0.012, is the third-smallest source of systematic uncertainty in this work. We find limited (1.6σ) evidence for evolution of the SN color-luminosity relation with redshift, a possible systematic that could constitute a significant uncertainty in future high-z analyses. Our data provide one of the best current constraints on w, demonstrating that samples with ∼5% CC SN contamination can give competitive cosmological constraints when the contaminating distribution is marginalized over in a Bayesian framework.

KiDS-450: testing extensions to the standard cosmological model

NASA Astrophysics Data System (ADS)

Joudaki, Shahab; Mead, Alexander; Blake, Chris; Choi, Ami; de Jong, Jelte; Erben, Thomas; Fenech Conti, Ian; Herbonnet, Ricardo; Heymans, Catherine; Hildebrandt, Hendrik; Hoekstra, Henk; Joachimi, Benjamin; Klaes, Dominik; Köhlinger, Fabian; Kuijken, Konrad; McFarland, John; Miller, Lance; Schneider, Peter; Viola, Massimo

2017-10-01

We test extensions to the standard cosmological model with weak gravitational lensing tomography using 450 deg2 of imaging data from the Kilo Degree Survey (KiDS). In these extended cosmologies, which include massive neutrinos, non-zero curvature, evolving dark energy, modified gravity and running of the scalar spectral index, we also examine the discordance between KiDS and cosmic microwave background (CMB) measurements from Planck. The discordance between the two data sets is largely unaffected by a more conservative treatment of the lensing systematics and the removal of angular scales most sensitive to non-linear physics. The only extended cosmology that simultaneously alleviates the discordance with Planck and is at least moderately favoured by the data includes evolving dark energy with a time-dependent equation of state (in the form of the w0 - wa parametrization). In this model, the respective S_8=σ _8√{Ω m/0.3} constraints agree at the 1σ level, and there is 'substantial concordance' between the KiDS and Planck data sets when accounting for the full parameter space. Moreover, the Planck constraint on the Hubble constant is wider than in Λ cold dark matter (ΛCDM) and in agreement with the Riess et al. (2016) direct measurement of H0. The dark energy model is moderately favoured as compared to ΛCDM when combining the KiDS and Planck measurements, and marginalized constraints in the w0-wa plane are discrepant with a cosmological constant at the 3σ level. KiDS further constrains the sum of neutrino masses to 4.0 eV (95% CL), finds no preference for time or scale-dependent modifications to the metric potentials, and is consistent with flatness and no running of the spectral index.

Functional renormalization group for the U (1 )-T56 tensorial group field theory with closure constraint

NASA Astrophysics Data System (ADS)

Lahoche, Vincent; Ousmane Samary, Dine

2017-02-01

This paper is focused on the functional renormalization group applied to the T56 tensor model on the Abelian group U (1 ) with closure constraint. For the first time, we derive the flow equations for the couplings and mass parameters in a suitable truncation around the marginal interactions with respect to the perturbative power counting. For the second time, we study the behavior around the Gaussian fixed point, and show that the theory is nonasymptotically free. Finally, we discuss the UV completion of the theory. We show the existence of several nontrivial fixed points, study the behavior of the renormalization group flow around them, and point out evidence in favor of an asymptotically safe theory.

The Cosmological Dependence of Galaxy Cluster Morphologies

NASA Astrophysics Data System (ADS)

Crone, Mary Margaret

1995-01-01

Measuring the density of the universe has been a fundamental problem in cosmology ever since the "Big Bang" model was developed over sixty years ago. In this simple and successful model, the age and eventual fate of the universe are determined by its density, its rate of expansion, and the value of a universal "cosmological constant". Analytic models suggest that many properties of galaxy clusters are sensitive to cosmological parameters. In this thesis, I use N-body simulations to examine cluster density profiles, abundances, and degree of subclustering to test the feasibility of using them as cosmological tests. The dependence on both cosmology and initial density field is examined, using a grid of cosmologies and scale-free initial power spectra P(k)~ k n. Einstein-deSitter ( Omegao=1), open ( Omegao=0.2 and 0.1) and flat, low density (Omegao=0.2, lambdao=0.8) models are studied, with initial spectral indices n=-2, -1 and 0. Of particular interest are the results for cluster profiles and substructure. The average density profiles are well fit by a power law p(r)~ r ^{-alpha} for radii where the local density contrast is between 100 and 3000. There is a clear trend toward steeper slopes with both increasing n and decreasing Omegao, with profile slopes in the open models consistently higher than Omega=1 values for the range of n examined. The amount of substructure in each model is quantified and explained in terms of cluster merger histories and the behavior of substructure statistics. The statistic which best distinguishes models is a very simple measure of deviations from symmetry in the projected mass distribution --the "Center-of-Mass Shift" as a function of overdensity. Some statistics which are quite sensitive to substructure perform relatively poorly as cosmological indicators. Density profiles and the Center-of-Mass test are both well-suited for comparison with weak lensing data and galaxy distributions. Such data are currently being collected and should

Planck 2015 results. XXIV. Cosmology from Sunyaev-Zeldovich cluster counts

NASA Astrophysics Data System (ADS)

Planck Collaboration; Ade, P. A. R.; Aghanim, N.; Arnaud, M.; Ashdown, M.; Aumont, J.; Baccigalupi, C.; Banday, A. J.; Barreiro, R. B.; Bartlett, J. G.; Bartolo, N.; Battaner, E.; Battye, R.; Benabed, K.; Benoît, A.; Benoit-Lévy, A.; Bernard, J.-P.; Bersanelli, M.; Bielewicz, P.; Bock, J. J.; Bonaldi, A.; Bonavera, L.; Bond, J. R.; Borrill, J.; Bouchet, F. R.; Bucher, M.; Burigana, C.; Butler, R. C.; Calabrese, E.; Cardoso, J.-F.; Catalano, A.; Challinor, A.; Chamballu, A.; Chary, R.-R.; Chiang, H. C.; Christensen, P. R.; Church, S.; Clements, D. L.; Colombi, S.; Colombo, L. P. L.; Combet, C.; Comis, B.; Couchot, F.; Coulais, A.; Crill, B. P.; Curto, A.; Cuttaia, F.; Danese, L.; Davies, R. D.; Davis, R. J.; de Bernardis, P.; de Rosa, A.; de Zotti, G.; Delabrouille, J.; Désert, F.-X.; Diego, J. M.; Dolag, K.; Dole, H.; Donzelli, S.; Doré, O.; Douspis, M.; Ducout, A.; Dupac, X.; Efstathiou, G.; Elsner, F.; Enßlin, T. A.; Eriksen, H. K.; Falgarone, E.; Fergusson, J.; Finelli, F.; Forni, O.; Frailis, M.; Fraisse, A. A.; Franceschi, E.; Frejsel, A.; Galeotta, S.; Galli, S.; Ganga, K.; Giard, M.; Giraud-Héraud, Y.; Gjerløw, E.; González-Nuevo, J.; Górski, K. M.; Gratton, S.; Gregorio, A.; Gruppuso, A.; Gudmundsson, J. E.; Hansen, F. K.; Hanson, D.; Harrison, D. L.; Henrot-Versillé, S.; Hernández-Monteagudo, C.; Herranz, D.; Hildebrandt, S. R.; Hivon, E.; Hobson, M.; Holmes, W. A.; Hornstrup, A.; Hovest, W.; Huffenberger, K. M.; Hurier, G.; Jaffe, A. H.; Jaffe, T. R.; Jones, W. C.; Juvela, M.; Keihänen, E.; Keskitalo, R.; Kisner, T. S.; Kneissl, R.; Knoche, J.; Kunz, M.; Kurki-Suonio, H.; Lagache, G.; Lähteenmäki, A.; Lamarre, J.-M.; Lasenby, A.; Lattanzi, M.; Lawrence, C. R.; Leonardi, R.; Lesgourgues, J.; Levrier, F.; Liguori, M.; Lilje, P. B.; Linden-Vørnle, M.; López-Caniego, M.; Lubin, P. M.; Macías-Pérez, J. F.; Maggio, G.; Maino, D.; Mandolesi, N.; Mangilli, A.; Maris, M.; Martin, P. G.; Martínez-González, E.; Masi, S.; Matarrese, S.; McGehee, P.; Meinhold, P. R.; Melchiorri, A.; Melin, J.-B.; Mendes, L.; Mennella, A.; Migliaccio, M.; Mitra, S.; Miville-Deschênes, M.-A.; Moneti, A.; Montier, L.; Morgante, G.; Mortlock, D.; Moss, A.; Munshi, D.; Murphy, J. A.; Naselsky, P.; Nati, F.; Natoli, P.; Netterfield, C. B.; Nørgaard-Nielsen, H. U.; Noviello, F.; Novikov, D.; Novikov, I.; Oxborrow, C. A.; Paci, F.; Pagano, L.; Pajot, F.; Paoletti, D.; Partridge, B.; Pasian, F.; Patanchon, G.; Pearson, T. J.; Perdereau, O.; Perotto, L.; Perrotta, F.; Pettorino, V.; Piacentini, F.; Piat, M.; Pierpaoli, E.; Pietrobon, D.; Plaszczynski, S.; Pointecouteau, E.; Polenta, G.; Popa, L.; Pratt, G. W.; Prézeau, G.; Prunet, S.; Puget, J.-L.; Rachen, J. P.; Rebolo, R.; Reinecke, M.; Remazeilles, M.; Renault, C.; Renzi, A.; Ristorcelli, I.; Rocha, G.; Roman, M.; Rosset, C.; Rossetti, M.; Roudier, G.; Rubiño-Martín, J. A.; Rusholme, B.; Sandri, M.; Santos, D.; Savelainen, M.; Savini, G.; Scott, D.; Seiffert, M. D.; Shellard, E. P. S.; Spencer, L. D.; Stolyarov, V.; Stompor, R.; Sudiwala, R.; Sunyaev, R.; Sutton, D.; Suur-Uski, A.-S.; Sygnet, J.-F.; Tauber, J. A.; Terenzi, L.; Toffolatti, L.; Tomasi, M.; Tristram, M.; Tucci, M.; Tuovinen, J.; Türler, M.; Umana, G.; Valenziano, L.; Valiviita, J.; Van Tent, B.; Vielva, P.; Villa, F.; Wade, L. A.; Wandelt, B. D.; Wehus, I. K.; Weller, J.; White, S. D. M.; Yvon, D.; Zacchei, A.; Zonca, A.

2016-09-01

We present cluster counts and corresponding cosmological constraints from the Planck full mission data set. Our catalogue consists of 439 clusters detected via their Sunyaev-Zeldovich (SZ) signal down to a signal-to-noise ratio of 6, and is more than a factor of 2 larger than the 2013 Planck cluster cosmology sample. The counts are consistent with those from 2013 and yield compatible constraints under the same modelling assumptions. Taking advantage of the larger catalogue, we extend our analysis to the two-dimensional distribution in redshift and signal-to-noise. We use mass estimates from two recent studies of gravitational lensing of background galaxies by Planck clusters to provide priors on the hydrostatic bias parameter, (1-b). In addition, we use lensing of cosmic microwave background (CMB) temperature fluctuations by Planck clusters as an independent constraint on this parameter. These various calibrations imply constraints on the present-day amplitude of matter fluctuations in varying degrees of tension with those from the Planck analysis of primary fluctuations in the CMB; for the lowest estimated values of (1-b) the tension is mild, only a little over one standard deviation, while it remains substantial (3.7σ) for the largest estimated value. We also examine constraints on extensions to the base flat ΛCDM model by combining the cluster and CMB constraints. The combination appears to favour non-minimal neutrino masses, but this possibility does little to relieve the overall tension because it simultaneously lowers the implied value of the Hubble parameter, thereby exacerbating the discrepancy with most current astrophysical estimates. Improving the precision of cluster mass calibrations from the current 10%-level to 1% would significantly strengthen these combined analyses and provide a stringent test of the base ΛCDM model.

Planck 2015 results: XXIV. Cosmology from Sunyaev-Zeldovich cluster counts

DOE PAGES

Ade, P. A. R.; Aghanim, N.; Arnaud, M.; ...

2016-09-20

In this work, we present cluster counts and corresponding cosmological constraints from the Planck full mission data set. Our catalogue consists of 439 clusters detected via their Sunyaev-Zeldovich (SZ) signal down to a signal-to-noise ratio of 6, and is more than a factor of 2 larger than the 2013 Planck cluster cosmology sample. The counts are consistent with those from 2013 and yield compatible constraints under the same modelling assumptions. Taking advantage of the larger catalogue, we extend our analysis to the two-dimensional distribution in redshift and signal-to-noise. We use mass estimates from two recent studies of gravitational lensing ofmore » background galaxies by Planck clusters to provide priors on the hydrostatic bias parameter, (1-b). In addition, we use lensing of cosmic microwave background (CMB) temperature fluctuations by Planck clusters as an independent constraint on this parameter. These various calibrations imply constraints on the present-day amplitude of matter fluctuations in varying degrees of tension with those from the Planck analysis of primary fluctuations in the CMB; for the lowest estimated values of (1-b) the tension is mild, only a little over one standard deviation, while it remains substantial (3.7σ) for the largest estimated value. We also examine constraints on extensions to the base flat ΛCDM model by combining the cluster and CMB constraints. The combination appears to favour non-minimal neutrino masses, but this possibility does little to relieve the overall tension because it simultaneously lowers the implied value of the Hubble parameter, thereby exacerbating the discrepancy with most current astrophysical estimates. In conclusion, improving the precision of cluster mass calibrations from the current 10%-level to 1% would significantly strengthen these combined analyses and provide a stringent test of the base ΛCDM model.« less

Planck 2015 results: XXIV. Cosmology from Sunyaev-Zeldovich cluster counts

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ade, P. A. R.; Aghanim, N.; Arnaud, M.

In this work, we present cluster counts and corresponding cosmological constraints from the Planck full mission data set. Our catalogue consists of 439 clusters detected via their Sunyaev-Zeldovich (SZ) signal down to a signal-to-noise ratio of 6, and is more than a factor of 2 larger than the 2013 Planck cluster cosmology sample. The counts are consistent with those from 2013 and yield compatible constraints under the same modelling assumptions. Taking advantage of the larger catalogue, we extend our analysis to the two-dimensional distribution in redshift and signal-to-noise. We use mass estimates from two recent studies of gravitational lensing ofmore » background galaxies by Planck clusters to provide priors on the hydrostatic bias parameter, (1-b). In addition, we use lensing of cosmic microwave background (CMB) temperature fluctuations by Planck clusters as an independent constraint on this parameter. These various calibrations imply constraints on the present-day amplitude of matter fluctuations in varying degrees of tension with those from the Planck analysis of primary fluctuations in the CMB; for the lowest estimated values of (1-b) the tension is mild, only a little over one standard deviation, while it remains substantial (3.7σ) for the largest estimated value. We also examine constraints on extensions to the base flat ΛCDM model by combining the cluster and CMB constraints. The combination appears to favour non-minimal neutrino masses, but this possibility does little to relieve the overall tension because it simultaneously lowers the implied value of the Hubble parameter, thereby exacerbating the discrepancy with most current astrophysical estimates. In conclusion, improving the precision of cluster mass calibrations from the current 10%-level to 1% would significantly strengthen these combined analyses and provide a stringent test of the base ΛCDM model.« less

Integrable cosmological potentials

NASA Astrophysics Data System (ADS)

Sokolov, V. V.; Sorin, A. S.

2017-09-01

The problem of classification of the Einstein-Friedman cosmological Hamiltonians H with a single scalar inflaton field φ, which possess an additional integral of motion polynomial in momenta on the shell of the Friedman constraint H=0, is considered. Necessary and sufficient conditions for the existence of the first-, second- and third-degree integrals are derived. These conditions have the form of ODEs for the cosmological potential V(φ). In the case of linear and quadratic integrals we find general solutions of the ODEs and construct the corresponding integrals explicitly. A new wide class of Hamiltonians that possess a cubic integral is derived. The corresponding potentials are represented in parametric form in terms of the associated Legendre functions. Six families of special elementary solutions are described, and sporadic superintegrable cases are discussed.

Solar system and equivalence principle constraints on f(R) gravity by the chameleon approach

DOE Office of Scientific and Technical Information (OSTI.GOV)

Capozziello, Salvatore; Tsujikawa, Shinji

2008-05-15

We study constraints on f(R) dark energy models from solar system experiments combined with experiments on the violation of the equivalence principle. When the mass of an equivalent scalar field degree of freedom is heavy in a region with high density, a spherically symmetric body has a thin shell so that an effective coupling of the fifth force is suppressed through a chameleon mechanism. We place experimental bounds on the cosmologically viable models recently proposed in the literature that have an asymptotic form f(R)=R-{lambda}R{sub c}[1-(R{sub c}/R){sup 2n}] in the regime R>>R{sub c}. From the solar system constraints on the post-Newtonianmore » parameter {gamma}, we derive the bound n>0.5, whereas the constraints from the violations of the weak and strong equivalence principles give the bound n>0.9. This allows a possibility to find the deviation from the {lambda}-cold dark matter ({lambda}CDM) cosmological model. For the model f(R)=R-{lambda}R{sub c}(R/R{sub c}){sup p} with 01 the severest constraint is found to be p<10{sup -10}, which shows that this model is hardly distinguishable from the {lambda}CDM cosmology.« less

TESTING NONSTANDARD COSMOLOGICAL MODELS WITH SNLS3 SUPERNOVA DATA AND OTHER COSMOLOGICAL PROBES

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li Zhengxiang; Yu Hongwei; Wu Puxun, E-mail: hwyu@hunnu.edu.cn

2012-01-10

We investigate the implications for some nonstandard cosmological models using data from the first three years of the Supernova Legacy Survey (SNLS3), assuming a spatially flat universe. A comparison between the constraints from the SNLS3 and those from other SN Ia samples, such as the ESSENCE, Union2, SDSS-II, and Constitution samples, is given and the effects of different light-curve fitters are considered. We find that analyzing SNe Ia with SALT2 or SALT or SiFTO can give consistent results and the tensions between different data sets and different light-curve fitters are obvious for fewer-free-parameters models. At the same time, we alsomore » study the constraints from SNLS3 along with data from the cosmic microwave background and the baryonic acoustic oscillations (CMB/BAO), and the latest Hubble parameter versus redshift (H(z)). Using model selection criteria such as {chi}{sup 2}/dof, goodness of fit, Akaike information criterion, and Bayesian information criterion, we find that, among all the cosmological models considered here ({Lambda}CDM, constant w, varying w, Dvali-Gabadadze-Porrati (DGP), modified polytropic Cardassian, and the generalized Chaplygin gas), the flat DGP is favored by SNLS3 alone. However, when additional CMB/BAO or H(z) constraints are included, this is no longer the case, and the flat {Lambda}CDM becomes preferred.« less

Ultracompact Minihalos as Probes of Inflationary Cosmology.

PubMed

Aslanyan, Grigor; Price, Layne C; Adams, Jenni; Bringmann, Torsten; Clark, Hamish A; Easther, Richard; Lewis, Geraint F; Scott, Pat

2016-09-30

Cosmological inflation generates primordial density perturbations on all scales, including those far too small to contribute to the cosmic microwave background. At these scales, isolated ultracompact minihalos of dark matter can form well before standard structure formation, if the perturbations have sufficient amplitude. Minihalos affect pulsar timing data and are potentially bright sources of gamma rays. The resulting constraints significantly extend the observable window of inflation in the presence of cold dark matter, coupling two of the key problems in modern cosmology.

Thermodynamic constraints on a varying cosmological-constant-like term from the holographic equipartition law with a power-law corrected entropy

NASA Astrophysics Data System (ADS)

Komatsu, Nobuyoshi

2017-11-01

A power-law corrected entropy based on a quantum entanglement is considered to be a viable black-hole entropy. In this study, as an alternative to Bekenstein-Hawking entropy, a power-law corrected entropy is applied to Padmanabhan's holographic equipartition law to thermodynamically examine an extra driving term in the cosmological equations for a flat Friedmann-Robertson-Walker universe at late times. Deviations from the Bekenstein-Hawking entropy generate an extra driving term (proportional to the α th power of the Hubble parameter, where α is a dimensionless constant for the power-law correction) in the acceleration equation, which can be derived from the holographic equipartition law. Interestingly, the value of the extra driving term in the present model is constrained by the second law of thermodynamics. From the thermodynamic constraint, the order of the driving term is found to be consistent with the order of the cosmological constant measured by observations. In addition, the driving term tends to be constantlike when α is small, i.e., when the deviation from the Bekenstein-Hawking entropy is small.

Information gains from cosmological probes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Grandis, S.; Seehars, S.; Refregier, A.

In light of the growing number of cosmological observations, it is important to develop versatile tools to quantify the constraining power and consistency of cosmological probes. Originally motivated from information theory, we use the relative entropy to compute the information gained by Bayesian updates in units of bits. This measure quantifies both the improvement in precision and the 'surprise', i.e. the tension arising from shifts in central values. Our starting point is a WMAP9 prior which we update with observations of the distance ladder, supernovae (SNe), baryon acoustic oscillations (BAO), and weak lensing as well as the 2015 Planck release.more » We consider the parameters of the flat ΛCDM concordance model and some of its extensions which include curvature and Dark Energy equation of state parameter w . We find that, relative to WMAP9 and within these model spaces, the probes that have provided the greatest gains are Planck (10 bits), followed by BAO surveys (5.1 bits) and SNe experiments (3.1 bits). The other cosmological probes, including weak lensing (1.7 bits) and (H{sub 0}) measures (1.7 bits), have contributed information but at a lower level. Furthermore, we do not find any significant surprise when updating the constraints of WMAP9 with any of the other experiments, meaning that they are consistent with WMAP9. However, when we choose Planck15 as the prior, we find that, accounting for the full multi-dimensionality of the parameter space, the weak lensing measurements of CFHTLenS produce a large surprise of 4.4 bits which is statistically significant at the 8 σ level. We discuss how the relative entropy provides a versatile and robust framework to compare cosmological probes in the context of current and future surveys.« less

KiDS+GAMA: cosmology constraints from a joint analysis of cosmic shear, galaxy-galaxy lensing, and angular clustering

NASA Astrophysics Data System (ADS)

van Uitert, Edo; Joachimi, Benjamin; Joudaki, Shahab; Amon, Alexandra; Heymans, Catherine; Köhlinger, Fabian; Asgari, Marika; Blake, Chris; Choi, Ami; Erben, Thomas; Farrow, Daniel J.; Harnois-Déraps, Joachim; Hildebrandt, Hendrik; Hoekstra, Henk; Kitching, Thomas D.; Klaes, Dominik; Kuijken, Konrad; Merten, Julian; Miller, Lance; Nakajima, Reiko; Schneider, Peter; Valentijn, Edwin; Viola, Massimo

2018-06-01

We present cosmological parameter constraints from a joint analysis of three cosmological probes: the tomographic cosmic shear signal in ˜450 deg2 of data from the Kilo Degree Survey (KiDS), the galaxy-matter cross-correlation signal of galaxies from the Galaxies And Mass Assembly (GAMA) survey determined with KiDS weak lensing, and the angular correlation function of the same GAMA galaxies. We use fast power spectrum estimators that are based on simple integrals over the real-space correlation functions, and show that they are practically unbiased over relevant angular frequency ranges. We test our full pipeline on numerical simulations that are tailored to KiDS and retrieve the input cosmology. By fitting different combinations of power spectra, we demonstrate that the three probes are internally consistent. For all probes combined, we obtain S_8≡ σ _8 √{Ω _m/0.3}=0.800_{-0.027}^{+0.029}, consistent with Planck and the fiducial KiDS-450 cosmic shear correlation function results. Marginalizing over wide priors on the mean of the tomographic redshift distributions yields consistent results for S8 with an increase of 28 {per cent} in the error. The combination of probes results in a 26 per cent reduction in uncertainties of S8 over using the cosmic shear power spectra alone. The main gain from these additional probes comes through their constraining power on nuisance parameters, such as the galaxy intrinsic alignment amplitude or potential shifts in the redshift distributions, which are up to a factor of 2 better constrained compared to using cosmic shear alone, demonstrating the value of large-scale structure probe combination.

Inflationary cosmology: First 30+ years

NASA Astrophysics Data System (ADS)

Sato, Katsuhiko; Yokoyama, Jun'ichi

2015-08-01

Starting with an account of historical developments in Japan and Russia, we review inflationary cosmology and its basic predictions in a pedagogical manner. We also introduce the generalized G-inflation model, in terms of which all the known single-field inflation models may be described. This formalism allows us to analyze and compare the many inflationary models that have been proposed simultaneously and within a common framework. Finally, current observational constraints on inflation are reviewed, with particular emphasis on the sensitivity of the inferred constraints to the choice of datasets used.

Constraints on Cosmological Parameters from the Angular Power Spectrum of a Combined 2500 deg2 SPT-SZ and Planck Gravitational Lensing Map

NASA Astrophysics Data System (ADS)

Simard, G.; Omori, Y.; Aylor, K.; Baxter, E. J.; Benson, B. A.; Bleem, L. E.; Carlstrom, J. E.; Chang, C. L.; Cho, H.-M.; Chown, R.; Crawford, T. M.; Crites, A. T.; de Haan, T.; Dobbs, M. A.; Everett, W. B.; George, E. M.; Halverson, N. W.; Harrington, N. L.; Henning, J. W.; Holder, G. P.; Hou, Z.; Holzapfel, W. L.; Hrubes, J. D.; Knox, L.; Lee, A. T.; Leitch, E. M.; Luong-Van, D.; Manzotti, A.; McMahon, J. J.; Meyer, S. S.; Mocanu, L. M.; Mohr, J. J.; Natoli, T.; Padin, S.; Pryke, C.; Reichardt, C. L.; Ruhl, J. E.; Sayre, J. T.; Schaffer, K. K.; Shirokoff, E.; Staniszewski, Z.; Stark, A. A.; Story, K. T.; Vanderlinde, K.; Vieira, J. D.; Williamson, R.; Wu, W. L. K.

2018-06-01

We report constraints on cosmological parameters from the angular power spectrum of a cosmic microwave background (CMB) gravitational lensing potential map created using temperature data from 2500 deg2 of South Pole Telescope (SPT) data supplemented with data from Planck in the same sky region, with the statistical power in the combined map primarily from the SPT data. We fit the lensing power spectrum to a model including cold dark matter and a cosmological constant ({{Λ }}{CDM}), and to models with single-parameter extensions to {{Λ }}{CDM}. We find constraints that are comparable to and consistent with those found using the full-sky Planck CMB lensing data, e.g., {σ }8{{{Ω }}}{{m}}0.25 = 0.598 ± 0.024 from the lensing data alone with weak priors placed on other parameters. Combining with primary CMB data, we explore single-parameter extensions to {{Λ }}{CDM}. We find {{{Ω }}}k =-{0.012}-0.023+0.021 or {M}ν < 0.70 eV at 95% confidence, in good agreement with results including the lensing potential as measured by Planck. We include two parameters that scale the effect of lensing on the CMB: {A}L, which scales the lensing power spectrum in both the lens reconstruction power and in the smearing of the acoustic peaks, and {A}φ φ , which scales only the amplitude of the lensing reconstruction power spectrum. We find {A}φ φ × {A}L = 1.01 ± 0.08 for the lensing map made from combined SPT and Planck data, indicating that the amount of lensing is in excellent agreement with expectations from the observed CMB angular power spectrum when not including the information from smearing of the acoustic peaks.

Quantum supersymmetric Bianchi IX cosmology

NASA Astrophysics Data System (ADS)

Damour, Thibault; Spindel, Philippe

2014-11-01

We study the quantum dynamics of a supersymmetric squashed three-sphere by dimensionally reducing (to one timelike dimension) the action of D =4 simple supergravity for a S U (2 ) -homogeneous (Bianchi IX) cosmological model. The quantization of the homogeneous gravitino field leads to a 64-dimensional fermionic Hilbert space. After imposition of the diffeomorphism constraints, the wave function of the Universe becomes a 64-component spinor of spin(8,4) depending on the three squashing parameters, which satisfies Dirac-like, and Klein-Gordon-like, wave equations describing the propagation of a "quantum spinning particle" reflecting off spin-dependent potential walls. The algebra of the supersymmetry constraints and of the Hamiltonian one is found to close. One finds that the quantum Hamiltonian is built from operators that generate a 64-dimensional representation of the (infinite-dimensional) maximally compact subalgebra of the rank-3 hyperbolic Kac-Moody algebra A E3 . The (quartic-in-fermions) squared-mass term μ^ 2 entering the Klein-Gordon-like equation has several remarkable properties: (i) it commutes with all the other (Kac-Moody-related) building blocks of the Hamiltonian; (ii) it is a quadratic function of the fermion number NF; and (iii) it is negative in most of the Hilbert space. The latter property leads to a possible quantum avoidance of the singularity ("cosmological bounce"), and suggests imposing the boundary condition that the wave function of the Universe vanish when the volume of space tends to zero (a type of boundary condition which looks like a final-state condition when considering the big crunch inside a black hole). The space of solutions is a mixture of "discrete-spectrum states" (parametrized by a few constant parameters, and known in explicit form) and of continuous-spectrum states (parametrized by arbitrary functions entering some initial-value problem). The predominantly negative values of the squared-mass term lead to a "bottle

SKA weak lensing - I. Cosmological forecasts and the power of radio-optical cross-correlations

NASA Astrophysics Data System (ADS)

Harrison, Ian; Camera, Stefano; Zuntz, Joe; Brown, Michael L.

2016-12-01

We construct forecasts for cosmological parameter constraints from weak gravitational lensing surveys involving the Square Kilometre Array (SKA). Considering matter content, dark energy and modified gravity parameters, we show that the first phase of the SKA (SKA1) can be competitive with other Stage III experiments such as the Dark Energy Survey and that the full SKA (SKA2) can potentially form tighter constraints than Stage IV optical weak lensing experiments, such as those that will be conducted with LSST, WFIRST-AFTA or Euclid-like facilities. Using weak lensing alone, going from SKA1 to SKA2 represents improvements by factors of ˜10 in matter, ˜10 in dark energy and ˜5 in modified gravity parameters. We also show, for the first time, the powerful result that comparably tight constraints (within ˜5 per cent) for both Stage III and Stage IV experiments, can be gained from cross-correlating shear maps between the optical and radio wavebands, a process which can also eliminate a number of potential sources of systematic errors which can otherwise limit the utility of weak lensing cosmology.

Gauge Fields in Homogeneous and Inhomogeneous Cosmologies

NASA Astrophysics Data System (ADS)

Darian, Bahman K.

Despite its formidable appearance, the study of classical Yang-Mills (YM) fields on homogeneous cosmologies is amenable to a formal treatment. This dissertation is a report on a systematic approach to the general construction of invariant YM fields on homogeneous cosmologies undertaken for the first time in this context. This construction is subsequently followed by the investigation of the behavior of YM field variables for the most simple of self-gravitating YM fields. Particularly interesting was a dynamical system analysis and the discovery of chaotic signature in the axially symmetric Bianchi I-YM cosmology. Homogeneous YM fields are well studied and are known to have chaotic properties. The chaotic behavior of YM field variables in homogeneous cosmologies might eventually lead to an invariant definition of chaos in (general) relativistic cosmological models. By choosing the gauge fields to be Abelian, the construction and the field equations presented so far reduce to that of electromagnetic field in homogeneous cosmologies. A perturbative analysis of gravitationally interacting electromagnetic and scalar fields in inhomogeneous cosmologies is performed via the Hamilton-Jacobi formulation of general relativity. An essential feature of this analysis is the spatial gradient expansion of the generating functional (Hamilton principal function) to solve the Hamiltonian constraint. Perturbations of a spatially flat Friedman-Robertson-Walker cosmology with an exponential potential for the scalar field are presented.

Neutrino mass priors for cosmology from random matrices

DOE PAGES

Long, Andrew J.; Raveri, Marco; Hu, Wayne; ...

2018-02-13

Cosmological measurements of structure are placing increasingly strong constraints on the sum of the neutrino masses, Σm ν, through Bayesian inference. Because these constraints depend on the choice for the prior probability π(Σm ν), we argue that this prior should be motivated by fundamental physical principles rather than the ad hoc choices that are common in the literature. The first step in this direction is to specify the prior directly at the level of the neutrino mass matrix M ν, since this is the parameter appearing in the Lagrangian of the particle physics theory. Thus by specifying a probability distribution overmore » M ν, and by including the known squared mass splittings, we predict a theoretical probability distribution over Σm ν that we interpret as a Bayesian prior probability π(Σm ν). Assuming a basis-invariant probability distribution on M ν, also known as the anarchy hypothesis, we find that π(Σm ν) peaks close to the smallest Σm ν allowed by the measured mass splittings, roughly 0.06 eV (0.1 eV) for normal (inverted) ordering, due to the phenomenon of eigenvalue repulsion in random matrices. We consider three models for neutrino mass generation: Dirac, Majorana, and Majorana via the seesaw mechanism; differences in the predicted priors π(Σm ν) allow for the possibility of having indications about the physical origin of neutrino masses once sufficient experimental sensitivity is achieved. In conclusion, we present fitting functions for π(Σm ν), which provide a simple means for applying these priors to cosmological constraints on the neutrino masses or marginalizing over their impact on other cosmological parameters.« less

Neutrino mass priors for cosmology from random matrices

DOE Office of Scientific and Technical Information (OSTI.GOV)

Long, Andrew J.; Raveri, Marco; Hu, Wayne

Cosmological measurements of structure are placing increasingly strong constraints on the sum of the neutrino masses, Σm ν, through Bayesian inference. Because these constraints depend on the choice for the prior probability π(Σm ν), we argue that this prior should be motivated by fundamental physical principles rather than the ad hoc choices that are common in the literature. The first step in this direction is to specify the prior directly at the level of the neutrino mass matrix M ν, since this is the parameter appearing in the Lagrangian of the particle physics theory. Thus by specifying a probability distribution overmore » M ν, and by including the known squared mass splittings, we predict a theoretical probability distribution over Σm ν that we interpret as a Bayesian prior probability π(Σm ν). Assuming a basis-invariant probability distribution on M ν, also known as the anarchy hypothesis, we find that π(Σm ν) peaks close to the smallest Σm ν allowed by the measured mass splittings, roughly 0.06 eV (0.1 eV) for normal (inverted) ordering, due to the phenomenon of eigenvalue repulsion in random matrices. We consider three models for neutrino mass generation: Dirac, Majorana, and Majorana via the seesaw mechanism; differences in the predicted priors π(Σm ν) allow for the possibility of having indications about the physical origin of neutrino masses once sufficient experimental sensitivity is achieved. In conclusion, we present fitting functions for π(Σm ν), which provide a simple means for applying these priors to cosmological constraints on the neutrino masses or marginalizing over their impact on other cosmological parameters.« less

Do cosmological data rule out f (R ) with w ≠-1 ?

NASA Astrophysics Data System (ADS)

Battye, Richard A.; Bolliet, Boris; Pace, Francesco

2018-05-01

We review the equation of state (EoS) approach to dark sector perturbations and apply it to f (R ) gravity models of dark energy. We show that the EoS approach is numerically stable and use it to set observational constraints on designer models. Within the EoS approach we build an analytical understanding of the dynamics of cosmological perturbations for the designer class of f (R ) gravity models, characterized by the parameter B0 and the background equation of state of dark energy w . When we use the Planck cosmic microwave background temperature anisotropy, polarization, and lensing data as well as the baryonic acoustic oscillation data from SDSS and WiggleZ, we find B0<0.006 (95% C.L.) for the designer models with w =-1 . Furthermore, we find B0<0.0045 and |w +1 |<0.002 (95% C.L.) for the designer models with w ≠-1 . Previous analyses found similar results for designer and Hu-Sawicki f (R ) gravity models using the effective field theory approach [Raveri et al., Phys. Rev. D 90, 043513 (2014), 10.1103/PhysRevD.90.043513; Hu et al., Mon. Not. R. Astron. Soc. 459, 3880 (2016), 10.1093/mnras/stw775]; therefore this hints for the fact that generic f (R ) models with w ≠-1 can be tightly constrained by current cosmological data, complementary to solar system tests [Brax et al., Phys. Rev. D 78, 104021 (2008), 10.1103/PhysRevD.78.104021; Faulkner et al., Phys. Rev. D 76, 063505 (2007), 10.1103/PhysRevD.76.063505]. When compared to a w CDM fluid with the same sound speed, we find that the equation of state for f (R ) models is better constrained to be close to -1 by about an order of magnitude, due to the strong dependence of the perturbations on w .

Cosmology with the largest galaxy cluster surveys: going beyond Fisher matrix forecasts

DOE Office of Scientific and Technical Information (OSTI.GOV)

Khedekar, Satej; Majumdar, Subhabrata, E-mail: satej@mpa-garching.mpg.de, E-mail: subha@tifr.res.in

2013-02-01

We make the first detailed MCMC likelihood study of cosmological constraints that are expected from some of the largest, ongoing and proposed, cluster surveys in different wave-bands and compare the estimates to the prevalent Fisher matrix forecasts. Mock catalogs of cluster counts expected from the surveys — eROSITA, WFXT, RCS2, DES and Planck, along with a mock dataset of follow-up mass calibrations are analyzed for this purpose. A fair agreement between MCMC and Fisher results is found only in the case of minimal models. However, for many cases, the marginalized constraints obtained from Fisher and MCMC methods can differ bymore » factors of 30-100%. The discrepancy can be alarmingly large for a time dependent dark energy equation of state, w(a); the Fisher methods are seen to under-estimate the constraints by as much as a factor of 4-5. Typically, Fisher estimates become more and more inappropriate as we move away from ΛCDM, to a constant-w dark energy to varying-w dark energy cosmologies. Fisher analysis, also, predicts incorrect parameter degeneracies. There are noticeable offsets in the likelihood contours obtained from Fisher methods that is caused due to an asymmetry in the posterior likelihood distribution as seen through a MCMC analysis. From the point of mass-calibration uncertainties, a high value of unknown scatter about the mean mass-observable relation, and its redshift dependence, is seen to have large degeneracies with the cosmological parameters σ{sub 8} and w(a) and can degrade the cosmological constraints considerably. We find that the addition of mass-calibrated cluster datasets can improve dark energy and σ{sub 8} constraints by factors of 2-3 from what can be obtained from CMB+SNe+BAO only . Finally, we show that a joint analysis of datasets of two (or more) different cluster surveys would significantly tighten cosmological constraints from using clusters only. Since, details of future cluster surveys are still being planned, we

Helium synthesis, neutrino flavors, and cosmological implications

NASA Technical Reports Server (NTRS)

Stecker, F. W.

1979-01-01

The problem of the production of helium in big bang cosmology is re-examined in the light of several recent astrophysical observations. These data, and theoretical particle physics considerations, lead to some important inconsistencies in the standard big bang model and suggest that a more complicated picture is needed. Thus, recent constraints on the number of neutrino flavors, as well as constraints on the mean density (openness) of the universe, need not be valid.

Cosmology from cosmic shear with Dark Energy Survey Science Verification data

DOE PAGES

Becker, M. R.

2016-07-06

We present the first constraints on cosmology from the Dark Energy Survey (DES), using weak lensing measurements from the preliminary Science Verification (SV) data. We use 139 square degrees of SV data, which is less than 3% of the full DES survey area. Using cosmic shear 2-point measurements over three redshift bins we find σ 8(m=0.3) 0.5 = 0:81 ± 0:06 (68% confidence), after marginalising over 7 systematics parameters and 3 other cosmological parameters. Furthermore, we examine the robustness of our results to the choice of data vector and systematics assumed, and find them to be stable. About 20% ofmore » our error bar comes from marginalising over shear and photometric redshift calibration uncertainties. The current state-of-the-art cosmic shear measurements from CFHTLenS are mildly discrepant with the cosmological constraints from Planck CMB data. Our results are consistent with both datasets. Our uncertainties are ~30% larger than those from CFHTLenS when we carry out a comparable analysis of the two datasets, which we attribute largely to the lower number density of our shear catalogue. We investigate constraints on dark energy and find that, with this small fraction of the full survey, the DES SV constraints make negligible impact on the Planck constraints. The moderate disagreement between the CFHTLenS and Planck values of σ 8(Ω m=0.3) 0.5 is present regardless of the value of w.« less

Cosmology from cosmic shear with Dark Energy Survey Science Verification data

DOE Office of Scientific and Technical Information (OSTI.GOV)

Becker, M. R.

We present the first constraints on cosmology from the Dark Energy Survey (DES), using weak lensing measurements from the preliminary Science Verification (SV) data. We use 139 square degrees of SV data, which is less than 3% of the full DES survey area. Using cosmic shear 2-point measurements over three redshift bins we find σ 8(m=0.3) 0.5 = 0:81 ± 0:06 (68% confidence), after marginalising over 7 systematics parameters and 3 other cosmological parameters. Furthermore, we examine the robustness of our results to the choice of data vector and systematics assumed, and find them to be stable. About 20% ofmore » our error bar comes from marginalising over shear and photometric redshift calibration uncertainties. The current state-of-the-art cosmic shear measurements from CFHTLenS are mildly discrepant with the cosmological constraints from Planck CMB data. Our results are consistent with both datasets. Our uncertainties are ~30% larger than those from CFHTLenS when we carry out a comparable analysis of the two datasets, which we attribute largely to the lower number density of our shear catalogue. We investigate constraints on dark energy and find that, with this small fraction of the full survey, the DES SV constraints make negligible impact on the Planck constraints. The moderate disagreement between the CFHTLenS and Planck values of σ 8(Ω m=0.3) 0.5 is present regardless of the value of w.« less

Power spectrum constraints from spectral distortions in the cosmic microwave background

NASA Technical Reports Server (NTRS)

Hu, Wayne; Scott, Douglas; Silk, Joseph

1994-01-01

Using recent experimental limits on chemical potential distortions from Cosmic Background Explorer (COBE) Far Infrared Astronomy Satellite (FIRAS), and the large lever-arm spanning the damping of sub-Jeans scale fluctuations to the COBE DMR fluctuations, we set a constraint on the slope of the primordial power spectrum n. It is possible to analytically calculate the contribution over the full range of scales and redshifts, correctly taking into account fluctuation growth and damping as well as thermalization processes. Assuming conservatively that mu is less than 1.76 x 10(exp -4), we find that the 95% upper limit on n is only weakly dependent on other cosmological parameters, e.g., n is less than 1.60 (h=0.5) and n is less than 1.63 (h=1.0) for Omega(sub 0) = 1, with marginally weaker constraints for Omega(sub 0) is less than 1 in a flat model with a cosmological constant.

Constraints on massive gravity theory from big bang nucleosynthesis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lambiase, G., E-mail: lambiase@sa.infn.it

The massive gravity cosmology is studied in the scenario of big bang nucleosynthesis. By making use of current bounds on the deviation from the fractional mass, we derive the constraints on the free parameters of the theory. The cosmological consequences of the model are also analyzed in the framework of the PAMELA experiment, i.e. an excess of positron events, that the conventional cosmology and particle physics cannot explain.

Cosmological constraints with weak-lensing peak counts and second-order statistics in a large-field survey

NASA Astrophysics Data System (ADS)

Peel, Austin; Lin, Chieh-An; Lanusse, François; Leonard, Adrienne; Starck, Jean-Luc; Kilbinger, Martin

2017-03-01

Peak statistics in weak-lensing maps access the non-Gaussian information contained in the large-scale distribution of matter in the Universe. They are therefore a promising complementary probe to two-point and higher-order statistics to constrain our cosmological models. Next-generation galaxy surveys, with their advanced optics and large areas, will measure the cosmic weak-lensing signal with unprecedented precision. To prepare for these anticipated data sets, we assess the constraining power of peak counts in a simulated Euclid-like survey on the cosmological parameters Ωm, σ8, and w0de. In particular, we study how Camelus, a fast stochastic model for predicting peaks, can be applied to such large surveys. The algorithm avoids the need for time-costly N-body simulations, and its stochastic approach provides full PDF information of observables. Considering peaks with a signal-to-noise ratio ≥ 1, we measure the abundance histogram in a mock shear catalogue of approximately 5000 deg2 using a multiscale mass-map filtering technique. We constrain the parameters of the mock survey using Camelus combined with approximate Bayesian computation, a robust likelihood-free inference algorithm. Peak statistics yield a tight but significantly biased constraint in the σ8-Ωm plane, as measured by the width ΔΣ8 of the 1σ contour. We find Σ8 = σ8(Ωm/ 0.27)α = 0.77-0.05+0.06 with α = 0.75 for a flat ΛCDM model. The strong bias indicates the need to better understand and control the model systematics before applying it to a real survey of this size or larger. We perform a calibration of the model and compare results to those from the two-point correlation functions ξ± measured on the same field. We calibrate the ξ± result as well, since its contours are also biased, although not as severely as for peaks. In this case, we find for peaks Σ8 = 0.76-0.03+0.02 with α = 0.65, while for the combined ξ+ and ξ- statistics the values are Σ8 = 0.76-0.01+0.02 and α = 0

Cosmological signals of a mirror twin Higgs

DOE PAGES

Craig, Nathaniel; Koren, Seth; Trott, Timothy

2017-05-08

We investigate the cosmology of the minimal model of neutral naturalness, the mirror Twin Higgs. The softly-broken mirror symmetry relating the Standard Model to its twin counterpart leads to significant dark radiation in tension with BBN and CMB observations. We quantify this tension and illustrate how it can be mitigated in several simple scenarios that alter the relative energy densities of the two sectors while respecting the softly-broken mirror symmetry. In particular, we consider both the out-of-equilibrium decay of a new scalar as well as reheating in a toy model of twinned inflation, Twinflation. In both cases the dilution ofmore » energy density in the twin sector does not merely reconcile the existence of a mirror Twin Higgs with cosmological constraints, but predicts contributions to cosmological observables that may be probed in current and future CMB experiments. This raises the prospect of discovering evidence of neutral naturalness through cosmology rather than colliders.« less

SU(5)×U(1)X grand unification with minimal seesaw and Z‧-portal dark matter

NASA Astrophysics Data System (ADS)

Okada, Nobuchika; Okada, Satomi; Raut, Digesh

2018-05-01

We propose a grand unified SU (5) × U(1)X model, where the standard SU(5) grand unified theory is supplemented by minimal seesaw and a right-handed neutrino dark matter with an introduction of a global Z2-parity. In the presence of three right-handed neutrinos (RHNs), the model is free from all gauge and mixed-gravitational anomalies. The SU(5) symmetry is broken into the Standard Model (SM) gauge group at MGUT ≃ 4 ×1016GeV in the standard manner, while the U(1)X symmetry breaking occurs at the TeV scale, which generates the TeV-scale mass of the U(1)X gauge boson (Z‧ boson) and the three Majorana RHNs. A unique Z2-odd RHN is stable and serves as the dark matter (DM) in the present Universe, while the remaining two RHNs work to generate the SM neutrino masses through the minimal seesaw. We investigate the Z‧-portal RHN DM scenario in this model context. We find that the constraints from the DM relic abundance, and the Z‧ boson search at the Large Hadron Collider (LHC), and the perturbativity bound on the U(1)X gauge coupling are complementary to narrow down the allowed parameter region in the range of 3.0 ≤mZ‧ [TeV ] ≤ 9.2 for the Z‧ boson mass. The allowed region for mZ‧ ≤ 5TeV will be fully covered by the future LHC experiments. We also briefly discuss the successful implementation of Baryogenesis and cosmological inflation scenarios in the present model.

