scholarly journals A new method to build the (inverse) distance ladder

2020 ◽  
Vol 495 (3) ◽  
pp. 2630-2644 ◽  
Author(s):  
David Camarena ◽  
Valerio Marra
Keyword(s):  
High Redshift ◽  
Photon Number ◽  
Hubble Constant ◽  
New Physics ◽  
New Method ◽  
Luminosity Distance ◽  
Local Measurements ◽  
The Impact ◽  
Distance Relation ◽  
Inverse Distance

ABSTRACT The cosmic distance ladder is the succession of techniques by which it is possible to determine distances to astronomical objects. Here, we present a new method to build the cosmic distance ladder, going from local astrophysical measurements to the CMB. Instead of relying on high-redshift cosmography in order to model the luminosity–distance relation and calibrate supernovae with BAO, we exploit directly the distance–duality relation dL = (1 + z)2dA – valid if photon number is conserved and gravity is described by a metric theory. The advantage is that the results will not depend on the parametrization of the luminosity–distance relation at z > 0.15: no model is adopted in order to calibrate BAO with supernovae. This method yields local measurements of the Hubble constant and deceleration parameter. Furthermore, it can directly assess the impact of BAO observations on the strong 4–5σ tension between local and global H0. Using the latest supernova, BAO and CMB observations, we found a consistently low value of q0 and strong inconsistency between angular-only BAO constraints and anisotropic BAO measurements, which are, or not, in agreement with CMB depending on the kind of analysis (see Table 4). We conclude that, in order to understand the reasons behind the H0 crisis, a first step should be clarifying the tension between angular and perpendicular anisotropic BAO as this will help understanding if new physics is required at the pre-recombination epoch or/and during the dark energy era.

scholarly journals Determining the Hubble constant without the sound horizon scale: measurements