On anthropic solutions of the cosmological constant problem

NASA Astrophysics Data System (ADS)

Banks, Tom; Dine, Michael; Motl, Lubos

2001-01-01

Motivated by recent work of Bousso and Polchinski (BP), we study theories which explain the small value of the cosmological constant using the anthropic principle. We argue that simultaneous solution of the gauge hierarchy problem is a strong constraint on any such theory. We exhibit three classes of models which satisfy these constraints. The first is a version of the BP model with precisely two large dimensions. The second involves 6-branes and antibranes wrapped on supersymmetric 3-cycles of Calabi-Yau manifolds, and the third is a version of the irrational axion model. All of them have possible problems in explaining the size of microwave background fluctuations. We also find that most models of this type predict that all constants in the low energy lagrangian, as well as the gauge groups and representation content, are chosen from an ensemble and cannot be uniquely determined from the fundamental theory. In our opinion, this significantly reduces the appeal of this kind of solution of the cosmological constant problem. On the other hand, we argue that the vacuum selection problem of string theory might plausibly have an anthropic, cosmological solution.

Approximate Bayesian computation for forward modeling in cosmology

DOE Office of Scientific and Technical Information (OSTI.GOV)

Akeret, Joël; Refregier, Alexandre; Amara, Adam

Bayesian inference is often used in cosmology and astrophysics to derive constraints on model parameters from observations. This approach relies on the ability to compute the likelihood of the data given a choice of model parameters. In many practical situations, the likelihood function may however be unavailable or intractable due to non-gaussian errors, non-linear measurements processes, or complex data formats such as catalogs and maps. In these cases, the simulation of mock data sets can often be made through forward modeling. We discuss how Approximate Bayesian Computation (ABC) can be used in these cases to derive an approximation to themore » posterior constraints using simulated data sets. This technique relies on the sampling of the parameter set, a distance metric to quantify the difference between the observation and the simulations and summary statistics to compress the information in the data. We first review the principles of ABC and discuss its implementation using a Population Monte-Carlo (PMC) algorithm and the Mahalanobis distance metric. We test the performance of the implementation using a Gaussian toy model. We then apply the ABC technique to the practical case of the calibration of image simulations for wide field cosmological surveys. We find that the ABC analysis is able to provide reliable parameter constraints for this problem and is therefore a promising technique for other applications in cosmology and astrophysics. Our implementation of the ABC PMC method is made available via a public code release.« less

Cosmological element production.

PubMed

Wagoner, R V

1967-03-17

Two recent observations appear to have provided critical information about the past history of the universe. The thermal character of the microwave background radiation suggests that the universe has expanded from a state of high temperature and density, and places constraints on such a big-bang cosmology. The observations of very weak helium lines in the spectra of certain stars in the halo of our galaxy are possibly due to a low primeval abundance of this element. However, the simplest model of a big-bang cosmology leads to much higher helium abundances, such as are observed in the solar system and in many stars. The production of helium can be reduced either by altering the early expansion rate or by introducing degenerate electron neutrinos. Observations of interstellar and intergalactic deuterium and He(4), and possibly even He(3) and Li(7), are needed to test the various models.

Observational exclusion of a consistent loop quantum cosmology scenario

NASA Astrophysics Data System (ADS)

Bolliet, Boris; Barrau, Aurélien; Grain, Julien; Schander, Susanne

2016-06-01

It is often argued that inflation erases all the information about what took place before it started. Quantum gravity, relevant in the Planck era, seems therefore mostly impossible to probe with cosmological observations. In general, only very ad hoc scenarios or hyper fine-tuned initial conditions can lead to observationally testable theories. Here we consider a well-defined and well-motivated candidate quantum cosmology model that predicts inflation. Using the most recent observational constraints on the cosmic microwave background B-modes, we show that the model is excluded for all its parameter space, without any tuning. Some important consequences are drawn for the deformed algebra approach to loop quantum cosmology. We emphasize that neither loop quantum cosmology in general nor loop quantum gravity are disfavored by this study but their falsifiability is established.

The cosmology of interacting spin-2 fields

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tamanini, Nicola; Saridakis, Emmanuel N.; Koivisto, Tomi S., E-mail: n.tamanini.11@ucl.ac.uk, E-mail: Emmanuel_Saridakis@baylor.edu, E-mail: t.s.koivisto@astro.uio.no

2014-02-01

We investigate the cosmology of interacting spin-2 particles, formulating the multi-gravitational theory in terms of vierbeins and without imposing any Deser-van Nieuwen-huizen-like constraint. The resulting multi-vierbein theory represents a wider class of gravitational theories if compared to the corresponding multi-metric models. Moreover, as opposed to its metric counterpart which in general seems to contain ghosts, it has already been proved to be ghost-free. We outline a discussion about the possible matter couplings and we focus on the study of cosmological scenarios in the case of three and four interacting vierbeins. We find rich behavior, including de Sitter solutions with anmore » effective cosmological constant arising from the multi-vierbein interaction, dark-energy solutions and nonsingular bouncing behavior.« less

Cosmological constraints from multiple tracers in spectroscopic surveys

NASA Astrophysics Data System (ADS)

Alarcon, Alex; Eriksen, Martin; Gaztanaga, Enrique

2018-01-01

We use the Fisher matrix formalism to study the expansion and growth history of the Universe using galaxy clustering with 2D angular cross-correlation tomography in spectroscopic or high-resolution photometric redshift surveys. The radial information is contained in the cross-correlations between narrow redshift bins. We show how multiple tracers with redshift space distortions cancel sample variance and arbitrarily improve the constraints on the dark energy equation of state ω(z) and the growth parameter γ in the noiseless limit. The improvement for multiple tracers quickly increases with the bias difference between the tracers, up to a factor ∼4 in FoMγω. We model a magnitude limited survey with realistic density and bias using a conditional luminosity function, finding a factor 1.3-9.0 improvement in FoMγω - depending on global density - with a split in a halo mass proxy. Partly overlapping redshift bins improve the constraints in multiple tracer surveys a factor ∼1.3 in FoMγω. This finding also applies to photometric surveys, where the effect of using multiple tracers is magnified. We also show large improvement on the FoM with increasing density, which could be used as a trade-off to compensate some possible loss with radial resolution.

A model with isospin doublet U(1)D gauge symmetry

NASA Astrophysics Data System (ADS)

Nomura, Takaaki; Okada, Hiroshi

2018-05-01

We propose a model with an extra isospin doublet U(1)D gauge symmetry, in which we introduce several extra fermions with odd parity under a discrete Z2 symmetry in order to cancel the gauge anomalies out. A remarkable issue is that we impose nonzero U(1)D charge to the Standard Model Higgs, and it gives the most stringent constraint to the vacuum expectation value of a scalar field breaking the U(1)D symmetry that is severer than the LEP bound. We then explore relic density of a Majorana dark matter candidate without conflict of constraints from lepton flavor violating processes. A global analysis is carried out to search for parameters which can accommodate with the observed data.

Precision Cosmology

NASA Astrophysics Data System (ADS)

Jones, Bernard J. T.

2017-04-01

Preface; Notation and conventions; Part I. 100 Years of Cosmology: 1. Emerging cosmology; 2. The cosmic expansion; 3. The cosmic microwave background; 4. Recent cosmology; Part II. Newtonian Cosmology: 5. Newtonian cosmology; 6. Dark energy cosmological models; 7. The early universe; 8. The inhomogeneous universe; 9. The inflationary universe; Part III. Relativistic Cosmology: 10. Minkowski space; 11. The energy momentum tensor; 12. General relativity; 13. Space-time geometry and calculus; 14. The Einstein field equations; 15. Solutions of the Einstein equations; 16. The Robertson-Walker solution; 17. Congruences, curvature and Raychaudhuri; 18. Observing and measuring the universe; Part IV. The Physics of Matter and Radiation: 19. Physics of the CMB radiation; 20. Recombination of the primeval plasma; 21. CMB polarisation; 22. CMB anisotropy; Part V. Precision Tools for Precision Cosmology: 23. Likelihood; 24. Frequentist hypothesis testing; 25. Statistical inference: Bayesian; 26. CMB data processing; 27. Parametrising the universe; 28. Precision cosmology; 29. Epilogue; Appendix A. SI, CGS and Planck units; Appendix B. Magnitudes and distances; Appendix C. Representing vectors and tensors; Appendix D. The electromagnetic field; Appendix E. Statistical distributions; Appendix F. Functions on a sphere; Appendix G. Acknowledgements; References; Index.

Cosmological constraints on exotic injection of electromagnetic energy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Poulin, Vivian; Serpico, Pasquale D.; Lesgourgues, Julien, E-mail: Vivian.Poulin@lapth.cnrs.fr, E-mail: Pasquale.Serpico@lapth.cnrs.fr, E-mail: Julien.Lesgourgues@physik.rwth-aachen.de

We compute cosmic microwave background (CMB) anisotropy constraints on exotic forms of energy injection in electromagnetic (e.m.) channels over a large range of timescales. We show that these constraints are very powerful around or just after recombination, although CMB keeps some sensitivity e.g. to decaying species with lifetimes as long as 10{sup 25} s. These bounds are complementary to CMB spectral distortions and primordial nucleosynthesis ones, which dominate at earlier timescales, as we also review here. For the first time, we describe the effects of the e.m. energy injection on the CMB power spectra as a function of the injectionmore » epoch , using the lifetime of a decaying particle as proxy. We also identify a suitable on-the-spot approximation, that can be used to derive accurate constraints, and describe its differences with the most up-to-date treatment. Our results are of interest not only for early universe relics constituting (a fraction of) the dark matter, but also for other exotic injection of e.m. radiation. For illustration, we apply our formalism to: i) Primordial black holes of mass 10{sup 13.5} g ∼< M ∼< 10{sup 16.8} g, showing that the constraints are comparable to the ones obtained from gamma-ray background studies and even dominate below ∼ 10{sup 14} g. ii) To a peculiar mass-mixing range in the sterile neutrino parameter space, complementary to other astrophysical and laboratory probes. iii) Finally, we provide a first estimate of the room for improvement left for forthcoming 21 cm experiments, comparing it with the reach of proposed CMB spectral distortion (PiXiE) and CMB angular power spectrum (CORE) missions. We show that the best and most realistic opportunity to look for this signal (or to improve over current constraints) in the 21 cm probe is to focus on the Cosmic Dawn epoch, 15 ∼< z ∼< 30, where the qualitatively unambiguous signature of a spectrum in emission can be expected for models that evade all current

Cosmological constraints on exotic injection of electromagnetic energy

NASA Astrophysics Data System (ADS)

Poulin, Vivian; Lesgourgues, Julien; Serpico, Pasquale D.

2017-03-01

We compute cosmic microwave background (CMB) anisotropy constraints on exotic forms of energy injection in electromagnetic (e.m.) channels over a large range of timescales. We show that these constraints are very powerful around or just after recombination, although CMB keeps some sensitivity e.g. to decaying species with lifetimes as long as 1025 s. These bounds are complementary to CMB spectral distortions and primordial nucleosynthesis ones, which dominate at earlier timescales, as we also review here. For the first time, we describe the effects of the e.m. energy injection on the CMB power spectra as a function of the injection epoch, using the lifetime of a decaying particle as proxy. We also identify a suitable on-the-spot approximation, that can be used to derive accurate constraints, and describe its differences with the most up-to-date treatment. Our results are of interest not only for early universe relics constituting (a fraction of) the dark matter, but also for other exotic injection of e.m. radiation. For illustration, we apply our formalism to: i) Primordial black holes of mass 1013.5 g lesssim M lesssim 1016.8 g, showing that the constraints are comparable to the ones obtained from gamma-ray background studies and even dominate below ~ 1014 g. ii) To a peculiar mass-mixing range in the sterile neutrino parameter space, complementary to other astrophysical and laboratory probes. iii) Finally, we provide a first estimate of the room for improvement left for forthcoming 21 cm experiments, comparing it with the reach of proposed CMB spectral distortion (PiXiE) and CMB angular power spectrum (CORE) missions. We show that the best and most realistic opportunity to look for this signal (or to improve over current constraints) in the 21 cm probe is to focus on the Cosmic Dawn epoch, 15 lesssim z lesssim 30, where the qualitatively unambiguous signature of a spectrum in emission can be expected for models that evade all current constraints.

Cosmological constraints on neutrinos with Planck data

NASA Astrophysics Data System (ADS)

Spinelli, M.

2015-07-01

Neutrinos take part in the dance of the evolving Universe influencing its history from leptogenesis, to Big Bang nucleosynthesis, until late time structure formation. This makes cosmology, and in particular one of its primary observables the Cosmic Microwave Background (CMB), an unusual but valuable tool for testing Neutrino Physics. The best measurement to date of full-sky CMB anisotropies comes from the Planck satellite launched in 2009 by the European Space Agency (ESA) and successful follower of COBE and WMAP. Testing Planck data against precise theoretical predictions allow us to shed light on various interesting open questions such as the value of the absolute scale of neutrino masses or their energy density. We revise here the results concerning neutrinos obtained by the Planck Collaboration in the 2013 data release.

Cosmological constraints on neutrinos with Planck data

DOE Office of Scientific and Technical Information (OSTI.GOV)

Spinelli, M.

2015-07-15

Neutrinos take part in the dance of the evolving Universe influencing its history from leptogenesis, to Big Bang nucleosynthesis, until late time structure formation. This makes cosmology, and in particular one of its primary observables the Cosmic Microwave Background (CMB), an unusual but valuable tool for testing Neutrino Physics. The best measurement to date of full-sky CMB anisotropies comes from the Planck satellite launched in 2009 by the European Space Agency (ESA) and successful follower of COBE and WMAP. Testing Planck data against precise theoretical predictions allow us to shed light on various interesting open questions such as the valuemore » of the absolute scale of neutrino masses or their energy density. We revise here the results concerning neutrinos obtained by the Planck Collaboration in the 2013 data release.« less

Cosmological implications of baryon acoustic oscillation measurements

DOE PAGES

Aubourg, Eric

2015-12-01

Here, we derive constraints on cosmological parameters and tests of dark energy models from the combination of baryon acoustic oscillation (BAO) measurements with cosmic microwave background (CMB) data and a recent reanalysis of Type Ia supernova (SN) data. Particularly, we take advantage of high-precision BAO measurements from galaxy clustering and the Lyman-α forest (LyaF) in the SDSS-III Baryon Oscillation Spectroscopic Survey (BOSS). Treating the BAO scale as an uncalibrated standard ruler, BAO data alone yield a high confidence detection of dark energy; in combination with the CMB angular acoustic scale they further imply a nearly flat universe. Adding the CMB-calibratedmore » physical scale of the sound horizon, the combination of BAO and SN data into an “inverse distance ladder” yields a measurement of H 0=67.3±1.1 km s -1 Mpc -1, with 1.7% precision. This measurement assumes standard prerecombination physics but is insensitive to assumptions about dark energy or space curvature, so agreement with CMB-based estimates that assume a flat ΛCDM cosmology is an important corroboration of this minimal cosmological model. For constant dark energy (Λ), our BAO+SN+CMB combination yields matter density Ω m=0.301±0.008 and curvature Ω k=-0.003±0.003. When we allow more general forms of evolving dark energy, the BAO+SN+CMB parameter constraints are always consistent with flat ΛCDM values at ≈1σ. And while the overall χ 2 of model fits is satisfactory, the LyaF BAO measurements are in moderate (2–2.5σ) tension with model predictions. Models with early dark energy that tracks the dominant energy component at high redshift remain consistent with our expansion history constraints, and they yield a higher H 0 and lower matter clustering amplitude, improving agreement with some low redshift observations. Expansion history alone yields an upper limit on the summed mass of neutrino species, Σm ν<0.56 eV (95% confidence), improving to Σm ν<0.25 eV if we

Cosmology in time asymmetric extensions of general relativity

DOE Office of Scientific and Technical Information (OSTI.GOV)

Leon, Genly; Saridakis, Emmanuel N., E-mail: genly.leon@ucv.cl, E-mail: Emmanuel_Saridakis@baylor.edu

We investigate the cosmological behavior in a universe governed by time asymmetric extensions of general relativity, which is a novel modified gravity based on the addition of new, time-asymmetric, terms on the Hamiltonian framework, in a way that the algebra of constraints and local physics remain unchanged. Nevertheless, at cosmological scales these new terms can have significant effects that can alter the universe evolution, both at early and late times, and the freedom in the choice of the involved modification function makes the scenario able to produce a huge class of cosmological behaviors. For basic ansatzes of modification, we performmore » a detailed dynamical analysis, extracting the stable late-time solutions. Amongst others, we find that the universe can result in dark-energy dominated, accelerating solutions, even in the absence of an explicit cosmological constant, in which the dark energy can be quintessence-like, phantom-like, or behave as an effective cosmological constant. Moreover, it can result to matter-domination, or to a Big Rip, or experience the sequence from matter to dark energy domination. Additionally, in the case of closed curvature, the universe may experience a cosmological bounce or turnaround, or even cyclic behavior. Finally, these scenarios can easily satisfy the observational and phenomenological requirements. Hence, time asymmetric cosmology can be a good candidate for the description of the universe.« less

Statistical Hierarchy of Varying Speed of Light Cosmologies

NASA Astrophysics Data System (ADS)

Salzano, Vincenzo; Da¸browski, Mariusz P.

2017-12-01

Many varying speed of light (VSL) theories have been developed recently. Here we address the issue of their observational verification in a fully comprehensive way. By using the most updated cosmological probes, we test three different candidates for a VSL theory (Barrow & Magueijo, Avelino & Martins, and Moffat). We consider many different Ansätze for both the functional form of c(z) and the dark energy dynamics. We compare these results using a reliable statistical tool such as the Bayesian evidence. We find that the present cosmological data are perfectly compatible with any of these VSL scenarios, but for the Moffat model there is a higher Bayesian evidence ratio in favor of VSL rather than the c = constant ΛCDM scenario. Moreover, in such a scenario, the VSL signal can help to strengthen constraints on the spatial curvature (with indication toward an open universe), to clarify some properties of dark energy (exclusion of a cosmological constant at 2σ level), and is also falsifiable in the near future owing to peculiar issues that differentiate this model from the standard one. Finally, we apply an information prior and entropy prior in order to put physical constraints on the models, though still in favor Moffat’s proposal.

The role of energy conditions in f(R) cosmology

NASA Astrophysics Data System (ADS)

Capozziello, S.; Nojiri, S.; Odintsov, S. D.

2018-06-01

Energy conditions can play an important role in defining the cosmological evolution. Specifically acceleration/deceleration of cosmic fluid, as well as the emergence of Big Rip singularities, can be related to the constraints imposed by the energy conditions. Here we discuss this issue for f (R) gravity considering also conformal transformations. Cosmological solutions and equations of state can be classified according to energy conditions. The qualitative change of some energy conditions when transformation from the Jordan frame to the Einstein frame done is also observed.

Constraints on secret neutrino interactions after Planck

DOE Office of Scientific and Technical Information (OSTI.GOV)

Forastieri, Francesco; Lattanzi, Massimiliano; Natoli, Paolo, E-mail: francesco.forastieri@unife.it, E-mail: lattanzi@fe.infn.it, E-mail: natoli@fe.infn.it

Neutrino interactions beyond the standard model of particle physics may affect the cosmological evolution and can be constrained through observations. We consider the possibility that neutrinos possess secret scalar or pseudoscalar interactions mediated by the Nambu-Goldstone boson of a still unknown spontaneously broken global U(1) symmetry, as in, e.g., Majoron models. In such scenarios, neutrinos still decouple at T≅ 1 MeV, but become tightly coupled again (''recouple'') at later stages of the cosmological evolution. We use available observations of the cosmic microwave background (CMB) anisotropies, including Planck 2013 and the joint BICEP2/Planck 2015 data, to derive constraints on the quantity γ{submore » νν}{sup 4}, parameterizing the neutrino collision rate due to scalar or pseudoscalar interactions. We consider both a minimal extension of the standard ΛCDM model, and more complicated scenarios with extra relativistic degrees of freedom or non-vanishing tensor amplitude. For a wide range of dataset and model combinations, we find a typical constraint γ{sub νν}{sup 4} ∼< 0.9× 10{sup −27} (95% C.L.), implying an upper limit on the redshift z{sub νrec} of neutrino recoupling 0∼< 850, leaving open the possibility that the latter occured well before hydrogen recombination. In the framework of Majoron models, the upper limit on γ{sub νν} roughly translates on a constraint g ∼< 8.2× 10{sup −7} on the Majoron-neutrino coupling constant g. In general, the data show a weak (∼ 1σ) but intriguing preference for non-zero values of γ{sub νν}{sup 4}, with best fits in the range γ{sub νν}{sup 4} = (0.15–0.35)× 10{sup −27}, depending on the particular dataset. This is more evident when either high-resolution CMB observations from the ACT and SPT experiments are included, or the possibility of non-vanishing tensor modes is considered. In particular, for the minimal model ΛCDM+γ{sub νν} and including the Planck 2013

Cosmological perturbation theory in 1+1 dimensions

NASA Astrophysics Data System (ADS)

McQuinn, Matthew; White, Martin

2016-01-01

Many recent studies have highlighted certain failures of the standard Eulerian-space cosmological perturbation theory (SPT). Its problems include (1) not capturing large-scale bulk flows [leading to an Script O( 1) error in the 1-loop SPT prediction for the baryon acoustic peak in the correlation function], (2) assuming that the Universe behaves as a pressureless, inviscid fluid, and (3) treating fluctuations on scales that are non-perturbative as if they were. Recent studies have highlighted the successes of perturbation theory in Lagrangian space or theories that solve equations for the effective dynamics of smoothed fields. Both approaches mitigate some or all of the aforementioned issues with SPT. We discuss these physical developments by specializing to the simplified 1D case of gravitationally interacting sheets, which allows us to substantially reduces the analytic overhead and still (as we show) maintain many of the same behaviors as in 3D. In 1D, linear-order Lagrangian perturbation theory ("the Zeldovich approximation") is exact up to shell crossing, and we prove that nth-order Eulerian perturbation theory converges to the Zeldovich approximation as narrow ∞. In no 1D cosmology that we consider (including a CDM-like case and power-law models) do these theories describe accurately the matter power spectrum on any mildly nonlinear scale. We find that theories based on effective equations are much more successful at describing the dynamics. Finally, we discuss many topics that have recently appeared in the perturbation theory literature such as beat coupling, the shift and smearing of the baryon acoustic oscillation feature, and the advantages of Fourier versus configuration space. Our simplified 1D case serves as an intuitive review of these perturbation theory results.

Cosmological measurements with general relativistic galaxy correlations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Raccanelli, Alvise; Montanari, Francesco; Durrer, Ruth

We investigate the cosmological dependence and the constraining power of large-scale galaxy correlations, including all redshift-distortions, wide-angle, lensing and gravitational potential effects on linear scales. We analyze the cosmological information present in the lensing convergence and in the gravitational potential terms describing the so-called ''relativistic effects'', and we find that, while smaller than the information contained in intrinsic galaxy clustering, it is not negligible. We investigate how neglecting them does bias cosmological measurements performed by future spectroscopic and photometric large-scale surveys such as SKA and Euclid. We perform a Fisher analysis using the CLASS code, modified to include scale-dependent galaxymore » bias and redshift-dependent magnification and evolution bias. Our results show that neglecting relativistic terms, especially lensing convergence, introduces an error in the forecasted precision in measuring cosmological parameters of the order of a few tens of percent, in particular when measuring the matter content of the Universe and primordial non-Gaussianity parameters. The analysis suggests a possible substantial systematic error in cosmological parameter constraints. Therefore, we argue that radial correlations and integrated relativistic terms need to be taken into account when forecasting the constraining power of future large-scale number counts of galaxy surveys.« less

Did God create our universe? Theological reflections on the Big Bang, inflation, and quantum cosmologies.

PubMed

Russell, R J

2001-12-01

The sciences and the humanities, including theology, form an epistemic hierarchy that ensures both constraint and irreducibility. At the same time, theological methodology is analogous to scientific methodology, though with several important differences. This model of interaction between science and theology can be seen illustrated in a consideration of the relation between contemporary cosmology (Big Bang cosmology, cosmic inflation, and quantum cosmology) and Christian systematic and natural theology. In light of developments in cosmology, the question of origins has become theologically less interesting than that of the cosmic evolution of a contingent universe.

Cosmological CPT violation and CMB polarization measurements

NASA Astrophysics Data System (ADS)

Xia, Jun-Qing

2012-01-01

In this paper we study the possibility of testing Charge-Parity-Time Reversal (CPT) symmetry with cosmic microwave background (CMB) experiments. We consider two kinds of Chern-Simons (CS) term, electromagnetic CS term and gravitational CS term, and study their effects on the CMB polarization power spectra in detail. By combining current CMB polarization measurements, the seven-year WMAP, BOOMERanG 2003 and BICEP observations, we obtain a tight constraint on the rotation angle Δα = -2.28±1.02 deg (1 σ), indicating a 2.2 σ detection of the CPT violation. Here, we particularly take the systematic errors of CMB measurements into account. After adding the QUaD polarization data, the constraint becomes -1.34 < Δα < 0.82 deg at 95% confidence level. When comparing with the effect of electromagnetic CS term, the gravitational CS term could only generate TB and EB power spectra with much smaller amplitude. Therefore, the induced parameter epsilon can not be constrained from the current polarization data. Furthermore, we study the capabilities of future CMB measurements, Planck and CMBPol, on the constraints of Δα and epsilon. We find that the constraint of Δα can be significantly improved by a factor of 15. Therefore, if this rotation angle effect can not be taken into account properly, the constraints of cosmological parameters will be biased obviously. For the gravitational CS term, the future Planck data still can not constrain epsilon very well, if the primordial tensor perturbations are small, r < 0.1. We need the more accurate CMBPol experiment to give better constraint on epsilon.

Constraints on Non-flat Cosmologies with Massive Neutrinos after Planck 2015

NASA Astrophysics Data System (ADS)

Chen, Yun; Ratra, Bharat; Biesiada, Marek; Li, Song; Zhu, Zong-Hong

2016-10-01

We investigate two dark energy cosmological models (I.e., the ΛCDM and ϕCDM models) with massive neutrinos assuming two different neutrino mass hierarchies in both the spatially flat and non-flat scenarios, where in the ϕCDM model the scalar field possesses an inverse power-law potential, V(ϕ) ∝ ϕ -α (α > 0). Cosmic microwave background data from Planck 2015, baryon acoustic oscillation data from 6dFGS, SDSS-MGS, BOSS-LOWZ and BOSS CMASS-DR11, the joint light-curve analysis compilation of SNe Ia apparent magnitude observations, and the Hubble Space Telescope H 0 prior, are jointly employed to constrain the model parameters. We first determine constraints assuming three species of degenerate massive neutrinos. In the spatially flat (non-flat) ΛCDM model, the sum of neutrino masses is bounded as Σm ν < 0.165(0.299) eV at 95% confidence level (CL). Correspondingly, in the flat (non-flat) ϕCDM model, we find Σm ν < 0.164(0.301) eV at 95% CL. The inclusion of spatial curvature as a free parameter results in a significant broadening of confidence regions for Σm ν and other parameters. In the scenario where the total neutrino mass is dominated by the heaviest neutrino mass eigenstate, we obtain similar conclusions to those obtained in the degenerate neutrino mass scenario. In addition, the results show that the bounds on Σm ν based on two different neutrino mass hierarchies have insignificant differences in the spatially flat case for both the ΛCDM and ϕCDM models; however, the corresponding differences are larger in the non-flat case.

How does pressure gravitate? Cosmological constant problem confronts observational cosmology

NASA Astrophysics Data System (ADS)

Narimani, Ali; Afshordi, Niayesh; Scott, Douglas

2014-08-01

An important and long-standing puzzle in the history of modern physics is the gross inconsistency between theoretical expectations and cosmological observations of the vacuum energy density, by at least 60 orders of magnitude, otherwise known as the cosmological constant problem. A characteristic feature of vacuum energy is that it has a pressure with the same amplitude, but opposite sign to its energy density, while all the precision tests of General Relativity are either in vacuum, or for media with negligible pressure. Therefore, one may wonder whether an anomalous coupling to pressure might be responsible for decoupling vacuum from gravity. We test this possibility in the context of the Gravitational Aether proposal, using current cosmological observations, which probe the gravity of relativistic pressure in the radiation era. Interestingly, we find that the best fit for anomalous pressure coupling is about half-way between General Relativity (GR), and Gravitational Aether (GA), if we include Planck together with WMAP and BICEP2 polarization cosmic microwave background (CMB) observations. Taken at face value, this data combination excludes both GR and GA at around the 3 σ level. However, including higher resolution CMB observations (``highL'') or baryonic acoustic oscillations (BAO) pushes the best fit closer to GR, excluding the Gravitational Aether solution to the cosmological constant problem at the 4- 5 σ level. This constraint effectively places a limit on the anomalous coupling to pressure in the parametrized post-Newtonian (PPN) expansion, ζ4 = 0.105 ± 0.049 (+highL CMB), or ζ4 = 0.066 ± 0.039 (+BAO). These represent the most precise measurement of this parameter to date, indicating a mild tension with GR (for ΛCDM including tensors, with 0ζ4=), and also among different data sets.

A compendium of chameleon constraints

DOE Office of Scientific and Technical Information (OSTI.GOV)

Burrage, Clare; Sakstein, Jeremy, E-mail: clare.burrage@nottingham.ac.uk, E-mail: jeremy.sakstein@port.ac.uk

2016-11-01

The chameleon model is a scalar field theory with a screening mechanism that explains how a cosmologically relevant light scalar can avoid the constraints of intra-solar-system searches for fifth-forces. The chameleon is a popular dark energy candidate and also arises in f ( R ) theories of gravity. Whilst the chameleon is designed to avoid historical searches for fifth-forces it is not unobservable and much effort has gone into identifying the best observables and experiments to detect it. These results are not always presented for the same models or in the same language, a particular problem when comparing astrophysical andmore » laboratory searches making it difficult to understand what regions of parameter space remain. Here we present combined constraints on the chameleon model from astrophysical and laboratory searches for the first time and identify the remaining windows of parameter space. We discuss the implications for cosmological chameleon searches and future small-scale probes.« less

Cosmology in bimetric theory with an effective composite coupling to matter

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gümrükçüoğlu, A. Emir; Heisenberg, Lavinia; Mukohyama, Shinji

We study the cosmology of bimetric theory with a composite matter coupling. We find two possible branches of background evolution. We investigate the question of stability of cosmological perturbations. For the tensor and vector perturbations, we derive conditions on the absence of ghost and gradient instabilities. For the scalar modes, we obtain conditions for avoiding ghost degrees. In the first branch, we find that one of the scalar modes becomes a ghost at the late stages of the evolution. Conversely, this problem can be avoided in the second branch. However, we also find that the constraint for the second branchmore » prevents the doubly coupled matter fields from being the standard ingredients of cosmology. We thus conclude that a realistic and stable cosmological model requires additional minimally coupled matter fields.« less

Cosmological constraints from X-ray all sky surveys, from CODEX to eROSITA

NASA Astrophysics Data System (ADS)

Finoguenov, A.

2017-10-01

Large area cluster cosmology has long become a multiwavelength discipline. Understanding the effect of various selections is currently the main path to improving on the validity of cluster cosmological results. Many of these results are based on the large area sample derived from RASS data. We perform wavelet detection of X-ray sources and make extensive simulations of the detection of clusters in the RASS data. We assign an optical richness to each of the 25,000 detected X-ray sources in the 10,000 square degrees of SDSS BOSS area. We show that there is no obvious separation of sources on galaxy clusters and AGN, based on distribution of systems on their richness. We conclude that previous catalogs, such as MACS, REFLEX are all subject to a complex optical selection function, in addition to an X-ray selection. We provide a complete model of identification of cluster counts are galaxy clusters, which includes chance identification, effect of AGN halo occupation distribution and the thermal emission of ICM. Finally we present the cosmological results obtained using this sample.

Constraints on the Energy Density Content of the Universe Using Only Clusters of Galaxies

NASA Technical Reports Server (NTRS)

Molnar, Sandor M.; Haiman, Zoltan; Birkinshaw, Mark

2003-01-01

We demonstrate that it is possible to constrain the energy content of the Universe with high accuracy using observations of clusters of galaxies only. The degeneracies in the cosmological parameters are lifted by combining constraints from different observables of galaxy clusters. We show that constraints on cosmological parameters from galaxy cluster number counts as a function of redshift and accurate angular diameter distance measurements to clusters are complementary to each other and their combination can constrain the energy density content of the Universe well. The number counts can be obtained from X-ray and/or SZ (Sunyaev-Zeldovich effect) surveys, the angular diameter distances can be determined from deep observations of the intra-cluster gas using their thermal bremsstrahlung X-ray emission and the SZ effect (X-SZ method). In this letter we combine constraints from simulated cluster number counts expected from a 12 deg2 SZ cluster survey and constraints from simulated angular diameter distance measurements based on using the X-SZ method assuming an expected accuracy of 7% in the angular diameter distance determination of 70 clusters with redshifts less than 1.5. We find that R, can be determined within about 25%, A within 20%, and w within 16%. Any cluster survey can be used to select clusters for high accuracy distance measurements, but we assumed accurate angular diameter distance measurements for only 70 clusters since long observations are necessary to achieve high accuracy in distance measurements. Thus the question naturally arises: How to select clusters of galaxies for accurate diameter distance determinations? In this letter, as an example, we demonstrate that it is possible to optimize this selection changing the number of clusters observed, and the upper cut off of their redshift range. We show that constraints on cosmological parameters from combining cluster number counts and angular diameter distance measurements, as opposed to general

Constraints on the sum of neutrino masses using cosmological data including the latest extended Baryon Oscillation Spectroscopic Survey DR14 quasar sample

NASA Astrophysics Data System (ADS)

Wang, Sai; Wang, Yi-Fan; Xia, Dong-Mei

2018-05-01

We investigate the constraints on the sum of neutrino masses ({{Σ }}{m}ν ) using the most recent cosmological data, which combines the distance measurement from baryonic acoustic oscillation in the extended Baryon Oscillation Spectroscopic Survey DR14 quasar sample with the power spectra of temperature and polarization anisotropies in the cosmic microwave background from the Planck 2015 data release. We also use other low-redshift observations, including the baryonic acoustic oscillation at relatively low redshifts, Type Ia supernovae, and the local measurement of the Hubble constant. In the standard cosmological constant Λ cold dark matter plus massive neutrino model, we obtain the 95% upper limit to be {{Σ }}{m}ν < 0.129{eV} for the degenerate mass hierarchy, {{Σ }}{m}ν < 0.159{eV} for the normal mass hierarchy, and {{Σ }}{m}ν < 0.189{eV} for the inverted mass hierarchy. Based on Bayesian evidence, we find that the degenerate hierarchy is positively supported, and the current data combination cannot distinguish between normal and inverted hierarchies. Assuming the degenerate mass hierarchy, we extend our study to non-standard cosmological models including generic dark energy, spatial curvature, and extra relativistic degrees of freedom, but find these models are not favored by the data. SW is Supported by a grant from the Research Grant Council of the Hong Kong Special Administrative Region, China (14301214), DMX is Supported by the National Natural Science Foundation of China (11505018) and the Chongqing Science and Technology Plan Project (Cstc2015jvyj40031)

Cosmological Results from High-z Supernovae

NASA Astrophysics Data System (ADS)

Tonry, John L.; Schmidt, Brian P.; Barris, Brian; Candia, Pablo; Challis, Peter; Clocchiatti, Alejandro; Coil, Alison L.; Filippenko, Alexei V.; Garnavich, Peter; Hogan, Craig; Holland, Stephen T.; Jha, Saurabh; Kirshner, Robert P.; Krisciunas, Kevin; Leibundgut, Bruno; Li, Weidong; Matheson, Thomas; Phillips, Mark M.; Riess, Adam G.; Schommer, Robert; Smith, R. Chris; Sollerman, Jesper; Spyromilio, Jason; Stubbs, Christopher W.; Suntzeff, Nicholas B.

2003-09-01

The High-z Supernova Search Team has discovered and observed eight new supernovae in the redshift interval z=0.3-1.2. These independent observations, analyzed by similar but distinct methods, confirm the results of Riess and Perlmutter and coworkers that supernova luminosity distances imply an accelerating universe. More importantly, they extend the redshift range of consistently observed Type Ia supernovae (SNe Ia) to z~1, where the signature of cosmological effects has the opposite sign of some plausible systematic effects. Consequently, these measurements not only provide another quantitative confirmation of the importance of dark energy, but also constitute a powerful qualitative test for the cosmological origin of cosmic acceleration. We find a rate for SN Ia of (1.4+/-0.5)×10-4h3Mpc-3yr-1 at a mean redshift of 0.5. We present distances and host extinctions for 230 SN Ia. These place the following constraints on cosmological quantities: if the equation of state parameter of the dark energy is w=-1, then H0t0=0.96+/-0.04, and ΩΛ-1.4ΩM=0.35+/-0.14. Including the constraint of a flat universe, we find ΩM=0.28+/-0.05, independent of any large-scale structure measurements. Adopting a prior based on the Two Degree Field (2dF) Redshift Survey constraint on ΩM and assuming a flat universe, we find that the equation of state parameter of the dark energy lies in the range -1.48-1, we obtain w<-0.73 at 95% confidence. These constraints are similar in precision and in value to recent results reported using the WMAP satellite, also in combination with the 2dF Redshift Survey. Based in part on observations with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy (AURA), Inc., under NASA contract NAS 5-26555. This research is primarily associated with proposal GO-8177, but also uses and reports

TASI Lectures on Cosmological Observables and String Theory

NASA Astrophysics Data System (ADS)

Silverstein, Eva

These lectures provide an updated pedagogical treatment of the theoretical structure and phenomenology of some basic mechanisms for inflation, along with an overview of the structure of cosmological uplifts of holographic duality. A full treatment of the problem requires `ultraviolet completion' because of the sensitivity of inflation to quantum gravity effects, including back reaction and non-adiabatic production of heavy degrees of freedom. Cosmological observations imply accelerated expansion of the late universe, and provide increasingly precise constraints and discovery potential on the amplitude and shape of primordial tensor and scalar perturbations, and some of their correlation functions. Most backgrounds of string theory have positive potential energy, with a rich but still highly constrained landscape of solutions. The theory contains novel mechanisms for inflation, some subject to significant observational tests, with highly UV-sensitive tensor mode measurements being a prime example along with certain shapes of primordial correlation functions. Although the detailed ultraviolet completion is not accessible experimentally, some of these mechanisms directly stimulate a more systematic analysis of the space of low energy theories and signatures relevant for analysis of data, which is sensitive to physics orders of magnitude above the energy scale of inflation as a result of long time evolution (dangerous irrelevance) and the substantial amount of data (allowing constraints on quantities with signal/noise. Portions of these lectures appeared previously in Les Houches 2013, "Post-Planck Cosmology".

Non-minimally coupled condensate cosmologies: a phase space analysis

NASA Astrophysics Data System (ADS)

Carloni, Sante; Vignolo, Stefano; Cianci, Roberto

2014-09-01

We present an analysis of the phase space of cosmological models based on a non-minimal coupling between the geometry and a fermionic condensate. We observe that the strong constraint coming from the Dirac equations allows a detailed design of the cosmology of these models, and at the same time guarantees an evolution towards a state indistinguishable from general relativistic cosmological models. In this light, we show in detail how the use of some specific potentials can naturally reproduce a phase of accelerated expansion. In particular, we find for the first time that an exponential potential is able to induce two de Sitter phases separated by a power law expansion, which could be an interesting model for the unification of an inflationary phase and a dark energy era.

Unveiling ν secrets with cosmological data: Neutrino masses and mass hierarchy

NASA Astrophysics Data System (ADS)

Vagnozzi, Sunny; Giusarma, Elena; Mena, Olga; Freese, Katherine; Gerbino, Martina; Ho, Shirley; Lattanzi, Massimiliano

2017-12-01

Using some of the latest cosmological data sets publicly available, we derive the strongest bounds in the literature on the sum of the three active neutrino masses, Mν, within the assumption of a background flat Λ CDM cosmology. In the most conservative scheme, combining Planck cosmic microwave background temperature anisotropies and baryon acoustic oscillations (BAO) data, as well as the up-to-date constraint on the optical depth to reionization (τ ), the tightest 95% confidence level upper bound we find is Mν<0.151 eV . The addition of Planck high-ℓ polarization data, which, however, might still be contaminated by systematics, further tightens the bound to Mν<0.118 eV . A proper model comparison treatment shows that the two aforementioned combinations disfavor the inverted hierarchy at ˜64 % C .L . and ˜71 % C .L . , respectively. In addition, we compare the constraining power of measurements of the full-shape galaxy power spectrum versus the BAO signature, from the BOSS survey. Even though the latest BOSS full-shape measurements cover a larger volume and benefit from smaller error bars compared to previous similar measurements, the analysis method commonly adopted results in their constraining power still being less powerful than that of the extracted BAO signal. Our work uses only cosmological data; imposing the constraint Mν>0.06 eV from oscillations data would raise the quoted upper bounds by O (0.1 σ ) and would not affect our conclusions.

Soft inflation. [in cosmology

NASA Technical Reports Server (NTRS)

Berkin, Andrew L.; Maeda, Kei-Ichi; Yokoyama, Jun'ichi

1990-01-01

The cosmology resulting from two coupled scalar fields was studied, one which is either a new inflation or chaotic type inflation, and the other which has an exponentially decaying potential. Such a potential may appear in the conformally transformed frame of generalized Einstein theories like the Jordan-Brans-Dicke theory. The constraints necessary for successful inflation are examined. Conventional GUT models such as SU(5) were found to be compatible with new inflation, while restrictions on the self-coupling constant are significantly loosened for chaotic inflation.

The Atacama Cosmology Telescope: cosmological parameters from three seasons of data

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sievers, Jonathan L.; Appel, John William; Hlozek, Renée A.

2013-10-01

We present constraints on cosmological and astrophysical parameters from high-resolution microwave background maps at 148 GHz and 218 GHz made by the Atacama Cosmology Telescope (ACT) in three seasons of observations from 2008 to 2010. A model of primary cosmological and secondary foreground parameters is fit to the map power spectra and lensing deflection power spectrum, including contributions from both the thermal Sunyaev-Zeldovich (tSZ) effect and the kinematic Sunyaev-Zeldovich (kSZ) effect, Poisson and correlated anisotropy from unresolved infrared sources, radio sources, and the correlation between the tSZ effect and infrared sources. The power ℓ{sup 2}C{sub ℓ}/2π of the thermal SZmore » power spectrum at 148 GHz is measured to be 3.4±1.4  μK{sup 2} at ℓ = 3000, while the corresponding amplitude of the kinematic SZ power spectrum has a 95% confidence level upper limit of 8.6  μK{sup 2}. Combining ACT power spectra with the WMAP 7-year temperature and polarization power spectra, we find excellent consistency with the LCDM model. We constrain the number of effective relativistic degrees of freedom in the early universe to be N{sub eff} = 2.79±0.56, in agreement with the canonical value of N{sub eff} = 3.046 for three massless neutrinos. We constrain the sum of the neutrino masses to be Σm{sub ν} < 0.39 eV at 95% confidence when combining ACT and WMAP 7-year data with BAO and Hubble constant measurements. We constrain the amount of primordial helium to be Y{sub p} = 0.225±0.034, and measure no variation in the fine structure constant α since recombination, with α/α{sub 0} = 1.004±0.005. We also find no evidence for any running of the scalar spectral index, dn{sub s}/dln k = −0.004±0.012.« less

The Atacama Cosmology Telescope: Cosmological Parameters from Three Seasons of Data

NASA Technical Reports Server (NTRS)

Seivers, Jonathan L.; Hlozek, Renee A.; Nolta, Michael R.; Acquaviva, Viviana; Addison, Graeme E.; Ade, Peter A. R.; Aguirre, Paula; Amiri, Mandana; Appel, John W.; Barrientos, L. Felipe;

Dangerous angular Kaluza-Klein/glueball relics in string theory cosmology

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dufaux, J. F.; CITA, University of Toronto, 60 St. George st., Toronto, ON M5S 3H8; Kofman, L.

2008-07-15

The presence of Kaluza-Klein (KK) particles in the universe is a potential manifestation of string theory cosmology. In general, they can be present in the high temperature bath of the early universe. In particular examples, string theory inflation often ends with brane-antibrane annihilation followed by the energy cascading through massive closed string loops to KK modes which then decay into lighter standard model particles. However, massive KK modes in the early universe may become dangerous cosmological relics if the inner manifold contains warped throat(s) with approximate isometries. In the complimentary picture, in the AdS/CFT dual gauge theory with extra isometries,more » massive glueballs of various spins become the dangerous cosmological relics. The decay of these angular KK modes/glueballs, located around the tip of the throat, is caused by isometry breaking which results from gluing the throat to the compact Calabi-Yau (CY) manifold. We address the problem of these angular KK particles/glueballs, studying their interactions and decay channels, from the theory side, and the resulting cosmological constraints on the warped compactification parameters, from the phenomenology side. The abundance and decay time of the long-lived nonrelativistic angular KK modes depend strongly on the parameters of the warped geometry, so that observational constraints rule out a significant fraction of the parameter space. In particular, the coupling of the angular KK particles can be weaker than gravitational.« less

Cosmological imprints of frozen-in light sterile neutrinos

DOE Office of Scientific and Technical Information (OSTI.GOV)

Roland, Samuel B.; Shakya, Bibhushan, E-mail: rolandsa@umich.edu, E-mail: bshakya@umich.edu

We investigate observable cosmological aspects of sterile neutrino dark matter produced via the freeze-in mechanism. The study is performed in a framework that admits many cosmologically interesting variations: high temperature production via annihilation processes from higher dimensional operators or low temperature production from decays of a scalar, with the decaying scalar in or out of equilibrium with the thermal bath, in supersymmetric or non-supersymmetric setups, thus allowing us to both extract generic properties and highlight features unique to particular variations. We find that while such sterile neutrinos are generally compatible with all cosmological constraints, interesting scenarios can arise where darkmore » matter is cold, warm, or hot, has nontrivial momentum distributions, or provides contributions to the effective number of relativistic degrees of freedom N {sub eff} during Big Bang nucleosynthesis large enough to be probed by future measurements.« less

Cosmological simulation with dust formation and destruction

NASA Astrophysics Data System (ADS)

Aoyama, Shohei; Hou, Kuan-Chou; Hirashita, Hiroyuki; Nagamine, Kentaro; Shimizu, Ikkoh

2018-06-01

To investigate the evolution of dust in a cosmological volume, we perform hydrodynamic simulations, in which the enrichment of metals and dust is treated self-consistently with star formation and stellar feedback. We consider dust evolution driven by dust production in stellar ejecta, dust destruction by sputtering, grain growth by accretion and coagulation, and grain disruption by shattering, and treat small and large grains separately to trace the grain size distribution. After confirming that our model nicely reproduces the observed relation between dust-to-gas ratio and metallicity for nearby galaxies, we concentrate on the dust abundance over the cosmological volume in this paper. The comoving dust mass density has a peak at redshift z ˜ 1-2, coincident with the observationally suggested dustiest epoch in the Universe. In the local Universe, roughly 10 per cent of the dust is contained in the intergalactic medium (IGM), where only 1/3-1/4 of the dust survives against dust destruction by sputtering. We also show that the dust mass function is roughly reproduced at ≲ 108 M⊙, while the massive end still has a discrepancy, which indicates the necessity of stronger feedback in massive galaxies. In addition, our model broadly reproduces the observed radial profile of dust surface density in the circum-galactic medium (CGM). While our model satisfies the observational constraints for the dust extinction on cosmological scales, it predicts that the dust in the CGM and IGM is dominated by large (>0.03 μm) grains, which is in tension with the steep reddening curves observed in the CGM.

Cosmological effects of scalar-photon couplings: dark energy and varying-α Models

DOE Office of Scientific and Technical Information (OSTI.GOV)

Avgoustidis, A.; Martins, C.J.A.P.; Monteiro, A.M.R.V.L.

2014-06-01

We study cosmological models involving scalar fields coupled to radiation and discuss their effect on the redshift evolution of the cosmic microwave background temperature, focusing on links with varying fundamental constants and dynamical dark energy. We quantify how allowing for the coupling of scalar fields to photons, and its important effect on luminosity distances, weakens current and future constraints on cosmological parameters. In particular, for evolving dark energy models, joint constraints on the dark energy equation of state combining BAO radial distance and SN luminosity distance determinations, will be strongly dominated by BAO. Thus, to fully exploit future SN datamore » one must also independently constrain photon number non-conservation arising from the possible coupling of SN photons to the dark energy scalar field. We discuss how observational determinations of the background temperature at different redshifts can, in combination with distance measures data, set tight constraints on interactions between scalar fields and photons, thus breaking this degeneracy. We also discuss prospects for future improvements, particularly in the context of Euclid and the E-ELT and show that Euclid can, even on its own, provide useful dark energy constraints while allowing for photon number non-conservation.« less

Revisiting cosmological bounds on sterile neutrinos

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vincent, Aaron C.; Martínez, Enrique Fernández; Hernández, Pilar

2015-04-01

We employ state-of-the art cosmological observables including supernova surveys and BAO information to provide constraints on the mass and mixing angle of a non-resonantly produced sterile neutrino species, showing that cosmology can effectively rule out sterile neutrinos which decay between BBN and the present day. The decoupling of an additional heavy neutrino species can modify the time dependence of the Universe's expansion between BBN and recombination and, in extreme cases, lead to an additional matter-dominated period; while this could naively lead to a younger Universe with a larger Hubble parameter, it could later be compensated by the extra radiation expectedmore » in the form of neutrinos from sterile decay. However, recombination-era observables including the Cosmic Microwave Background (CMB), the shift parameter R{sub CMB} and the sound horizon r{sub s} from Baryon Acoustic Oscillations (BAO) severely constrain this scenario. We self-consistently include the full time-evolution of the coupled sterile neutrino and standard model sectors in an MCMC, showing that if decay occurs after BBN, the sterile neutrino is essentially bounded by the constraint sin{sup 2}θ ∼< 0.026 (m{sub s}/eV){sup −2}.« less

Bouncing cosmologies via modified gravity in the ADM formalism: Application to loop quantum cosmology

NASA Astrophysics Data System (ADS)

de Haro, Jaume; Amorós, Jaume

2018-03-01

We consider the Arnowitt-Deser-Misner formalism as a tool to build bouncing cosmologies. In this approach, the foliation of the spacetime has to be fixed in order to go beyond general relativity modifying the gravitational sector. Once a preferred slicing, which we choose based on the matter content of the Universe following the spirit of Weyl's postulate, has been fixed, f theories depending on the extrinsic and intrinsic curvature of the slicing are covariant for all the reference frames preserving the foliation; i.e., the constraint and dynamical equations have the same form for all these observers. Moreover, choosing multivalued f functions, bouncing backgrounds emerge in a natural way. In fact, the simplest is the one corresponding to holonomy corrected loop quantum cosmology. The final goal of this work is to provide the equations of perturbations which, unlike the full equations, become gauge invariant in this theory, and apply them to the so-called matter bounce scenario.

Impact of relativistic effects on cosmological parameter estimation

NASA Astrophysics Data System (ADS)

Lorenz, Christiane S.; Alonso, David; Ferreira, Pedro G.

2018-01-01

Future surveys will access large volumes of space and hence very long wavelength fluctuations of the matter density and gravitational field. It has been argued that the set of secondary effects that affect the galaxy distribution, relativistic in nature, will bring new, complementary cosmological constraints. We study this claim in detail by focusing on a subset of wide-area future surveys: Stage-4 cosmic microwave background experiments and photometric redshift surveys. In particular, we look at the magnification lensing contribution to galaxy clustering and general-relativistic corrections to all observables. We quantify the amount of information encoded in these effects in terms of the tightening of the final cosmological constraints as well as the potential bias in inferred parameters associated with neglecting them. We do so for a wide range of cosmological parameters, covering neutrino masses, standard dark-energy parametrizations and scalar-tensor gravity theories. Our results show that, while the effect of lensing magnification to number counts does not contain a significant amount of information when galaxy clustering is combined with cosmic shear measurements, this contribution does play a significant role in biasing estimates on a host of parameter families if unaccounted for. Since the amplitude of the magnification term is controlled by the slope of the source number counts with apparent magnitude, s (z ), we also estimate the accuracy to which this quantity must be known to avoid systematic parameter biases, finding that future surveys will need to determine s (z ) to the ˜5 %- 10 % level. On the contrary, large-scale general-relativistic corrections are irrelevant both in terms of information content and parameter bias for most cosmological parameters but significant for the level of primordial non-Gaussianity.

Observational Constraints on Models of the Universe with Time Variable Gravitational and Cosmological Constants Along MOG

NASA Astrophysics Data System (ADS)

Khurshudyan, M.; Mazhari, N. S.; Momeni, D.; Myrzakulov, R.; Raza, M.

2015-02-01

The subject of this paper is to investigate the weak regime covariant scalar-tensor-vector gravity (STVG) theory, known as the MOdified gravity (MOG) theory of gravity. First, we show that the MOG in the absence of scalar fields is converted into Λ( t), G( t) models. Time evolution of the cosmological parameters for a family of viable models have been investigated. Numerical results with the cosmological data have been adjusted. We've introduced a model for dark energy (DE) density and cosmological constant which involves first order derivatives of Hubble parameter. To extend this model, correction terms including the gravitational constant are added. In our scenario, the cosmological constant is a function of time. To complete the model, interaction terms between dark energy and dark matter (DM) manually entered in phenomenological form. Instead of using the dust model for DM, we have proposed DM equivalent to a barotropic fluid. Time evolution of DM is a function of other cosmological parameters. Using sophisticated algorithms, the behavior of various quantities including the densities, Hubble parameter, etc. have been investigated graphically. The statefinder parameters have been used for the classification of DE models. Consistency of the numerical results with experimental data of S n e I a + B A O + C M B are studied by numerical analysis with high accuracy.

Probing dark energy with braneworld cosmology in the light of recent cosmological data

NASA Astrophysics Data System (ADS)

García-Aspeitia, Miguel A.; Magaña, Juan; Hernández-Almada, A.; Motta, V.

We investigate a brane model based on Randall-Sundrum scenarios with a generic dark energy component. The latter drives the accelerated expansion at late-times of the universe. In this scheme, extra terms are added into Einstein Field equations that are propagated to the Friedmann equations. To constrain the dark energy equation-of-state (EoS) and the brane tension we use observational data with different energy levels (Supernovae Type Ia, H(z), baryon acoustic oscillations, and cosmic microwave background radiation distance, and a joint analysis) in a background cosmology. Beside EoS being consistent with a cosmological constant at the 3σ confidence level for each dataset, the baryon acoustic oscillations probe favors an EoS consistent with a quintessence dark energy. Although we found different lower limit bounds on the brane tension for each dataset, being the most restricted for CMB, there is not enough evidence of modifications in the cosmological evolution of the universe by the existence of an extra dimension within observational uncertainties. Nevertheless, these new bounds are complementary to those obtained by other probes like table-top experiments, Big Bang Nucleosynthesis, and stellar dynamics. Our results show that a further test of the braneworld model with appropriate correction terms or a profound analysis with perturbations, may be needed to improve the constraints provided by the current data.

Running of the spectrum of cosmological perturbations in string gas cosmology

NASA Astrophysics Data System (ADS)

Brandenberger, Robert; Franzmann, Guilherme; Liang, Qiuyue

2017-12-01

We compute the running of the spectrum of cosmological perturbations in string gas cosmology, making use of a smooth parametrization of the transition between the early Hagedorn phase and the later radiation phase. We find that the running has the same sign as in simple models of single scalar field inflation. Its magnitude is proportional to (1 -ns) (ns being the slope index of the spectrum), and it is thus parametrically larger than for inflationary cosmology, where it is proportional to (1 -ns)2 .

Effect of cosmological evolution on Solar System constraints and on the scalarization of neutron stars in massless scalar-tensor theories

NASA Astrophysics Data System (ADS)

Anderson, David; Yunes, Nicolás; Barausse, Enrico

2016-11-01

Certain scalar-tensor theories of gravity that generalize Jordan-Fierz-Brans-Dicke theory are known to predict nontrivial phenomenology for neutron stars. In these theories, first proposed by Damour and Esposito-Farèse, the scalar field has a standard kinetic term and couples conformally to the matter fields. The weak equivalence principle is therefore satisfied, but scalar effects may arise in strong-field regimes, e.g., allowing for violations of the strong equivalence principle in neutron stars ("spontaneous scalarization") or in sufficiently tight binary neutron-star systems ("dynamical/induced scalarization"). The original scalar-tensor theory proposed by Damour and Esposito-Farèse is in tension with Solar System constraints (for couplings that lead to scalarization), if one accounts for cosmological evolution of the scalar field and no mass term is included in the action. We extend here the conformal coupling of that theory, in order to ascertain if, in this way, Solar System tests can be passed, while retaining a nontrivial phenomenology for neutron stars. We find that, even with this generalized conformal coupling, it is impossible to construct a theory that passes both big bang nucleosynthesis and Solar System constraints, while simultaneously allowing for scalarization in isolated/binary neutron stars.

Ultrahigh precision cosmology from gravitational waves

NASA Astrophysics Data System (ADS)

Cutler, Curt; Holz, Daniel E.

2009-11-01

We show that the Big Bang Observer (BBO), a proposed space-based gravitational-wave (GW) detector, would provide ultraprecise measurements of cosmological parameters. By detecting ˜3×105 compact-star binaries, and utilizing them as standard sirens, BBO would determine the Hubble constant to ˜0.1%, and the dark-energy parameters w0 and wa to ˜0.01 and ˜0.1, respectively. BBO’s dark-energy figure-of-merit would be approximately an order of magnitude better than all other proposed, dedicated dark-energy missions. To date, BBO has been designed with the primary goal of searching for gravitational waves from inflation, down to the level ΩGW˜10-17; this requirement determines BBO’s frequency band (deci-Hz) and its sensitivity requirement (strain measured to ˜10-24). To observe an inflationary GW background, BBO would first have to detect and subtract out ˜3×105 merging compact-star binaries, out to a redshift z˜5. It is precisely this carefully measured foreground which would enable high-precision cosmology. BBO would determine the luminosity distance to each binary to ˜ percent accuracy. In addition, BBO’s angular resolution would be sufficient to uniquely identify the host galaxy for the majority of binaries; a coordinated optical/infrared observing campaign could obtain the redshifts. Combining the GW-derived distances and the electromagnetically-derived redshifts for such a large sample of objects, out to such high redshift, naturally leads to extraordinarily tight constraints on cosmological parameters. We emphasize that such “standard siren” measurements of cosmology avoid many of the systematic errors associated with other techniques: GWs offer a physics-based, absolute measurement of distance. In addition, we show that BBO would also serve as an exceptionally powerful gravitational-lensing mission, and we briefly discuss other astronomical uses of BBO, including providing an early warning system for all short/hard gamma-ray bursts.

Cluster cosmology with next-generation surveys.

NASA Astrophysics Data System (ADS)

Ascaso, B.

2017-03-01

The advent of next-generation surveys will provide a large number of cluster detections that will serve the basis for constraining cos mological parameters using cluster counts. The main two observational ingredients needed are the cluster selection function and the calibration of the mass-observable relation. In this talk, we present the methodology designed to obtain robust predictions of both ingredients based on realistic cosmological simulations mimicking the following next-generation surveys: J-PAS, LSST and Euclid. We display recent results on the selection functions for these mentioned surveys together with others coming from other next-generation surveys such as eROSITA, ACTpol and SPTpol. We notice that the optical and IR surveys will reach the lowest masses between 0.31.5 and will be complemented by the X-rays at lower-redshift and SZ at higher redshifts. We also present results on the mass-observable relation calibrated from the simulations, obtaining similar scatter to other observational results limited to higher redshifts. Finally, we describe the technique that we are developing to perform a Fisher Matrix analysis to provide cosmological constraints for the considered next-generation surveys and introduce very preliminary results.

Supernova Cosmology Without Spectroscopy

NASA Astrophysics Data System (ADS)

Johnson, Elizabeth; Scolnic, Daniel; Kessler, Rick; Rykoff, Eli; Rozo, Eduardo

2018-01-01

Present and future supernovae (SN) surveys face several challenges: the ability to acquire redshifts of either the SN or its host galaxy, the ability to classify a SN without a spectrum, and unknown relations between SN luminosity and host galaxy type. We present here a new approach that addresses these challenges. From the large sample of SNe discovered and measured by the Dark Energy Survey (DES), we cull the sample to only supernovae (SNe) located in luminous red galaxies (LRGs). For these galaxies, photometric redshift estimates are expected to be accurate to a standard deviation of 0.02x(1+z). In addition, only Type Ia Supernovae are expected to exist in these galaxies, thereby providing a pure SNIa sample. Furthermore, we can combine this high-redshift sample with a low-redshift SN sample of only SNe located in LRGs, thereby producing a sample that is less sensitive to host galaxy relations because the host galaxy demographic is consistent across the redshift range. We find that the current DES sample has ~250 SNe in LRGs, a similar amount to current SNIa samples used to measure cosmological parameters. We present our method to produce a photometric-only Hubble diagram and measure cosmological parameters. Finally, we discuss systematic uncertainties from this approach, and forecast constraints from this method for LSST, which should have a sample roughly 200 times as large.

The large-scale microwave background anisotropy in decaying particle cosmology

NASA Technical Reports Server (NTRS)

Panek, Miroslaw

1988-01-01

The quadrupole anisotropy of the microwave background radiation in cosmological models with decaying particles is investigated. A conservative upper limit on value of the quadrupole moment combined with other constraints gives an upper limit on the redshift of the decay z(d) of less than 3-6.

Constraints on Janus Cosmological model from recent observations of supernovae type Ia

NASA Astrophysics Data System (ADS)

D'Agostini, G.; Petit, J. P.

2018-07-01

From our exact solution of the Janus Cosmological equation we derive the relation of the predicted magnitude of distant sources versus their red shift. The comparison, through this one free parameter model, to the available data from 740 distant supernovae shows an excellent fit.

Planck 2013 results. XVI. Cosmological parameters

NASA Astrophysics Data System (ADS)

Planck Collaboration; Ade, P. A. R.; Aghanim, N.; Armitage-Caplan, C.; Arnaud, M.; Ashdown, M.; Atrio-Barandela, F.; Aumont, J.; Baccigalupi, C.; Banday, A. J.; Barreiro, R. B.; Bartlett, J. G.; Battaner, E.; Benabed, K.; Benoît, A.; Benoit-Lévy, A.; Bernard, J.-P.; Bersanelli, M.; Bielewicz, P.; Bobin, J.; Bock, J. J.; Bonaldi, A.; Bond, J. R.; Borrill, J.; Bouchet, F. R.; Bridges, M.; Bucher, M.; Burigana, C.; Butler, R. C.; Calabrese, E.; Cappellini, B.; Cardoso, J.-F.; Catalano, A.; Challinor, A.; Chamballu, A.; Chary, R.-R.; Chen, X.; Chiang, H. C.; Chiang, L.-Y.; Christensen, P. R.; Church, S.; Clements, D. L.; Colombi, S.; Colombo, L. P. L.; Couchot, F.; Coulais, A.; Crill, B. P.; Curto, A.; Cuttaia, F.; Danese, L.; Davies, R. D.; Davis, R. J.; de Bernardis, P.; de Rosa, A.; de Zotti, G.; Delabrouille, J.; Delouis, J.-M.; Désert, F.-X.; Dickinson, C.; Diego, J. M.; Dolag, K.; Dole, H.; Donzelli, S.; Doré, O.; Douspis, M.; Dunkley, J.; Dupac, X.; Efstathiou, G.; Elsner, F.; Enßlin, T. A.; Eriksen, H. K.; Finelli, F.; Forni, O.; Frailis, M.; Fraisse, A. A.; Franceschi, E.; Gaier, T. C.; Galeotta, S.; Galli, S.; Ganga, K.; Giard, M.; Giardino, G.; Giraud-Héraud, Y.; Gjerløw, E.; González-Nuevo, J.; Górski, K. M.; Gratton, S.; Gregorio, A.; Gruppuso, A.; Gudmundsson, J. E.; Haissinski, J.; Hamann, J.; Hansen, F. K.; Hanson, D.; Harrison, D.; Henrot-Versillé, S.; Hernández-Monteagudo, C.; Herranz, D.; Hildebrandt, S. R.; Hivon, E.; Hobson, M.; Holmes, W. A.; Hornstrup, A.; Hou, Z.; Hovest, W.; Huffenberger, K. M.; Jaffe, A. H.; Jaffe, T. R.; Jewell, J.; Jones, W. C.; Juvela, M.; Keihänen, E.; Keskitalo, R.; Kisner, T. S.; Kneissl, R.; Knoche, J.; Knox, L.; Kunz, M.; Kurki-Suonio, H.; Lagache, G.; Lähteenmäki, A.; Lamarre, J.-M.; Lasenby, A.; Lattanzi, M.; Laureijs, R. J.; Lawrence, C. R.; Leach, S.; Leahy, J. P.; Leonardi, R.; León-Tavares, J.; Lesgourgues, J.; Lewis, A.; Liguori, M.; Lilje, P. B.; Linden-Vørnle, M.; López-Caniego, M.; Lubin, P. M.; Macías-Pérez, J. F.; Maffei, B.; Maino, D.; Mandolesi, N.; Maris, M.; Marshall, D. J.; Martin, P. G.; Martínez-González, E.; Masi, S.; Massardi, M.; Matarrese, S.; Matthai, F.; Mazzotta, P.; Meinhold, P. R.; Melchiorri, A.; Melin, J.-B.; Mendes, L.; Menegoni, E.; Mennella, A.; Migliaccio, M.; Millea, M.; Mitra, S.; Miville-Deschênes, M.-A.; Moneti, A.; Montier, L.; Morgante, G.; Mortlock, D.; Moss, A.; Munshi, D.; Murphy, J. A.; Naselsky, P.; Nati, F.; Natoli, P.; Netterfield, C. B.; Nørgaard-Nielsen, H. U.; Noviello, F.; Novikov, D.; Novikov, I.; O'Dwyer, I. J.; Osborne, S.; Oxborrow, C. A.; Paci, F.; Pagano, L.; Pajot, F.; Paladini, R.; Paoletti, D.; Partridge, B.; Pasian, F.; Patanchon, G.; Pearson, D.; Pearson, T. J.; Peiris, H. V.; Perdereau, O.; Perotto, L.; Perrotta, F.; Pettorino, V.; Piacentini, F.; Piat, M.; Pierpaoli, E.; Pietrobon, D.; Plaszczynski, S.; Platania, P.; Pointecouteau, E.; Polenta, G.; Ponthieu, N.; Popa, L.; Poutanen, T.; Pratt, G. W.; Prézeau, G.; Prunet, S.; Puget, J.-L.; Rachen, J. P.; Reach, W. T.; Rebolo, R.; Reinecke, M.; Remazeilles, M.; Renault, C.; Ricciardi, S.; Riller, T.; Ristorcelli, I.; Rocha, G.; Rosset, C.; Roudier, G.; Rowan-Robinson, M.; Rubiño-Martín, J. A.; Rusholme, B.; Sandri, M.; Santos, D.; Savelainen, M.; Savini, G.; Scott, D.; Seiffert, M. D.; Shellard, E. P. S.; Spencer, L. D.; Starck, J.-L.; Stolyarov, V.; Stompor, R.; Sudiwala, R.; Sunyaev, R.; Sureau, F.; Sutton, D.; Suur-Uski, A.-S.; Sygnet, J.-F.; Tauber, J. A.; Tavagnacco, D.; Terenzi, L.; Toffolatti, L.; Tomasi, M.; Tristram, M.; Tucci, M.; Tuovinen, J.; Türler, M.; Umana, G.; Valenziano, L.; Valiviita, J.; Van Tent, B.; Vielva, P.; Villa, F.; Vittorio, N.; Wade, L. A.; Wandelt, B. D.; Wehus, I. K.; White, M.; White, S. D. M.; Wilkinson, A.; Yvon, D.; Zacchei, A.; Zonca, A.

2014-11-01

This paper presents the first cosmological results based on Planck measurements of the cosmic microwave background (CMB) temperature and lensing-potential power spectra. We find that the Planck spectra at high multipoles (ℓ ≳ 40) are extremely well described by the standard spatially-flat six-parameter ΛCDM cosmology with a power-law spectrum of adiabatic scalar perturbations. Within the context of this cosmology, the Planck data determine the cosmological parameters to high precision: the angular size of the sound horizon at recombination, the physical densities of baryons and cold dark matter, and the scalar spectral index are estimated to be θ∗ = (1.04147 ± 0.00062) × 10-2, Ωbh2 = 0.02205 ± 0.00028, Ωch2 = 0.1199 ± 0.0027, and ns = 0.9603 ± 0.0073, respectively(note that in this abstract we quote 68% errors on measured parameters and 95% upper limits on other parameters). For this cosmology, we find a low value of the Hubble constant, H0 = (67.3 ± 1.2) km s-1 Mpc-1, and a high value of the matter density parameter, Ωm = 0.315 ± 0.017. These values are in tension with recent direct measurements of H0 and the magnitude-redshift relation for Type Ia supernovae, but are in excellent agreement with geometrical constraints from baryon acoustic oscillation (BAO) surveys. Including curvature, we find that the Universe is consistent with spatial flatness to percent level precision using Planck CMB data alone. We use high-resolution CMB data together with Planck to provide greater control on extragalactic foreground components in an investigation of extensions to the six-parameter ΛCDM model. We present selected results from a large grid of cosmological models, using a range of additional astrophysical data sets in addition to Planck and high-resolution CMB data. None of these models are favoured over the standard six-parameter ΛCDM cosmology. The deviation of the scalar spectral index from unity isinsensitive to the addition of tensor modes and to

A simple cosmology with a varying fine structure constant.

PubMed

Sandvik, Håvard Bunes; Barrow, John D; Magueijo, João

2002-01-21

We investigate the cosmological consequences of a theory in which the electric charge e can vary. In this theory the fine structure "constant," alpha, remains almost constant in the radiation era, undergoes a small increase in the matter era, but approaches a constant value when the universe starts accelerating because of a positive cosmological constant. This model satisfies geonuclear, nucleosynthesis, and cosmic microwave background constraints on time variation in alpha, while fitting the observed accelerating Universe and evidence for small alpha variations in quasar spectra. It also places specific restrictions on the nature of the dark matter. Further tests, involving stellar spectra and Eötvös experiments, are proposed.

Power law cosmology model comparison with CMB scale information

NASA Astrophysics Data System (ADS)

Tutusaus, Isaac; Lamine, Brahim; Blanchard, Alain; Dupays, Arnaud; Zolnierowski, Yves; Cohen-Tanugi, Johann; Ealet, Anne; Escoffier, Stéphanie; Le Fèvre, Olivier; Ilić, Stéphane; Pisani, Alice; Plaszczynski, Stéphane; Sakr, Ziad; Salvatelli, Valentina; Schücker, Thomas; Tilquin, André; Virey, Jean-Marc

2016-11-01

Despite the ability of the cosmological concordance model (Λ CDM ) to describe the cosmological observations exceedingly well, power law expansion of the Universe scale radius, R (t )∝tn, has been proposed as an alternative framework. We examine here these models, analyzing their ability to fit cosmological data using robust model comparison criteria. Type Ia supernovae (SNIa), baryonic acoustic oscillations (BAO) and acoustic scale information from the cosmic microwave background (CMB) have been used. We find that SNIa data either alone or combined with BAO can be well reproduced by both Λ CDM and power law expansion models with n ˜1.5 , while the constant expansion rate model (n =1 ) is clearly disfavored. Allowing for some redshift evolution in the SNIa luminosity essentially removes any clear preference for a specific model. The CMB data are well known to provide the most stringent constraints on standard cosmological models, in particular, through the position of the first peak of the temperature angular power spectrum, corresponding to the sound horizon at recombination, a scale physically related to the BAO scale. Models with n ≥1 lead to a divergence of the sound horizon and do not naturally provide the relevant scales for the BAO and the CMB. We retain an empirical footing to overcome this issue: we let the data choose the preferred values for these scales, while we recompute the ionization history in power law models, to obtain the distance to the CMB. In doing so, we find that the scale coming from the BAO data is not consistent with the observed position of the first peak of the CMB temperature angular power spectrum for any power law cosmology. Therefore, we conclude that when the three standard probes (SNIa, BAO, and CMB) are combined, the Λ CDM model is very strongly favored over any of these alternative models, which are then essentially ruled out.

Cosmological constraints on generalized Chaplygin gas model: Markov Chain Monte Carlo approach

DOE Office of Scientific and Technical Information (OSTI.GOV)

Xu, Lixin; Lu, Jianbo, E-mail: lxxu@dlut.edu.cn, E-mail: lvjianbo819@163.com

2010-03-01

We use the Markov Chain Monte Carlo method to investigate a global constraints on the generalized Chaplygin gas (GCG) model as the unification of dark matter and dark energy from the latest observational data: the Constitution dataset of type supernovae Ia (SNIa), the observational Hubble data (OHD), the cluster X-ray gas mass fraction, the baryon acoustic oscillation (BAO), and the cosmic microwave background (CMB) data. In a non-flat universe, the constraint results for GCG model are, Ω{sub b}h{sup 2} = 0.0235{sup +0.0021}{sub −0.0018} (1σ) {sup +0.0028}{sub −0.0022} (2σ), Ω{sub k} = 0.0035{sup +0.0172}{sub −0.0182} (1σ) {sup +0.0226}{sub −0.0204} (2σ), A{submore » s} = 0.753{sup +0.037}{sub −0.035} (1σ) {sup +0.045}{sub −0.044} (2σ), α = 0.043{sup +0.102}{sub −0.106} (1σ) {sup +0.134}{sub −0.117} (2σ), and H{sub 0} = 70.00{sup +3.25}{sub −2.92} (1σ) {sup +3.77}{sub −3.67} (2σ), which is more stringent than the previous results for constraint on GCG model parameters. Furthermore, according to the information criterion, it seems that the current observations much support ΛCDM model relative to the GCG model.« less

Evidence for a Cosmological Phase Transition on the TeVScale

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lindesay, James V.; Noyes, H.Pierre; /SLAC

Examining the reverse evolution of the universe from the present, long before reaching Planck density dynamics one expects major modifications from the de-coherent thermal equations of state, suggesting a prior phase that has macroscopic coherence properties. The assumption that the phase transition occurs during the radiation dominated epoch, and that zero-point motions drive the fluctuations associated with this transition, specifies a class of cosmological models in which the cosmic microwave background fluctuation amplitude at last scattering is approximately 10{sup -5}. Quantum measurability constraints (e.g. uncertainly relations) define cosmological scales whose expansion rates can be at most luminal.

Dark Energy Survey Year 1 Results: The Photometric Data Set for Cosmology

NASA Astrophysics Data System (ADS)

Drlica-Wagner, A.; Sevilla-Noarbe, I.; Rykoff, E. S.; Gruendl, R. A.; Yanny, B.; Tucker, D. L.; Hoyle, B.; Carnero Rosell, A.; Bernstein, G. M.; Bechtol, K.; Becker, M. R.; Benoit-Lévy, A.; Bertin, E.; Carrasco Kind, M.; Davis, C.; de Vicente, J.; Diehl, H. T.; Gruen, D.; Hartley, W. G.; Leistedt, B.; Li, T. S.; Marshall, J. L.; Neilsen, E.; Rau, M. M.; Sheldon, E.; Smith, J.; Troxel, M. A.; Wyatt, S.; Zhang, Y.; Abbott, T. M. C.; Abdalla, F. B.; Allam, S.; Banerji, M.; Brooks, D.; Buckley-Geer, E.; Burke, D. L.; Capozzi, D.; Carretero, J.; Cunha, C. E.; D’Andrea, C. B.; da Costa, L. N.; DePoy, D. L.; Desai, S.; Dietrich, J. P.; Doel, P.; Evrard, A. E.; Fausti Neto, A.; Flaugher, B.; Fosalba, P.; Frieman, J.; García-Bellido, J.; Gerdes, D. W.; Giannantonio, T.; Gschwend, J.; Gutierrez, G.; Honscheid, K.; James, D. J.; Jeltema, T.; Kuehn, K.; Kuhlmann, S.; Kuropatkin, N.; Lahav, O.; Lima, M.; Lin, H.; Maia, M. A. G.; Martini, P.; McMahon, R. G.; Melchior, P.; Menanteau, F.; Miquel, R.; Nichol, R. C.; Ogando, R. L. C.; Plazas, A. A.; Romer, A. K.; Roodman, A.; Sanchez, E.; Scarpine, V.; Schindler, R.; Schubnell, M.; Smith, M.; Smith, R. C.; Soares-Santos, M.; Sobreira, F.; Suchyta, E.; Tarle, G.; Vikram, V.; Walker, A. R.; Wechsler, R. H.; Zuntz, J.; DES Collaboration

2018-04-01

We describe the creation, content, and validation of the Dark Energy Survey (DES) internal year-one cosmology data set, Y1A1 GOLD, in support of upcoming cosmological analyses. The Y1A1 GOLD data set is assembled from multiple epochs of DES imaging and consists of calibrated photometric zero-points, object catalogs, and ancillary data products—e.g., maps of survey depth and observing conditions, star–galaxy classification, and photometric redshift estimates—that are necessary for accurate cosmological analyses. The Y1A1 GOLD wide-area object catalog consists of ∼ 137 million objects detected in co-added images covering ∼ 1800 {\\deg }2 in the DES grizY filters. The 10σ limiting magnitude for galaxies is g=23.4, r=23.2, i=22.5, z=21.8, and Y=20.1. Photometric calibration of Y1A1 GOLD was performed by combining nightly zero-point solutions with stellar locus regression, and the absolute calibration accuracy is better than 2% over the survey area. DES Y1A1 GOLD is the largest photometric data set at the achieved depth to date, enabling precise measurements of cosmic acceleration at z ≲ 1.

Deconstructing the neutrino mass constraint from galaxy redshift surveys

NASA Astrophysics Data System (ADS)

Boyle, Aoife; Komatsu, Eiichiro

2018-03-01

The total mass of neutrinos can be constrained in a number of ways using galaxy redshift surveys. Massive neutrinos modify the expansion rate of the Universe, which can be measured using baryon acoustic oscillations (BAOs) or the Alcock-Paczynski (AP) test. Massive neutrinos also change the structure growth rate and the amplitude of the matter power spectrum, which can be measured using redshift-space distortions (RSD). We use the Fisher matrix formalism to disentangle these information sources, to provide projected neutrino mass constraints from each of these probes alone and to determine how sensitive each is to the assumed cosmological model. We isolate the distinctive effect of neutrino free-streaming on the matter power spectrum and structure growth rate as a signal unique to massive neutrinos that can provide the most robust constraints, which are relatively insensitive to extensions to the cosmological model beyond ΛCDM . We also provide forecasted constraints using all of the information contained in the observed galaxy power spectrum combined, and show that these maximally optimistic constraints are primarily limited by the accuracy to which the optical depth of the cosmic microwave background, τ, is known.

Constraints to Dark Energy Using PADE Parameterizations

NASA Astrophysics Data System (ADS)

Rezaei, M.; Malekjani, M.; Basilakos, S.; Mehrabi, A.; Mota, D. F.

2017-07-01

We put constraints on dark energy (DE) properties using PADE parameterization, and compare it to the same constraints using Chevalier-Polarski-Linder (CPL) and ΛCDM, at both the background and the perturbation levels. The DE equation of the state parameter of the models is derived following the mathematical treatment of PADE expansion. Unlike CPL parameterization, PADE approximation provides different forms of the equation of state parameter that avoid the divergence in the far future. Initially we perform a likelihood analysis in order to put constraints on the model parameters using solely background expansion data, and we find that all parameterizations are consistent with each other. Then, combining the expansion and the growth rate data, we test the viability of PADE parameterizations and compare them with CPL and ΛCDM models, respectively. Specifically, we find that the growth rate of the current PADE parameterizations is lower than ΛCDM model at low redshifts, while the differences among the models are negligible at high redshifts. In this context, we provide for the first time a growth index of linear matter perturbations in PADE cosmologies. Considering that DE is homogeneous, we recover the well-known asymptotic value of the growth index (namely {γ }∞ =\\tfrac{3({w}∞ -1)}{6{w}∞ -5}), while in the case of clustered DE, we obtain {γ }∞ ≃ \\tfrac{3{w}∞ (3{w}∞ -5)}{(6{w}∞ -5)(3{w}∞ -1)}. Finally, we generalize the growth index analysis in the case where γ is allowed to vary with redshift, and we find that the form of γ (z) in PADE parameterization extends that of the CPL and ΛCDM cosmologies, respectively.

Is There a Cosmological Constant?

NASA Technical Reports Server (NTRS)

Kochanek, Christopher; Oliversen, Ronald J. (Technical Monitor)

2002-01-01

The grant contributed to the publication of 18 refereed papers and 5 conference proceedings. The primary uses of the funding have been for page charges, travel for invited talks related to the grant research, and the support of a graduate student, Charles Keeton. The refereed papers address four of the primary goals of the proposal: (1) the statistics of radio lenses as a probe of the cosmological model (#1), (2) the role of spiral galaxies as lenses (#3), (3) the effects of dust on statistics of lenses (#7, #8), and (4) the role of groups and clusters as lenses (#2, #6, #10, #13, #15, #16). Four papers (#4, #5, #11, #12) address general issues of lens models, calibrations, and the relationship between lens galaxies and nearby galaxies. One considered cosmological effects in lensing X-ray sources (#9), and two addressed issues related to the overall power spectrum and theories of gravity (#17, #18). Our theoretical studies combined with the explosion in the number of lenses and the quality of the data obtained for them is greatly increasing our ability to characterize and understand the lens population. We can now firmly conclude both from our study of the statistics of radio lenses and our survey of extinctions in individual lenses that the statistics of optically selected quasars were significantly affected by extinction. However, the limits on the cosmological constant remain at lambda < 0.65 at a 2-sigma confidence level, which is in mild conflict with the results of the Type la supernova surveys. We continue to find that neither spiral galaxies nor groups and clusters contribute significantly to the production of gravitational lenses. The lack of group and cluster lenses is strong evidence for the role of baryonic cooling in increasing the efficiency of galaxies as lenses compared to groups and clusters of higher mass but lower central density. Unfortunately for the ultimate objective of the proposal, improved constraints on the cosmological constant, the next

The outskirts of galaxy clusters: astrophysics and cosmology

NASA Astrophysics Data System (ADS)

Morandi, Andrea; Sun, Ming

2017-08-01

Exploring the virialization region of galaxy clusters has recently raised the attention of the scientific community, offering a direct view of structure formation. In this talk, I will present recent results on the physical properties of the intracluster medium in the outer volumes of a sample of 320 clusters (0.056 1.24, kT>3 keV) in the Chandra archive, with a total integration time of ~20 Ms. We stacked the emission measure profiles of the clusters to detect a signal out to R100. We then measured the average emission measure, gas density and gas fraction, which scale according to the self-similar model of cluster formation. We observe a steepening of the density profiles beyond R500 with slope β~0.68 at R500 and β~1 at R200 and beyond. By tracking the direction of the cosmic filaments where the clusters are embedded, we report that galaxy clusters deviate from spherical symmetry. We finally used, for the first time, the high level of similarity of the emission measure in the cluster outskirts as cosmology proxy. The cosmological parameters are thus constrained assuming that the emission measure profiles at different redshift are weakly self-similar, that is their shape is universal, explicitly allowing for temperature and redshift dependence of the gas fraction. This cosmological test, in combination with Planck+SNIa data, allows us to put a tight constraint on the dark energy models. For a constant-w model, we have w=-1.010±0.030 and Ωm=0.311±0.014, while for a time-evolving equation of state of dark energy w(z) we have Ωm=0.308±0.017, w0=-0.993±0.046 and wa=-0.123±0.400 We checked that our method is robust towards different sources of systematics, including background modelling, outlier measurements, selection effects, inhomogeneities of the gas distribution and cosmic filaments. We also provided for the first time constraints on which definition of cluster boundary radius is more tenable, namely based on a fixed overdensity with respect to the

Distance measurements from supernovae and dark energy constraints

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang Yun

2009-12-15

Constraints on dark energy from current observational data are sensitive to how distances are measured from Type Ia supernova (SN Ia) data. We find that flux averaging of SNe Ia can be used to test the presence of unknown systematic uncertainties, and yield more robust distance measurements from SNe Ia. We have applied this approach to the nearby+SDSS+ESSENCE+SNLS+HST set of 288 SNe Ia, and the 'Constitution' set of 397 SNe Ia. Combining the SN Ia data with cosmic microwave background anisotropy data from Wilkinson Microwave Anisotropy Probe 5 yr observations, the Sloan Digital Sky Survey baryon acoustic oscillation measurements, themore » data of 69 gamma-ray bursts (GRBs) , and the Hubble constant measurement from the Hubble Space Telescope project SHOES, we measure the dark energy density function X(z){identical_to}{rho}{sub X}(z)/{rho}{sub X}(0) as a free function of redshift (assumed to be a constant at z>1 or z>1.5). Without the flux averaging of SNe Ia, the combined data using the Constitution set of SNe Ia seem to indicate a deviation from a cosmological constant at {approx}95% confidence level at 0 < or apporx. z < or approx. 0.8; they are consistent with a cosmological constant at {approx}68% confidence level when SNe Ia are flux averaged. The combined data using the nearby+SDSS+ESSENCE+SNLS+HST data set of SNe Ia are consistent with a cosmological constant at 68% confidence level with or without flux averaging of SNe Ia, and give dark energy constraints that are significantly more stringent than that using the Constitution set of SNe Ia. Assuming a flat Universe, dark energy is detected at >98% confidence level for z{<=}0.75 using the combined data with 288 SNe Ia from nearby+SDSS+ESSENCE+SNLS+HST, independent of the assumptions about X(z{>=}1). We quantify dark energy constraints without assuming a flat Universe using the dark energy figure of merit for both X(z) and a dark energy equation-of-state linear in the cosmic scale factor.« less

Improved constraints on the expansion rate of the Universe up to z ∼ 1.1 from the spectroscopic evolution of cosmic chronometers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Moresco, M.; Cimatti, A.; Jimenez, R.

2012-08-01

We present new improved constraints on the Hubble parameter H(z) in the redshift range 0.15 < z < 1.1, obtained from the differential spectroscopic evolution of early-type galaxies as a function of redshift. We extract a large sample of early-type galaxies ( ∼ 11000) from several spectroscopic surveys, spanning almost 8 billion years of cosmic lookback time (0.15 < z < 1.42). We select the most massive, red elliptical galaxies, passively evolving and without signature of ongoing star formation. Those galaxies can be used as standard cosmic chronometers, as firstly proposed by Jimenez and Loeb (2002), whose differential age evolutionmore » as a function of cosmic time directly probes H(z). We analyze the 4000 Å break (D4000) as a function of redshift, use stellar population synthesis models to theoretically calibrate the dependence of the differential age evolution on the differential D4000, and estimate the Hubble parameter taking into account both statistical and systematical errors. We provide 8 new measurements of H(z), and determine its change in H(z) to a precision of 5–12% mapping homogeneously the redshift range up to z ∼ 1.1; for the first time, we place a constraint on H(z) at z≠0 with a precision comparable with the one achieved for the Hubble constant (about 5–6% at z ∼ 0.2), and covered a redshift range (0.5 < z < 0.8) which is crucial to distinguish many different quintessence cosmologies. These measurements have been tested to best match a ΛCDM model, clearly providing a statistically robust indication that the Universe is undergoing an accelerated expansion. This method shows the potentiality to open a new avenue in constrain a variety of alternative cosmologies, especially when future surveys (e.g. Euclid) will open the possibility to extend it up to z ∼ 2.« less

Primordial black holes survive SN lensing constraints

NASA Astrophysics Data System (ADS)

García-Bellido, Juan; Clesse, Sébastien; Fleury, Pierre

2018-06-01

It has been claimed in [arxiv:1712.02240] that massive primordial black holes (PBH) cannot constitute all of the dark matter (DM), because their gravitational-lensing imprint on the Hubble diagram of type Ia supernovae (SN) would be incompatible with present observations. In this note, we critically review those constraints and find several caveats on the analysis. First of all, the constraints on the fraction α of PBH in matter seem to be driven by a very restrictive choice of priors on the cosmological parameters. In particular, the degeneracy between Ωm and α was ignored and thus, by fixing Ωm, transferred the constraining power of SN magnitudes to α. Furthermore, by considering more realistic physical sizes for the type-Ia supernovae, we find an effect on the SN lensing magnification distribution that leads to significantly looser constraints. Moreover, considering a wide mass spectrum of PBH, such as a lognormal distribution, further softens the constraints from SN lensing. Finally, we find that the fraction of PBH that could constitute DM today is bounded by fPBH < 1 . 09(1 . 38) , for JLA (Union 2.1) catalogs, and thus it is perfectly compatible with an all-PBH dark matter scenario in the LIGO band.

Disformal theories of gravity: from the solar system to cosmology

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sakstein, Jeremy, E-mail: j.a.sakstein@damtp.cam.ac.uk

This paper is concerned with theories of gravity that contain a scalar coupled both conformally and disformally to matter through the metric. By systematically deriving the non-relativistic limit, it is shown that no new non-linear screening mechanisms are present beyond the Vainshtein mechanism and chameleon-like screening. If one includes the cosmological expansion of the universe, disformal effects that are usually taken to be absent can be present in the solar system. When the conformal factor is absent, fifth-forces can be screened on all scales when the cosmological field is slowly-rolling. We investigate the cosmology of these models and use localmore » tests of gravity to place new constraints on the disformal coupling and find M ∼> O(eV), which is not competitive with laboratory tests. Finally, we discuss the future prospects for testing these theories and the implications for other theories of modified gravity. In particular, the Vainshtein radius of solar system objects can be altered from the static prediction when cosmological time-derivatives are non-negligible.« less

Redshift remapping and cosmic acceleration in dark-matter-dominated cosmological models

NASA Astrophysics Data System (ADS)

Wojtak, Radosław; Prada, Francisco

2017-10-01

The standard relation between the cosmological redshift and cosmic scalefactor underlies cosmological inference from virtually all kinds of cosmological observations, leading to the emergence of the Λ cold-dark-matter (ΛCDM) cosmological model. This relation is not a fundamental theory and thus observational determination of this function (redshift remapping) should be regarded as an insightful alternative to holding its standard form in analyses of cosmological data. Here we present non-parametric reconstructions of redshift remapping in dark-matter-dominated models and constraints on cosmological parameters from a joint analysis of all primary cosmological probes including the local measurement of the Hubble constant, Type Ia supernovae, baryon acoustic oscillations (BAO), Planck observations of the cosmic microwave background (CMB) radiation (temperature power spectrum) and cosmic chronometers. The reconstructed redshift remapping points to an additional boost of redshift operating in late epoch of cosmic evolution, but affecting both low-redshift observations and the CMB. The model predicts a significant difference between the actual Hubble constant, h = 0.48 ± 0.02, and its local determination, hobs = 0.73 ± 0.02. The ratio of these two values coincides closely with the maximum expansion rate inside voids formed in the corresponding open cosmological model with Ωm = 0.87 ± 0.03, whereas the actual value of the Hubble constant implies the age of the Universe that is compatible with the Planck ΛCDM cosmology. The model with redshift remapping provides excellent fits to all data and eliminates recently reported tensions between the PlanckΛCDM cosmology, the local determination of the Hubble constant and the BAO measurements from the Ly α forest of high-redshift quasars.

A MAGNIFIED GLANCE INTO THE DARK SECTOR: PROBING COSMOLOGICAL MODELS WITH STRONG LENSING IN A1689

DOE Office of Scientific and Technical Information (OSTI.GOV)

Magaña, Juan; Motta, V.; Cárdenas, Victor H.

2015-11-01

In this paper we constrain four alternative models to the late cosmic acceleration in the universe: Chevallier–Polarski–Linder (CPL), interacting dark energy (IDE), Ricci holographic dark energy (HDE), and modified polytropic Cardassian (MPC). Strong lensing (SL) images of background galaxies produced by the galaxy cluster Abell 1689 are used to test these models. To perform this analysis we modify the LENSTOOL lens modeling code. The value added by this probe is compared with other complementary probes: Type Ia supernovae (SN Ia), baryon acoustic oscillations (BAO), and cosmic microwave background (CMB). We found that the CPL constraints obtained for the SL datamore » are consistent with those estimated using the other probes. The IDE constraints are consistent with the complementary bounds only if large errors in the SL measurements are considered. The Ricci HDE and MPC constraints are weak, but they are similar to the BAO, SN Ia, and CMB estimations. We also compute the figure of merit as a tool to quantify the goodness of fit of the data. Our results suggest that the SL method provides statistically significant constraints on the CPL parameters but is weak for those of the other models. Finally, we show that the use of the SL measurements in galaxy clusters is a promising and powerful technique to constrain cosmological models. The advantage of this method is that cosmological parameters are estimated by modeling the SL features for each underlying cosmology. These estimations could be further improved by SL constraints coming from other galaxy clusters.« less

Model independent constraints on transition redshift

NASA Astrophysics Data System (ADS)

Jesus, J. F.; Holanda, R. F. L.; Pereira, S. H.

2018-05-01

This paper aims to put constraints on the transition redshift zt, which determines the onset of cosmic acceleration, in cosmological-model independent frameworks. In order to perform our analyses, we consider a flat universe and assume a parametrization for the comoving distance DC(z) up to third degree on z, a second degree parametrization for the Hubble parameter H(z) and a linear parametrization for the deceleration parameter q(z). For each case, we show that type Ia supernovae and H(z) data complement each other on the parameter space and tighter constrains for the transition redshift are obtained. By combining the type Ia supernovae observations and Hubble parameter measurements it is possible to constrain the values of zt, for each approach, as 0.806± 0.094, 0.870± 0.063 and 0.973± 0.058 at 1σ c.l., respectively. Then, such approaches provide cosmological-model independent estimates for this parameter.

A critical review of classical bouncing cosmologies

NASA Astrophysics Data System (ADS)

Battefeld, Diana; Peter, Patrick

2015-04-01

Given the proliferation of bouncing models in recent years, we gather and critically assess these proposals in a comprehensive review. The PLANCK data shows an unmistakably red, quasi scale-invariant, purely adiabatic primordial power spectrum and no primary non-Gaussianities. While these observations are consistent with inflationary predictions, bouncing cosmologies aspire to provide an alternative framework to explain them. Such models face many problems, both of the purely theoretical kind, such as the necessity of violating the NEC and instabilities, and at the cosmological application level, as exemplified by the possible presence of shear. We provide a pedagogical introduction to these problems and also assess the fitness of different proposals with respect to the data. For example, many models predict a slightly blue spectrum and must be fine-tuned to generate a red spectral index; as a side effect, large non-Gaussianities often result. We highlight several promising attempts to violate the NEC without introducing dangerous instabilities at the classical and/or quantum level. If primordial gravitational waves are observed, certain bouncing cosmologies, such as the cyclic scenario, are in trouble, while others remain valid. We conclude that, while most bouncing cosmologies are far from providing an alternative to the inflationary paradigm, a handful of interesting proposals have surfaced, which warrant further research. The constraints and lessons learned as laid out in this review might guide future research.

Dark Energy Survey Year 1 Results: The Photometric Data Set for Cosmology

DOE Office of Scientific and Technical Information (OSTI.GOV)

Drlica-Wagner, A.; Sevilla-Noarbe, I.; Rykoff, E. S.

In this paper, we describe the creation, content, and validation of the Dark Energy Survey (DES) internal year-one cosmology data set, Y1A1 GOLD, in support of upcoming cosmological analyses. The Y1A1 GOLD data set is assembled from multiple epochs of DES imaging and consists of calibrated photometric zero-points, object catalogs, and ancillary data products—e.g., maps of survey depth and observing conditions, star–galaxy classification, and photometric redshift estimates—that are necessary for accurate cosmological analyses. The Y1A1 GOLD wide-area object catalog consists ofmore » $$\\sim 137$$ million objects detected in co-added images covering $$\\sim 1800\\,{\\deg }^{2}$$ in the DES grizY filters. The 10σ limiting magnitude for galaxies is $g=23.4$, $r=23.2$, $i=22.5$, $z=21.8$, and $Y=20.1$. Photometric calibration of Y1A1 GOLD was performed by combining nightly zero-point solutions with stellar locus regression, and the absolute calibration accuracy is better than 2% over the survey area. Finally, DES Y1A1 GOLD is the largest photometric data set at the achieved depth to date, enabling precise measurements of cosmic acceleration at z ≲ 1.« less

Dark Energy Survey Year 1 Results: The Photometric Data Set for Cosmology

DOE PAGES

Drlica-Wagner, A.; Sevilla-Noarbe, I.; Rykoff, E. S.; ...

2018-04-03

In this paper, we describe the creation, content, and validation of the Dark Energy Survey (DES) internal year-one cosmology data set, Y1A1 GOLD, in support of upcoming cosmological analyses. The Y1A1 GOLD data set is assembled from multiple epochs of DES imaging and consists of calibrated photometric zero-points, object catalogs, and ancillary data products—e.g., maps of survey depth and observing conditions, star–galaxy classification, and photometric redshift estimates—that are necessary for accurate cosmological analyses. The Y1A1 GOLD wide-area object catalog consists ofmore » $$\\sim 137$$ million objects detected in co-added images covering $$\\sim 1800\\,{\\deg }^{2}$$ in the DES grizY filters. The 10σ limiting magnitude for galaxies is $g=23.4$, $r=23.2$, $i=22.5$, $z=21.8$, and $Y=20.1$. Photometric calibration of Y1A1 GOLD was performed by combining nightly zero-point solutions with stellar locus regression, and the absolute calibration accuracy is better than 2% over the survey area. Finally, DES Y1A1 GOLD is the largest photometric data set at the achieved depth to date, enabling precise measurements of cosmic acceleration at z ≲ 1.« less

Cosmological evolution and Solar System consistency of massive scalar-tensor gravity

NASA Astrophysics Data System (ADS)

de Pirey Saint Alby, Thibaut Arnoulx; Yunes, Nicolás

2017-09-01

The scalar-tensor theory of Damour and Esposito-Farèse recently gained some renewed interest because of its ability to suppress modifications to general relativity in the weak field, while introducing large corrections in the strong field of compact objects through a process called scalarization. A large sector of this theory that allows for scalarization, however, has been shown to be in conflict with Solar System observations when accounting for the cosmological evolution of the scalar field. We here study an extension of this theory by endowing the scalar field with a mass to determine whether this allows the theory to pass Solar System constraints upon cosmological evolution for a larger sector of coupling parameter space. We show that the cosmological scalar field goes first through a quiescent phase, similar to the behavior of a massless field, but then it enters an oscillatory phase, with an amplitude (and frequency) that decays (and grows) exponentially. We further show that after the field enters the oscillatory phase, its effective energy density and pressure are approximately those of dust, as expected from previous cosmological studies. Due to these oscillations, we show that the scalar field cannot be treated as static today on astrophysical scales, and so we use time-dependent perturbation theory to compute the scalar-field-induced modifications to Solar System observables. We find that these modifications are suppressed when the mass of the scalar field and the coupling parameter of the theory are in a wide range, allowing the theory to pass Solar System constraints, while in principle possibly still allowing for scalarization.

CMB constraints on β-exponential inflationary models

NASA Astrophysics Data System (ADS)

Santos, M. A.; Benetti, M.; Alcaniz, J. S.; Brito, F. A.; Silva, R.

2018-03-01

We analyze a class of generalized inflationary models proposed in ref. [1], known as β-exponential inflation. We show that this kind of potential can arise in the context of brane cosmology, where the field describing the size of the extra-dimension is interpreted as the inflaton. We discuss the observational viability of this class of model in light of the latest Cosmic Microwave Background (CMB) data from the Planck Collaboration through a Bayesian analysis, and impose tight constraints on the model parameters. We find that the CMB data alone prefer weakly the minimal standard model (ΛCDM) over the β-exponential inflation. However, when current local measurements of the Hubble parameter, H0, are considered, the β-inflation model is moderately preferred over the ΛCDM cosmology, making the study of this class of inflationary models interesting in the context of the current H0 tension.

Observational constraints on varying neutrino-mass cosmology

DOE Office of Scientific and Technical Information (OSTI.GOV)

Geng, Chao-Qiang; Lee, Chung-Chi; Myrzakulov, R.

We consider generic models of quintessence and we investigate the influence of massive neutrino matter with field-dependent masses on the matter power spectrum. In case of minimally coupled neutrino matter, we examine the effect in tracker models with inverse power-law and double exponential potentials. We present detailed investigations for the scaling field with a steep exponential potential, non-minimally coupled to massive neutrino matter, and we derive constraints on field-dependent neutrino masses from the observational data.

The Philosophy of Cosmology

NASA Astrophysics Data System (ADS)

Chamcham, Khalil; Silk, Joseph; Barrow, John D.; Saunders, Simon

2017-04-01

Part I. Issues in the Philosophy of Cosmology: 1. Cosmology, cosmologia and the testing of cosmological theories George F. R. Ellis; 2. Black holes, cosmology and the passage of time: three problems at the limits of science Bernard Carr; 3. Moving boundaries? - comments on the relationship between philosophy and cosmology Claus Beisbart; 4. On the question why there exists something rather than nothing Roderich Tumulka; Part II. Structures in the Universe and the Structure of Modern Cosmology: 5. Some generalities about generality John D. Barrow; 6. Emergent structures of effective field theories Jean-Philippe Uzan; 7. Cosmological structure formation Joel R. Primack; 8. Formation of galaxies Joseph Silk; Part III. Foundations of Cosmology: Gravity and the Quantum: 9. The observer strikes back James Hartle and Thomas Hertog; 10. Testing inflation Chris Smeenk; 11. Why Boltzmann brains do not fluctuate into existence from the de Sitter vacuum Kimberly K. Boddy, Sean M. Carroll and Jason Pollack; 12. Holographic inflation revised Tom Banks; 13. Progress and gravity: overcoming divisions between general relativity and particle physics and between physics and HPS J. Brian Pitts; Part IV. Quantum Foundations and Quantum Gravity: 14. Is time's arrow perspectival? Carlo Rovelli; 15. Relational quantum cosmology Francesca Vidotto; 16. Cosmological ontology and epistemology Don N. Page; 17. Quantum origin of cosmological structure and dynamical reduction theories Daniel Sudarsky; 18. Towards a novel approach to semi-classical gravity Ward Struyve; Part V. Methodological and Philosophical Issues: 19. Limits of time in cosmology Svend E. Rugh and Henrik Zinkernagel; 20. Self-locating priors and cosmological measures Cian Dorr and Frank Arntzenius; 21. On probability and cosmology: inference beyond data? Martin Sahlén; 22. Testing the multiverse: Bayes, fine-tuning and typicality Luke A. Barnes; 23. A new perspective on Einstein's philosophy of cosmology Cormac O

Constraining cosmologies with fundamental constants - I. Quintessence and K-essence

NASA Astrophysics Data System (ADS)

Thompson, Rodger I.; Martins, C. J. A. P.; Vielzeuf, P. E.

2013-01-01

Many cosmological models invoke rolling scalar fields to account for the observed acceleration of the expansion of the Universe. These theories generally include a potential V(φ) which is a function of the scalar field φ. Although V(φ) can be represented by a very diverse set of functions, recent work has shown that under some conditions, such as the slow-roll conditions, the equation of state parameter w is either independent of the form of V(φ) or part of family of solutions with only a few parameters. In realistic models of this type the scalar field couples to other sectors of the model leading to possibly observable changes in the fundamental constants such as the fine structure constant α and the proton to electron mass ratio μ. Although the current situation on a possible variance of α is complicated, there are firm limitations on the variance of μ in the early universe. This paper explores the limits this puts on the validity of various cosmologies that invoke rolling scalar fields. We find that the limit on the variation of μ puts significant constraints on the product of a cosmological parameter w + 1 and a new physics parameter ζ2μ, the coupling constant between μ and the rolling scalar field. Even when the cosmologies are restricted to very slow roll conditions either the value of ζμ must be at the lower end of or less than its expected values or the value of w + 1 must be restricted to values vanishingly close to 0. This implies that either the rolling scalar field is very weakly coupled to the electromagnetic field, small ζμ, very weakly coupled to gravity, (w + 1) ≈ 0 or both. These results stress that adherence to the measured invariance in μ is a very significant test of the validity of any proposed cosmology and any new physics it requires. The limits on the variation of μ also produces a significant tension with the reported changes in the value of α.

f(T) teleparallel gravity and cosmology.

PubMed

Cai, Yi-Fu; Capozziello, Salvatore; De Laurentis, Mariafelicia; Saridakis, Emmanuel N

2016-10-01

Over recent decades, the role of torsion in gravity has been extensively investigated along the main direction of bringing gravity closer to its gauge formulation and incorporating spin in a geometric description. Here we review various torsional constructions, from teleparallel, to Einstein-Cartan, and metric-affine gauge theories, resulting in extending torsional gravity in the paradigm of f (T) gravity, where f (T) is an arbitrary function of the torsion scalar. Based on this theory, we further review the corresponding cosmological and astrophysical applications. In particular, we study cosmological solutions arising from f (T) gravity, both at the background and perturbation levels, in different eras along the cosmic expansion. The f (T) gravity construction can provide a theoretical interpretation of the late-time universe acceleration, alternative to a cosmological constant, and it can easily accommodate with the regular thermal expanding history including the radiation and cold dark matter dominated phases. Furthermore, if one traces back to very early times, for a certain class of f (T) models, a sufficiently long period of inflation can be achieved and hence can be investigated by cosmic microwave background observations-or, alternatively, the Big Bang singularity can be avoided at even earlier moments due to the appearance of non-singular bounces. Various observational constraints, especially the bounds coming from the large-scale structure data in the case of f (T) cosmology, as well as the behavior of gravitational waves, are described in detail. Moreover, the spherically symmetric and black hole solutions of the theory are reviewed. Additionally, we discuss various extensions of the f (T) paradigm. Finally, we consider the relation with other modified gravitational theories, such as those based on curvature, like f (R) gravity, trying to illuminate the subject of which formulation, or combination of formulations, might be more suitable

Non-linear matter power spectrum covariance matrix errors and cosmological parameter uncertainties

NASA Astrophysics Data System (ADS)

Blot, L.; Corasaniti, P. S.; Amendola, L.; Kitching, T. D.

2016-06-01

The covariance of the matter power spectrum is a key element of the analysis of galaxy clustering data. Independent realizations of observational measurements can be used to sample the covariance, nevertheless statistical sampling errors will propagate into the cosmological parameter inference potentially limiting the capabilities of the upcoming generation of galaxy surveys. The impact of these errors as function of the number of realizations has been previously evaluated for Gaussian distributed data. However, non-linearities in the late-time clustering of matter cause departures from Gaussian statistics. Here, we address the impact of non-Gaussian errors on the sample covariance and precision matrix errors using a large ensemble of N-body simulations. In the range of modes where finite volume effects are negligible (0.1 ≲ k [h Mpc-1] ≲ 1.2), we find deviations of the variance of the sample covariance with respect to Gaussian predictions above ˜10 per cent at k > 0.3 h Mpc-1. Over the entire range these reduce to about ˜5 per cent for the precision matrix. Finally, we perform a Fisher analysis to estimate the effect of covariance errors on the cosmological parameter constraints. In particular, assuming Euclid-like survey characteristics we find that a number of independent realizations larger than 5000 is necessary to reduce the contribution of sampling errors to the cosmological parameter uncertainties at subpercent level. We also show that restricting the analysis to large scales k ≲ 0.2 h Mpc-1 results in a considerable loss in constraining power, while using the linear covariance to include smaller scales leads to an underestimation of the errors on the cosmological parameters.

Cosmological and supernova neutrinos

NASA Astrophysics Data System (ADS)

Kajino, T.; Aoki, W.; Balantekin, A. B.; Cheoun, M.-K.; Hayakawa, T.; Hidaka, J.; Hirai, Y.; Kusakabe, M.; Mathews, G. J.; Nakamura, K.; Pehlivan, Y.; Shibagaki, S.; Suzuki, T.

2014-06-01

The Big Bang nucleosynthesis (BBN) and the cosmic microwave background (CMB) anisotropies are the pillars of modern cosmology. It has recently been suggested that axion which is a dark matter candidate in the framework of the standard model could condensate in the early universe and induce photon cooling before the epoch of the photon last scattering. Although this may render a solution to the overproduction problem of primordial 7Li abundance, there arises another serious difficulty of overproducing D abundance. We propose a hybrid dark matter model with both axions and relic supersymmetric (SUSY) particles to solve both overproduction problems of the primordial D and 7Li abundances simultaneously. The BBN also serves to constrain the nature of neutrinos. Considering non-thermal photons produced in the decay of the heavy sterile neutrinos due to the magnetic moment, we explore the cosmological constraint on the strength of neutrino magnetic moment consistent with the observed light element abundances. Core-collapse supernovae eject huge flux of energetic neutrinos which affect explosive nucleosynthesis of rare isotopes like 7Li, 11B, 92Nb, 138La and 180Ta and r-process elements. Several isotopes depend strongly on the neutrino flavor oscillation due to the Mikheyev-Smirnov-Wolfenstein (MSW) effect. Combining the recent experimental constraints on θ13 with predicted and observed supernova-produced abundance ratio 11B/7Li encapsulated in the presolar grains from the Murchison meteorite, we show a marginal preference for an inverted neutrino mass hierarchy. We also discuss supernova relic neutrinos (SRN) that may indicate the softness of the equation of state (EoS) of nuclear matter and adiabatic conditions of the neutrino oscillation.

Phenomenological constraints on Lemaître-Tolman-Bondi cosmological inhomogeneities from solar system dynamics

NASA Astrophysics Data System (ADS)

Iorio, Lorenzo

2010-06-01

We, first, analytically work out the long-term, i.e. averaged over one orbital revolution, perturbations on the orbit of a test particle moving in a local Fermi frame induced therein by the cosmological tidal effects of the inhomogeneous Lemaître-Tolman-Bondi (LTB) model. The LTB solution has recently attracted attention, among other things, as a possible explanation of the observed cosmic acceleration without resorting to dark energy. Then, we phenomenologically constrain both the parameters K1 doteq ddot frakR / frakR and K2 doteq ddot frakR' / frakR' of the LTB metric in the Fermi frame by using different kinds of solar system data. The corrections Δdot varpi to the standard Newtonian/Einsteinian precessions of the perihelia of the inner planets recently estimated with the EPM ephemerides, compared to our predictions for them, yield preliminarily K1 = (4±8) × 10-26 s-2, K2 = (3±7) × 10-23 s-2. The residuals of the Cassini-based Earth-Saturn range, compared with the numerically integrated LTB range signature, allow to preliminarily obtain K1 approx K2 approx 10-27 s-2. Actually, the LTB effects should be explicitly modeled in the ephemerides softwares, so that the entire planetary and spacecraft data sets should be accordingly re-processed. The LTB-induced distortions of the orbit of a typical object of the Oort cloud with respect to the commonly accepted Newtonian picture, based on the observations of the comet showers from that remote region of the solar system, point towards K1 approx K2lesssim10-30-10-32 s-2. Such figures have to be compared with those inferred from cosmological data which are of the order of K1 approx K2 = -4 × 10-36 s-2.

Constraints on deviations from ΛCDM within Horndeski gravity

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bellini, Emilio; Cuesta, Antonio J.; Jimenez, Raul

2016-02-01

Recent anomalies found in cosmological datasets such as the low multipoles of the Cosmic Microwave Background or the low redshift amplitude and growth of clustering measured by e.g., abundance of galaxy clusters and redshift space distortions in galaxy surveys, have motivated explorations of models beyond standard ΛCDM. Of particular interest are models where general relativity (GR) is modified on large cosmological scales. Here we consider deviations from ΛCDM+GR within the context of Horndeski gravity, which is the most general theory of gravity with second derivatives in the equations of motion. We adopt a parametrization in which the four additional Horndeskimore » functions of time α{sub i}(t) are proportional to the cosmological density of dark energy Ω{sub DE}(t). Constraints on this extended parameter space using a suite of state-of-the art cosmological observations are presented for the first time. Although the theory is able to accommodate the low multipoles of the Cosmic Microwave Background and the low amplitude of fluctuations from redshift space distortions, we find no significant tension with ΛCDM+GR when performing a global fit to recent cosmological data and thus there is no evidence against ΛCDM+GR from an analysis of the value of the Bayesian evidence ratio of the modified gravity models with respect to ΛCDM, despite introducing extra parameters. The posterior distribution of these extra parameters that we derive return strong constraints on any possible deviations from ΛCDM+GR in the context of Horndeski gravity. We illustrate how our results can be applied to a more general frameworks of modified gravity models.« less

Redshift remapping and cosmic acceleration in dark-matter-dominated cosmological models

DOE PAGES

Wojtak, Radosław; Prada, Francisco

2017-06-21

The standard relation between the cosmological redshift and cosmic scale factor underlies cosmological inference from virtually all kinds of cosmological observations, leading to the emergence of the LambdaCDM cosmological model. This relation is not a fundamental theory and thus observational determination of this function (redshift remapping) should be regarded as an insightful alternative to holding its standard form in analyses of cosmological data. We present non-parametric reconstructions of redshift remapping in dark-matter-dominated models and constraints on cosmological parameters from a joint analysis of all primary cosmological probes including the local measurement of the Hubble constant, Type Ia supernovae, baryonic acousticmore » oscillations (BAO), Planck observations of the cosmic microwave background (CMB) radiation (temperature power spectrum) and cosmic chronometers. The reconstructed redshift remapping points to an additional boost of redshift operating in late epoch of cosmic evolution, but affecting both low-redshift observations and the CMB. The model then predicts a significant difference between the actual Hubble constant, h=0.48±0.02, and its local determination, h obs=0.73±0.02. The ratio of these two values coincides closely with the maximum expansion rate inside voids formed in the corresponding open cosmological model with Ω m=0.87±0.03, whereas the actual value of the Hubble constant implies the age of the Universe that is compatible with the Planck LambdaCDM cosmology. The new dark-matter-dominated model with redshift remapping provides excellent fits to all data and eliminates recently reported tensions between the Planck LambdaCDM cosmology, the local determination of the Hubble constant and the BAO measurements from the Ly α forest of high-redshift quasars.« less

Dynamics and phenomenology of higher order gravity cosmological models

NASA Astrophysics Data System (ADS)

Moldenhauer, Jacob Andrew

2010-10-01

I present here some new results about a systematic approach to higher-order gravity (HOG) cosmological models. The HOG models are derived from curvature invariants that are more general than the Einstein-Hilbert action. Some of the models exhibit late-time cosmic acceleration without the need for dark energy and fit some current observations. The open question is that there are an infinite number of invariants that one could select, and many of the published papers have stressed the need to find a systematic approach that will allow one to study methodically the various possibilities. We explore a new connection that we made between theorems from the theory of invariants in general relativity and these cosmological models. In summary, the theorems demonstrate that curvature invariants are not all independent from each other and that for a given Ricci Segre type and Petrov type (symmetry classification) of the space-time, there exists a complete minimal set of independent invariants (a basis) in terms of which all the other invariants can be expressed. As an immediate consequence of the proposed approach, the number of invariants to consider is dramatically reduced from infinity to four invariants in the worst case and to only two invariants in the cases of interest, including all Friedmann-Lemaitre-Robertson-Walker metrics. We derive models that pass stability and physical acceptability conditions. We derive dynamical equations and phase portrait analyses that show the promise of the systematic approach. We consider observational constraints from magnitude-redshift Supernovae Type Ia data, distance to the last scattering surface of the Cosmic Microwave Background radiation, and Baryon Acoustic Oscillations. We put observational constraints on general HOG models. We constrain different forms of the Gauss-Bonnet, f(G), modified gravity models with these observations. We show some of these models pass solar system tests. We seek to find models that pass physical and

Cosmological structure formation

NASA Technical Reports Server (NTRS)

Schramm, David N.

1991-01-01

A summary of the current forefront problem of physical cosmology, the formation of structures (galaxies, clusters, great walls, etc.) in the universe is presented. Solutions require two key ingredients: (1) matter; and (2) seeds. Regarding the matter, it now seems clear that both baryonic and non-baryonic matter are required. Whether the non-baryonic matter is hot or cold depends on the choice of seeds. Regarding the seeds, both density fluctuations and topological defects are discussed. The combination of isotropy of the microwave background and the recent observations indicating more power on large scales have severly constrained, if not eliminated, Gaussian fluctuations with equal power on all scales, regardless of the eventual resolution of both the matter and seed questions. It is important to note that all current structure formation ideas require new physics beyond SU(3) x SU(2) x U(1).

Cosmic Microwave Background: cosmology from the Planck perspective

NASA Astrophysics Data System (ADS)

De Zotti, Gianfranco

2016-07-01

The Planck mission has measured the angular anisotropies in the temperature of the Cosmic Microwave Background (CMB) with an accuracy set by fundamental limits. These data have allowed the determination of the cosmological parameters with extraordinary precision. These lecture notes present an overview of the mission and of its cosmological results. After a short history of the project, the Planck instruments and their performances are introduced and compared with those of the WMAP satellite. Next the approach to data analysis adopted by the Planck collaboration is described. This includes the techniques for dealing with the contamination of the CMB signal by astrophysical foreground emissions and for determining cosmological parameters from the analysis of the CMB power spectrum. The power spectra measured by Planck were found to be very well described by the standard spatially flat six-parameter ΛCDM cosmology with a power-law spectrum of adiabatic scalar perturbations. This is a remarkable result, considering that the six parameters account for the about 2500 independent power spectrum values measured by Planck (the power was measured for about 2500 multipoles), not to mention the about one trillion science samples produced. A large grid of cosmological models was also explored, using a range of additional astrophysical data sets in addition to Planck and high-resolution CMB data from ground-based experiments. On the whole, the Planck analysis of the CMB power spectrum allowed to vary and determined 16 parameters. Many other interesting parameters were derived from them. Although Planck was not initially designed to carry out high accuracy measurements of the CMB polarization anisotropies, its capabilities in this respect were significantly enhanced during its development. The quality of its polarization measurements have exceeded all original expectations. Planck's polarisation data confirmed and improved the understanding of the details of the cosmological

Cosmic Microwave Background: cosmology from the Planck perspective

NASA Astrophysics Data System (ADS)

De Zotti, Gianfranco

2017-08-01

The Planck mission has measured the angular anisotropies in the temperature of the Cosmic Microwave Background (CMB) with an accuracy set by fundamental limits. These data have allowed the determination of the cosmological parameters with extraordinary precision. These lecture notes present an overview of the mission and of its cosmological results. After a short history of the project, the Planck instruments and their performances are introduced and compared with those of the WMAP satellite. Next the approach to data analysis adopted by the Planck collaboration is described. This includes the techniques for dealing with the contamination of the CMB signal by astrophysical foreground emissions and for determining cosmological parameters from the analysis of the CMB power spectrum. The power spectra measured by Planck were found to be very well described by the standard spatially flat six-parameter ΛCDM cosmology with a power-law spectrum of adiabatic scalar perturbations. This is a remarkable result, considering that the six parameters account for the about 2500 independent power spectrum values measured by Planck (the power was measured for about 2500 multipoles), not to mention the about one trillion science samples produced. A large grid of cosmological models was also explored, using a range of additional astrophysical data sets in addition to Planck and high-resolution CMB data from ground-based experiments. On the whole, the Planck analysis of the CMB power spectrum allowed to vary and determined 16 parameters. Many other interesting parameters were derived from them. Although Planck was not initially designed to carry out high accuracy measurements of the CMB polarization anisotropies, its capabilities in this respect were significantly enhanced during its development. The quality of its polarization measurements have exceeded all original expectations. Planck's polarisation data confirmed and improved the understanding of the details of the cosmological

The clustering of galaxies in the completed SDSS-III Baryon Oscillation Spectroscopic Survey: Cosmological implications of the Fourier space wedges of the final sample

NASA Astrophysics Data System (ADS)

Grieb, Jan Niklas; Sánchez, Ariel G.; Salazar-Albornoz, Salvador; Scoccimarro, Román; Crocce, Martín; Dalla Vecchia, Claudio; Montesano, Francesco; Gil-Marín, Héctor; Ross, Ashley J.; Beutler, Florian; Rodríguez-Torres, Sergio; Chuang, Chia-Hsun; Prada, Francisco; Kitaura, Francisco-Shu; Cuesta, Antonio J.; Eisenstein, Daniel J.; Percival, Will J.; Vargas-Magaña, Mariana; Tinker, Jeremy L.; Tojeiro, Rita; Brownstein, Joel R.; Maraston, Claudia; Nichol, Robert C.; Olmstead, Matthew D.; Samushia, Lado; Seo, Hee-Jong; Streblyanska, Alina; Zhao, Gong-bo

2017-05-01

We extract cosmological information from the anisotropic power-spectrum measurements from the recently completed Baryon Oscillation Spectroscopic Survey (BOSS), extending the concept of clustering wedges to Fourier space. Making use of new fast-Fourier-transform-based estimators, we measure the power-spectrum clustering wedges of the BOSS sample by filtering out the information of Legendre multipoles ℓ > 4. Our modelling of these measurements is based on novel approaches to describe non-linear evolution, bias and redshift-space distortions, which we test using synthetic catalogues based on large-volume N-body simulations. We are able to include smaller scales than in previous analyses, resulting in tighter cosmological constraints. Using three overlapping redshift bins, we measure the angular-diameter distance, the Hubble parameter and the cosmic growth rate, and explore the cosmological implications of our full-shape clustering measurements in combination with cosmic microwave background and Type Ia supernova data. Assuming a Λ cold dark matter (ΛCDM) cosmology, we constrain the matter density to Ω M= 0.311_{-0.010}^{+0.009} and the Hubble parameter to H_0 = 67.6_{-0.6}^{+0.7} km s^{-1 Mpc^{-1}}, at a confidence level of 68 per cent. We also allow for non-standard dark energy models and modifications of the growth rate, finding good agreement with the ΛCDM paradigm. For example, we constrain the equation-of-state parameter to w = -1.019_{-0.039}^{+0.048}. This paper is part of a set that analyses the final galaxy-clustering data set from BOSS. The measurements and likelihoods presented here are combined with others in Alam et al. to produce the final cosmological constraints from BOSS.

An Introduction to Galaxies and Cosmology

NASA Astrophysics Data System (ADS)

Jones, Mark H.; Lambourne, Robert J. A.; Serjeant, Stephen

2015-01-01

Introduction; 1. The Milky Way - our galaxy; 2. Normal galaxies; 3. Active galaxies; 4. The spatial distribution of galaxies; 5. Introducing cosmology - the science of the Universe; 6. Big bang cosmology - the evolving Universe; 7. Observational cosmology - measuring the Universe; 8. Questioning cosmology - outstanding problems about the Universe; Answers and comments; Appendix; Glossary; Further reading; Acknowledgements; Figure references; Index.

Cosmological perturbations in teleparallel Loop Quantum Cosmology

DOE Office of Scientific and Technical Information (OSTI.GOV)

Haro, Jaime, E-mail: jaime.haro@upc.edu

2013-11-01

Cosmological perturbations in Loop Quantum Cosmology (LQC) are usually studied incorporating either holonomy corrections, where the Ashtekar connection is replaced by a suitable sinus function in order to have a well-defined quantum analogue, or inverse-volume corrections coming from the eigenvalues of the inverse-volume operator. In this paper we will develop an alternative approach to calculate cosmological perturbations in LQC based on the fact that, holonomy corrected LQC in the flat Friedmann-Lemaître-Robertson-Walker (FLRW) geometry could be also obtained as a particular case of teleparallel F(T) gravity (teleparallel LQC). The main idea of our approach is to mix the simple bounce providedmore » by holonomy corrections in LQC with the non-singular perturbation equations given by F(T) gravity, in order to obtain a matter bounce scenario as a viable alternative to slow-roll inflation. In our study, we have obtained an scale invariant power spectrum of cosmological perturbations. However, the ratio of tensor to scalar perturbations is of order 1, which does not agree with the current observations. For this reason, we suggest a model where a transition from the matter domination to a quasi de Sitter phase is produced in order to enhance the scalar power spectrum.« less

Inflection-point inflation in a hyper-charge oriented U ( 1 ) X model

DOE PAGES

Okada, Nobuchika; Okada, Satomi; Raut, Digesh

2017-03-31

Inflection-point inflation is an interesting possibility to realize a successful slow-roll inflation when inflation is driven by a single scalar field with its value during inflation below the Planck mass (ΦI≲M Pl). In order for a renormalization group (RG) improved effective λΦ 4 potential to develop an inflection-point, the running quartic coupling λ(Φ) must exhibit a minimum with an almost vanishing value in its RG evolution, namely λ(Φ I)≃0 and β λ(ΦI)≃0, where β λ is the beta-function of the quartic coupling. Here in this paper, we consider the inflection-point inflation in the context of the minimal gauged U(1) Xmore » extended Standard Model (SM), which is a generalization of the minimal U(1) B$-$L model, and is constructed as a linear combination of the SM U(1) Y and U(1) B$-$L gauge symmetries. We identify the U(1) X Higgs field with the inflaton field. For a successful inflection-point inflation to be consistent with the current cosmological observations, the mass ratios among the U(1) X gauge boson, the right-handed neutrinos and the U(1) X Higgs boson are fixed. Focusing on the case that the extra U(1) X gauge symmetry is mostly aligned along the SM U(1) Y direction, we investigate a consistency between the inflationary predictions and the latest LHC Run-2 results on the search for a narrow resonance with the di-lepton final state.« less

Inflection-point inflation in a hyper-charge oriented U ( 1 ) X model

DOE Office of Scientific and Technical Information (OSTI.GOV)

Okada, Nobuchika; Okada, Satomi; Raut, Digesh

Inflection-point inflation is an interesting possibility to realize a successful slow-roll inflation when inflation is driven by a single scalar field with its value during inflation below the Planck mass (ΦI≲M Pl). In order for a renormalization group (RG) improved effective λΦ 4 potential to develop an inflection-point, the running quartic coupling λ(Φ) must exhibit a minimum with an almost vanishing value in its RG evolution, namely λ(Φ I)≃0 and β λ(ΦI)≃0, where β λ is the beta-function of the quartic coupling. Here in this paper, we consider the inflection-point inflation in the context of the minimal gauged U(1) Xmore » extended Standard Model (SM), which is a generalization of the minimal U(1) B$-$L model, and is constructed as a linear combination of the SM U(1) Y and U(1) B$-$L gauge symmetries. We identify the U(1) X Higgs field with the inflaton field. For a successful inflection-point inflation to be consistent with the current cosmological observations, the mass ratios among the U(1) X gauge boson, the right-handed neutrinos and the U(1) X Higgs boson are fixed. Focusing on the case that the extra U(1) X gauge symmetry is mostly aligned along the SM U(1) Y direction, we investigate a consistency between the inflationary predictions and the latest LHC Run-2 results on the search for a narrow resonance with the di-lepton final state.« less

Testing Dark Energy with the Advanced Liquid-Mirror Probe of Asteroids, Cosmology and Astrophysics

NASA Astrophysics Data System (ADS)

LoVerde, M.; Corasaniti, P. S.; Crotts, A.; Blake, C.

2006-06-01

The Advanced Liquid-Mirror Probe of Asteroids, Cosmology and Astrophysics (ALPACA) is a proposed 8-meter liquid mirror telescope surveying ˜ 1000 deg2 of the southern-hemisphere sky. It will be a remarkably simple and inexpensive telescope that will nonetheless deliver a powerful sample of optical data for studying dark energy. The bulk of the cosmological data consists of nightly, high signal-to-noise, multiband light curves of SN Ia. At the end of the three-year run ALPACA is expected to collect ˜ 100,000 SN Ia up to z ˜ 1. This will allow accurate calibration of the standard-candle relation and reduce the systematic uncertainties. The survey will also provide several other datasets such as the detection of baryon acoustic oscillations in the matter power spectrum and shear weak lensing measurements. In this preliminary analysis we forecast constraints on dark energy parameters from SN Ia and baryon acoustic oscillations. The combination of these two datasets will provide competitive constraints on the dark energy parameters with minimal prior assumptions. Further studies are needed to address the accuracy of weak lensing measurements.

Testing dark energy with the Advanced Liquid-mirror Probe of Asteroids, Cosmology and Astrophysics

NASA Astrophysics Data System (ADS)

Corasaniti, Pier Stefano; LoVerde, Marilena; Crotts, Arlin; Blake, Chris

2006-06-01

The Advanced Liquid-mirror Probe of Asteroids, Cosmology and Astrophysics (ALPACA) is a proposed 8-m liquid-mirror telescope surveying ~1000deg2 of the Southern hemisphere sky. It will be a remarkably simple and inexpensive telescope that none the less will deliver a powerful sample of optical data for studying dark energy. The bulk of the cosmological data consist of nightly, high signal-to-noise ratio, multiband light curves of Type Ia supernovae (SNe Ia). At the end of the 3-yr run, ALPACA is expected to collect >~100000 SNe Ia up to z ~ 1. This will allow us to reduce present systematic uncertainties affecting the standard-candle relation. The survey will also provide several other data sets such as the detection of baryon acoustic oscillations in the matter power spectrum and shear weak-lensing measurements. In this preliminary analysis, we forecast constraints on dark energy parameters from SNe Ia and baryon acoustic oscillations. The combination of these two data sets will provide competitive constraints on the dark energy parameters under minimal prior assumptions. Further studies are needed to address the accuracy of weak-lensing measurements.

High-redshift post-reionization cosmology with 21cm intensity mapping

NASA Astrophysics Data System (ADS)

Obuljen, Andrej; Castorina, Emanuele; Villaescusa-Navarro, Francisco; Viel, Matteo

2018-05-01

We investigate the possibility of performing cosmological studies in the redshift range 2.51 and the primary beam wedge, we find that a HIRAX extension can constrain, within bins of Δ z=0.1: 1) the value of fσ8 at simeq4%, 2) the value of DA and H at simeq1%. In combination with data from Euclid-like galaxy surveys and CMB S4, the sum of the neutrino masses can be constrained with an error equal to 23 meV (1σ), while Neff can be constrained within 0.02 (1σ). We derive similar constraints for the extensions of the other instruments. We study in detail the dependence of our results on the instrument, amplitude of the HI bias, the foreground wedge coverage, the nonlinear scale used in the analysis, uncertainties in the theoretical modeling and the priors on bHI and Ω HI. We conclude that 21cm intensity mapping surveys operating in this redshift range can provide extremely competitive constraints on key cosmological parameters.

COSMOLOGY OF CHAMELEONS WITH POWER-LAW COUPLINGS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mota, David F.; Winther, Hans A.

2011-05-20

In chameleon field theories, a scalar field can couple to matter with gravitational strength and still evade local gravity constraints due to a combination of self-interactions and the couplings to matter. Originally, these theories were proposed with a constant coupling to matter; however, the chameleon mechanism also extends to the case where the coupling becomes field dependent. We study the cosmology of chameleon models with power-law couplings and power-law potentials. It is found that these generalized chameleons, when viable, have a background expansion very close to {Lambda}CDM, but can in some special cases enhance the growth of the linear perturbationsmore » at low redshifts. For the models we consider, it is found that this region of the parameter space is ruled out by local gravity constraints. Imposing a coupling to dark matter only, the local constraints are avoided, and it is possible to have observable signatures on the linear matter perturbations.« less

The clustering of galaxies in the SDSS-III Baryon Oscillation Spectroscopic Survey: signs of neutrino mass in current cosmological data sets

NASA Astrophysics Data System (ADS)

Beutler, Florian; Saito, Shun; Brownstein, Joel R.; Chuang, Chia-Hsun; Cuesta, Antonio J.; Percival, Will J.; Ross, Ashley J.; Ross, Nicholas P.; Schneider, Donald P.; Samushia, Lado; Sánchez, Ariel G.; Seo, Hee-Jong; Tinker, Jeremy L.; Wagner, Christian; Weaver, Benjamin A.

2014-11-01

We investigate the cosmological implications of the latest growth of structure measurement from the Baryon Oscillation Spectroscopic Survey (BOSS) CMASS Data Release 11 with particular focus on the sum of the neutrino masses, ∑mν. We examine the robustness of the cosmological constraints from the baryon acoustic oscillation (BAO) scale, the Alcock-Paczynski effect and redshift-space distortions (DV/rs, FAP, fσ8) of Beutler et al., when introducing a neutrino mass in the power spectrum template. We then discuss how the neutrino mass relaxes discrepancies between the cosmic microwave background (CMB) and other low-redshift measurements within Λ cold dark matter. Combining our cosmological constraints with 9-year Wilkinson Microwave Anisotropy Probe (WMAP9) yields ∑mν = 0.36 ± 0.14 eV (68 per cent c.l.), which represents a 2.6σ preference for non-zero neutrino mass. The significance can be increased to 3.3σ when including weak lensing results and other BAO constraints, yielding ∑mν = 0.35 ± 0.10 eV (68 per cent c.l.). However, combining CMASS with Planck data reduces the preference for neutrino mass to ˜2σ. When removing the CMB lensing effect in the Planck temperature power spectrum (by marginalizing over AL), we see shifts of ˜1σ in σ8 and Ωm, which have a significant effect on the neutrino mass constraints. In the case of CMASS plus Planck without the AL lensing signal, we find a preference for a neutrino mass of ∑mν = 0.34 ± 0.14 eV (68 per cent c.l.), in excellent agreement with the WMAP9+CMASS value. The constraint can be tightened to 3.4σ yielding ∑mν = 0.36 ± 0.10 eV (68 per cent c.l.) when weak lensing data and other BAO constraints are included.

Cosmological lepton asymmetry, primordial nucleosynthesis and sterile neutrinos

NASA Astrophysics Data System (ADS)

Abazajian, Kevork; Bell, Nicole F.; Fuller, George M.; Wong, Yvonne Y. Y.

2005-09-01

We study post weak decoupling coherent active-sterile and active-active matter-enhanced neutrino flavor transformation in the early Universe. We show that flavor conversion efficiency at Mikheyev-Smirnov-Wolfenstein resonances is likely to be high (adiabatic evolution) for relevant neutrino parameters and energies. However, we point out that these resonances cannot sweep smoothly and continuously with the expansion of the Universe. We show how neutrino flavor conversion in this way can leave both the active and sterile neutrinos with nonthermal energy spectra, and how, in turn, these distorted energy spectra can affect the neutron-to-proton ratio, primordial nucleosynthesis, and cosmological mass/closure constraints on sterile neutrinos. We demonstrate that the existence of a light sterile neutrino which mixes with active neutrinos can change fundamentally the relationship between the cosmological lepton numbers and the primordial nucleosynthesis He4 yield.

Colliders as a simultaneous probe of supersymmetric dark matter and Terascale cosmology

DOE Office of Scientific and Technical Information (OSTI.GOV)

Barenboim, Gabriela; /Valencia U.; Lykken, Joseph D.

2006-08-01

Terascale supersymmetry has the potential to provide a natural explanation of the dominant dark matter component of the standard {Lambda}CDM cosmology. However once we impose the constraints on minimal supersymmetry parameters from current particle physics data, a satisfactory dark matter abundance is no longer prima facie natural. This Neutralino Tuning Problem could be a hint of nonstandard cosmology during and/or after the Terascale era. To quantify this possibility, we introduce an alternative cosmological benchmark based upon a simple model of quintessential inflation. This benchmark has no free parameters, so for a given supersymmetry model it allows an unambiguous prediction ofmore » the dark matter relic density. As a example, we scan over the parameter space of the CMSSM, comparing the neutralino relic density predictions with the bounds from WMAP. We find that the WMAP-allowed regions of the CMSSM are an order of magnitude larger if we use the alternative cosmological benchmark, as opposed to {Lambda}CDM. Initial results from the CERN Large Hadron Collider will distinguish between the two allowed regions.« less

Colliders as a simultaneous probe of supersymmetric dark matter and Terascale cosmology

NASA Astrophysics Data System (ADS)

Barenboim, Gabriela; Lykken, Joseph D.

2006-12-01

Terascale supersymmetry has the potential to provide a natural explanation of the dominant dark matter component of the standard ΛCDM cosmology. However once we impose the constraints on minimal supersymmetry parameters from current particle physics data, a satisfactory dark matter abundance is no longer prima facie natural. This Neutralino Tuning Problem could be a hint of nonstandard cosmology during and/or after the Terascale era. To quantify this possibility, we introduce an alternative cosmological benchmark based upon a simple model of quintessential inflation. This benchmark has no free parameters, so for a given supersymmetry model it allows an unambiguous prediction of the dark matter relic density. As a example, we scan over the parameter space of the CMSSM, comparing the neutralino relic density predictions with the bounds from WMAP. We find that the WMAP allowed regions of the CMSSM are an order of magnitude larger if we use the alternative cosmological benchmark, as opposed to ΛCDM. Initial results from the CERN Large Hadron Collider will distinguish between the two allowed regions.

Gravity with free initial conditions: A solution to the cosmological constant problem testable by CMB B -mode polarization

NASA Astrophysics Data System (ADS)

Totani, Tomonori

2017-10-01

In standard general relativity the universe cannot be started with arbitrary initial conditions, because four of the ten components of the Einstein's field equations (EFE) are constraints on initial conditions. In the previous work it was proposed to extend the gravity theory to allow free initial conditions, with a motivation to solve the cosmological constant problem. This was done by setting four constraints on metric variations in the action principle, which is reasonable because the gravity's physical degrees of freedom are at most six. However, there are two problems about this theory; the three constraints in addition to the unimodular condition were introduced without clear physical meanings, and the flat Minkowski spacetime is unstable against perturbations. Here a new set of gravitational field equations is derived by replacing the three constraints with new ones requiring that geodesic paths remain geodesic against metric variations. The instability problem is then naturally solved. Implications for the cosmological constant Λ are unchanged; the theory converges into EFE with nonzero Λ by inflation, but Λ varies on scales much larger than the present Hubble horizon. Then galaxies are formed only in small Λ regions, and the cosmological constant problem is solved by the anthropic argument. Because of the increased degrees of freedom in metric dynamics, the theory predicts new non-oscillatory modes of metric anisotropy generated by quantum fluctuation during inflation, and CMB B -mode polarization would be observed differently from the standard predictions by general relativity.

Scalar dark matter interpretation of the DAMPE data with U(1) gauge interactions

NASA Astrophysics Data System (ADS)

Cao, Junjie; Feng, Lei; Guo, Xiaofei; Shang, Liangliang; Wang, Fei; Wu, Peiwen

2018-05-01

Recently, the Dark Matter Particle Explorer (DAMPE) experiment released the new measurement of the total cosmic e+e- flux between 25 GeV and 4.6 TeV, which indicates a spectral softening at around 0.9 TeV and a tentative peak at around 1.4 TeV. We utilize a scalar dark matter (DM) model to explain the DAMPE peak by χ χ →Z'Z'→ℓℓ ¯ ℓ'ℓ' ¯ with an additional anomaly-free gauged U (1 ) family symmetry, in which χ , Z', and ℓ(') denote, respectively, the scalar DM, the new gauge boson, and ℓ(')=e , μ , τ with mχ˜mZ'˜2 ×1.5 (TeV ) . We first illustrate that the minimal framework GSM×U (1 )Y' with the above mass choices can explain the DAMPE excess, which, however, be excluded by LHC constraints from the Z' searches. Then, we study a nonminimal framework GSM×U (1 )Y'×U (1 )Y'' in which U (1 )Y'' mixes with U (1)Y'. We show that such a framework can interpret the DAMPE data and at the same time survive all other constraints including the DM relic abundance, DM direct detection, and collider bounds. We also investigate the predicted e+e- spectrum in this framework and find that the mass splitting Δ m =mχ-mZ'' should be less than about 17 GeV to produce the peaklike structure.

Solar system constraints on planetary Coriolis-type effects induced by rotation of distant masses

DOE Office of Scientific and Technical Information (OSTI.GOV)

Iorio, Lorenzo, E-mail: lorenzo.iorio@libero.it

We phenomenologically put local constraints on the rotation of distant masses by using the planets of the solar system. First, we analytically compute the orbital secular precessions induced on the motion of a test particle about a massive primary by a Coriolis-like force, treated as a small perturbation, in the case of a constant angular velocity vector Ψ directed along a generic direction in space. The semimajor axis a and the eccentricity e of the test particle do not secularly change, contrary to the inclination I, the longitude of the ascending node Ω, the longitude of the pericenter varpi andmore » the mean anomaly M. Then, we compare our prediction for (dot varpi) with the corrections Δdot varpi to the usual perihelion precessions of the inner planets recently estimated by fitting long data sets with different versions of the EPM ephemerides. We obtain as preliminary upper bounds |Ψ{sub z}| ≤ 0.0006−0.013 arcsec cty{sup −1}, |Ψ{sub x}| ≤ 0.1−2.7 arcsec cty{sup −1}, |Ψ{sub y}| ≤ 0.3−2.3 arcsec cty{sup −1}. Interpreted in terms of models of space-time involving cosmic rotation, our results are able to yield constraints on cosmological parameters like the cosmological constant Λ and the Hubble parameter H{sub 0} not too far from their values determined with cosmological observations and, in some cases, several orders of magnitude better than the constraints usually obtained so far from space-time models not involving rotation. In the case of the rotation of the solar system throughout the Galaxy, occurring clockwise about the North Galactic Pole, our results for Ψ{sub z} are in disagreement with the expected value of it at more than 3−σ level. Modeling the Oort cloud as an Einstein-Thirring slowly rotating massive shell inducing Coriolis-type forces inside yields unphysical results for its putative rotation.« less

Exactly solvable quantum cosmologies from two killing field reductions of general relativity

NASA Astrophysics Data System (ADS)

Husain, Viqar; Smolin, Lee

1989-11-01

An exact and, possibly, general solution to the quantum constraints is given for the sector of general relativity containing cosmological solutions with two space-like, commuting, Killing fields. The dynamics of these model space-times, which are known as Gowdy space-times, is formulated in terms of Ashtekar's new variables. The quantization is done by using the recently introduced self-dual and loop representations. On the classical phase space we find four explicit physical observables, or constants of motion, which generate a GL(2) symmetry group on the space of solutions. In the loop representations we find that a complete description of the physical state space, consisting of the simultaneous solutions to all of the constraints, is given in terms of the equivalence classes, under Diff(S1), of a pair of densities on the circle. These play the same role that the link classes play in the loop representation solution to the full 3+1 theory. An infinite dimensional algebra of physical observables is found on the physical state space, which is a GL(2) loop algebra. In addition, by freezing the local degrees of freedom of the model, we find a finite dimensional quantum system which describes a set of degenerate quantum cosmologies on T3 in which the length of one of the S1's has gone to zero, while the area of the remaining S1×S1 is quantized in units of the Planck area. The quantum kinematics of this sector of the model is identical to that of a one-plaquette SU(2) lattice gauge theory.

Implications of Planck2015 for inflationary, ekpyrotic and anamorphic bouncing cosmologies

NASA Astrophysics Data System (ADS)

Ijjas, Anna; Steinhardt, Paul J.

2016-02-01

The results from Planck2015, when combined with earlier observations from the Wilkinson Microwave Anisotropy Probe, Atacama Cosmology Telescope, South Pole Telescope and other experiments, were the first observations to disfavor the ‘classic’ inflationary paradigm. To satisfy the observational constraints, inflationary theorists have been forced to consider plateau-like inflaton potentials that introduce more parameters and more fine-tuning, problematic initial conditions, multiverse-unpredictability issues, and a new ‘unlikeliness problem’. Some propose turning instead to a ‘postmodern’ inflationary paradigm in which the cosmological properties in our observable Universe are only locally valid and set randomly, with completely different properties (and perhaps even different physical laws) existing in most regions outside our horizon. By contrast, the new results are consistent with the simplest versions of ekpyrotic cyclic models in which the Universe is smoothed and flattened during a period of slow contraction followed by a bounce, and another promising bouncing theory, anamorphic cosmology, has been proposed that can produce distinctive predictions.

Initial conditions of inhomogeneous universe and the cosmological constant problem

DOE Office of Scientific and Technical Information (OSTI.GOV)

Totani, Tomonori, E-mail: totani@astron.s.u-tokyo.ac.jp

Deriving the Einstein field equations (EFE) with matter fluid from the action principle is not straightforward, because mass conservation must be added as an additional constraint to make rest-frame mass density variable in reaction to metric variation. This can be avoided by introducing a constraint 0δ(√− g ) = to metric variations δ g {sup μν}, and then the cosmological constant Λ emerges as an integration constant. This is a removal of one of the four constraints on initial conditions forced by EFE at the birth of the universe, and it may imply that EFE are unnecessarily restrictive about initialmore » conditions. I then adopt a principle that the theory of gravity should be able to solve time evolution starting from arbitrary inhomogeneous initial conditions about spacetime and matter. The equations of gravitational fields satisfying this principle are obtained, by setting four auxiliary constraints on δ g {sup μν} to extract six degrees of freedom for gravity. The cost of achieving this is a loss of general covariance, but these equations constitute a consistent theory if they hold in the special coordinate systems that can be uniquely specified with respect to the initial space-like hypersurface when the universe was born. This theory predicts that gravity is described by EFE with non-zero Λ in a homogeneous patch of the universe created by inflation, but Λ changes continuously across different patches. Then both the smallness and coincidence problems of the cosmological constant are solved by the anthropic argument. This is just a result of inhomogeneous initial conditions, not requiring any change of the fundamental physical laws in different patches.« less

Initial conditions of inhomogeneous universe and the cosmological constant problem

NASA Astrophysics Data System (ADS)

Totani, Tomonori

2016-06-01

Deriving the Einstein field equations (EFE) with matter fluid from the action principle is not straightforward, because mass conservation must be added as an additional constraint to make rest-frame mass density variable in reaction to metric variation. This can be avoided by introducing a constraint 0δ(√-g) = to metric variations δ gμν, and then the cosmological constant Λ emerges as an integration constant. This is a removal of one of the four constraints on initial conditions forced by EFE at the birth of the universe, and it may imply that EFE are unnecessarily restrictive about initial conditions. I then adopt a principle that the theory of gravity should be able to solve time evolution starting from arbitrary inhomogeneous initial conditions about spacetime and matter. The equations of gravitational fields satisfying this principle are obtained, by setting four auxiliary constraints on δ gμν to extract six degrees of freedom for gravity. The cost of achieving this is a loss of general covariance, but these equations constitute a consistent theory if they hold in the special coordinate systems that can be uniquely specified with respect to the initial space-like hypersurface when the universe was born. This theory predicts that gravity is described by EFE with non-zero Λ in a homogeneous patch of the universe created by inflation, but Λ changes continuously across different patches. Then both the smallness and coincidence problems of the cosmological constant are solved by the anthropic argument. This is just a result of inhomogeneous initial conditions, not requiring any change of the fundamental physical laws in different patches.

Cosmological ``Truths''

NASA Astrophysics Data System (ADS)

Bothun, Greg

2011-10-01

Ever since Aristotle placed us, with certainty, in the Center of the Cosmos, Cosmological models have more or less operated from a position of known truths for some time. As early as 1963, for instance, it was ``known'' that the Universe had to be 15-17 billion years old due to the suspected ages of globular clusters. For many years, attempts to determine the expansion age of the Universe (the inverse of the Hubble constant) were done against this preconceived and biased notion. Not surprisingly when more precise observations indicated a Hubble expansion age of 11-13 billion years, stellar models suddenly changed to produce a new age for globular cluster stars, consistent with 11-13 billion years. Then in 1980, to solve a variety of standard big bang problems, inflation was introduced in a fairly ad hoc manner. Inflation makes the simple prediction that the net curvature of spacetime is zero (i.e. spacetime is flat). The consequence of introducing inflation is now the necessary existence of a dark matter dominated Universe since the known baryonic material could comprise no more than 1% of the necessary energy density to make spacetime flat. As a result of this new cosmological ``truth'' a significant world wide effort was launched to detect the dark matter (which obviously also has particle physics implications). To date, no such cosmological component has been detected. Moreover, all available dynamical inferences of the mass density of the Universe showed in to be about 20% of that required for closure. This again was inconsistent with the truth that the real density of the Universe was the closure density (e.g. Omega = 1), that the observations were biased, and that 99% of the mass density had to be in the form of dark matter. That is, we know the universe is two component -- baryons and dark matter. Another prevailing cosmological truth during this time was that all the baryonic matter was known to be in galaxies that populated our galaxy catalogs. Subsequent

Constraints on the optical depth of galaxy groups and clusters

DOE Office of Scientific and Technical Information (OSTI.GOV)

Flender, Samuel; Nagai, Daisuke; McDonald, Michael

Here, future data from galaxy redshift surveys, combined with high-resolutions maps of the cosmic microwave background, will enable measurements of the pairwise kinematic Sunyaev–Zel'dovich (kSZ) signal with unprecedented statistical significance. This signal probes the matter-velocity correlation function, scaled by the average optical depth (τ) of the galaxy groups and clusters in the sample, and is thus of fundamental importance for cosmology. However, in order to translate pairwise kSZ measurements into cosmological constraints, external constraints on τ are necessary. In this work, we present a new model for the intracluster medium, which takes into account star formation, feedback, non-thermal pressure, and gas cooling. Our semi-analytic model is computationally efficient and can reproduce results of recent hydrodynamical simulations of galaxy cluster formation. We calibrate the free parameters in the model using recent X-ray measurements of gas density profiles of clusters, and gas masses of groups and clusters. Our observationally calibrated model predicts the averagemore » $${\\tau }_{500}$$ (i.e., the integrated τ within a disk of size R 500) to better than 6% modeling uncertainty (at 95% confidence level). If the remaining uncertainties associated with other astrophysical uncertainties and X-ray selection effects can be better understood, our model for the optical depth should break the degeneracy between optical depth and cluster velocity in the analysis of future pairwise kSZ measurements and improve cosmological constraints with the combination of upcoming galaxy and CMB surveys, including the nature of dark energy, modified gravity, and neutrino mass.« less

Constraints on the optical depth of galaxy groups and clusters

DOE PAGES

Flender, Samuel; Nagai, Daisuke; McDonald, Michael

2017-03-10

Here, future data from galaxy redshift surveys, combined with high-resolutions maps of the cosmic microwave background, will enable measurements of the pairwise kinematic Sunyaev–Zel'dovich (kSZ) signal with unprecedented statistical significance. This signal probes the matter-velocity correlation function, scaled by the average optical depth (τ) of the galaxy groups and clusters in the sample, and is thus of fundamental importance for cosmology. However, in order to translate pairwise kSZ measurements into cosmological constraints, external constraints on τ are necessary. In this work, we present a new model for the intracluster medium, which takes into account star formation, feedback, non-thermal pressure, and gas cooling. Our semi-analytic model is computationally efficient and can reproduce results of recent hydrodynamical simulations of galaxy cluster formation. We calibrate the free parameters in the model using recent X-ray measurements of gas density profiles of clusters, and gas masses of groups and clusters. Our observationally calibrated model predicts the averagemore » $${\\tau }_{500}$$ (i.e., the integrated τ within a disk of size R 500) to better than 6% modeling uncertainty (at 95% confidence level). If the remaining uncertainties associated with other astrophysical uncertainties and X-ray selection effects can be better understood, our model for the optical depth should break the degeneracy between optical depth and cluster velocity in the analysis of future pairwise kSZ measurements and improve cosmological constraints with the combination of upcoming galaxy and CMB surveys, including the nature of dark energy, modified gravity, and neutrino mass.« less

Stable cosmology in chameleon bigravity

NASA Astrophysics Data System (ADS)

De Felice, Antonio; Mukohyama, Shinji; Oliosi, Michele; Watanabe, Yota

2018-02-01

The recently proposed chameleonic extension of bigravity theory, by including a scalar field dependence in the graviton potential, avoids several fine-tunings found to be necessary in usual massive bigravity. In particular it ensures that the Higuchi bound is satisfied at all scales, that no Vainshtein mechanism is needed to satisfy Solar System experiments, and that the strong coupling scale is always above the scale of cosmological interest all the way up to the early Universe. This paper extends the previous work by presenting a stable example of cosmology in the chameleon bigravity model. We find a set of initial conditions and parameters such that the derived stability conditions on general flat Friedmann background are satisfied at all times. The evolution goes through radiation-dominated, matter-dominated, and de Sitter eras. We argue that the parameter space allowing for such a stable evolution may be large enough to encompass an observationally viable evolution. We also argue that our model satisfies all known constraints due to gravitational wave observations so far and thus can be considered as a unique testing ground of gravitational wave phenomenologies in bimetric theories of gravity.

Detecting dark energy in orbit: The cosmological chameleon

DOE Office of Scientific and Technical Information (OSTI.GOV)

Brax, Philippe; Bruck, Carsten van de; Davis, Anne-Christine

2004-12-15

We show that the chameleon scalar field can drive the current phase of cosmic acceleration for a large class of scalar potentials that are also consistent with local tests of gravity. These provide explicit realizations of a quintessence model where the quintessence scalar field couples directly to baryons and dark matter with gravitational strength. We analyze the cosmological evolution of the chameleon field and show the existence of an attractor solution with the chameleon following the minimum of its effective potential. For a wide range of initial conditions, spanning many orders of magnitude in initial chameleon energy density, the attractormore » is reached before nucleosynthesis. Surprisingly, the range of allowed initial conditions leading to a successful cosmology is wider than in normal quintessence. We discuss applications to the cyclic model of the universe and show how the chameleon mechanism weakens some of the constraints on cyclic potentials.« less

Forecast and analysis of the cosmological redshift drift.

PubMed

Lazkoz, Ruth; Leanizbarrutia, Iker; Salzano, Vincenzo

2018-01-01

The cosmological redshift drift could lead to the next step in high-precision cosmic geometric observations, becoming a direct and irrefutable test for cosmic acceleration. In order to test the viability and possible properties of this effect, also called Sandage-Loeb (SL) test, we generate a model-independent mock data set in order to compare its constraining power with that of the future mock data sets of Type Ia Supernovae (SNe) and Baryon Acoustic Oscillations (BAO). The performance of those data sets is analyzed by testing several cosmological models with the Markov chain Monte Carlo (MCMC) method, both independently as well as combining all data sets. Final results show that, in general, SL data sets allow for remarkable constraints on the matter density parameter today [Formula: see text] on every tested model, showing also a great complementarity with SNe and BAO data regarding dark energy parameters.

2HOT: An Improved Parallel Hashed Oct-Tree N-Body Algorithm for Cosmological Simulation

DOE PAGES

Warren, Michael S.

2014-01-01

We report on improvements made over the past two decades to our adaptive treecode N-body method (HOT). A mathematical and computational approach to the cosmological N-body problem is described, with performance and scalability measured up to 256k (2 18 ) processors. We present error analysis and scientific application results from a series of more than ten 69 billion (4096 3 ) particle cosmological simulations, accounting for 4×10 20 floating point operations. These results include the first simulations using the new constraints on the standard model of cosmology from the Planck satellite. Our simulations set a new standard for accuracy andmore » scientific throughput, while meeting or exceeding the computational efficiency of the latest generation of hybrid TreePM N-body methods.« less

Smoot Group Cosmology

Science.gov Websites

Image: NASA WMAP George F. Smoot and John Mather share the 2006 Nobel prize "for their the Universe About Cosmology Planck Satellite Launched Cosmology Videos Professor George Smoot's group science goals regarding cosmology. George Smoot named Director of Korean Cosmology Institute The GRB

Measures, Probability and Holography in Cosmology

NASA Astrophysics Data System (ADS)

Phillips, Daniel

This dissertation compiles four research projects on predicting values for cosmological parameters and models of the universe on the broadest scale. The first examines the Causal Entropic Principle (CEP) in inhomogeneous cosmologies. The CEP aims to predict the unexpectedly small value of the cosmological constant Lambda using a weighting by entropy increase on causal diamonds. The original work assumed a purely isotropic and homogeneous cosmology. But even the level of inhomogeneity observed in our universe forces reconsideration of certain arguments about entropy production. In particular, we must consider an ensemble of causal diamonds associated with each background cosmology and we can no longer immediately discard entropy production in the far future of the universe. Depending on our choices for a probability measure and our treatment of black hole evaporation, the prediction for Lambda may be left intact or dramatically altered. The second related project extends the CEP to universes with curvature. We have found that curvature values larger than rho k = 40rhom are disfavored by more than $99.99% and a peak value at rhoLambda = 7.9 x 10-123 and rhok =4.3rho m for open universes. For universes that allow only positive curvature or both positive and negative curvature, we find a correlation between curvature and dark energy that leads to an extended region of preferred values. Our universe is found to be disfavored to an extent depending the priors on curvature. We also provide a comparison to previous anthropic constraints on open universes and discuss future directions for this work. The third project examines how cosmologists should formulate basic questions of probability. We argue using simple models that all successful practical uses of probabilities originate in quantum fluctuations in the microscopic physical world around us, often propagated to macroscopic scales. Thus we claim there is no physically verified fully classical theory of probability. We

Linear perturbations in spherically symmetric dust cosmologies including a cosmological constant

NASA Astrophysics Data System (ADS)

Meyer, Sven; Bartelmann, Matthias

2017-12-01

We study the dynamical behaviour of gauge-invariant linear perturbations in spherically symmetric dust cosmologies including a cosmological constant. In contrast to spatially homogeneous FLRW models, the reduced degree of spatial symmetry causes a non-trivial dynamical coupling of gauge-invariant quantities already at first order perturbation theory and the strength and influence of this coupling on the spacetime evolution is investigated here. We present results on the underlying dynamical equations augmented by a cosmological constant and integrate them numerically. We also present a method to derive cosmologically relevant initial variables for this setup. Estimates of angular power spectra for each metric variable are computed and evaluated on the central observer's past null cone. By comparing the full evolution to the freely evolved initial profiles, the coupling strength will be determined for a best fit radially inhomogeneous patch obtained in previous works (see [1]). We find that coupling effects are not noticeable within the cosmic variance limit and can therefore safely be neglected for a relevant cosmological scenario. On the contrary, we find very strong coupling effects in a best fit spherical void model matching the distance redshift relation of SNe which is in accordance with previous findings using parametric void models.

Cosmology with decaying cosmological constant—exact solutions and model testing

DOE Office of Scientific and Technical Information (OSTI.GOV)

Szydłowski, Marek; Stachowski, Aleksander, E-mail: marek.szydlowski@uj.edu.pl, E-mail: aleksander.stachowski@uj.edu.pl

We study dynamics of Λ(t) cosmological models which are a natural generalization of the standard cosmological model (the ΛCDM model). We consider a class of models: the ones with a prescribed form of Λ(t)=Λ{sub bare}+α{sup 2}/t{sup 2}. This type of a Λ(t) parametrization is motivated by different cosmological approaches. We interpret the model with running Lambda (Λ(t)) as a special model of an interacting cosmology with the interaction term −dΛ(t)/dt in which energy transfer is between dark matter and dark energy sectors. For the Λ(t) cosmology with a prescribed form of Λ(t) we have found the exact solution in themore » form of Bessel functions. Our model shows that fractional density of dark energy Ω{sub e} is constant and close to zero during the early evolution of the universe. We have also constrained the model parameters for this class of models using the astronomical data such as SNIa data, BAO, CMB, measurements of H(z) and the Alcock-Paczyński test. In this context we formulate a simple criterion of variability of Λ with respect to t in terms of variability of the jerk or sign of estimator (1−Ω{sub m},0−Ω{sub Λ,0}). The case study of our model enable us to find an upper limit α{sup 2} < 0.012 (2σ C.L.) describing the variation from the cosmological constant while the LCDM model seems to be consistent with various data.« less

Anisotropies of gravitational-wave standard sirens as a new cosmological probe without redshift information

NASA Astrophysics Data System (ADS)

Nishizawa, Atsushi; Namikawa, Toshiya; Taruya, Atsushi

2016-03-01

Gravitational waves (GWs) from compact binary stars at cosmological distances are promising and powerful cosmological probes, referred to as the GW standard sirens. With future GW detectors, we will be able to precisely measure source luminosity distances out to a redshift z 5. To extract cosmological information, previous studies using the GW standard sirens rely on source redshift information obtained through an extensive electromagnetic follow-up campaign. However, the redshift identification is typically time-consuming and rather challenging. Here we propose a novel method for cosmology with the GW standard sirens free from the redshift measurements. Utilizing the anisotropies of the number density and luminosity distances of compact binaries originated from the large-scale structure, we show that (i) this anisotropies can be measured even at very high-redshifts (z = 2), (ii) the expected constraints on the primordial non-Gaussianity with Einstein Telescope would be comparable to or even better than the other large-scale structure probes at the same epoch, (iii) the cross-correlation with other cosmological observations is found to have high-statistical significance. A.N. was supported by JSPS Postdoctoral Fellowships for Research Abroad No. 25-180.

Thermodynamics and cosmological reconstruction in f(T , B) gravity

NASA Astrophysics Data System (ADS)

Bahamonde, Sebastian; Zubair, M.; Abbas, G.

2018-03-01

Recently, it was formulated a teleparallel theory called f(T , B) gravity which connects both f(T) and f(R) under suitable limits. In this theory, the function in the action is assumed to depend on the torsion scalar T and also on a boundary term related with the divergence of torsion, B = 2∇μTμ. In this work, we study different features of a flat Friedmann-Lemaître-Robertson-Walker (FLRW) cosmology in this theory. First, we show that the FLRW equations can be transformed to the form of Clausius relation TˆhSeff = - dE + WdV, where Tˆh is the horizon temperature and Seff is the entropy which contains contributions both from horizon entropy and an additional entropy term introduced due to the non-equilibrium. We also formulate the constraint for the validity of the generalised second law of thermodynamics (GSLT). Additionally, using a cosmological reconstruction technique, we show that both f(T , B) and - T + F(B) gravity can mimic power-law, de-Sitter and ΛCDM models. Finally, we formulate the perturbed evolution equations and analyse the stability of some important cosmological solutions.

Dark matter and cosmology

DOE Office of Scientific and Technical Information (OSTI.GOV)

Schramm, D.N.

1992-03-01

The cosmological dark matter problem is reviewed. The Big Bang Nucleosynthesis constraints on the baryon density are compared with the densities implied by visible matter, dark halos, dynamics of clusters, gravitational lenses, large-scale velocity flows, and the {Omega} = 1 flatness/inflation argument. It is shown that (1) the majority of baryons are dark; and (2) non-baryonic dark matter is probably required on large scales. It is also noted that halo dark matter could be either baryonic or non-baryonic. Descrimination between ``cold`` and ``hot`` non-baryonic candidates is shown to depend on the assumed ``seeds`` that stimulate structure formation. Gaussian density fluctuations,more » such as those induced by quantum fluctuations, favor cold dark matter, whereas topological defects such as strings, textures or domain walls may work equally or better with hot dark matter. A possible connection between cold dark matter, globular cluster ages and the Hubble constant is mentioned. Recent large-scale structure measurements, coupled with microwave anisotropy limits, are shown to raise some questions for the previously favored density fluctuation picture. Accelerator and underground limits on dark matter candidates are also reviewed.« less

Dark matter and cosmology

DOE Office of Scientific and Technical Information (OSTI.GOV)

Schramm, D.N.

1992-03-01

The cosmological dark matter problem is reviewed. The Big Bang Nucleosynthesis constraints on the baryon density are compared with the densities implied by visible matter, dark halos, dynamics of clusters, gravitational lenses, large-scale velocity flows, and the {Omega} = 1 flatness/inflation argument. It is shown that (1) the majority of baryons are dark; and (2) non-baryonic dark matter is probably required on large scales. It is also noted that halo dark matter could be either baryonic or non-baryonic. Descrimination between cold'' and hot'' non-baryonic candidates is shown to depend on the assumed seeds'' that stimulate structure formation. Gaussian density fluctuations,more » such as those induced by quantum fluctuations, favor cold dark matter, whereas topological defects such as strings, textures or domain walls may work equally or better with hot dark matter. A possible connection between cold dark matter, globular cluster ages and the Hubble constant is mentioned. Recent large-scale structure measurements, coupled with microwave anisotropy limits, are shown to raise some questions for the previously favored density fluctuation picture. Accelerator and underground limits on dark matter candidates are also reviewed.« less

Dark matter and cosmology

NASA Astrophysics Data System (ADS)

Schramm, David N.

1992-07-01

The cosmological dark matter problem is reviewed. The Big Bang Nucleosynthesis constraints on the baryon density are compared with the densities implied by visible matter, dark halos, dynamics of clusters, gravitational lenses, large-scale velocity flows, and the Ω = 1 flatness/inflation argument. It is shown that (1) the majority of baryons are dark; and (2) non-baryonic dark matter is probably required on large scales. It is also noted that halo dark matter could be either baryonic or non-baryonic. Descrimination between ``cold'' and ``hot'' non-baryonic candidates is shown to depend on the assumed ``seeds'' that stimulate structure formation. Gaussian density fluctuations, such as those induced by quantum fluctuations, favor cold dark matter, whereas topological defects such as strings, textures or domain walls may work equally or better with hot dark matter. A possible connection between cold dark matter, globular cluster ages and the Hubble constant is mentioned. Recent large-scale structure measurements, coupled with microwave anisotropy limits, are shown to raise some questions for the previously favored density fluctuation picture. Accelerator and underground limits on dark matter candidates are also reviewed.

Dark matter and cosmology

NASA Astrophysics Data System (ADS)

Schramm, D. N.

1992-03-01

The cosmological dark matter problem is reviewed. The Big Bang nucleosynthesis constraints on the baryon density are compared with the densities implied by visible matter, dark halos, dynamics of clusters, gravitational lenses, large-scale velocity flows, and the omega = 1 flatness/inflation argument. It is shown that (1) the majority of baryons are dark; and (2) non-baryonic dark matter is probably required on large scales. It is also noted that halo dark matter could be either baryonic or non-baryonic. Descrimination between 'cold' and 'hot' non-baryonic candidates is shown to depend on the assumed 'seeds' that stimulate structure formation. Gaussian density fluctuations, such as those induced by quantum fluctuations, favor cold dark matter, whereas topological defects such as strings, textures or domain walls may work equally or better with hot dark matter. A possible connection between cold dark matter, globular cluster ages, and the Hubble constant is mentioned. Recent large-scale structure measurements, coupled with microwave anisotropy limits, are shown to raise some questions for the previously favored density fluctuation picture. Accelerator and underground limits on dark matter candidates are also reviewed.

Causality and a -theorem constraints on Ricci polynomial and Riemann cubic gravities

NASA Astrophysics Data System (ADS)

Li, Yue-Zhou; Lü, H.; Wu, Jun-Bao

2018-01-01

In this paper, we study Einstein gravity extended with Ricci polynomials and derive the constraints on the coupling constants from the considerations of being ghost-free, exhibiting an a -theorem and maintaining causality. The salient feature is that Einstein metrics with appropriate effective cosmological constants continue to be solutions with the inclusion of such Ricci polynomials and the causality constraint is automatically satisfied. The ghost-free and a -theorem conditions can only be both met starting at the quartic order. We also study these constraints on general Riemann cubic gravities.

Relaxion cosmology and the price of fine-tuning

NASA Astrophysics Data System (ADS)

Di Chiara, Stefano; Kannike, Kristjan; Marzola, Luca; Racioppi, Antonio; Raidal, Martti; Spethmann, Christian

2016-05-01

The relaxion scenario presents an intriguing extension of the standard model in which the particle introduced to solve to the strong C P problem, the axion, also achieves the dynamical relaxation of the Higgs boson mass term. In this work we complete this framework by proposing a scenario of inflationary cosmology that is consistent with all the observational constraints: the relaxion hybrid inflation with an asymmetric waterfall. In our scheme, the vacuum energy of the inflaton drives inflation in a natural way while the relaxion slow rolls. The constraints on the present inflationary observables are then matched through a subsequent inflationary epoch driven by the inflaton. We quantify the amount of fine-tuning of the proposed inflation scenario, concluding that the inflaton sector severely decreases the naturalness of the theory.

Sterile neutrinos with secret interactions—lasting friendship with cosmology

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chu, Xiaoyong; Dasgupta, Basudeb; Kopp, Joachim, E-mail: xchu@ictp.it, E-mail: bdasgupta@theory.tifr.res.in, E-mail: jkopp@uni-mainz.de

Sterile neutrinos with mass ≅ 1 eV and order 10% mixing with active neutrinos have been proposed as a solution to anomalies in neutrino oscillation data, but are tightly constrained by cosmological limits. It was recently shown that these constraints are avoided if sterile neutrinos couple to a new MeV-scale gauge boson A'. However, even this scenario is restricted by structure formation constraints when A'-mediated collisional processes lead to efficient active-to-sterile neutrino conversion after neutrinos have decoupled. In view of this, we reevaluate in this paper the viability of sterile neutrinos with such ''secret'' interactions. We carefully dissect their evolution inmore » the early Universe, including the various production channels and the expected modifications to large scale structure formation. We argue that there are two regions in parameter space—one at very small A' coupling, one at relatively large A' coupling—where all constraints from big bang nucleosynthesis (BBN), cosmic microwave background (CMB), and large scale structure (LSS) data are satisfied. Interestingly, the large A' coupling region is precisely the region that was previously shown to have potentially important consequences for the small scale structure of dark matter halos if the A' boson couples also to the dark matter in the Universe.« less

Deuterium Abundance in Consciousness and Current Cosmology

NASA Astrophysics Data System (ADS)

Rauscher, Elizabeth A.

We utilize the deuterium-hydrogen abundances and their role in setting limits on the mass and other conditions of cosmogenesis and cosmological evolution. We calculate the dependence of a set of physical variables such as density, temperature, energy mass, entropy and other physical variable parameters through the evolution of the universe under the Schwarzschild conditions as a function from early to present time. Reconciliation with the 3°K and missing mass is made. We first examine the Schwarzschild condition; second, the geometrical constraints of a multidimensional Cartesian space on closed cosmologies, and third we will consider the cosmogenesis and evolution of the universe in a multidimensional Cartesian space, obeying the Schwarzschild condition. Implications of this model for matter creation are made. We also examine experimental evidence for closed versus open cosmologies; x-ray detection of the "missing mass" density. Also the interstellar deuterium abundance, along with the value of the Hubble constant set a general criterion on the value of the curvature constant, k. Once the value of the Hubble constant, H is determined, the deuterium abundance sets stringent restrictions on the value of the curvature constant k by an detailed discussion is presented. The experimental evidences for the determination of H and the primary set of coupled equations to determine D abundance is given. 'The value of k for an open, closed, or flat universe will be discussed in terms of the D abundance which will affect the interpretation of the Schwarzschild, black hole universe. We determine cosmology solutions to Einstein's field obeying the Schwarzschild solutions condition. With this model, we can form a reconciliation of the black hole, from galactic to cosmological scale. Continuous creation occurs at the dynamic blackhole plasma field. We term this new model the multiple big bang or "little whimper model". We utilize the deuteriumhydrogen abundances and their role in

The Compatibility of Friedmann Cosmological Models with Observed Properties of Gamma-Ray Bursts and a Large Hubble Constant

NASA Technical Reports Server (NTRS)

Horack, John M.; Koshut, Thomas M.; Mallozzi, Robert S.; Emslie, A. Gordon; Meegan, Charles A.

1996-01-01

The distance scale to cosmic gamma-ray bursts (GRB's) is still uncertain by many orders of magnitude; however, one viable scenario places GRB's at cosmological distances, thereby permitting them to be used as tracers of the cosmological expansion over a significant range of redshifts zeta. Also, several recent measurements of the Hubble constant H(sub 0) appearing in the referred literature report values of 70-80 km/s /Mpc. Although there is significant debate regarding these measurements, we proceed here under the assumption that they are evidence of a large value for H(sub 0). This is done in order to investigate the additional constraints on cosmological models that can be obtained under this hypothesis when combined with the age of the universe and the brightness distribution of cosmological gamma-ray bursts. We show that the range of cosmological models that can be consistent with the GRB brightness distribution, a Hubble constant of 70-80 km/s/Mpc, and a minimum age of the universe of 13-15 Gyr is constrained significantly, largely independent of a wide range of assumptions regarding the evolutionary nature of the burst population. Low-density, Lambda greater than 0 cosmological models with deceleration parameter in the range -1 less than q(sub 0) less than 0 and density parameter sigma(sub 0) in the range approximately equals 0.10-0.25(Omega(sub 0) approximately equals 0.2-0.5) are strongly favored.

Probing sub-GeV dark matter-baryon scattering with cosmological observables

NASA Astrophysics Data System (ADS)

Xu, Weishuang Linda; Dvorkin, Cora; Chael, Andrew

2018-05-01

We derive new limits on the elastic scattering cross section between baryons and dark matter using cosmic microwave background data from the Planck satellite and measurements of the Lyman-alpha forest flux power spectrum from the Sloan Digital Sky Survey. Our analysis addresses generic cross sections of the form σ ∝vn , where v is the dark matter-baryon relative velocity, allowing for constraints on the cross section independent of specific particle physics models. We include high-ℓ polarization data from Planck in our analysis, improving over previous constraints. We apply a more careful treatment of dark matter thermal evolution than previously done, allowing us to extend our constraints down to dark matter masses of ˜MeV . We show in this work that cosmological probes are complementary to current direct detection and astrophysical searches.

Curvature Constraints from the Causal Entropic Principle

NASA Astrophysics Data System (ADS)

Bozek, Brandon

2010-01-01

Current cosmological observations indicate a preference for a cosmological constant that is drastically smaller than what can be explained by conventional particle physics. The Causal Entropic Principle (Bousso, et al.) provides an alternative approach to anthropic attempts to predict our observed value of the cosmological constant by calculating the entropy created within a causal diamond. We have extended this work to use the Causal Entropic Principle to predict the preferred curvature within the "multiverse." We have found that values larger than ρk = 40*ρm are disfavored by more than 99.99% and a peak value at ρΛ = 7.9*10-123 and ρk =4.3*ρm for open universes. For universes that allow only positive curvature or both positive and negative curvature, we find a correlation between curvature and dark energy that leads to an extended region of preferred values. Our universe is found to be disfavored to an extent depending on the priors on curvature. We also provide a comparison to previous anthropic constraints on open universes and discuss future directions for this work.

Curvature constraints from the causal entropic principle

NASA Astrophysics Data System (ADS)

Bozek, Brandon; Albrecht, Andreas; Phillips, Daniel

2009-07-01

Current cosmological observations indicate a preference for a cosmological constant that is drastically smaller than what can be explained by conventional particle physics. The causal entropic principle (Bousso et al.) provides an alternative approach to anthropic attempts to predict our observed value of the cosmological constant by calculating the entropy created within a causal diamond. We have extended this work to use the causal entropic principle to predict the preferred curvature within the “multiverse.” We have found that values larger than ρk=40ρm are disfavored by more than 99.99% peak value at ρΛ=7.9×10-123 and ρk=4.3ρm for open universes. For universes that allow only positive curvature or both positive and negative curvature, we find a correlation between curvature and dark energy that leads to an extended region of preferred values. Our universe is found to be disfavored to an extent depending on the priors on curvature. We also provide a comparison to previous anthropic constraints on open universes and discuss future directions for this work.

Gravitational lensing limits on the cosmological constant in a flat universe

NASA Technical Reports Server (NTRS)

Turner, Edwin L.

1990-01-01

Inflationary cosmological theories predict, and some more general aesthetic criteria suggest, that the large-scale spatial curvature of the universe k should be accurately zero (i.e., flat), a condition which is satisfied when the universe's present mean density and the value of the cosmological constant Lambda have certain pairs of values. Available data on the frequency of multiple image-lensing of high-redshift quasars by galaxies suggest that the cosmological constant cannot make a dominant contribution to producing a flat universe. In particular, if the mean density of the universe is as small as the baryon density inferred from standard cosmic nucleosynthesis calculations or as determined from typical dynamical studies of galaxies and galaxy clusters, then a value of Lambda large enough to produce a k = 0 universe would result in a substantially higher frequency of multiple-image lensing of quasars than has been observed so far. Shortcomings of the available lens data and uncertainties concerning galaxy properties allow some possibility of escaping this conclusion, but systematic searches for a gravitational lenses and continuing investigations of galaxy mass distributions should soon provide decisive information. It is also noted that nonzero-curvature cosmological models can account for the observed frequency of galaxy-quasar lens systems and for a variety of other constraints.

A novel approach to quantifying the sensitivity of current and future cosmological datasets to the neutrino mass ordering through Bayesian hierarchical modeling

NASA Astrophysics Data System (ADS)

Gerbino, Martina; Lattanzi, Massimiliano; Mena, Olga; Freese, Katherine

2017-12-01

We present a novel approach to derive constraints on neutrino masses, as well as on other cosmological parameters, from cosmological data, while taking into account our ignorance of the neutrino mass ordering. We derive constraints from a combination of current as well as future cosmological datasets on the total neutrino mass Mν and on the mass fractions fν,i =mi /Mν (where the index i = 1 , 2 , 3 indicates the three mass eigenstates) carried by each of the mass eigenstates mi, after marginalizing over the (unknown) neutrino mass ordering, either normal ordering (NH) or inverted ordering (IH). The bounds on all the cosmological parameters, including those on the total neutrino mass, take therefore into account the uncertainty related to our ignorance of the mass hierarchy that is actually realized in nature. This novel approach is carried out in the framework of Bayesian analysis of a typical hierarchical problem, where the distribution of the parameters of the model depends on further parameters, the hyperparameters. In this context, the choice of the neutrino mass ordering is modeled via the discrete hyperparameterhtype, which we introduce in the usual Markov chain analysis. The preference from cosmological data for either the NH or the IH scenarios is then simply encoded in the posterior distribution of the hyperparameter itself. Current cosmic microwave background (CMB) measurements assign equal odds to the two hierarchies, and are thus unable to distinguish between them. However, after the addition of baryon acoustic oscillation (BAO) measurements, a weak preference for the normal hierarchical scenario appears, with odds of 4 : 3 from Planck temperature and large-scale polarization in combination with BAO (3 : 2 if small-scale polarization is also included). Concerning next-generation cosmological experiments, forecasts suggest that the combination of upcoming CMB (COrE) and BAO surveys (DESI) may determine the neutrino mass hierarchy at a high statistical

Cosmological structure formation in Decaying Dark Matter models

NASA Astrophysics Data System (ADS)

Cheng, Dalong; Chu, M.-C.; Tang, Jiayu

2015-07-01

The standard cold dark matter (CDM) model predicts too many and too dense small structures. We consider an alternative model that the dark matter undergoes two-body decays with cosmological lifetime τ into only one type of massive daughters with non-relativistic recoil velocity Vk. This decaying dark matter model (DDM) can suppress the structure formation below its free-streaming scale at time scale comparable to τ. Comparing with warm dark matter (WDM), DDM can better reduce the small structures while being consistent with high redshfit observations. We study the cosmological structure formation in DDM by performing self-consistent N-body simulations and point out that cosmological simulations are necessary to understand the DDM structures especially on non-linear scales. We propose empirical fitting functions for the DDM suppression of the mass function and the concentration-mass relation, which depend on the decay parameters lifetime τ, recoil velocity Vk and redshift. The fitting functions lead to accurate reconstruction of the the non-linear power transfer function of DDM to CDM in the framework of halo model. Using these results, we set constraints on the DDM parameter space by demanding that DDM does not induce larger suppression than the Lyman-α constrained WDM models. We further generalize and constrain the DDM models to initial conditions with non-trivial mother fractions and show that the halo model predictions are still valid after considering a global decayed fraction. Finally, we point out that the DDM is unlikely to resolve the disagreement on cluster numbers between the Planck primary CMB prediction and the Sunyaev-Zeldovich (SZ) effect number count for τ ~ H0-1.

Nuclear physics and cosmology

NASA Technical Reports Server (NTRS)

Schramm, David N.

1989-01-01

Nuclear physics has provided one of two critical observational tests of all Big Bang cosmology, namely Big Bang Nucleosynthesis. Furthermore, this same nuclear physics input enables a prediction to be made about one of the most fundamental physics questions of all, the number of elementary particle families. The standard Big Bang Nucleosynthesis arguments are reviewed. The primordial He abundance is inferred from He-C and He-N and He-O correlations. The strengthened Li constraint as well as D-2 plus He-3 are used to limit the baryon density. This limit is the key argument behind the need for non-baryonic dark matter. The allowed number of neutrino families, N(nu), is delineated using the new neutron lifetime value of tau(n) = 890 + or - 4s (tau(1/2) = 10.3 min). The formal statistical result is N(nu) = 2.6 + or - 0.3 (1 sigma), providing a reasonable fit (1.3 sigma) to three families but making a fourth light (m(nu) less than or equal to 10 MeV) neutrino family exceedly unlikely (approx. greater than 4.7 sigma). It is also shown that uncertainties induced by postulating a first-order quark-baryon phase transition do not seriously affect the conclusions.

Constraints on the cosmological parameters from BICEP2, Planck, and WMAP

NASA Astrophysics Data System (ADS)

Cheng, Cheng; Huang, Qing-Guo

2014-11-01

In this paper we constrain the cosmological parameters, in particular the tilt of tensor power spectrum, by adopting Background Imaging of Cosmic Extragalactic Polarization (B2), Planck released in 2013 and Wilkinson Microwaves Anisotropy Probe 9-year Polarization data. We find that a blue tilted tensor power spectrum is preferred at more than confidence level if the data from B2 are assumed to be totally interpreted as the relic gravitational waves, but a scale-invariant tensor power spectrum is consistent with the data once the polarized dust is taken into account. The recent Planck 353 GHz HFI dust polarization data imply that the B2 data are perfectly consistent with there being no gravitational wave signal.

GRB Diversity vs. Utility as Cosmological Probes

NASA Technical Reports Server (NTRS)

Norris, J. P.; Scargle, J. D.; Bonnell, J. T.; Nemiroff, R. J.; Young, Richard E. (Technical Monitor)

1997-01-01

Recent detections of apparent gamma-ray burst (GRB) counterparts in optical and radio wavebands strongly favor the cosmological distance scale, at least for some GRBs, opening the possibility of GRBs serving as cosmological probes. But GRBs exhibit great diversity: in total duration; in number, width and pulse configuration; and in pulse and overall spectral evolution. However, it is possible that a portion of this behavior reflects a luminosity distribution, and possible that evolution of with cosmic time introduces dispersion into the average GRB characteristics -- issues analogous to those encountered with quasars. The temporal domain offers a rich avenue to investigate this problem. When corrected for assumed spectral redshift, time dilation of event durations, pulse widths, and intervals between pulses must yield the same time-dilation factor as a function of peak flux, or else a luminosity distribution may be the cause of observed time dilation effects. We describe results of burst analysis using an automated, Bayesian-based algorithm to determine burst temporal characteristics for different peak flux groups, and derived constraints on any physical process that would introduce a luminosity distribution.

Towards cosmological dynamics from loop quantum gravity

NASA Astrophysics Data System (ADS)

Li, Bao-Fei; Singh, Parampreet; Wang, Anzhong

2018-04-01

We present a systematic study of the cosmological dynamics resulting from an effective Hamiltonian, recently derived in loop quantum gravity using Thiemann's regularization and earlier obtained in loop quantum cosmology (LQC) by keeping the Lorentzian term explicit in the Hamiltonian constraint. We show that quantum geometric effects result in higher than quadratic corrections in energy density in comparison to LQC, causing a nonsingular bounce. Dynamics can be described by the Hamilton or Friedmann-Raychaudhuri equations, but the map between the two descriptions is not one to one. A careful analysis resolves the tension on symmetric versus asymmetric bounce in this model, showing that the bounce must be asymmetric and symmetric bounce is physically inconsistent, in contrast to the standard LQC. In addition, the current observations only allow a scenario where the prebounce branch is asymptotically de Sitter, similar to a quantization of the Schwarzschild interior in LQC, and the postbounce branch yields the classical general relativity. For a quadratic potential, we find that a slow-roll inflation generically happens after the bounce, which is quite similar to what happens in LQC.

On the cosmological gravitational waves and cosmological distances

NASA Astrophysics Data System (ADS)

Belinski, V. A.; Vereshchagin, G. V.

2018-03-01

We show that solitonic cosmological gravitational waves propagated through the Friedmann universe and generated by the inhomogeneities of the gravitational field near the Big Bang can be responsible for increase of cosmological distances.

Problem of time in slightly inhomogeneous cosmology

NASA Astrophysics Data System (ADS)

Anderson, Edward

2016-07-01

The problem of time (PoT) is a multi-faceted conceptual incompatibility between various areas of Theoretical Physics. While usually stated as between GR and QM, in fact 8/9ths of it is already present at the classical level. Thus we adopt a ‘top-down’ classical and then quantum approach. I consider a local resolution to the PoT that is Machian, which was previously realized for relational triangle and minisuperspace models. This resolution has three levels: classical, semiclassical and combined semiclassical-histories-records. This article’s specific model is a slightly inhomogeneous cosmology considered for now at the classical level. This is motivated by how the inhomogeneous fluctuations that underlie structure formation—galaxies and CMB hotspots—might have been seeded by quantum cosmological fluctuations, as magnified by some inflationary mechanism. In particular, I consider the perturbations about {{{S}}}3 case of this involving up to second order, which has a number of parallels with the Halliwell-Hawking model but has a number of conceptual differences and useful upgrades. The article’s main features are that the elimination part of the model’s thin sandwich is straightforward, but the modewise split of the constraints fail to be first-class constraints. Thus the elimination part only arises as an intermediate geometry between superspace and Riem. The reduced geometries have surprising singularities influenced by the matter content of the Universe, though the N-body problem anticipates these with its collinear singularities. I also give a ‘basis set’ of Kuchař beables for this model arena.

The Atacama Cosmology Telescope: Two-season spectrum and parameters

NASA Astrophysics Data System (ADS)

Hlozek, Renée; Louis, Thibaut; Grace, Emily; Hasselfield, Matthew; Lungu, Marius; Maurin, Loic; Atacama Cosmology Telescope

2017-01-01

We present the temperature and polarization angular power spectra measured by the Atacama Cosmology Telescope polarimeter (ACTPol) over 548 deg^2 of sky on the celestial Equator, from nighttime data collected during 2013-14 using two kilo-detector arrays at 146 GHz. We use these spectra, and the spectra measured with the MBAC camera on ACT from 2008-10, in combination with Planck and WMAP satellite data to estimate cosmological parameters from the temperature, polarization, and temperature-polarization cross-correlations. We find the new ACTPol data to be consistent with the ΛCDM model. The ACTPol temperature-polarization cross-spectrum now provides stronger constraints on multiple parameters than the ACTPol temperature power spectrum, including the baryon density and the acoustic peak position angle, and the derived Hubble constant. Adding the new data to Planck temperature data tightens the limits on damping tail parameters, which we present here.

Cosmological viability conditions for f(T) dark energy models

DOE Office of Scientific and Technical Information (OSTI.GOV)

Setare, M.R.; Mohammadipour, N., E-mail: rezakord@ipm.ir, E-mail: N.Mohammadipour@uok.ac.ir

2012-11-01

Recently f(T) modified teleparallel gravity where T is the torsion scalar has been proposed as the natural gravitational alternative for dark energy. We perform a detailed dynamical analysis of these models and find conditions for the cosmological viability of f(T) dark energy models as geometrical constraints on the derivatives of these models. We show that in the phase space exists two cosmologically viable trajectory which (i) The universe would start from an unstable radiation point, then pass a saddle standard matter point which is followed by accelerated expansion de sitter point. (ii) The universe starts from a saddle radiation epoch,more » then falls onto the stable matter era and the system can not evolve to the dark energy dominated epoch. Finally, for a number of f(T) dark energy models were proposed in the more literature, the viability conditions are investigated.« less

The clustering of galaxies in the completed SDSS-III Baryon Oscillation Spectroscopic Survey: Cosmological implications of the configuration-space clustering wedges

NASA Astrophysics Data System (ADS)

Sánchez, Ariel G.; Scoccimarro, Román; Crocce, Martín; Grieb, Jan Niklas; Salazar-Albornoz, Salvador; Dalla Vecchia, Claudio; Lippich, Martha; Beutler, Florian; Brownstein, Joel R.; Chuang, Chia-Hsun; Eisenstein, Daniel J.; Kitaura, Francisco-Shu; Olmstead, Matthew D.; Percival, Will J.; Prada, Francisco; Rodríguez-Torres, Sergio; Ross, Ashley J.; Samushia, Lado; Seo, Hee-Jong; Tinker, Jeremy; Tojeiro, Rita; Vargas-Magaña, Mariana; Wang, Yuting; Zhao, Gong-Bo

2017-01-01

We explore the cosmological implications of anisotropic clustering measurements in configuration space of the final galaxy samples from Data Release 12 of the Sloan Digital Sky Survey III Baryon Oscillation Spectroscopic Survey. We implement a new detailed modelling of the effects of non-linearities, bias and redshift-space distortions that can be used to extract unbiased cosmological information from our measurements for scales s ≳ 20 h-1 Mpc. We combined the information from Baryon Oscillation Spectroscopic Survey (BOSS) with the latest cosmic microwave background (CMB) observations and Type Ia supernovae samples and found no significant evidence for a deviation from the Λ cold dark matter (ΛCDM) cosmological model. In particular, these data sets can constrain the dark energy equation-of-state parameter to wDE = -0.996 ± 0.042 when to be assumed time independent, the curvature of the Universe to Ωk = -0.0007 ± 0.0030 and the sum of the neutrino masses to ∑mν < 0.25 eV at 95 per cent confidence levels. We explore the constraints on the growth rate of cosmic structures assuming f(z) = Ωm(z)γ and obtain γ = 0.609 ± 0.079, in good agreement with the predictions of general relativity of γ = 0.55. We compress the information of our clustering measurements into constraints on the parameter combinations DV(z)/rd, FAP(z) and fσ8(z) at zeff = 0.38, 0.51 and 0.61 with their respective covariance matrices and find good agreement with the predictions for these parameters obtained from the best-fitting ΛCDM model to the CMB data from the Planck satellite. This paper is part of a set that analyses the final galaxy clustering data set from BOSS. The measurements and likelihoods presented here are combined with others by Alam et al. to produce the final cosmological constraints from BOSS.

Exploring the supersymmetric U(1 ) B -L×U(1 ) R model with dark matter, muon g - 2 , and Z' mass limits

NASA Astrophysics Data System (ADS)

Frank, Mariana; Özdal, Özer

2018-01-01

We study the low scale predictions of the supersymmetric standard model extended by U (1 )B -L×U (1 )R symmetry, obtained from S O (10 ) breaking via a left-right supersymmetric model, imposing universal boundary conditions. Two singlet Higgs fields are responsible for the radiative U (1 )B -L×U (1 )R symmetry breaking, and a singlet fermion S is introduced to generate neutrino masses through an inverse seesaw mechanism. The lightest neutralino or sneutrino emerge as dark matter candidates, with different low scale implications. We find that the composition of the neutralino lightest supersymmetric particle (LSP) changes considerably depending on the neutralino LSP mass, from roughly half U (1 )R bino, half minimal supersymmetric model (MSSM) bino, to a singlet higgsino, or completely dominated by the MSSM higgsino. The sneutrino LSP is statistically much less likely, and when it occurs it is a 50-50 mixture of right-handed sneutrino and the scalar S ˜. Most of the solutions consistent with the relic density constraint survive the XENON 1T exclusion curve for both LSP cases. We compare the two scenarios and investigate parameter space points and find consistency with the muon anomalous magnetic moment only at the edge of a 2 σ deviation from the measured value. However, we find that the sneutrino LSP solutions could be ruled out completely by the strict reinforcement of the recent Z' mass bounds. We finally discuss collider prospects for testing the model.

Current observations with a decaying cosmological constant allow for chaotic cyclic cosmology

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ellis, George F.R.; Platts, Emma; Weltman, Amanda

2016-04-01

We use the phase plane analysis technique of Madsen and Ellis [1] to consider a universe with a true cosmological constant as well as a cosmological 'constant' that is decaying. Time symmetric dynamics for the inflationary era allows eternally bouncing models to occur. Allowing for scalar field dynamic evolution, we find that if dark energy decays in the future, chaotic cyclic universes exist provided the spatial curvature is positive. This is particularly interesting in light of current observations which do not yet rule out either closed universes or possible evolution of the cosmological constant. We present only a proof ofmore » principle, with no definite claim on the physical mechanism required for the present dark energy to decay.« less

Super-Eddington accreting massive black holes explore high-z cosmology: Monte-Carlo simulations

NASA Astrophysics Data System (ADS)

Cai, Rong-Gen; Guo, Zong-Kuan; Huang, Qing-Guo; Yang, Tao

2018-06-01

In this paper, we simulate Super-Eddington accreting massive black holes (SEAMBHs) as the candles to probe cosmology for the first time. SEAMBHs have been demonstrated to be able to provide a new tool for estimating cosmological distance. Thus, we create a series of mock data sets of SEAMBHs, especially in the high redshift region, to check their abilities to probe the cosmology. To fulfill the potential of the SEAMBHs on the cosmology, we apply the simulated data to three projects. The first is the exploration of their abilities to constrain the cosmological parameters, in which we combine different data sets of current observations such as the cosmic microwave background from Planck and type Ia supernovae from Joint Light-curve Analysis (JLA). We find that the high redshift SEAMBHs can help to break the degeneracies of the background cosmological parameters constrained by Planck and JLA, thus giving much tighter constraints of the cosmological parameters. The second uses the high redshift SEAMBHs as the complements of the low redshift JLA to constrain the early expansion rate and the dark energy density evolution in the cold dark matter frame. Our results show that these high redshift SEAMBHs are very powerful on constraining the early Hubble rate and the evolution of the dark energy density; thus they can give us more information about the expansion history of our Universe, which is also crucial for testing the Λ CDM model in the high redshift region. Finally, we check the SEAMBH candles' abilities to reconstruct the equation of state for dark energy at high redshift. In summary, our results show that the SEAMBHs, as the rare candles in the high redshift region, can provide us a new and independent observation to probe cosmology in the future.

Cosmological test using strong gravitational lensing systems

NASA Astrophysics Data System (ADS)

Yuan, C. C.; Wang, F. Y.

2015-09-01

As one of the probes of universe, strong gravitational lensing systems allow us to compare different cosmological models and constrain vital cosmological parameters. This purpose can be reached from the dynamic and geometry properties of strong gravitational lensing systems, for instance, time-delay Δτ of images, the velocity dispersion σ of the lensing galaxies and the combination of these two effects, Δτ/σ2. In this paper, in order to carry out one-on-one comparisons between ΛCDM universe and Rh = ct universe, we use a sample containing 36 strong lensing systems with the measurement of velocity dispersion from the Sloan Lens Advanced Camera for Surveys (SLACS) and Lens Structure and Dynamic survey (LSD) survey. Concerning the time-delay effect, 12 two-image lensing systems with Δτ are also used. In addition, Monte Carlo simulations are used to compare the efficiency of the three methods as mentioned above. From simulations, we estimate the number of lenses required to rule out one model at the 99.7 per cent confidence level. Comparing with constraints from Δτ and the velocity dispersion σ, we find that using Δτ/σ2 can improve the discrimination between cosmological models. Despite the independence tests of these methods reveal a correlation between Δτ/σ2 and σ, Δτ/σ2 could be considered as an improved method of σ if more data samples are available.

Constraining f(T) teleparallel gravity by big bang nucleosynthesis: f(T) cosmology and BBN.

PubMed

Capozziello, S; Lambiase, G; Saridakis, E N

2017-01-01

We use Big Bang Nucleosynthesis (BBN) observational data on the primordial abundance of light elements to constrain f ( T ) gravity. The three most studied viable f ( T ) models, namely the power law, the exponential and the square-root exponential are considered, and the BBN bounds are adopted in order to extract constraints on their free parameters. For the power-law model, we find that the constraints are in agreement with those obtained using late-time cosmological data. For the exponential and the square-root exponential models, we show that for reliable regions of parameters space they always satisfy the BBN bounds. We conclude that viable f ( T ) models can successfully satisfy the BBN constraints.

Curvature constraints from large scale structure

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dio, Enea Di; Montanari, Francesco; Raccanelli, Alvise

We modified the CLASS code in order to include relativistic galaxy number counts in spatially curved geometries; we present the formalism and study the effect of relativistic corrections on spatial curvature. The new version of the code is now publicly available. Using a Fisher matrix analysis, we investigate how measurements of the spatial curvature parameter Ω {sub K} with future galaxy surveys are affected by relativistic effects, which influence observations of the large scale galaxy distribution. These effects include contributions from cosmic magnification, Doppler terms and terms involving the gravitational potential. As an application, we consider angle and redshift dependentmore » power spectra, which are especially well suited for model independent cosmological constraints. We compute our results for a representative deep, wide and spectroscopic survey, and our results show the impact of relativistic corrections on spatial curvature parameter estimation. We show that constraints on the curvature parameter may be strongly biased if, in particular, cosmic magnification is not included in the analysis. Other relativistic effects turn out to be subdominant in the studied configuration. We analyze how the shift in the estimated best-fit value for the curvature and other cosmological parameters depends on the magnification bias parameter, and find that significant biases are to be expected if this term is not properly considered in the analysis.« less

Higgs cosmology

NASA Astrophysics Data System (ADS)

Rajantie, Arttu

2018-01-01

The discovery of the Higgs boson in 2012 and other results from the Large Hadron Collider have confirmed the standard model of particle physics as the correct theory of elementary particles and their interactions up to energies of several TeV. Remarkably, the theory may even remain valid all the way to the Planck scale of quantum gravity, and therefore it provides a solid theoretical basis for describing the early Universe. Furthermore, the Higgs field itself has unique properties that may have allowed it to play a central role in the evolution of the Universe, from inflation to cosmological phase transitions and the origin of both baryonic and dark matter, and possibly to determine its ultimate fate through the electroweak vacuum instability. These connections between particle physics and cosmology have given rise to a new and growing field of Higgs cosmology, which promises to shed new light on some of the most puzzling questions about the Universe as new data from particle physics experiments and cosmological observations become available. This article is part of the Theo Murphy meeting issue `Higgs cosmology'.

Retrieving cosmological signal using cosmic flows

NASA Astrophysics Data System (ADS)

Bouillot, V.; Alimi, J.-M.

2011-12-01

To understand the origin of the anomalously high bulk flow at large scales, we use very large simulations in various cosmological models. To disentangle between cosmological and environmental effects, we select samples with bulk flow profiles similar to the observational data Watkins et al. (2009) which exhibit a maximum in the bulk flow at 53 h^{-1} Mpc. The estimation of the cosmological parameters Ω_M and σ_8, done on those samples, is correct from the rms mass fluctuation whereas this estimation gives completely false values when done on bulk flow measurements, hence showing a dependance of velocity fields on larger scales. By drawing a clear link between velocity fields at 53 h^{-1} Mpc and asymmetric patterns of the density field at 85 h^{-1} Mpc, we show that the bulk flow can depend largely on the environment. The retrieving of the cosmological signal is achieved by studying the convergence of the bulk flow towards the linear prediction at very large scale (˜ 150 h^{-1} Mpc).

Curvature constraints from the causal entropic principle

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bozek, Brandon; Albrecht, Andreas; Phillips, Daniel

2009-07-15

Current cosmological observations indicate a preference for a cosmological constant that is drastically smaller than what can be explained by conventional particle physics. The causal entropic principle (Bousso et al.) provides an alternative approach to anthropic attempts to predict our observed value of the cosmological constant by calculating the entropy created within a causal diamond. We have extended this work to use the causal entropic principle to predict the preferred curvature within the 'multiverse'. We have found that values larger than {rho}{sub k}=40{rho}{sub m} are disfavored by more than 99.99% peak value at {rho}{sub {lambda}}=7.9x10{sup -123} and {rho}{sub k}=4.3{rho}{sub m}more » for open universes. For universes that allow only positive curvature or both positive and negative curvature, we find a correlation between curvature and dark energy that leads to an extended region of preferred values. Our universe is found to be disfavored to an extent depending on the priors on curvature. We also provide a comparison to previous anthropic constraints on open universes and discuss future directions for this work.« less

Systematic Biases in Weak Lensing Cosmology with the Dark Energy Survey

DOE Office of Scientific and Technical Information (OSTI.GOV)

Samuroff, Simon

cosmo logical impact to be subdominant to statistical error at the! current level of precision. Another major uncertainity in shear cosmology is the accuracy of our ensemble redshift distributions. Chapter 5 presents a numerical investigation into the combined constraining power of cosmic shear, galaxy clustering and their cross-correlation in DES Y1, and the potential for internal calibration of redshift errors. Introducing a moderate uniform bias into the redshift distributions used to model the weak lensing (WL) galaxies is shown to produce a $$> 2\\sigma$$ bias in $$S_8$$. We demonstrate that this cosmological bias can be eliminated by marginalising over redshift error nuisance parameters. Strikingly, the cosmological constraint of the combined dataset is largely undiminished by the loss of prior information on the WL distributions. We demonstrate that this implicit self-calibration is the result of complementary degeneracy directions in the combined data. In Chapter 6 we present the preliminary results of an investigation into galaxy intrin sic alignments. Using the DES Y1 data, we show a clear dependence in alignment amplitude on galaxy type, in agreement with previous results. We subject these findings to a series of initial robustness tests. We conclude with a short overview of the work presented, and discuss prospects for the future.« less

The Dirac-Milne cosmology

NASA Astrophysics Data System (ADS)

Benoit-Lévy, Aurélien; Chardin, Gabriel

2014-05-01

We study an unconventional cosmology, in which we investigate the consequences that antigravity would pose to cosmology. We present the main characteristics of the Dirac-Milne Universe, a cosmological model where antimatter has a negative active gravitational mass. In this non-standard Universe, separate domains of matter and antimatter coexist at our epoch without annihilation, separated by a gravitationally induced depletion zone. We show that this cosmology does not require a priori the Dark Matter and Dark Energy components of the standard model of cosmology. Additionally, inflation becomes an unnecessary ingredient. Investigating this model, we show that the classical cosmological tests such as primordial nucleosynthesis, Type Ia supernovæ and Cosmic Microwave Background are surprisingly concordant.

BOOK REVIEW: Observational Cosmology Observational Cosmology

NASA Astrophysics Data System (ADS)

Howell, Dale Andrew

2013-04-01

Observational Cosmology by Stephen Serjeant fills a niche that was underserved in the textbook market: an up-to-date, thorough cosmology textbook focused on observations, aimed at advanced undergraduates. Not everything about the book is perfect - some subjects get short shrift, in some cases jargon dominates, and there are too few exercises. Still, on the whole, the book is a welcome addition. For decades, the classic textbooks of cosmology have focused on theory. But for every Sunyaev-Zel'dovich effect there is a Butcher-Oemler effect; there are as many cosmological phenomena established by observations, and only explained later by theory, as there were predicted by theory and confirmed by observations. In fact, in the last decade, there has been an explosion of new cosmological findings driven by observations. Some are so new that you won't find them mentioned in books just a few years old. So it is not just refreshing to see a book that reflects the new realities of cosmology, it is vital, if students are to truly stay up on a field that has widened in scope considerably. Observational Cosmology is filled with full-color images, and graphs from the latest experiments. How exciting it is that we live in an era where satellites and large experiments have gathered so much data to reveal astounding details about the origin of the universe and its evolution. To have all the latest data gathered together and explained in one book will be a revelation to students. In fact, at times it was to me. I've picked up modern cosmological knowledge through a patchwork of reading papers, going to colloquia, and serving on grant and telescope allocation panels. To go back and see them explained from square one, and summarized succinctly, filled in quite a few gaps in my own knowledge and corrected a few misconceptions I'd acquired along the way. To make room for all these graphs and observational details, a few things had to be left out. For one, there are few derivations

Hamiltonian General Relativity in Finite Space and Cosmological Potential Perturbations

NASA Astrophysics Data System (ADS)

Barbashov, B. M.; Pervushin, V. N.; Zakharov, A. F.; Zinchuk, V. A.

The Hamiltonian formulation of general relativity is considered in finite space-time and a specific reference frame given by the diffeo-invariant components of the Fock simplex in terms of the Dirac-ADM variables. The evolution parameter and energy invariant with respect to the time-coordinate transformations are constructed by the separation of the cosmological scale factor a(x0) and its identification with the spatial averaging of the metric determinant, so that the dimension of the kinemetric group of diffeomorphisms coincides with the dimension of a set of variables whose velocities are removed by the Gauss-type constraints in accordance with the second Nöther theorem. This coincidence allows us to solve the energy constraint, fulfil Dirac's Hamiltonian reduction, and to describe the potential perturbations in terms of the Lichnerowicz scale-invariant variables distinguished by the absence of the time derivatives of the spatial metric determinant. It was shown that the Hamiltonian version of the cosmological perturbation theory acquires attributes of the theory of superfluid liquid, and it leads to a generalization of the Schwarzschild solution. The astrophysical application of this approach to general relativity is considered under supposition that the Dirac-ADM Hamiltonian frame is identified with that of the Cosmic Microwave Background radiation distinguished by its dipole component in the frame of an Earth observer.

Higgs cosmology.

PubMed

Rajantie, Arttu

2018-03-06

The discovery of the Higgs boson in 2012 and other results from the Large Hadron Collider have confirmed the standard model of particle physics as the correct theory of elementary particles and their interactions up to energies of several TeV. Remarkably, the theory may even remain valid all the way to the Planck scale of quantum gravity, and therefore it provides a solid theoretical basis for describing the early Universe. Furthermore, the Higgs field itself has unique properties that may have allowed it to play a central role in the evolution of the Universe, from inflation to cosmological phase transitions and the origin of both baryonic and dark matter, and possibly to determine its ultimate fate through the electroweak vacuum instability. These connections between particle physics and cosmology have given rise to a new and growing field of Higgs cosmology, which promises to shed new light on some of the most puzzling questions about the Universe as new data from particle physics experiments and cosmological observations become available.This article is part of the Theo Murphy meeting issue 'Higgs cosmology'. © 2018 The Author(s).

Kurtosis, skewness, and non-Gaussian cosmological density perturbations

NASA Technical Reports Server (NTRS)

Luo, Xiaochun; Schramm, David N.

1993-01-01

Cosmological topological defects as well as some nonstandard inflation models can give rise to non-Gaussian density perturbations. Skewness and kurtosis are the third and fourth moments that measure the deviation of a distribution from a Gaussian. Measurement of these moments for the cosmological density field and for the microwave background temperature anisotropy can provide a test of the Gaussian nature of the primordial fluctuation spectrum. In the case of the density field, the importance of measuring the kurtosis is stressed since it will be preserved through the weakly nonlinear gravitational evolution epoch. Current constraints on skewness and kurtosis of primeval perturbations are obtained from the observed density contrast on small scales and from recent COBE observations of temperature anisotropies on large scales. It is also shown how, in principle, future microwave anisotropy experiments might be able to reveal the initial skewness and kurtosis. It is shown that present data argue that if the initial spectrum is adiabatic, then it is probably Gaussian, but non-Gaussian isocurvature fluctuations are still allowed, and these are what topological defects provide.

From Planck Data to Planck Era: Observational Tests of Holographic Cosmology

NASA Astrophysics Data System (ADS)

Afshordi, Niayesh; Corianò, Claudio; Delle Rose, Luigi; Gould, Elizabeth; Skenderis, Kostas

2017-01-01

We test a class of holographic models for the very early Universe against cosmological observations and find that they are competitive to the standard cold dark matter model with a cosmological constant (Λ CDM ) of cosmology. These models are based on three-dimensional perturbative superrenormalizable quantum field theory (QFT), and, while they predict a different power spectrum from the standard power law used in Λ CDM , they still provide an excellent fit to the data (within their regime of validity). By comparing the Bayesian evidence for the models, we find that Λ CDM does a better job globally, while the holographic models provide a (marginally) better fit to the data without very low multipoles (i.e., l ≲30 ), where the QFT becomes nonperturbative. Observations can be used to exclude some QFT models, while we also find models satisfying all phenomenological constraints: The data rule out the dual theory being a Yang-Mills theory coupled to fermions only but allow for a Yang-Mills theory coupled to nonminimal scalars with quartic interactions. Lattice simulations of 3D QFTs can provide nonperturbative predictions for large-angle statistics of the cosmic microwave background and potentially explain its apparent anomalies.

From Planck Data to Planck Era: Observational Tests of Holographic Cosmology.

PubMed

Afshordi, Niayesh; Corianò, Claudio; Delle Rose, Luigi; Gould, Elizabeth; Skenderis, Kostas

2017-01-27

We test a class of holographic models for the very early Universe against cosmological observations and find that they are competitive to the standard cold dark matter model with a cosmological constant (ΛCDM) of cosmology. These models are based on three-dimensional perturbative superrenormalizable quantum field theory (QFT), and, while they predict a different power spectrum from the standard power law used in ΛCDM, they still provide an excellent fit to the data (within their regime of validity). By comparing the Bayesian evidence for the models, we find that ΛCDM does a better job globally, while the holographic models provide a (marginally) better fit to the data without very low multipoles (i.e., l≲30), where the QFT becomes nonperturbative. Observations can be used to exclude some QFT models, while we also find models satisfying all phenomenological constraints: The data rule out the dual theory being a Yang-Mills theory coupled to fermions only but allow for a Yang-Mills theory coupled to nonminimal scalars with quartic interactions. Lattice simulations of 3D QFTs can provide nonperturbative predictions for large-angle statistics of the cosmic microwave background and potentially explain its apparent anomalies.

Cosmological evolution as squeezing: a toy model for group field cosmology

NASA Astrophysics Data System (ADS)

Adjei, Eugene; Gielen, Steffen; Wieland, Wolfgang

2018-05-01

We present a simple model of quantum cosmology based on the group field theory (GFT) approach to quantum gravity. The model is formulated on a subspace of the GFT Fock space for the quanta of geometry, with a fixed volume per quantum. In this Hilbert space, cosmological expansion corresponds to the generation of new quanta. Our main insight is that the evolution of a flat Friedmann–Lemaître–Robertson–Walker universe with a massless scalar field can be described on this Hilbert space as squeezing, familiar from quantum optics. As in GFT cosmology, we find that the three-volume satisfies an effective Friedmann equation similar to the one of loop quantum cosmology, connecting the classical contracting and expanding solutions by a quantum bounce. The only free parameter in the model is identified with Newton’s constant. We also comment on the possible topological interpretation of our squeezed states. This paper can serve as an introduction into the main ideas of GFT cosmology without requiring the full GFT formalism; our results can also motivate new developments in GFT and its cosmological application.

Probing the standard model and beyond with CP violation and particle cosmology

NASA Astrophysics Data System (ADS)

Savastio, Michael Paul

We discuss topics related to CP violation and particle cosmology. First, we present some developments in improving the extraction of the CP violating parameter gamma from the decay B+/- → DK+/- followed by the subsequent decay D → KS pi +pi--. The mixing of the final state kaon is an additional CP violating effect which should be taken into account in the extraction of gamma, and we discuss how this should be done. We also discuss the optimization of phase space binning needed to extract gamma from these decays in a model independent way. Next, we discuss some cosmological constraints on R-parity violating, Minimally Flavor Violating (MFV) Supersymmetry (SUSY). Finally, we show that oribtally excited dark matter cannot persist over cosmic timescales for various model independent reasons.

Constraining f(R) gravity in solar system, cosmology and binary pulsar systems

NASA Astrophysics Data System (ADS)

Liu, Tan; Zhang, Xing; Zhao, Wen

2018-02-01

The f (R) gravity can be cast into the form of a scalar-tensor theory, and scalar degree of freedom can be suppressed in high-density regions by the chameleon mechanism. In this article, for the general f (R) gravity, using a scalar-tensor representation with the chameleon mechanism, we calculate the parametrized post-Newtonian parameters γ and β, the effective gravitational constant Geff, and the effective cosmological constant Λeff. In addition, for the general f (R) gravity, we also calculate the rate of orbital period decay of the binary system due to gravitational radiation. Then we apply these results to specific f (R) models (Hu-Sawicki model, Tsujikawa model and Starobinsky model) and derive the constraints on the model parameters by combining the observations in solar system, cosmological scales and the binary systems.

Nonminimal quartic inflation in classically conformal U(1 ) X extended standard model

NASA Astrophysics Data System (ADS)

Oda, Satsuki; Okada, Nobuchika; Raut, Digesh; Takahashi, Dai-suke

2018-03-01

We propose quartic inflation with nonminimal gravitational coupling in the context of the classically conformal U(1 ) X extension of the standard model (SM). In this model, the U(1 ) X gauge symmetry is radiatively broken through the Coleman-Weinberg mechanism, by which the U(1 ) X gauge boson (Z' boson) and the right-handed Majorana neutrinos acquire their masses. We consider their masses in the range of O (10 GeV )-O (10 TeV ) , which are accessible to high-energy collider experiments. The radiative U(1 ) X gauge symmetry breaking also generates a negative mass squared for the SM Higgs doublet, and the electroweak symmetry breaking occurs subsequently. We identify the U(1 ) X Higgs field with inflaton and calculate the inflationary predictions. Because of the Coleman-Weinberg mechanism, the inflaton quartic coupling during inflation, which determines the inflationary predictions, is correlated to the U(1 ) X gauge coupling. With this correlation, we investigate complementarities between the inflationary predictions and the current constraint from the Z' boson resonance search at the LHC Run 2 as well as the prospect of the search for the Z' boson and the right-handed neutrinos at the future collider experiments.

Revisiting the decoupling effects in the running of the Cosmological Constant

NASA Astrophysics Data System (ADS)

Antipin, Oleg; Melić, Blaženka

2017-09-01

We revisit the decoupling effects associated with heavy particles in the renormalization group running of the vacuum energy in a mass-dependent renormalization scheme. We find the running of the vacuum energy stemming from the Higgs condensate in the entire energy range and show that it behaves as expected from the simple dimensional arguments meaning that it exhibits the quadratic sensitivity to the mass of the heavy particles in the infrared regime. The consequence of such a running to the fine-tuning problem with the measured value of the Cosmological Constant is analyzed and the constraint on the mass spectrum of a given model is derived. We show that in the Standard Model (SM) this fine-tuning constraint is not satisfied while in the massless theories this constraint formally coincides with the well known Veltman condition. We also provide a remarkably simple extension of the SM where saturation of this constraint enables us to predict the radiative Higgs mass correctly. Generalization to constant curvature spaces is also given.

Constraints on the composite photon theory

NASA Astrophysics Data System (ADS)

Low, Lerh Feng

2016-10-01

In a 2015 paper [W. A. Perkins, Mod. Phys. Lett. A 30, 1550157 (2015)], Perkins argued that based on the composite photon theory (CPT), antiphotons should not interact with ordinary matter. This implies that antiphotons are undetectable by detectors made of ordinary matter, and hence that antimatter galaxies are a possible candidate for dark matter. The purpose of this short letter is to argue that this conclusion is highly unlikely, because of cosmological constraints on the density of radiation, the distribution of dark matter and C-symmetry.

Progress Report to the U.S. Department of Energy, Grant DE-FG02-91ER40626: Neutrino Physics, Particle Theory and Cosmology

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shafi, Qaisar; Barr, Stephen M; Gaisser, Thomas K

2009-07-30

Research conducted under this grant over the past year has been driven by the impending operation of the Large Hadron Collider (LHC), and by the ongoing developments in neutrino physics and cosmology. The recent launch of the Planck satellite should have far reaching implications for cosmology in the coming years. Research topics include particle astrophysics, neutrino physics, grand unified theories, Higgs and sparticle spectroscopy, dark energy and dark matter, inflationary cosmology, and baryo/lepto-genesis. Faculty members on the grant are Stephen Barr, Thomas Gaisser, Qaisar Shafi and Todor Stanev. Ilia Gogoladze and Hasan Yuksel are the two postdoctoral scientists supported bymore » the DOE grant. There are currently several excellent students in our research program. One of them, Mansoor Rehman, has been awarded a competitive university fellowship on which he will be supported from September 1, 2009 – June 30, 2010. Another student, Joshua Wickman, has been awarded a fellowship by the Delaware Space Grant Consortium (in affiliation with NASA), and will be supported by this fellowship from September 1, 2009 – August 31, 2010. Both of these students also attended the TASI Summer School in June 2009, at which they each presented a student talk on topics in inflationary cosmology.« less

Supersymmetric solutions of the cosmological, gauged, ℂ magic model

NASA Astrophysics Data System (ADS)

Chimento, Samuele; Ortín, Tomás; Ruipérez, Alejandro

2018-05-01

We construct supersymmetric solutions of theories of gauged N = 1 , d = 5 supergravity coupled to vector multiplets with a U(1)R Abelian (Fayet-Iliopoulos) gauging and an independent SU(2) gauging associated to an SU(2) isometry group of the Real Special scalar manifold. These theories provide minimal supersymmetrizations of 5-dimensional SU(2) Einstein-Yang-Mills theories with negative cosmological constant. We consider a minimal model with these gauge groups and the "magic model" based on the Jordan algebra J 3 ℂ with gauge group SU(3) × U(1)R, which is a consistent truncation of maximal SO(6)-gauged supergravity in d = 5 and whose solutions can be embedded in Type IIB Superstring Theory. We find several solutions containing selfdual SU(2) instantons, some of which asymptote to AdS5 and some of which are very small, supersymmetric, deformations of AdS5. We also show how some of those solutions can be embedded in Romans' SU(2) × U(1)-gauged half-maximal supergravity, which was obtained by Lu, Pope and Tran by compactification of the Type IIB Superstring effective action. This provides another way of uplifting those solutions to 10 dimensions.

The Abacus Cosmos: A Suite of Cosmological N-body Simulations

NASA Astrophysics Data System (ADS)

Garrison, Lehman H.; Eisenstein, Daniel J.; Ferrer, Douglas; Tinker, Jeremy L.; Pinto, Philip A.; Weinberg, David H.

2018-06-01

We present a public data release of halo catalogs from a suite of 125 cosmological N-body simulations from the ABACUS project. The simulations span 40 wCDM cosmologies centered on the Planck 2015 cosmology at two mass resolutions, 4 × 1010 h ‑1 M ⊙ and 1 × 1010 h ‑1 M ⊙, in 1.1 h ‑1 Gpc and 720 h ‑1 Mpc boxes, respectively. The boxes are phase-matched to suppress sample variance and isolate cosmology dependence. Additional volume is available via 16 boxes of fixed cosmology and varied phase; a few boxes of single-parameter excursions from Planck 2015 are also provided. Catalogs spanning z = 1.5 to 0.1 are available for friends-of-friends and ROCKSTAR halo finders and include particle subsamples. All data products are available at https://lgarrison.github.io/AbacusCosmos.

The cosmological principle is not in the sky

NASA Astrophysics Data System (ADS)

Park, Chan-Gyung; Hyun, Hwasu; Noh, Hyerim; Hwang, Jai-chan

2017-08-01

The homogeneity of matter distribution at large scales, known as the cosmological principle, is a central assumption in the standard cosmological model. The case is testable though, thus no longer needs to be a principle. Here we perform a test for spatial homogeneity using the Sloan Digital Sky Survey Luminous Red Galaxies (LRG) sample by counting galaxies within a specified volume with the radius scale varying up to 300 h-1 Mpc. We directly confront the large-scale structure data with the definition of spatial homogeneity by comparing the averages and dispersions of galaxy number counts with allowed ranges of the random distribution with homogeneity. The LRG sample shows significantly larger dispersions of number counts than the random catalogues up to 300 h-1 Mpc scale, and even the average is located far outside the range allowed in the random distribution; the deviations are statistically impossible to be realized in the random distribution. This implies that the cosmological principle does not hold even at such large scales. The same analysis of mock galaxies derived from the N-body simulation, however, suggests that the LRG sample is consistent with the current paradigm of cosmology, thus the simulation is also not homogeneous in that scale. We conclude that the cosmological principle is neither in the observed sky nor demanded to be there by the standard cosmological world model. This reveals the nature of the cosmological principle adopted in the modern cosmology paradigm, and opens a new field of research in theoretical cosmology.

BMS in cosmology

NASA Astrophysics Data System (ADS)

Kehagias, A.; Riotto, A.

2016-05-01

Symmetries play an interesting role in cosmology. They are useful in characterizing the cosmological perturbations generated during inflation and lead to consistency relations involving the soft limit of the statistical correlators of large-scale structure dark matter and galaxies overdensities. On the other hand, in observational cosmology the carriers of the information about these large-scale statistical distributions are light rays traveling on null geodesics. Motivated by this simple consideration, we study the structure of null infinity and the associated BMS symmetry in a cosmological setting. For decelerating Friedmann-Robertson-Walker backgrounds, for which future null infinity exists, we find that the BMS transformations which leaves the asymptotic metric invariant to leading order. Contrary to the asymptotic flat case, the BMS transformations in cosmology generate Goldstone modes corresponding to scalar, vector and tensor degrees of freedom which may exist at null infinity and perturb the asymptotic data. Therefore, BMS transformations generate physically inequivalent vacua as they populate the universe at null infinity with these physical degrees of freedom. We also discuss the gravitational memory effect when cosmological expansion is taken into account. In this case, there are extra contribution to the gravitational memory due to the tail of the retarded Green functions which are supported not only on the light-cone, but also in its interior. The gravitational memory effect can be understood also from an asymptotic point of view as a transition among cosmological BMS-related vacua.

BMS in cosmology

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kehagias, A.; Riotto, A.; Center for Astroparticle Physics

Symmetries play an interesting role in cosmology. They are useful in characterizing the cosmological perturbations generated during inflation and lead to consistency relations involving the soft limit of the statistical correlators of large-scale structure dark matter and galaxies overdensities. On the other hand, in observational cosmology the carriers of the information about these large-scale statistical distributions are light rays traveling on null geodesics. Motivated by this simple consideration, we study the structure of null infinity and the associated BMS symmetry in a cosmological setting. For decelerating Friedmann-Robertson-Walker backgrounds, for which future null infinity exists, we find that the BMS transformationsmore » which leaves the asymptotic metric invariant to leading order. Contrary to the asymptotic flat case, the BMS transformations in cosmology generate Goldstone modes corresponding to scalar, vector and tensor degrees of freedom which may exist at null infinity and perturb the asymptotic data. Therefore, BMS transformations generate physically inequivalent vacua as they populate the universe at null infinity with these physical degrees of freedom. We also discuss the gravitational memory effect when cosmological expansion is taken into account. In this case, there are extra contribution to the gravitational memory due to the tail of the retarded Green functions which are supported not only on the light-cone, but also in its interior. The gravitational memory effect can be understood also from an asymptotic point of view as a transition among cosmological BMS-related vacua.« less

X-Ray Constraints on the Warm-Hot Intergalactic Medium

NASA Technical Reports Server (NTRS)

Kuntz, K. D.; Snowden, S. I.; Mushotzky, R. F.; White, Nicholas E. (Technical Monitor)

2000-01-01

Three observational constraints can be placed on a warm-hot intergalactic medium (WHIM) using ROSAT Position Sensitive Proportional Counter (PSPC) pointed and survey data, the emission strength, the energy spectrum, and the fluctuation spectrum. The upper limit to the emission strength of the WHIM is 7.5 +/- 1.0 keV/(s*sq cm*sr*keV) in the 3/4 keV band, an unknown portion of which value may be due to our own Galactic halo. The spectral stape of the WHIM emission can be described as thermal emission with logT = 6.42, although the true spectrum is more likely to come from a range of temperatures. The values of emission strength and spectral shape are in reasonable agreement with hydrodynamical cosmological models. The autocorrelation function in the 0.44 keV < E < 1.21 keV band range, w(theta), for the extragalactic soft X-ray background (SXRB) which includes both the WHIM and contributions due to point sources, is approx. < 0.002 for 10 min < 0 < 20 min in the 3/4 keV band. This value is lower than the Croft et al. (2000) cosmological model by a factor of approx. 5, but is still not inconsistent with cosmological models. It is also found that the normalization of the extragalactic power law component of the soft X-ray background spectrum must be 9.5 +/- 0.9 keV/(s*sq cm*sr*keV) to be consistent with the ROSAT All-Sky Survey.

Ultra-compact structure in intermediate-luminosity radio quasars: building a sample of standard cosmological rulers and improving the dark energy constraints up to z 3

NASA Astrophysics Data System (ADS)

Cao, Shuo; Zheng, Xiaogang; Biesiada, Marek; Qi, Jingzhao; Chen, Yun; Zhu, Zong-Hong

2017-09-01

Context. Ultra-compact structure in radio sources (especially in quasars that can be observed up to very high redshifts), with milliarcsecond angular sizes measured by very-long-baseline interferometry (VLBI), is becoming an important astrophysical tool for probing both cosmology and the physical properties of AGN. Aims: We present a newly compiled data set of 120 milliarcsec. compact radio sources representing intermediate-luminosity quasars covering the redshift range 0.46 < z < 2.76 and check the possibility of using these sources as independent cosmological probes. These quasars observed at 2.29 GHz show negligible dependence on redshifts and intrinsic luminosity, and thus represent a fixed comoving-length of standard ruler. Methods: For a cosmological ruler with intrinsic length lm, the angular size-redshift relation can be written as θ(z) = lm/DA(z, where θ(z) is the angular size at redshift z, and DA(z) is the corresponding angular diameter distance. We use a compilation of angular size and redshift data for ultra-compact radio sources from a well-known VLBI survey, and implement a new cosmology-independent technique to calibrate the linear size of this standard ruler, which is also used to test different cosmological models with and without the flat universe assumption. Results: We determine the linear size of this standard ruler as lm = 11.03 ± 0.25 pc, which is the typical radius at which AGN jets become opaque at the observed frequency ν 2 GHz. Our measurement of this linear size is also consistent with the previous and recent radio observations at other different frequencies. In the framework of flat ΛCDM model, we find a high value of the matter density parameter, Ωm = 0.322+0.244-0.141, and a low value of the Hubble constant, H0 = 67.6+7.8-7.4 km s-1 Mpc-1, which is in excellent agreement with the cosmic microwave background (CMB) anisotropy measurements by Planck. We obtain Ωm = 0.309+0.215-0.151, w = -0.970+0.500-1.730 at 68.3% CL for the

A coasting cosmology

NASA Technical Reports Server (NTRS)

Kolb, Edward W.

1989-01-01

A Friedmann-Robertson-Walker cosmology with energy density decreasing in expansion as 1/R-squared, where R is the Robertson-Walker scale factor, is studied. In such a model the universe expands with constant velocity; hence the term coasting cosmology. Observational consequences of such a model include the age of the universe, the luminosity distance-redshift relation (the Hubble diagram), the angular diameter distance-redshift relation, and the galaxy number count as a function of redshift. These observations are used to limit the parameters of the model. Among the interesting consequences of the model are the possibility of an ever-expanding closed universe, a model universe with multiple images at different redshifts of the same object, a universe with Omega - 1 not equal to 0 stable in expansion, and a closed universe with radius smaller than 1/H(0).

Philosophical Roots of Cosmology

NASA Astrophysics Data System (ADS)

Ivanovic, M.

2008-10-01

We shall consider the philosophical roots of cosmology in the earlier Greek philosophy. Our goal is to answer the question: Are earlier Greek theories of pure philosophical-mythological character, as often philosophers cited it, or they have scientific character. On the bases of methodological criteria, we shall contend that the latter is the case. In order to answer the question about contemporary situation of the relation philosophy-cosmology, we shall consider the next question: Is contemporary cosmology completely independent of philosophical conjectures? The answer demands consideration of methodological character about scientific status of contemporary cosmology. We also consider some aspects of the relation contemporary philosophy-cosmology.

On Rosen's theory of gravity and cosmology

NASA Technical Reports Server (NTRS)

Barnes, R. C.

1980-01-01

Formal similarities between general relativity and Rosen's bimetric theory of gravity were used to analyze various bimetric cosmologies. The following results were found: (1) physically plausible model universes which have a flat static background metric, have a Robertson-Walker fundamental metric, and which allow co-moving coordinates do not exist in bimetric cosmology. (2) it is difficult to use the Robertson-Walker metric for both the background metric (gamma mu nu) and the fundamental metric tensor of Riemannian geometry( g mu nu) and require that g mu nu and gamma mu nu have different time dependences. (3) A consistency relation for using co-moving coordinates in bimetric cosmology was derived. (4) Certain spatially flat bimetric cosmologies of Babala were tested for the presence of particle horizons. (5) An analytic solution for Rosen's k = +1 model was found. (6) Rosen's singularity free k = +1 model arises from what appears to be an arbitary choice for the time dependent part of gamma mu nu.

Did I Say Cosmology? On Modern Cosmologies and Ancient World-views

NASA Astrophysics Data System (ADS)

Iwaniszewski, S.

2009-08-01

The modern cosmology that emerged from observational astronomy in 16th century Europe meant a radical break-away from earlier conceptions of the world. While all ancient and nonwestern worldviews usually describe a multidimensional reality in which diverse environmental, economic, sociopolitical and ideological factors intersect, modern cosmologies espouse the vision of a radically different universe which is completely dehumanized, ethically indifferent and universally valid. Despite these differences cosmology and worldview tend to be used interchangeably to depict ancient and nonwestern worldviews.Any correspondences which can be found between different parts of ancient and/or nonwestern worldviews and modern cosmologies tend to transfer modern conceptions to the premodern world. Ignoring ancient cultural contexts, we risk imposing modern cosmological concepts on past worldview categories. While we have to describe ancient astronomies in our own terms, our ultimate goal is to understand them on their own terms.

Nine-Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations: Cosmological Parameter Results

NASA Technical Reports Server (NTRS)

Hinshaw, G.; Larson, D.; Komatsu, E.; Spergel, D. N.; Bennett, C. L.; Dunkley, J.; Nolta, M. R.; Halpern, M.; Hill, R. S.; Odegard, N.;

Sterile neutrinos with secret interactions — lasting friendship with cosmology

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chu, Xiaoyong; Dasgupta, Basudeb; Kopp, Joachim

Sterile neutrinos with mass ≃1 eV and order 10% mixing with active neutrinos have been proposed as a solution to anomalies in neutrino oscillation data, but are tightly constrained by cosmological limits. It was recently shown that these constraints are avoided if sterile neutrinos couple to a new MeV-scale gauge boson A{sup ′}. However, even this scenario is restricted by structure formation constraints when A{sup ′}-mediated collisional processes lead to efficient active-to-sterile neutrino conversion after neutrinos have decoupled. In view of this, we reevaluate in this paper the viability of sterile neutrinos with such “secret” interactions. We carefully dissect theirmore » evolution in the early Universe, including the various production channels and the expected modifications to large scale structure formation. We argue that there are two regions in parameter space — one at very small A{sup ′} coupling, one at relatively large A{sup ′} coupling — where all constraints from big bang nucleosynthesis (BBN), cosmic microwave background (CMB), and large scale structure (LSS) data are satisfied. Interestingly, the large A{sup ′} coupling region is precisely the region that was previously shown to have potentially important consequences for the small scale structure of dark matter halos if the A{sup ′} boson couples also to the dark matter in the Universe.« less

The Atacama Cosmology Telescope: two-season ACTPol spectra and parameters

NASA Astrophysics Data System (ADS)

Louis, Thibaut; Grace, Emily; Hasselfield, Matthew; Lungu, Marius; Maurin, Loïc; Addison, Graeme E.; Ade, Peter A. R.; Aiola, Simone; Allison, Rupert; Amiri, Mandana; Angile, Elio; Battaglia, Nicholas; Beall, James A.; de Bernardis, Francesco; Bond, J. Richard; Britton, Joe; Calabrese, Erminia; Cho, Hsiao-mei; Choi, Steve K.; Coughlin, Kevin; Crichton, Devin; Crowley, Kevin; Datta, Rahul; Devlin, Mark J.; Dicker, Simon R.; Dunkley, Joanna; Dünner, Rolando; Ferraro, Simone; Fox, Anna E.; Gallardo, Patricio; Gralla, Megan; Halpern, Mark; Henderson, Shawn; Hill, J. Colin; Hilton, Gene C.; Hilton, Matt; Hincks, Adam D.; Hlozek, Renée; Ho, S. P. Patty; Huang, Zhiqi; Hubmayr, Johannes; Huffenberger, Kevin M.; Hughes, John P.; Infante, Leopoldo; Irwin, Kent; Muya Kasanda, Simon; Klein, Jeff; Koopman, Brian; Kosowsky, Arthur; Li, Dale; Madhavacheril, Mathew; Marriage, Tobias A.; McMahon, Jeff; Menanteau, Felipe; Moodley, Kavilan; Munson, Charles; Naess, Sigurd; Nati, Federico; Newburgh, Laura; Nibarger, John; Niemack, Michael D.; Nolta, Michael R.; Nuñez, Carolina; Page, Lyman A.; Pappas, Christine; Partridge, Bruce; Rojas, Felipe; Schaan, Emmanuel; Schmitt, Benjamin L.; Sehgal, Neelima; Sherwin, Blake D.; Sievers, Jon; Simon, Sara; Spergel, David N.; Staggs, Suzanne T.; Switzer, Eric R.; Thornton, Robert; Trac, Hy; Treu, Jesse; Tucker, Carole; Van Engelen, Alexander; Ward, Jonathan T.; Wollack, Edward J.

2017-06-01

We present the temperature and polarization angular power spectra measured by the Atacama Cosmology Telescope Polarimeter (ACTPol). We analyze night-time data collected during 2013-14 using two detector arrays at 149 GHz, from 548 deg2 of sky on the celestial equator. We use these spectra, and the spectra measured with the MBAC camera on ACT from 2008-10, in combination with planck and wmap data to estimate cosmological parameters from the temperature, polarization, and temperature-polarization cross-correlations. We find the new ACTPol data to be consistent with the ΛCDM model. The ACTPol temperature-polarization cross-spectrum now provides stronger constraints on multiple parameters than the ACTPol temperature spectrum, including the baryon density, the acoustic peak angular scale, and the derived Hubble constant. The new ACTPol data provide information on damping tail parameters. The joint uncertainty on the number of neutrino species and the primordial helium fraction is reduced by 20% when adding ACTPol to Planck temperature data alone.

Observable gravitational waves in pre-big bang cosmology: an update

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gasperini, M., E-mail: gasperini@ba.infn.it

In the light of the recent results concerning CMB observations and GW detection we address the question of whether it is possible, in a self-consistent inflationary framework, to simultaneously generate a spectrum of scalar metric perturbations in agreement with Planck data and a stochastic background of primordial gravitational radiation compatible with the design sensitivity of aLIGO/Virgo and/or eLISA. We suggest that this is possible in a string cosmology context, for a wide region of the parameter space of the so-called pre-big bang models. We also discuss the associated values of the tensor-to-scalar ratio relevant to the CMB polarization experiments. Wemore » conclude that future, cross-correlated results from CMB observations and GW detectors will be able to confirm or disprove pre-big bang models and—in any case—will impose new significant constraints on the basic string theory/cosmology parameters.« less

The Atacama Cosmology Telescope: Two-Season ACTPol Spectra and Parameters

NASA Technical Reports Server (NTRS)

Louis, Thibaut; Grace, Emily; Hasselfield, Matthew; Lungu, Marius; Maurin, Loic; Addison, Graeme E.; Adem Peter A. R.; Aiola, Simone; Allison, Rupert; Amiri, Mandana;

Observational constraints on generalized Proca theories

NASA Astrophysics Data System (ADS)

De Felice, Antonio; Heisenberg, Lavinia; Tsujikawa, Shinji

2017-06-01

In a model of the late-time cosmic acceleration within the framework of generalized Proca theories, there exists a de Sitter attractor preceded by the dark energy equation of state wDE=-1 -s , where s is a positive constant. We run the Markov-chain-Monte Carlo code to confront the model with the observational data of the cosmic microwave background (CMB), baryon acoustic oscillations, supernovae type Ia, and local measurements of the Hubble expansion rate for the background cosmological solutions and obtain the bound s =0.254-0.097+0.118 at 95% confidence level (C.L.). Existence of the additional parameter s to those in the Λ -cold-dark-matter (Λ CDM ) model allows to reduce tensions of the Hubble constant H0 between the CMB and the low-redshift measurements. Including the cosmic growth data of redshift-space distortions in the galaxy power spectrum and taking into account no-ghost and stability conditions of cosmological perturbations, we find that the bound on s is shifted to s =0.1 6-0.08+0.08 (95% C.L.) and hence the model with s >0 is still favored over the Λ CDM model. Apart from the quantities s ,H0 and the today's matter density parameter Ωm 0, the constraints on other model parameters associated with perturbations are less stringent, reflecting the fact that there are different sets of parameters that give rise to a similar cosmic expansion and growth history.

Asymptotic dynamics of the exceptional Bianchi cosmologies

NASA Astrophysics Data System (ADS)

Hewitt, C. G.; Horwood, J. T.; Wainwright, J.

2003-05-01

In this paper we give, for the first time, a qualitative description of the asymptotic dynamics of a class of non-tilted spatially homogeneous (SH) cosmologies, the so-called exceptional Bianchi cosmologies, which are of Bianchi type VI$_{-1/9}$. This class is of interest for two reasons. Firstly, it is generic within the class of non-tilted SH cosmologies, being of the same generality as the models of Bianchi types VIII and IX. Secondly, it is the SH limit of a generic class of spatially inhomogeneous $G_{2}$ cosmologies. Using the orthonormal frame formalism and Hubble-normalized variables, we show that the exceptional Bianchi cosmologies differ from the non-exceptional Bianchi cosmologies of type VI$_{h}$ in two significant ways. Firstly, the models exhibit an oscillatory approach to the initial singularity and hence are not asymptotically self-similar. Secondly, at late times, although the models are asymptotically self-similar, the future attractor for the vacuum-dominated models is the so-called Robinson-Trautman SH model instead of the vacuum SH plane wave models.

Cosmology with gamma-ray bursts. II. Cosmography challenges and cosmological scenarios for the accelerated Universe

NASA Astrophysics Data System (ADS)

Demianski, Marek; Piedipalumbo, Ester; Sawant, Disha; Amati, Lorenzo

2017-02-01

Context. Explaining the accelerated expansion of the Universe is one of the fundamental challenges in physics today. Cosmography provides information about the evolution of the universe derived from measured distances, assuming only that the space time geometry is described by the Friedman-Lemaitre-Robertson-Walker metric, and adopting an approach that effectively uses only Taylor expansions of basic observables. Aims: We perform a high-redshift analysis to constrain the cosmographic expansion up to the fifth order. It is based on the Union2 type Ia supernovae data set, the gamma-ray burst Hubble diagram, a data set of 28 independent measurements of the Hubble parameter, baryon acoustic oscillations measurements from galaxy clustering and the Lyman-α forest in the SDSS-III Baryon Oscillation Spectroscopic Survey (BOSS), and some Gaussian priors on h and ΩM. Methods: We performed a statistical analysis and explored the probability distributions of the cosmographic parameters. By building up their regions of confidence, we maximized our likelihood function using the Markov chain Monte Carlo method. Results: Our high-redshift analysis confirms that the expansion of the Universe currently accelerates; the estimation of the jerk parameter indicates a possible deviation from the standard ΛCDM cosmological model. Moreover, we investigate implications of our results for the reconstruction of the dark energy equation of state (EOS) by comparing the standard technique of cosmography with an alternative approach based on generalized Padé approximations of the same observables. Because these expansions converge better, is possible to improve the constraints on the cosmographic parameters and also on the dark matter EOS. Conclusions: The estimation of the jerk and the DE parameters indicates at 1σ a possible deviation from the ΛCDM cosmological model.

Cosmology and astrophysics from relaxed galaxy clusters - IV: Robustly calibrating hydrostatic masses with weak lensing

DOE Office of Scientific and Technical Information (OSTI.GOV)

Applegate, D. E; Mantz, A.; Allen, S. W.

This is the fourth in a series of papers studying the astrophysics and cosmology of massive, dynamically relaxed galaxy clusters. Here, we use measurements of weak gravitational lensing from the Weighing the Giants project to calibrate Chandra X-ray measurements of total mass that rely on the assumption of hydrostatic equilibrium. This comparison of X-ray and lensing masses measures the combined bias of X-ray hydrostatic masses from both astrophysical and instrumental sources. While we cannot disentangle the two sources of bias, only the combined bias is relevant for calibrating cosmological measurements using relaxed clusters. Assuming a fixed cosmology, and within amore » characteristic radius (r 2500) determined from the X-ray data, we measure a lensing to X-ray mass ratio of 0.96 ± 9% (stat) ± 9% (sys). We find no significant trends of this ratio with mass, redshift or the morphological indicators used to select the sample. Our results imply that any departures from hydrostatic equilibrium at these radii are offset by calibration errors of comparable magnitude, with large departures of tens-of-percent unlikely. In addition, we find a mean concentration of the sample measured from lensing data of c 200 = 3.0 +4.4 –1.8. In conclusion, anticipated short-term improvements in lensing systematics, and a modest expansion of the relaxed lensing sample, can easily increase the measurement precision by 30–50%, leading to similar improvements in cosmological constraints that employ X-ray hydrostatic mass estimates, such as on Ω m from the cluster gas mass fraction.« less

Cosmology and astrophysics from relaxed galaxy clusters - IV. Robustly calibrating hydrostatic masses with weak lensing

NASA Astrophysics Data System (ADS)

Applegate, D. E.; Mantz, A.; Allen, S. W.; von der Linden, A.; Morris, R. Glenn; Hilbert, S.; Kelly, Patrick L.; Burke, D. L.; Ebeling, H.; Rapetti, D. A.; Schmidt, R. W.

2016-04-01

This is the fourth in a series of papers studying the astrophysics and cosmology of massive, dynamically relaxed galaxy clusters. Here, we use measurements of weak gravitational lensing from the Weighing the Giants project to calibrate Chandra X-ray measurements of total mass that rely on the assumption of hydrostatic equilibrium. This comparison of X-ray and lensing masses measures the combined bias of X-ray hydrostatic masses from both astrophysical and instrumental sources. While we cannot disentangle the two sources of bias, only the combined bias is relevant for calibrating cosmological measurements using relaxed clusters. Assuming a fixed cosmology, and within a characteristic radius (r2500) determined from the X-ray data, we measure a lensing to X-ray mass ratio of 0.96 ± 9 per cent (stat) ± 9 per cent (sys). We find no significant trends of this ratio with mass, redshift or the morphological indicators used to select the sample. Our results imply that any departures from hydrostatic equilibrium at these radii are offset by calibration errors of comparable magnitude, with large departures of tens-of-percent unlikely. In addition, we find a mean concentration of the sample measured from lensing data of c_{200} = 3.0_{-1.8}^{+4.4}. Anticipated short-term improvements in lensing systematics, and a modest expansion of the relaxed lensing sample, can easily increase the measurement precision by 30-50 per cent, leading to similar improvements in cosmological constraints that employ X-ray hydrostatic mass estimates, such as on Ωm from the cluster gas mass fraction.

Cosmology and astrophysics from relaxed galaxy clusters - IV: Robustly calibrating hydrostatic masses with weak lensing

DOE PAGES

Applegate, D. E; Mantz, A.; Allen, S. W.; ...

2016-02-04

This is the fourth in a series of papers studying the astrophysics and cosmology of massive, dynamically relaxed galaxy clusters. Here, we use measurements of weak gravitational lensing from the Weighing the Giants project to calibrate Chandra X-ray measurements of total mass that rely on the assumption of hydrostatic equilibrium. This comparison of X-ray and lensing masses measures the combined bias of X-ray hydrostatic masses from both astrophysical and instrumental sources. While we cannot disentangle the two sources of bias, only the combined bias is relevant for calibrating cosmological measurements using relaxed clusters. Assuming a fixed cosmology, and within amore » characteristic radius (r 2500) determined from the X-ray data, we measure a lensing to X-ray mass ratio of 0.96 ± 9% (stat) ± 9% (sys). We find no significant trends of this ratio with mass, redshift or the morphological indicators used to select the sample. Our results imply that any departures from hydrostatic equilibrium at these radii are offset by calibration errors of comparable magnitude, with large departures of tens-of-percent unlikely. In addition, we find a mean concentration of the sample measured from lensing data of c 200 = 3.0 +4.4 –1.8. In conclusion, anticipated short-term improvements in lensing systematics, and a modest expansion of the relaxed lensing sample, can easily increase the measurement precision by 30–50%, leading to similar improvements in cosmological constraints that employ X-ray hydrostatic mass estimates, such as on Ω m from the cluster gas mass fraction.« less

Testable solution of the cosmological constant and coincidence problems

NASA Astrophysics Data System (ADS)

Shaw, Douglas J.; Barrow, John D.

2011-02-01

We present a new solution to the cosmological constant (CC) and coincidence problems in which the observed value of the CC, Λ, is linked to other observable properties of the Universe. This is achieved by promoting the CC from a parameter that must be specified, to a field that can take many possible values. The observed value of Λ≈(9.3Gyrs)-2 [≈10-120 in Planck units] is determined by a new constraint equation which follows from the application of a causally restricted variation principle. When applied to our visible Universe, the model makes a testable prediction for the dimensionless spatial curvature of Ωk0=-0.0056(ζb/0.5), where ζb˜1/2 is a QCD parameter. Requiring that a classical history exist, our model determines the probability of observing a given Λ. The observed CC value, which we successfully predict, is typical within our model even before the effects of anthropic selection are included. When anthropic selection effects are accounted for, we find that the observed coincidence between tΛ=Λ-1/2 and the age of the Universe, tU, is a typical occurrence in our model. In contrast to multiverse explanations of the CC problems, our solution is independent of the choice of a prior weighting of different Λ values and does not rely on anthropic selection effects. Our model includes no unnatural small parameters and does not require the introduction of new dynamical scalar fields or modifications to general relativity, and it can be tested by astronomical observations in the near future.

Testable solution of the cosmological constant and coincidence problems

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shaw, Douglas J.; Barrow, John D.

2011-02-15

We present a new solution to the cosmological constant (CC) and coincidence problems in which the observed value of the CC, {Lambda}, is linked to other observable properties of the Universe. This is achieved by promoting the CC from a parameter that must be specified, to a field that can take many possible values. The observed value of {Lambda}{approx_equal}(9.3 Gyrs){sup -2}[{approx_equal}10{sup -120} in Planck units] is determined by a new constraint equation which follows from the application of a causally restricted variation principle. When applied to our visible Universe, the model makes a testable prediction for the dimensionless spatial curvaturemore » of {Omega}{sub k0}=-0.0056({zeta}{sub b}/0.5), where {zeta}{sub b}{approx}1/2 is a QCD parameter. Requiring that a classical history exist, our model determines the probability of observing a given {Lambda}. The observed CC value, which we successfully predict, is typical within our model even before the effects of anthropic selection are included. When anthropic selection effects are accounted for, we find that the observed coincidence between t{sub {Lambda}={Lambda}}{sup -1/2} and the age of the Universe, t{sub U}, is a typical occurrence in our model. In contrast to multiverse explanations of the CC problems, our solution is independent of the choice of a prior weighting of different {Lambda} values and does not rely on anthropic selection effects. Our model includes no unnatural small parameters and does not require the introduction of new dynamical scalar fields or modifications to general relativity, and it can be tested by astronomical observations in the near future.« less

Smoot Cosmology Group

Science.gov Websites

Links We bring the universe to you! University of California Berkeley Cosmology Group Lawrence Computational Cosmology Center Institute for Nuclear & Particle Astrophysics Supernova Acceleration Probe

Variety of (d + 1) dimensional cosmological evolutions with and without bounce in a class of LQC-inspired models

NASA Astrophysics Data System (ADS)

Rama, S. Kalyana

2017-08-01

The bouncing evolution of an universe in Loop Quantum Cosmology can be described very well by a set of effective equations, involving a function sin x. Recently, we have generalised these effective equations to (d + 1) dimensions and to any function f( x). Depending on f( x) in these models inspired by Loop Quantum Cosmology, a variety of cosmological evolutions are possible, singular as well as non singular. In this paper, we study them in detail. Among other things, we find that the scale factor a(t) ∝ t^{ 2 q/(2 q - 1) (1 + w) d} for f(x) = x^q, and find explicit Kasner-type solutions if w = 2 q - 1 also. A result which we find particularly fascinating is that, for f(x) = √{x}, the evolution is non singular and the scale factor a( t) grows exponentially at a rate set, not by a constant density, but by a quantum parameter related to the area quantum.

Cosmology with the cosmic microwave background temperature-polarization correlation

NASA Astrophysics Data System (ADS)

Couchot, F.; Henrot-Versillé, S.; Perdereau, O.; Plaszczynski, S.; Rouillé d'Orfeuil, B.; Spinelli, M.; Tristram, M.

2017-06-01

We demonstrate that the cosmic microwave background (CMB) temperature-polarization cross-correlation provides accurate and robust constraints on cosmological parameters. We compare them with the results from temperature or polarization and investigate the impact of foregrounds, cosmic variance, and instrumental noise. This analysis makes use of the Planck high-ℓ HiLLiPOP likelihood based on angular power spectra, which takes into account systematics from the instrument and foreground residuals directly modelled using Planck measurements. The temperature-polarization correlation (TE) spectrum is less contaminated by astrophysical emissions than the temperature power spectrum (TT), allowing constraints that are less sensitive to foreground uncertainties to be derived. For ΛCDM parameters, TE gives very competitive results compared to TT. For basic ΛCDM model extensions (such as AL, ∑mν, or Neff), it is still limited by the instrumental noise level in the polarization maps.

Cosmological implications of a large complete quasar sample

PubMed Central

Segal, I. E.; Nicoll, J. F.

1998-01-01

Objective and reproducible determinations of the probabilistic significance levels of the deviations between theoretical cosmological prediction and direct model-independent observation are made for the Large Bright Quasar Sample [Foltz, C., Chaffee, F. H., Hewett, P. C., MacAlpine, G. M., Turnshek, D. A., et al. (1987) Astron. J. 94, 1423–1460]. The Expanding Universe model as represented by the Friedman–Lemaitre cosmology with parameters qo = 0, Λ = 0 denoted as C1 and chronometric cosmology (no relevant adjustable parameters) denoted as C2 are the cosmologies considered. The mean and the dispersion of the apparent magnitudes and the slope of the apparent magnitude–redshift relation are the directly observed statistics predicted. The C1 predictions of these cosmology-independent quantities are deviant by as much as 11σ from direct observation; none of the C2 predictions deviate by >2σ. The C1 deviations may be reconciled with theory by the hypothesis of quasar “evolution,” which, however, appears incapable of being substantiated through direct observation. The excellent quantitative agreement of the C1 deviations with those predicted by C2 without adjustable parameters for the results of analysis predicated on C1 indicates that the evolution hypothesis may well be a theoretical artifact. PMID:9560182

Cosmological implications of a large complete quasar sample.

PubMed

Segal, I E; Nicoll, J F

1998-04-28

Objective and reproducible determinations of the probabilistic significance levels of the deviations between theoretical cosmological prediction and direct model-independent observation are made for the Large Bright Quasar Sample [Foltz, C., Chaffee, F. H., Hewett, P. C., MacAlpine, G. M., Turnshek, D. A., et al. (1987) Astron. J. 94, 1423-1460]. The Expanding Universe model as represented by the Friedman-Lemaitre cosmology with parameters qo = 0, Lambda = 0 denoted as C1 and chronometric cosmology (no relevant adjustable parameters) denoted as C2 are the cosmologies considered. The mean and the dispersion of the apparent magnitudes and the slope of the apparent magnitude-redshift relation are the directly observed statistics predicted. The C1 predictions of these cosmology-independent quantities are deviant by as much as 11sigma from direct observation; none of the C2 predictions deviate by >2sigma. The C1 deviations may be reconciled with theory by the hypothesis of quasar "evolution," which, however, appears incapable of being substantiated through direct observation. The excellent quantitative agreement of the C1 deviations with those predicted by C2 without adjustable parameters for the results of analysis predicated on C1 indicates that the evolution hypothesis may well be a theoretical artifact.

Dynamics of the cosmological relaxation after reheating

NASA Astrophysics Data System (ADS)

Choi, Kiwoon; Kim, Hyungjin; Sekiguchi, Toyokazu

2017-04-01

We examine if the cosmological relaxation mechanism, which was proposed recently as a new solution to the hierarchy problem, can be compatible with high reheating temperature well above the weak scale. As the barrier potential disappears at high temperature, the relaxion rolls down further after the reheating, which may ruin the successful implementation of the relaxation mechanism. It is noted that if the relaxion is coupled to a dark gauge boson, the new frictional force arising from dark gauge boson production can efficiently slow down the relaxion motion, which allows the relaxion to be stabilized after the electroweak phase transition for a wide range of model parameters, while satisfying the known observational constraints.

Horava-Lifshitz Theory and Applications to Cosmology and Astrophysics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Anzhong

This final report describes the activities of the Baylor University Gravity, Cosmology and Astroparticle Physics (GCAP) group on the project: Horava-Lifshitz Theory and Applications to Cosmology and Astrophysics, during the time, August 15, 2010 - August 14, 2014. We are grateful for the financial support provided by the U.S. Department of Energy for this research, which leads to our exceptional success. We are very proud to say that we have achieved all the goals set up in our project and made significant contributions to the understanding of the field. In particular, with this DOE support, we have published 38 articlesmore » in the prestigious national/international journals, which have already received about 1000 citations so far.« less

Cosmologically allowed regions for the axion decay constant Fa

NASA Astrophysics Data System (ADS)

Kawasaki, Masahiro; Sonomoto, Eisuke; Yanagida, Tsutomu T.

2018-07-01

If the Peccei-Quinn symmetry is already broken during inflation, the decay constant Fa of the axion can be in a wide region from 1011GeV to 1018GeV for the axion being the dominant dark matter. In this case, however, the axion causes the serious cosmological problem, isocurvature perturbation problem, which severely constrains the Hubble parameter during inflation. The constraint is relaxed when Peccei-Quinn scalar field takes a large value ∼Mp (Planck scale) during inflation. In this letter, we point out that the allowed region of the decay constant Fa is reduced to a rather narrow region for a given tensor-to-scalar ratio r when Peccei-Quinn scalar field takes ∼Mp during inflation. For example, if the ratio r is determined as r ≳10-3 in future measurements, we can predict Fa ≃ (0.1- 1.4) ×1012GeV for domain wall number NDW = 6.

Beyond concordance cosmology with magnification of gravitational-wave standard sirens.

PubMed

Camera, Stefano; Nishizawa, Atsushi

2013-04-12

We show how future gravitational-wave detectors would be able to discriminate between the concordance Λ cold dark matter cosmological model and up-to-date competing alternatives, e.g., dynamical dark energy (DE) models or modified gravity (MG) theories. Our method consists of using the weak-lensing magnification effect that affects a standard-siren signal because of its traveling through the Universe's large scale structure. As a demonstration, we present constraints on DE and MG from proposed gravitational-wave detectors, namely Einstein Telescope and DECI-Hertz Interferometer Gravitational-Wave Observatory and Big-Bang Observer.

Supernova Cosmology Project

Science.gov Websites

, 2014 The Supernova Cosmology Project and High-Z Team share the 2015 Breakthrough Prize in Fundamental Perlmutter, leader of the international Supernova Cosmology Project, and principal investigator of the

Direct detection constraints on dark photon dark matter

NASA Astrophysics Data System (ADS)

An, Haipeng; Pospelov, Maxim; Pradler, Josef; Ritz, Adam

2015-07-01

Dark matter detectors built primarily to probe elastic scattering of WIMPs on nuclei are also precise probes of light, weakly coupled, particles that may be absorbed by the detector material. In this paper, we derive constraints on the minimal model of dark matter comprised of long-lived vector states V (dark photons) in the 0.01- 100 keV mass range. The absence of an ionization signal in direct detection experiments such as XENON10 and XENON100 places a very strong constraint on the dark photon mixing angle, down to O (10-15), assuming that dark photons comprise the dominant fraction of dark matter. This sensitivity to dark photon dark matter exceeds the indirect bounds derived from stellar energy loss considerations over a significant fraction of the available mass range. We also revisit indirect constraints from V → 3 γ decay and show that limits from modifications to the cosmological ionization history are comparable to the updated limits from the diffuse γ-ray flux.

Cosmology and astrophysics from relaxed galaxy clusters - V. Consistency with cold dark matter structure formation

NASA Astrophysics Data System (ADS)

Mantz, A. B.; Allen, S. W.; Morris, R. G.

2016-10-01

This is the fifth in a series of papers studying the astrophysics and cosmology of massive, dynamically relaxed galaxy clusters. Our sample comprises 40 clusters identified as being dynamically relaxed and hot in Papers I and II of this series. Here we use constraints on cluster mass profiles from X-ray data to test some of the basic predictions of cosmological structure formation in the cold dark matter (CDM) paradigm. We present constraints on the concentration-mass relation for massive clusters, finding a power-law mass dependence with a slope of κm = -0.16 ± 0.07, in agreement with CDM predictions. For this relaxed sample, the relation is consistent with a constant as a function of redshift (power-law slope with 1 + z of κζ = -0.17 ± 0.26), with an intrinsic scatter of σln c = 0.16 ± 0.03. We investigate the shape of cluster mass profiles over the radial range probed by the data (typically ˜50 kpc-1 Mpc), and test for departures from the simple Navarro-Frenk-White (NFW) form, for which the logarithmic slope of the density profile tends to -1 at small radii. Specifically, we consider as alternatives the generalized NFW (GNFW) and Einasto parametrizations. For the GNFW model, we find an average value of (minus) the logarithmic inner slope of β = 1.02 ± 0.08, with an intrinsic scatter of σβ = 0.22 ± 0.07, while in the Einasto case we constrain the average shape parameter to be α = 0.29 ± 0.04 with an intrinsic scatter of σα = 0.12 ± 0.04. Our results are thus consistent with the simple NFW model on average, but we clearly detect the presence of intrinsic, cluster-to-cluster scatter about the average.

Building cosmological frozen stars

NASA Astrophysics Data System (ADS)

Kastor, David; Traschen, Jennie

2017-02-01

Janis-Newman-Winicour (JNW) solutions generalize Schwarzschild to include a massless scalar field. While they share the familiar infinite redshift feature of Schwarzschild, they suffer from the presence of naked singularities. Cosmological versions of JNW spacetimes were discovered some years ago, in the most general case, by Fonarev. Fonarev solutions are also plagued by naked singularities, but have the virtue, unlike e.g. Schwarzschild-deSitter, of being dynamical. Given that exact dynamical cosmological black hole solutions are scarce, Fonarev solutions merit further study. We show how Fonarev solutions can be obtained via generalized dimensional reduction from simpler static vacuum solutions. These results may lead towards constructions of actual dynamical cosmological black holes. In particular, we note that cosmological versions of extremal charged dilaton black holes are known. JNW spacetimes represent a different limiting case of the family of charged dilaton black holes, which have been important in the context of string theory, and better understanding their cosmological versions of JNW spacetimes thus provides a second data point towards finding cosmological versions of the entire family.

Cosmological Models and Stability

NASA Astrophysics Data System (ADS)

Andersson, Lars

Principles in the form of heuristic guidelines or generally accepted dogma play an important role in the development of physical theories. In particular, philosophical considerations and principles figure prominently in the work of Albert Einstein. As mentioned in the talk by Jiří Bičák at this conference, Einstein formulated the equivalence principle, an essential step on the road to general relativity, during his time in Prague 1911-1912. In this talk, I would like to discuss some aspects of cosmological models. As cosmology is an area of physics where "principles" such as the "cosmological principle" or the "Copernican principle" play a prominent role in motivating the class of models which form part of the current standard model, I will start by comparing the role of the equivalence principle to that of the principles used in cosmology. I will then briefly describe the standard model of cosmology to give a perspective on some mathematical problems and conjectures on cosmological models, which are discussed in the later part of this paper.

Consistent cosmology with Higgs thermal inflation in a minimal extension of the MSSM

NASA Astrophysics Data System (ADS)

Hindmarsh, Mark; Jones, D. R. Timothy

2013-03-01

We consider a class of supersymmetric inflation models, in which minimal gauged F-term hybrid inflation is coupled renormalisably to the minimal supersymmetric standard model (MSSM), with no extra ingredients; we call this class the ``minimal hybrid inflationary supersymmetric standard model'' (MHISSM). The singlet inflaton couples to the Higgs as well as the waterfall fields, supplying the Higgs μ-term. We show how such models can exit inflation to a vacuum characterised by large Higgs vevs, whose vacuum energy is controlled by supersymmetry-breaking. The true ground state is reached after an intervening period of thermal inflation along the Higgs flat direction, which has important consequences for the cosmology of the F-term inflation scenario. The scalar spectral index is reduced, with a value of approximately 0.976 in the case where the inflaton potential is dominated by the 1-loop radiative corrections. The reheat temperature following thermal inflation is about 109 GeV, which solves the gravitino overclosure problem. A Higgs condensate reduces the cosmic string mass per unit length, rendering it compatible with the Cosmic Microwave Background constraints without tuning the inflaton coupling. With the minimal U(1)' gauge symmetry in the inflation sector, where one of the waterfall fields generates a right-handed neutrino mass, we investigate the Higgs thermal inflation scenario in three popular supersymmetry-breaking schemes: AMSB, GMSB and the CMSSM, focusing on the implications for the gravitino bound. In AMSB enough gravitinos can be produced to account for the observed dark matter abundance through decays into neutralinos. In GMSB we find an upper bound on the gravitino mass of about a TeV, while in the CMSSM the thermally generated gravitinos are sub-dominant. When Big Bang Nucleosynthesis constraints are taken into account, the unstable gravitinos of AMSB and the CMSSM must have a mass O(10) TeV or greater, while in GMSB we find an upper bound on the

On the cosmology of scalar-tensor-vector gravity theory

NASA Astrophysics Data System (ADS)

Jamali, Sara; Roshan, Mahmood; Amendola, Luca

2018-01-01

We consider the cosmological consequences of a special scalar-tensor-vector theory of gravity, known as MOG (for MOdified Gravity), proposed to address the dark matter problem. This theory introduces two scalar fields G(x) and μ(x), and one vector field phiα(x), in addition to the metric tensor. We set the corresponding self-interaction potentials to zero, as in the standard form of MOG. Then using the phase space analysis in the flat Friedmann-Robertson-Walker background, we show that the theory possesses a viable sequence of cosmological epochs with acceptable time dependency for the cosmic scale factor. We also investigate MOG's potential as a dark energy model and show that extra fields in MOG cannot provide a late time accelerated expansion. Furthermore, using a dynamical system approach to solve the non-linear field equations numerically, we calculate the angular size of the sound horizon, i.e. θs, in MOG. We find that 8× 10‑3rad<θs<8.2× 10‑3 rad which is way outside the current observational bounds. Finally, we generalize MOG to a modified form called mMOG, and we find that mMOG passes the sound-horizon constraint. However, mMOG also cannot be considered as a dark energy model unless one adds a cosmological constant, and more importantly, the matter dominated era is still slightly different from the standard case.

Theoretical Astrophysics - Volume 3, Galaxies and Cosmology

NASA Astrophysics Data System (ADS)

Padmanabhan, T.

2002-12-01

1. Overview: galaxies and cosmology; 2. Galactic structure and dynamics; 3. Friedmann model of the universe; 4. Thermal history of the universe; 5. Structure formation; 6. Cosmic microwave background radiation; 7. Formation of baryonic structures; 8. Active galactic nuclei; 9. Intergalactic medium and absorption systems; 10. Cosmological observations.

Testing and selection of cosmological models with (1+z){sup 6} corrections

DOE Office of Scientific and Technical Information (OSTI.GOV)

Szydlowski, Marek; Marc Kac Complex Systems Research Centre, Jagiellonian University, ul. Reymonta 4, 30-059 Cracow; Godlowski, Wlodzimierz

2008-02-15

In the paper we check whether the contribution of (-)(1+z){sup 6} type in the Friedmann equation can be tested. We consider some astronomical tests to constrain the density parameters in such models. We describe different interpretations of such an additional term: geometric effects of loop quantum cosmology, effects of braneworld cosmological models, nonstandard cosmological models in metric-affine gravity, and models with spinning fluid. Kinematical (or geometrical) tests based on null geodesics are insufficient to separate individual matter components when they behave like perfect fluid and scale in the same way. Still, it is possible to measure their overall effect. Wemore » use recent measurements of the coordinate distances from the Fanaroff-Riley type IIb radio galaxy data, supernovae type Ia data, baryon oscillation peak and cosmic microwave background radiation observations to obtain stronger bounds for the contribution of the type considered. We demonstrate that, while {rho}{sup 2} corrections are very small, they can be tested by astronomical observations--at least in principle. Bayesian criteria of model selection (the Bayesian factor, AIC, and BIC) are used to check if additional parameters are detectable in the present epoch. As it turns out, the {lambda}CDM model is favored over the bouncing model driven by loop quantum effects. Or, in other words, the bounds obtained from cosmography are very weak, and from the point of view of the present data this model is indistinguishable from the {lambda}CDM one.« less

Constraining the cosmology of the phantom brane using distance measures

NASA Astrophysics Data System (ADS)

Alam, Ujjaini; Bag, Satadru; Sahni, Varun

2017-01-01

The phantom brane has several important distinctive features: (i) Its equation of state is phantomlike, but there is no future "big rip" singularity, and (ii) the effective cosmological constant on the brane is dynamically screened, because of which the expansion rate is smaller than that in Λ CDM at high redshifts. In this paper, we constrain the Phantom braneworld using distance measures such as type-Ia supernovae (SNeIa), baryon acoustic oscillations (BAO), and the compressed cosmic microwave background (CMB) data. We find that the simplest braneworld models provide a good fit to the data. For instance, BAO +SNeIa data can be accommodated by the braneworld for a large region in parameter space 0 ≤Ωℓ≲0.3 at 1 σ . The Hubble parameter can be as high as H0≲78 km s-1 Mpc-1 , and the effective equation of state at present can show phantomlike behavior with w0≲-1.2 at 1 σ . We note a correlation between H0 and w0, with higher values of H0 leading to a lower, and more phantomlike, value of w0. Inclusion of CMB data provides tighter constraints Ωℓ≲0.1 . (Here Ωℓ encodes the ratio of the five- and four-dimensional Planck mass.) The Hubble parameter in this case is more tightly constrained to H0≲71 km s-1 Mpc-1 , and the effective equation of state to w0≲-1.1 . Interestingly, we find that the Universe is allowed to be closed or open, with -0.5 ≲Ωκ≲0.5 , even on including the compressed CMB data. There appears to be some tension in the low and high-z BAO data which may either be resolved by future data, or act as a pointer to interesting new cosmology.

Search for sterile neutrinos in holographic dark energy cosmology: Reconciling Planck observation with the local measurement of the Hubble constant

NASA Astrophysics Data System (ADS)

Zhao, Ming-Ming; He, Dong-Ze; Zhang, Jing-Fei; Zhang, Xin

2017-08-01

We search for sterile neutrinos in the holographic dark energy cosmology by using the latest observational data. To perform the analysis, we employ the current cosmological observations, including the cosmic microwave background temperature power spectrum data from the Planck mission, the baryon acoustic oscillation measurements, the type Ia supernova data, the redshift space distortion measurements, the shear data of weak lensing observation, the Planck lensing measurement, and the latest direct measurement of H0 as well. We show that, compared to the Λ CDM cosmology, the holographic dark energy cosmology with sterile neutrinos can relieve the tension between the Planck observation and the direct measurement of H0 much better. Once we include the H0 measurement in the global fit, we find that the hint of the existence of sterile neutrinos in the holographic dark energy cosmology can be given. Under the constraint of the all-data combination, we obtain Neff=3.76 ±0.26 and mν,sterile eff<0.215 eV , indicating that the detection of Δ Neff>0 in the holographic dark energy cosmology is at the 2.75 σ level and the massless or very light sterile neutrino is favored by the current observations.

Cosmological parameter extraction and biases from type Ia supernova magnitude evolution

NASA Astrophysics Data System (ADS)

Linden, S.; Virey, J.-M.; Tilquin, A.

2009-11-01

We study different one-parametric models of type Ia supernova magnitude evolution on cosmic time scales. Constraints on cosmological and supernova evolution parameters are obtained by combined fits on the actual data coming from supernovae, the cosmic microwave background, and baryonic acoustic oscillations. We find that the best-fit values imply supernova magnitude evolution such that high-redshift supernovae appear some percent brighter than would be expected in a standard cosmos with a dark energy component. However, the errors on the evolution parameters are of the same order, and data are consistent with nonevolving magnitudes at the 1σ level, except for special cases. We simulate a future data scenario where SN magnitude evolution is allowed for, and neglect the possibility of such an evolution in the fit. We find the fiducial models for which the wrong model assumption of nonevolving SN magnitude is not detectable, and for which biases on the fitted cosmological parameters are introduced at the same time. Of the cosmological parameters, the overall mass density ΩM has the strongest chances to be biased due to the wrong model assumption. Whereas early-epoch models with a magnitude offset Δ m˜ z2 show up to be not too dangerous when neglected in the fitting procedure, late epoch models with Δ m˜√{z} have high chances of undetectably biasing the fit results. Centre de Physique Théorique is UMR 6207 - “Unité Mixte de Recherche” of CNRS and of the Universities “de Provence”, “de la Mediterranée”, and “du Sud Toulon-Var” - Laboratory affiliated with FRUMAM (FR2291).

Anomalous Galactic Dynamics by Collusion of Rindler and Cosmological Horizons

NASA Astrophysics Data System (ADS)

van Putten, Maurice H. P. M.

2017-03-01

In holography, the dimensional reduction of phase space to two dimensions defines a dynamical dark energy of {{Λ }}=(1-q){H}2, associated with the cosmological horizon at a Hubble radius of {R}H=c/H, and inertia m of baryonic matter at acceleration α in terms of a thermodynamic potential U={{mc}}2 of Rindler horizons at ξ ={c}2/α . Here, H is the Hubble parameter with deceleration q and c is the velocity of light. In weak gravity, m drops below Newton’s value m 0 as α < {a}H, when Rindler horizons fall beyond the cosmological horizon. The onset to weak gravity across α ={a}H is sharp by causality. Striking evidence is found in galaxy rotation curves, whose asymptotic dynamics is parameterized by Milgrom’s scale of acceleration {a}0=({cH}/2π )\\sqrt{1-q}. This onset presents a new challenge for canonical dark matter distributions on galactic scales in ΛCDM. Instead, future galaxy surveys may determine {Q}0={{dq}(z)/{dz}| }z=0, to provide a direct test of dynamical dark energy ({Q}0> 2.5) versus ΛCDM ({Q}0< 1) and establish a bound of {10}-30 {{eV}} on the mass of the putative dark matter particle with clustering limited to galaxy clusters.

Higgs cosmology

PubMed Central

2018-01-01

The discovery of the Higgs boson in 2012 and other results from the Large Hadron Collider have confirmed the standard model of particle physics as the correct theory of elementary particles and their interactions up to energies of several TeV. Remarkably, the theory may even remain valid all the way to the Planck scale of quantum gravity, and therefore it provides a solid theoretical basis for describing the early Universe. Furthermore, the Higgs field itself has unique properties that may have allowed it to play a central role in the evolution of the Universe, from inflation to cosmological phase transitions and the origin of both baryonic and dark matter, and possibly to determine its ultimate fate through the electroweak vacuum instability. These connections between particle physics and cosmology have given rise to a new and growing field of Higgs cosmology, which promises to shed new light on some of the most puzzling questions about the Universe as new data from particle physics experiments and cosmological observations become available. This article is part of the Theo Murphy meeting issue ‘Higgs cosmology’. PMID:29358352

Effects of scale-dependent non-Gaussianity on cosmological structures

DOE Office of Scientific and Technical Information (OSTI.GOV)

LoVerde, Marilena; Miller, Amber; Shandera, Sarah

2008-04-15

The detection of primordial non-Gaussianity could provide a powerful means to test various inflationary scenarios. Although scale-invariant non-Gaussianity (often described by the f{sub NL} formalism) is currently best constrained by the CMB, single-field models with changing sound speed can have strongly scale-dependent non-Gaussianity. Such models could evade the CMB constraints but still have important effects at scales responsible for the formation of cosmological objects such as clusters and galaxies. We compute the effect of scale-dependent primordial non-Gaussianity on cluster number counts as a function of redshift, using a simple ansatz to model scale-dependent features. We forecast constraints on these modelsmore » achievable with forthcoming datasets. We also examine consequences for the galaxy bispectrum. Our results are relevant for the Dirac-Born-Infeld model of brane inflation, where the scale dependence of the non-Gaussianity is directly related to the geometry of the extra dimensions.« less

Early-time cosmology with stiff era from modified gravity

NASA Astrophysics Data System (ADS)

Odintsov, S. D.; Oikonomou, V. K.

2017-11-01

In this work, we shall incorporate a stiff era in the Universe's evolution in the context of F (R ) gravity. After deriving the vacuum F (R ) gravity, which may realize a stiff evolution, we combine the stiff F (R ) gravity with an R2 model, and we construct a qualitative model for the inflationary and stiff era, with the latter commencing after the end of the inflationary era. We assume that the baryogenesis occurs during the stiff era, and we calculate the baryon to entropy ratio, which effectively constraints the functional form of the stiff F (R ) gravity. Further constraints on the stiff F (R ) gravity may come from the primordial gravitational waves, and particularly their scalar mode, which is characteristic of the F (R ) gravity theory. The stiff era presence does not contradict the standard cosmology era, namely, inflation, and the radiation-matter domination eras. Furthermore, we investigate which F (R ) gravity may realize a dust and stiff matter dominated Einstein-Hilbert evolution.

U-series constraints on the Holocene human presence in the Cuatro Cienegas basin, Mexico

NASA Astrophysics Data System (ADS)

Noble, S. R.; Felstead, N.; Gonzalez, S.; Leng, M. J.; Metcalfe, S. E.; Patchett, P. J.

2010-12-01

U-series tufa ages dating a human trackway have been obtained, part of a larger Late Pleistocene - Recent palaeoclimate and human occupation study of the Cuatro Cienegas basin, NE Mexico. Our analytical approach, including tracer calibration, couples aspects of what we consider best practice in the U-series community with our U-Pb experiences which includes the EarthTime U-Pb tracer calibration exercise. The recently discovered trackway is near a small hydrothermal pool within the basin [1], an ecologically highly significant oasis in the Chihuahuan desert. The oasis comprises >200 freshwater hydrothermal pools and a river system, and the related ecosystem hosts >70 endemic species[2]. Pools are fed by waters that circulate a deep karstic system and that originate in the surrounding upper Jurassic-lower Cretaceous Sierra Madre Oriental mountains (>3000m) [3]. The area hosted nomadic hunter-gatherers during the Holocene, and possibly as early as Late Pleistocene (~12 ka BP). Despite the basin's ecological significance, only three palaeoenvironmental studies have been published to date, and limited geochronological constraints are available. A pollen study of drill core through peats and tufas proximal to the pools suggested a long period of climatic stability and biogeographic isolation[4], a notion supported by the large number of endemic species, but other palynological and plant macrofossil data suggest that large climatic changes occurred post Late Pleistocene [5]. The 10 m long in situ trackway is preserved in tufa and five samples from the uppermost surfaces were analysed to date the footprints. The tufas comprise clean carbonate with no petrographic evidence of replacement and little contaminant detrital material (on some exposed upper surfaces). Powdered tufa was processed following [6-8], and analysed by TIMS (Triton, U) and MC-ICP-MS (Th, Nu HR), although our future analyses will primarily be obtained on a Neptune. Samples were spiked with a 229Th/236U

Effect of different cosmologies on the galaxy stellar mass function

NASA Astrophysics Data System (ADS)

Lopes, Amanda R.; Gruppioni, C.; Ribeiro, M. B.; Pozzetti, L.; February, S.; Ilbert, O.; Pozzi, F.

2017-11-01

The goal of this paper is to understand how the underlying cosmological models may affect the analysis of the stellar masses in galaxies. We computed the galaxy stellar mass function (GSMF) assuming the observationally constrained Lemaître-Tolman-Bondi (LTB) `giant-void' models and compared them with the results from the standard cosmological model. Based on a sample of 220 000 KS-band selected galaxies from the UltraVISTA data, we computed the GSMF up to z ≈ 4 assuming different cosmologies, since, from a cosmological perspective, the two quantities that affect the stellar mass estimation are the luminosity distance and time. The results show that the stellar mass decreased on average by ˜1.1-27.1 per cent depending on the redshift value. For the GSMF, we fitted a double-Schechter function to the data and verified that a change is only seen in two parameters, M^{*} and φ ^{*}1, but always with less than a 3σ significance. We also carried out an additional analysis for the blue and red populations in order to verify a possible change on the galaxy evolution scenario. The results showed that the GSMF derived with the red population sample is more affected by the change of cosmology than the blue one. We also found out that the LTB models overestimated the number density of galaxies with M < 10^{11} M_{⊙}, and underestimate it for M> 10^{11} M_{⊙}, as compared to the standard model over the whole studied redshift range. This feature is noted in the complete, red plus blue, sample. Once we compared the general behaviour of the GSMF derived from the alternative cosmological models with the one based on the standard cosmology we found out that the variation was not large enough to change the shape of the function. Hence, the GSMF was found to be robust under this change of cosmology. This means that all physical interpretations of the GSMF based in the standard cosmological model are valid on the LTB cosmology.

Observational constraints on finite scale factor singularities

DOE Office of Scientific and Technical Information (OSTI.GOV)

Denkiewicz, Tomasz, E-mail: atomekd@wmf.univ.szczecin.pl

2012-07-01

We discuss the combined constraints on a Finite Scale Factor Singularity (FSF) universe evolution scenario, which come from the shift parameter R, baryon acoustic oscillations (BAO) A, and from the type Ia supernovae. We show that observations allow existence of such singularities in the 2 × 10{sup 9} years in future (at 1σ CL) which is much farther than a Sudden Future Singularity (SFS), and that at the present moment of the cosmic evolution, one cannot differentiate between cosmological scenario which allow finite scale factor singularities and the standard ΛCDM dark energy models. We also show that there is anmore » allowed value of m = 2/3 within 1σ CL, which corresponds to a dust-filled Einstein-de-Sitter universe limit of the early time evolution and so it is pasted into a standard early-time scenario.« less

Sociology of Modern Cosmology

NASA Astrophysics Data System (ADS)

López-Corredoira, M.

2009-08-01

Certain results of observational cosmology cast critical doubt on the foundations of standard cosmology but leave most cosmologists untroubled. Alternative cosmological models that differ from the Big Bang have been published and defended by heterodox scientists; however, most cosmologists do not heed these. This may be because standard theory is correct and all other ideas and criticisms are incorrect, but it is also to a great extent due to sociological phenomena such as the ``snowball effect'' or ``groupthink''. We might wonder whether cosmology, the study of the Universe as a whole, is a science like other branches of physics or just a dominant ideology.

BOOK REVIEW: Cosmology

NASA Astrophysics Data System (ADS)

Silk, Joseph

2008-11-01

The field of cosmology has been transformed since the glorious decades of the 1920's and 1930's when theory and observation converged to develop the current model of the expanding universe. It was a triumph of the theory of general relativity and astronomy. The first revolution came when the nuclear physicists entered the fray. This marked the debut of the hot big bang, in which the light elements were synthesized in the first three minutes. It was soon realised that elements like carbon and iron were synthesized in exploding stars. However helium, as well as deuterium and lithium, remain as George Gamow envisaged, the detritus of the big bang. The climax arrived with one of the most remarkable discoveries of the twentieth century, the cosmic microwave background radiation, in 1964. The fossil glow turned out to have the spectrum of an ideal black body. One could not imagine a stronger confirmation of the hot and dense origin of the universe. This discovery set the scene for the next major advance. It was now the turn of the particle physicists, who realized that the energies attained near the beginning of the universe, and unachievable in any conceivable terrestrial accelerator, provided a unique testing ground for theories of grand unification of the fundamental forces. This led Alan Guth and Andrei Linde in 1980 to propose the theory of inflation, which solved outstanding puzzles of the big bang. One could now understand why the universe is so large and homogeneous, and the origin of the seed fluctuations that gave rise to large-scale structure. A key prediction was that the universe should have Euclidean geometry, now verified to a precision of a few percent. Modern cosmology is firmly embedded in particle physics. It merits a text written by a particle physicist who can however appreciate the contributions of astronomy that provide the foundation and infrastructure for the theory of the expanding universe. There are now several such texts available. The most

Cosmology and the Bispectrum

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sefusatti, Emiliano; /Fermilab /CCPP, New York; Crocce, Martin

The present spatial distribution of galaxies in the Universe is non-Gaussian, with 40% skewness in 50 h{sup -1} Mpc spheres, and remarkably little is known about the information encoded in it about cosmological parameters beyond the power spectrum. In this work they present an attempt to bridge this gap by studying the bispectrum, paying particular attention to a joint analysis with the power spectrum and their combination with CMB data. They address the covariance properties of the power spectrum and bispectrum including the effects of beat coupling that lead to interesting cross-correlations, and discuss how baryon acoustic oscillations break degeneracies.more » They show that the bispectrum has significant information on cosmological parameters well beyond its power in constraining galaxy bias, and when combined with the power spectrum is more complementary than combining power spectra of different samples of galaxies, since non-Gaussianity provides a somewhat different direction in parameter space. In the framework of flat cosmological models they show that most of the improvement of adding bispectrum information corresponds to parameters related to the amplitude and effective spectral index of perturbations, which can be improved by almost a factor of two. Moreover, they demonstrate that the expected statistical uncertainties in {sigma}s of a few percent are robust to relaxing the dark energy beyond a cosmological constant.« less

Fundamental Particle Structure in the Cosmological Dark Matter

NASA Astrophysics Data System (ADS)

Khlopov, Maxim

2013-11-01

The nonbaryonic dark matter of the universe is assumed to consist of new stable forms of matter. Their stability reflects symmetry of micro-world and mechanisms of its symmetry breaking. Particle candidates for cosmological dark matter are lightest particles that bear new conserved quantum numbers. Dark matter particles may represent ideal gas of noninteracting particles. Self-interacting dark matter weakly or superweakly coupled to ordinary matter is also possible, reflecting nontrivial pattern of particle symmetry in the hidden sector of particle theory. In the early universe the structure of particle symmetry breaking gives rise to cosmological phase transitions, from which macroscopic cosmological defects or primordial nonlinear structures can be originated. Primordial black holes (PBHs) can be not only a candidate for dark matter, but also represent a universal probe for superhigh energy physics in the early universe. Evaporating PBHs turn to be a source of even superweakly interacting particles, while clouds of massive PBHs can serve as nonlinear seeds for galaxy formation. The observed broken symmetry of the three known families may provide a simultaneous solution for the problems of the mass of neutrino and strong CP-violation in the unique framework of models of horizontal unification. Dark matter candidates can also appear in the new families of quarks and leptons and the existence of new stable charged leptons and quarks is possible, hidden in elusive "dark atoms." Such possibility, strongly restricted by the constraints on anomalous isotopes of light elements, is not excluded in scenarios that predict stable double charged particles. The excessive -2 charged particles are bound in these scenarios with primordial helium in O-helium "atoms," maintaining specific nuclear-interacting form of the dark matter, which may provide an interesting solution for the puzzles of the direct dark matter searches. In the context of cosmoparticle physics, studying

Quasar populations in a cosmological constant-dominated flat universe

NASA Technical Reports Server (NTRS)

Malhotra, Sangeeta; Turner, Edwin L.

1995-01-01

Most physical properties derived for quasars, as single entities or as a population, depend upon the cosmology assumed. In this paper, we calculate the quasar luminosity function and some related quantities for a flat universe dominated by a cosmological constant Lambda (Lambda = 0.9, Omega = 0.1) and compare them with those deduced for a flat universe with zero cosmological constant (Lambda = 0, Omega = 1). We use the ATT quasar survey data (Boyle et al. 1990) as input in both cases. The data are fitted well by a pure luminosity evolution model for both the cosmologies but with different evolutionary parameters. From the luminosity function, we predict (extrapolate) a greater number of quasars at faint apparent magnitudes (twice the number at B = 24, z is less than 2.2) for the Lambda-dominated universe. This population of faint quasars at high redshift would result in a higher incidence of gravitational lensing. The total luminosity of the quasar population and the total mass tied up in black hole remnants of quasars is not sensitive to the cosmology. However, for a Lambda cosmology, this mass is tied up in fewer but more massive black holes.

Gamma-ray Burst Cosmology

NASA Astrophysics Data System (ADS)

Wang, F. Y.

2011-07-01

growth rate of perturbations, and find that the ΛCDM is the best fitted model. The transition redshift z_{T} is from 0.40_{-0.08}^{+0.14} to 0.65_{-0.05}^{+0.10}. This is the first time to combine GRBs with other observations to constrain the cosmological parameters, dark energy and transition redshift. In chapter 4, we investigate the early dark energy model using GRBs, SNe Ia, CMB and BAO. The negligible dark energy at high redshift will influence the growth of cosmic structures and leave observable signatures that are different from the standard cosmology. We propose that GRBs are promising tools to study the early dark energy. We find that the fractional dark energy density is less than 0.03 and the linear growth index of perturbations is 0.66. In chapter 5, we use a model-independent method to constrain the dark energy equation of state (EOS) w(z). Among the parameters describing the properties of dark energy, EOS is the most important. Whether and how it evolves with time are crucial in distinguishing different cosmological models. In our analysis, we include high-redshift GRBs. We find that w(z)<0 at z>1.7, and EOS deviates from the cosmological constant at z>0.5 at 95.4% confidence level. In chapter 6, we probe the cosmographic parameters to distinguish between the dark energy and modified gravity models. These two families of models can drive the universe to acclerate. We first derive the expressions of deceleration, jerk and snap parameters in the dark energy and modified gravity models. The snap parameters in these models are different, so they can be used to distinguish between the models. In chapter 7, we measure the high-redshift SFR using long GRBs. Swift observations reveal that the number of high-redshift GRBs is larger than the predication from SFR. We find that the evolving initial mass function can interpret this discrepancy. We study the high-redshift SFR up to z˜ 8.2 considering the Swift GRBs tracing the star formation history and the cosmic

Cosmological Distance Scale to Gamma-Ray Bursts

NASA Astrophysics Data System (ADS)

Azzam, W. J.; Linder, E. V.; Petrosian, V.

1993-05-01

The source counts or the so-called log N -- log S relations are the primary data that constrain the spatial distribution of sources with unknown distances, such as gamma-ray bursts. In order to test galactic, halo, and cosmological models for gamma-ray bursts we compare theoretical characteristics of the log N -- log S relations to those obtained from data gathered by the BATSE instrument on board the Compton Observatory (GRO) and other instruments. We use a new and statistically correct method, that takes proper account of the variable nature of the triggering threshold, to analyze the data. Constraints on models obtained by this comparison will be presented. This work is supported by NASA grants NAGW 2290, NAG5 2036, and NAG5 1578.

Cosmology and astrophysics from relaxed galaxy clusters – V. Consistency with cold dark matter structure formation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mantz, A. B.; Allen, S. W.; Morris, R. G.

This is the fifth in a series of papers studying the astrophysics and cosmology of massive, dynamically relaxed galaxy clusters. Our sample comprises 40 clusters identified as being dynamically relaxed and hot in Papers I and II of this series. Here we use constraints on cluster mass profiles from X-ray data to test some of the basic predictions of cosmological structure formation in the cold dark matter (CDM) paradigm. In addition, we present constraints on the concentration–mass relation for massive clusters, finding a power-law mass dependence with a slope of κ m = –0.16 ± 0.07, in agreement with CDMmore » predictions. For this relaxed sample, the relation is consistent with a constant as a function of redshift (power-law slope with 1 + z of κ ζ = –0.17 ± 0.26), with an intrinsic scatter of σln c = 0.16 ± 0.03. We investigate the shape of cluster mass profiles over the radial range probed by the data (typically ~50 kpc–1 Mpc), and test for departures from the simple Navarro–Frenk–White (NFW) form, for which the logarithmic slope of the density profile tends to –1 at small radii. Specifically, we consider as alternatives the generalized NFW (GNFW) and Einasto parametrizations. For the GNFW model, we find an average value of (minus) the logarithmic inner slope of β = 1.02 ± 0.08, with an intrinsic scatter of σ β = 0.22 ± 0.07, while in the Einasto case we constrain the average shape parameter to be α = 0.29 ± 0.04 with an intrinsic scatter of σ α = 0.12 ± 0.04. Our results are thus consistent with the simple NFW model on average, but we clearly detect the presence of intrinsic, cluster-to-cluster scatter about the average.« less

Cosmology and astrophysics from relaxed galaxy clusters – V. Consistency with cold dark matter structure formation

DOE PAGES

Mantz, A. B.; Allen, S. W.; Morris, R. G.

2016-07-15

This is the fifth in a series of papers studying the astrophysics and cosmology of massive, dynamically relaxed galaxy clusters. Our sample comprises 40 clusters identified as being dynamically relaxed and hot in Papers I and II of this series. Here we use constraints on cluster mass profiles from X-ray data to test some of the basic predictions of cosmological structure formation in the cold dark matter (CDM) paradigm. In addition, we present constraints on the concentration–mass relation for massive clusters, finding a power-law mass dependence with a slope of κ m = –0.16 ± 0.07, in agreement with CDMmore » predictions. For this relaxed sample, the relation is consistent with a constant as a function of redshift (power-law slope with 1 + z of κ ζ = –0.17 ± 0.26), with an intrinsic scatter of σln c = 0.16 ± 0.03. We investigate the shape of cluster mass profiles over the radial range probed by the data (typically ~50 kpc–1 Mpc), and test for departures from the simple Navarro–Frenk–White (NFW) form, for which the logarithmic slope of the density profile tends to –1 at small radii. Specifically, we consider as alternatives the generalized NFW (GNFW) and Einasto parametrizations. For the GNFW model, we find an average value of (minus) the logarithmic inner slope of β = 1.02 ± 0.08, with an intrinsic scatter of σ β = 0.22 ± 0.07, while in the Einasto case we constrain the average shape parameter to be α = 0.29 ± 0.04 with an intrinsic scatter of σ α = 0.12 ± 0.04. Our results are thus consistent with the simple NFW model on average, but we clearly detect the presence of intrinsic, cluster-to-cluster scatter about the average.« less

Constraints on gravitino decay and the scale of inflation using CMB spectral distortions

NASA Astrophysics Data System (ADS)

Dimastrogiovanni, Emanuela; Krauss, Lawrence M.; Chluba, Jens

2016-07-01

If local supersymmetry is the correct extension of the standard model of particle physics, then following inflation the early Universe would have been populated by gravitinos produced from scatterings in the hot plasma during reheating. Their abundance is directly related to the magnitude of the reheating temperature. The gravitino lifetime is fixed as a function of its mass, and for gravitinos with lifetimes longer than the age of the Universe at redshift z ≃2 ×1 06 (or roughly 6 ×1 06 s ), decay products can produce spectral distortion of the cosmic microwave background. Currently available COBE/FIRAS limits on spectral distortion can, in certain cases, already be competitive with respect to cosmological constraints from primordial nucleosynthesis for some gravitino decay scenarios. We show how the sensitivity limits on μ and y distortions that can be reached with current technology will improve constraints and possibly rule out a significant portion of the parameter space for gravitino masses and inflation reheating temperatures.

The Atacama Cosmology Telescope: two-season ACTPol spectra and parameters

DOE Office of Scientific and Technical Information (OSTI.GOV)

Louis, Thibaut; Grace, Emily; Aiola, Simone

We present the temperature and polarization angular power spectra measured by the Atacama Cosmology Telescope Polarimeter (ACTPol). We analyze night-time data collected during 2013–14 using two detector arrays at 149 GHz, from 548 deg{sup 2} of sky on the celestial equator. We use these spectra, and the spectra measured with the MBAC camera on ACT from 2008–10, in combination with planck and wmap data to estimate cosmological parameters from the temperature, polarization, and temperature-polarization cross-correlations. We find the new ACTPol data to be consistent with the ΛCDM model. The ACTPol temperature-polarization cross-spectrum now provides stronger constraints on multiple parameters thanmore » the ACTPol temperature spectrum, including the baryon density, the acoustic peak angular scale, and the derived Hubble constant. The new ACTPol data provide information on damping tail parameters. The joint uncertainty on the number of neutrino species and the primordial helium fraction is reduced by 20% when adding ACTPol to Planck temperature data alone.« less

Bayesian analysis of anisotropic cosmologies: Bianchi VIIh and WMAP

NASA Astrophysics Data System (ADS)

McEwen, J. D.; Josset, T.; Feeney, S. M.; Peiris, H. V.; Lasenby, A. N.

2013-12-01

We perform a definitive analysis of Bianchi VIIh cosmologies with Wilkinson Microwave Anisotropy Probe (WMAP) observations of the cosmic microwave background (CMB) temperature anisotropies. Bayesian analysis techniques are developed to study anisotropic cosmologies using full-sky and partial-sky masked CMB temperature data. We apply these techniques to analyse the full-sky internal linear combination (ILC) map and a partial-sky masked W-band map of WMAP 9 yr observations. In addition to the physically motivated Bianchi VIIh model, we examine phenomenological models considered in previous studies, in which the Bianchi VIIh parameters are decoupled from the standard cosmological parameters. In the two phenomenological models considered, Bayes factors of 1.7 and 1.1 units of log-evidence favouring a Bianchi component are found in full-sky ILC data. The corresponding best-fitting Bianchi maps recovered are similar for both phenomenological models and are very close to those found in previous studies using earlier WMAP data releases. However, no evidence for a phenomenological Bianchi component is found in the partial-sky W-band data. In the physical Bianchi VIIh model, we find no evidence for a Bianchi component: WMAP data thus do not favour Bianchi VIIh cosmologies over the standard Λ cold dark matter (ΛCDM) cosmology. It is not possible to discount Bianchi VIIh cosmologies in favour of ΛCDM completely, but we are able to constrain the vorticity of physical Bianchi VIIh cosmologies at (ω/H)0 < 8.6 × 10-10 with 95 per cent confidence.

D-term contributions and CEDM constraints in E6 × SU(2)F × U(1)A SUSY GUT model

NASA Astrophysics Data System (ADS)

Shigekami, Yoshihiro

2017-11-01

We focus on E6 × SU(2)F × U(1)A supersymmetric (SUSY) grand unified theory (GUT) model. In this model, realistic Yukawa hierarchies and mixings are realized by introducing all allowed interactions with 𝓞(1) coefficients. Moreover, we can take stop mass is smaller than the other sfermion masses. This type of spectrum called by natural SUSY type sfermion mass spectrum can suppress the SUSY contributions to flavor changing neutral current (FCNC) and stabilize weak scale at the same time. However, light stop predicts large up quark CEDM and stop contributions are not decoupled. Since there is Kobayashi-Maskawa phase, stop contributions to the up quark CEDM is severely constrained even if all SUSY breaking parameters and Higgsino mass parameter μ are real. In this model, real up Yukawa couplings are realized at the GUT scale because of spontaneous CP violation. Therefore CEDM bounds are satisfied, although up Yukawa couplings are complex at the SUSY scale through the renormalization equation group effects. We calculated the CEDMs and found that EDM constraints can be satisfied even if stop mass is 𝓞(1) TeV. In addition, we investigate the size of D-terms in this model. Since these D-term contributions is flavor dependent, the degeneracy of sfermion mass spectrum is destroyed and the size of D-term is strongly constrained by FCNCs when SUSY breaking scale is the weak scale. However, SUSY breaking scale is larger than 1 TeV in order to obtain 125 GeV Higgs mass, and therefore sizable D-term contribution is allowed. Furthermore, we obtained the non-trivial prediction for the difference of squared sfermion mass.

Cosmology solved? Maybe

NASA Astrophysics Data System (ADS)

Turner, Michael S.

1999-03-01

For two decades the hot big-bang model as been referred to as the standard cosmology - and for good reason. For just as long cosmologists have known that there are fundamental questions that are not answered by the standard cosmology and point to a grander theory. The best candidate for that grander theory is inflation + cold dark matter. It holds that the Universe is flat, that slowly moving elementary particles left over from the earliest moments provide the cosmic infrastructure, and that the primeval density inhomogeneities that seed all the structure arose from quantum fluctuations. There is now prima facie evidence that supports two basic tenets of this paradigm. An avalanche of high-quality cosmological observations will soon make this case stronger or will break it. Key questions remain to be answered; foremost among them are: identification and detection of the cold dark matter particles and elucidation of the dark-energy component. These are exciting times in cosmology!

Cosmology with a stiff matter era

NASA Astrophysics Data System (ADS)

Chavanis, Pierre-Henri

2015-11-01

We consider the possibility that the Universe is made of a dark fluid described by a quadratic equation of state P =K ρ2 , where ρ is the rest-mass density and K is a constant. The energy density ɛ =ρ c2+K ρ2 is the sum of two terms: a rest-mass term ρ c2 that mimics "dark matter" (P =0 ) and an internal energy term u =K ρ2=P that mimics a "stiff fluid" (P =ɛ ) in which the speed of sound is equal to the speed of light. In the early universe, the internal energy dominates and the dark fluid behaves as a stiff fluid (P ˜ɛ , ɛ ∝a-6). In the late universe, the rest-mass energy dominates and the dark fluid behaves as pressureless dark matter (P ≃0 , ɛ ∝a-3). We provide a simple analytical solution of the Friedmann equations for a universe undergoing a stiff matter era, a dark matter era, and a dark energy era due to the cosmological constant. This analytical solution generalizes the Einstein-de Sitter solution describing the dark matter era, and the Λ CDM model describing the dark matter era and the dark energy era. Historically, the possibility of a primordial stiff matter era first appeared in the cosmological model of Zel'dovich where the primordial universe is assumed to be made of a cold gas of baryons. A primordial stiff matter era also occurs in recent cosmological models where dark matter is made of relativistic self-gravitating Bose-Einstein condensates (BECs). When the internal energy of the dark fluid mimicking stiff matter is positive, the primordial universe is singular like in the standard big bang theory. It expands from an initial state with a vanishing scale factor and an infinite density. We consider the possibility that the internal energy of the dark fluid is negative (while, of course, its total energy density is positive), so that it mimics anti-stiff matter. This happens, for example, when the BECs have an attractive self-interaction with a negative scattering length. In that case, the primordial universe is nonsingular and

Nonlinear evolution of f(R) cosmologies. II. Power spectrum

DOE Office of Scientific and Technical Information (OSTI.GOV)

Oyaizu, Hiroaki; Hu, Wayne; Department of Astronomy and Astrophysics, University of Chicago, Chicago Illinois 60637

2008-12-15

We carry out a suite of cosmological simulations of modified action f(R) models where cosmic acceleration arises from an alteration of gravity instead of dark energy. These models introduce an extra scalar degree of freedom which enhances the force of gravity below the inverse mass or Compton scale of the scalar. The simulations exhibit the so-called chameleon mechanism, necessary for satisfying local constraints on gravity, where this scale depends on environment, in particular, the depth of the local gravitational potential. We find that the chameleon mechanism can substantially suppress the enhancement of power spectrum in the nonlinear regime if themore » background field value is comparable to or smaller than the depth of the gravitational potentials of typical structures. Nonetheless power spectrum enhancements at intermediate scales remain at a measurable level for models even when the expansion history is indistinguishable from a cosmological constant, cold dark matter model. Simple scaling relations that take the linear power spectrum into a nonlinear spectrum fail to capture the modifications of f(R) due to the change in collapsed structures, the chameleon mechanism, and the time evolution of the modifications.« less

Higgs portal dark matter in non-standard cosmological histories

NASA Astrophysics Data System (ADS)

Hardy, Edward

2018-06-01

A scalar particle with a relic density set by annihilations through a Higgs portal operator is a simple and minimal possibility for dark matter. However, assuming a thermal cosmological history this model is ruled out over most of parameter space by collider and direct detection constraints. We show that in theories with a non-thermal cosmological history Higgs portal dark matter is viable for a wide range of dark matter masses and values of the portal coupling, evading existing limits. In particular, we focus on the string theory motivated scenario of a period of matter domination due to a light modulus with a decay rate that is suppressed by the Planck scale. Dark matter with a mass ≲ GeV is possible without additional hidden sector states, and this can have astrophysically relevant self-interactions. We also study the signatures of such models at future direct, indirect, and collider experiments. Searches for invisible Higgs decays at the high luminosity LHC or an e + e - collider could cover a significant proportion of the parameter space for low mass dark matter, and future direct detection experiments will play a complementary role.

Investigating dark matter substructure with pulsar timing - II. Improved limits on small-scale cosmology

NASA Astrophysics Data System (ADS)

Clark, Hamish A.; Lewis, Geraint F.; Scott, Pat

2016-02-01

Ultracompact minihaloes (UCMHs) have been proposed as a type of dark matter substructure seeded by large-amplitude primordial perturbations and topological defects. UCMHs are expected to survive to the present era, allowing constraints to be placed on their cosmic abundance using observations within our own Galaxy. Constraints on their number density can be linked to conditions in the early Universe that impact structure formation, such as increased primordial power on small scales, generic weak non-Gaussianity, and the presence of cosmic strings. We use new constraints on the abundance of UCMHs from pulsar timing to place generalized limits on the parameters of each of these cosmological scenarios. At some scales, the limits are the strongest to date, exceeding those from dark matter annihilation. Our new limits have the added advantage of being independent of the particle nature of dark matter, as they are based only on gravitational effects.

The large-scale environment from cosmological simulations - I. The baryonic cosmic web

NASA Astrophysics Data System (ADS)

Cui, Weiguang; Knebe, Alexander; Yepes, Gustavo; Yang, Xiaohu; Borgani, Stefano; Kang, Xi; Power, Chris; Staveley-Smith, Lister

2018-01-01

Using a series of cosmological simulations that includes one dark-matter-only (DM-only) run, one gas cooling-star formation-supernova feedback (CSF) run and one that additionally includes feedback from active galactic nuclei (AGNs), we classify the large-scale structures with both a velocity-shear-tensor code (VWEB) and a tidal-tensor code (PWEB). We find that the baryonic processes have almost no impact on large-scale structures - at least not when classified using aforementioned techniques. More importantly, our results confirm that the gas component alone can be used to infer the filamentary structure of the universe practically un-biased, which could be applied to cosmology constraints. In addition, the gas filaments are classified with its velocity (VWEB) and density (PWEB) fields, which can theoretically connect to the radio observations, such as H I surveys. This will help us to bias-freely link the radio observations with dark matter distributions at large scale.

Applying the theory of constraints in health care: Part 1--The philosophy.

PubMed

Breen, Anne M; Burton-Houle, Tracey; Aron, David C

2002-01-01

The imperative to improve both technical and service quality while simultaneously reducing costs is quite clear. The Theory of Constraints (TOC) is an emerging philosophy that rests on two assumptions: (1) systems thinking and (2) if a constraint "is anything that limits a system from achieving higher performance versus its goal," then every system must have at least one (and at most no more than a few) constraints or limiting factors. A constraint is neither good nor bad in itself. Rather, it just is. In fact, recognition of the existence of constraints represents an excellent opportunity for improvement because it allows one to focus ones efforts in the most productive area--identifying and managing the constraints. This is accomplished by using the five focusing steps of TOC: (1) identify the system's constraint; (2) decide how to exploit it; (3) subordinate/synchronize everything else to the above decisions; (4) elevate the system's constraint; and (5) if the constraint has shifted in the above steps, go back to step 1. Do not allow inertia to become the system's constraint. TOC also refers to a series of tools termed "thinking processes" and the sequence in which they are used.

Einstein-like field equations with conserved source and decreasing and Λ term; Their cosmological consequences

NASA Astrophysics Data System (ADS)

Massa, Corrado

1996-03-01

The consequences of a cosmological ∧ term varying asS -2 in a spatially isotropic universe with scale factorS and conserved matter tensor are investigated. One finds a perpetually expanding universe with positive ∧ and gravitational ‘constant’G that increases with time. The ‘hard’ equation of state 3P>U (U mass-energy density,P scalar pressure) applied to the early universe leads to the expansion lawS∝t (t cosmic time) which solves the horizon problem with no need of inflation. Also the flatness problem is resolved without inflation. The model does not affect the well known predictions on the cosmic light elements abundance which come from standard big bang cosmology. In the present, matter dominated universe one findsdG/dt=2∧H/U (H is the Hubble parameter) which is consistent with observations provided ∧<10-57 cm-2. Asymptotically (S→∞) the ∧ term equalsGU/2, in agreement with other studies.

New observational constraints on f ( R ) gravity from cosmic chronometers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nunes, Rafael C.; Pan, Supriya; Saridakis, Emmanuel N.

We use the recently released cosmic chronometer data and the latest measured value of the local Hubble parameter, combined with the latest joint light curves of Supernovae Type Ia, and Baryon Acoustic Oscillation distance measurements, in order to impose constraints on the viable and most used f ( R ) gravity models. We consider four f ( R ) models, namely the Hu-Sawicki, the Starobinsky, the Tsujikawa, and the exponential one, and we parametrize them introducing a distortion parameter b that quantifies the deviation from ΛCDM cosmology. Our analysis reveals that a small but non-zero deviation from ΛCDM cosmology ismore » slightly favored, with the corresponding fittings exhibiting very efficient AIC and BIC Information Criteria values. Clearly, f ( R ) gravity is consistent with observations, and it can serve as a candidate for modified gravity.« less

Is cosmology a historical science?

NASA Astrophysics Data System (ADS)

Grignon, Claude

2012-06-01

To explain the formation and the evolution of the Universe, cosmology settles universal laws. In this respect, cosmology belongs to the category of the nomothetic sciences, which write and think in mathematics. But cosmology is also akin to the historical sciences; like archaeology, geology or the biology of evolution, cosmology infers history from the vestiges of the past; moreover, it is not an experimental but an observational science. Due to this ambivalence, cosmology confronts divergent epistemological options. Nomothetic and historical sciences use indeed different, even opposite conceptions of such fundamental notions as time, causality and chance. Is it possible to make the history of the Universe intelligible without referring to the narrative conception of history congruent with the course of the historical world?.

On under-determination in cosmology

NASA Astrophysics Data System (ADS)

Butterfield, Jeremy

2014-05-01

I discuss how modern cosmology illustrates under-determination of theoretical hypotheses by data, in ways that are different from most philosophical discussions. I emphasise cosmology's concern with what data could in principle be collected by a single observer (Section 2); and I give a broadly sceptical discussion of cosmology's appeal to the cosmological principle as a way of breaking the under-determination (Section 3). I confine most of the discussion to the history of the observable universe from about one second after the Big Bang, as described by the mainstream cosmological model: in effect, what cosmologists in the early 1970s dubbed the 'standard model', as elaborated since then. But in the closing Section 4, I broach some questions about times earlier than one second.

Cosmological Entropy Bounds

NASA Astrophysics Data System (ADS)

Brustein, R.

I review some basic facts about entropy bounds in general and about cosmological entropy bounds. Then I review the causal entropy bound, the conditions for its validity and its application to the study of cosmological singularities. This article is based on joint work with Gabriele Veneziano and subsequent related research.

Cosmological test with the QSO Hubble diagram

NASA Astrophysics Data System (ADS)

López-Corredoira, M.; Melia, F.; Lusso, E.; Risaliti, G.

2016-03-01

A Hubble diagram (HD) has recently been constructed in the redshift range 0 ≲ z ≲ 6.5 using a nonlinear relation between the ultraviolet (UV) and X-ray luminosities of quasi stellar objects (QSOs). The Type Ia Supernovae (SN) HD has already provided a high-precision test of cosmological models, but the fact that the QSO distribution extends well beyond the supernova range (z ≲ 1.8), in principle provides us with an important complementary diagnostic whose significantly greater leverage in z can impose tighter constraints on the distance versus redshift relationship. In this paper, we therefore perform an independent test of nine different cosmological models, among which six are expanding, while three are static. Many of these are disfavored by other kinds of observations (including the aforementioned Type Ia SNe). We wish to examine whether the QSO HD confirms or rejects these earlier conclusions. We find that four of these models (Einstein-de Sitter, the Milne universe, the static universe with simple tired light and the static universe with plasma tired light) are excluded at the > 99% C.L. The quasi-steady state model is excluded at > 95% C.L. The remaining four models (ΛCDM/wCDM, the Rh = ct universe, the Friedmann open universe and a static universe with a linear Hubble law) all pass the test. However, only ΛCDM/wCDM and Rh = ct also pass the Alcock-Paczyński (AP) test. The optimized parameters in ΛCDM/wCDM are Ωm = 0.20-0.20+0.24 and wde = -1.2-∞+1.6 (the dark energy equation-of-state). Combined with the AP test, these values become Ωm = 0.38-0.19+0.20 and wde = -0.28-0.40+0.52. But whereas this optimization of parameters in ΛCDM/wCDM creates some tension with their concordance values, the Rh = ct universe has the advantage of fitting the QSO and AP data without any free parameters.

A Novel Intra-U1 snRNP Cross-Regulation Mechanism: Alternative Splicing Switch Links U1C and U1-70K Expression

PubMed Central

Rösel-Hillgärtner, Tanja Dorothe; Hung, Lee-Hsueh; Khrameeva, Ekaterina; Le Querrec, Patrick; Gelfand, Mikhail S.; Bindereif, Albrecht

2013-01-01

The U1 small nuclear ribonucleoprotein (snRNP)-specific U1C protein participates in 5′ splice site recognition and regulation of pre-mRNA splicing. Based on an RNA-Seq analysis in HeLa cells after U1C knockdown, we found a conserved, intra-U1 snRNP cross-regulation that links U1C and U1-70K expression through alternative splicing and U1 snRNP assembly. To investigate the underlying regulatory mechanism, we combined mutational minigene analysis, in vivo splice-site blocking by antisense morpholinos, and in vitro binding experiments. Alternative splicing of U1-70K pre-mRNA creates the normal (exons 7–8) and a non-productive mRNA isoform, whose balance is determined by U1C protein levels. The non-productive isoform is generated through a U1C-dependent alternative 3′ splice site, which requires an adjacent cluster of regulatory 5′ splice sites and binding of intact U1 snRNPs. As a result of nonsense-mediated decay (NMD) of the non-productive isoform, U1-70K mRNA and protein levels are down-regulated, and U1C incorporation into the U1 snRNP is impaired. U1-70K/U1C-deficient particles are assembled, shifting the alternative splicing balance back towards productive U1-70K splicing, and restoring assembly of intact U1 snRNPs. Taken together, we established a novel feedback regulation that controls U1-70K/U1C homeostasis and ensures correct U1 snRNP assembly and function. PMID:24146627

Loop quantum cosmology with self-dual variables

NASA Astrophysics Data System (ADS)

Wilson-Ewing, Edward

2015-12-01

Using the complex-valued self-dual connection variables, the loop quantum cosmology of a closed Friedmann space-time coupled to a massless scalar field is studied. It is shown how the reality conditions can be imposed in the quantum theory by choosing a particular inner product for the kinematical Hilbert space. While holonomies of the self-dual Ashtekar connection are not well defined in the kinematical Hilbert space, it is possible to introduce a family of generalized holonomylike operators of which some are well defined; these operators in turn are used in the definition of the Hamiltonian constraint operator where the scalar field can be used as a relational clock. The resulting quantum theory is closely related, although not identical, to standard loop quantum cosmology constructed from the Ashtekar-Barbero variables with a real Immirzi parameter. Effective Friedmann equations are derived which provide a good approximation to the full quantum dynamics for sharply peaked states whose volume remains much larger than the Planck volume, and they show that for these states quantum gravity effects resolve the big-bang and big-crunch singularities and replace them by a nonsingular bounce. Finally, the loop quantization in self-dual variables of a flat Friedmann space-time is recovered in the limit of zero spatial curvature and is identical to the standard loop quantization in terms of the real-valued Ashtekar-Barbero variables.

Cosmology as Science: From Inflation to the Future

ScienceCinema

Krass, Lawrence

2018-01-11

Recent developments in cosmology bring to the forefront fundamental questions about our ability to falsify various fundamental assumptions about the universe.  I will discuss three issues that reflect different aspects of these questions:  (1) "Proving" Inflation (2) Anthropic "Explanations" (3) Cosmology of the far future.

Direct detection constraints on dark photon dark matter

DOE PAGES

An, Haipeng; Pospelov, Maxim; Pradler, Josef; ...

2015-06-11

Dark matter detectors built primarily to probe elastic scattering of WIMPs on nuclei are also precise probes of light, weakly coupled, particles that may be absorbed by the detector material. In this paper, we derive constraints on the minimal model of dark matter comprised of long-lived vector states V (dark photons) in the 0.01–100KeV mass range. The absence of an ionization signal in direct detection experiments such as XENON10 and XENON100 places a very strong constraint on the dark photon mixing angle, down to Ο(10 –15), assuming that dark photons comprise the dominant fraction of dark matter. This sensitivity tomore » dark photon dark matter exceeds the indirect bounds derived from stellar energy loss considerations over a significant fraction of the available mass range. As a result, we also revisit indirect constraints from V → 3γ decay and show that limits from modifications to the cosmological ionization history are comparable to the updated limits from the diffuse γ-ray flux.« less

Philosophical aspects of modern cosmology

NASA Astrophysics Data System (ADS)

Zinkernagel, Henrik

2014-05-01

Cosmology is the attempt to understand in scientific terms the structure and evolution of the universe as a whole. This ambition has been with us since the ancient Greeks, even if the developments in modern cosmology have provided a picture of the universe dramatically different from that of Pythagoras, Plato and Aristotle. The cosmological thinking of these figures, e.g. the belief in uniform circular motion of the heavens, was closely related to their philosophical ideas, and it shaped the field of cosmology at least up to the times of Copernicus and Kepler.

Concordance cosmology without dark energy

NASA Astrophysics Data System (ADS)

Rácz, Gábor; Dobos, László; Beck, Róbert; Szapudi, István; Csabai, István

2017-07-01

According to the separate universe conjecture, spherically symmetric sub-regions in an isotropic universe behave like mini-universes with their own cosmological parameters. This is an excellent approximation in both Newtonian and general relativistic theories. We estimate local expansion rates for a large number of such regions, and use a scale parameter calculated from the volume-averaged increments of local scale parameters at each time step in an otherwise standard cosmological N-body simulation. The particle mass, corresponding to a coarse graining scale, is an adjustable parameter. This mean field approximation neglects tidal forces and boundary effects, but it is the first step towards a non-perturbative statistical estimation of the effect of non-linear evolution of structure on the expansion rate. Using our algorithm, a simulation with an initial Ωm = 1 Einstein-de Sitter setting closely tracks the expansion and structure growth history of the Λ cold dark matter (ΛCDM) cosmology. Due to small but characteristic differences, our model can be distinguished from the ΛCDM model by future precision observations. Moreover, our model can resolve the emerging tension between local Hubble constant measurements and the Planck best-fitting cosmology. Further improvements to the simulation are necessary to investigate light propagation and confirm full consistency with cosmic microwave background observations.

Cosmological backreaction within the Szekeres model and emergence of spatial curvature

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bolejko, Krzysztof, E-mail: krzysztof.bolejko@sydney.edu.au

This paper discusses the phenomenon of backreaction within the Szekeres model. Cosmological backreaction describes how the mean global evolution of the Universe deviates from the Friedmannian evolution. The analysis is based on models of a single cosmological environment and the global ensemble of the Szekeres models (of the Swiss-Cheese-type and Styrofoam-type). The obtained results show that non-linear growth of cosmic structures is associated with the growth of the spatial curvature Ω{sub R} (in the FLRW limit Ω{sub R} → Ω {sub k} ). If averaged over global scales the result depends on the assumed global model of the Universe. Withinmore » the Swiss-Cheese model, which does have a fixed background, the volume average follows the evolution of the background, and the global spatial curvature averages out to zero (the background model is the ΛCDM model, which is spatially flat). In the Styrofoam-type model, which does not have a fixed background, the mean evolution deviates from the spatially flat ΛCDM model, and the mean spatial curvature evolves from Ω{sub R} =0 at the CMB to Ω{sub R} ∼ 0.1 at 0 z =. If the Styrofoam-type model correctly captures evolutionary features of the real Universe then one should expect that in our Universe, the spatial curvature should build up (local growth of cosmic structures) and its mean global average should deviate from zero (backreaction). As a result, this paper predicts that the low-redshift Universe should not be spatially flat (i.e. Ω {sub k} ≠ 0, even if in the early Universe Ω {sub k} = 0) and therefore when analysing low- z cosmological data one should keep Ω {sub k} as a free parameter and independent from the CMB constraints.« less

Cosmological backreaction within the Szekeres model and emergence of spatial curvature

NASA Astrophysics Data System (ADS)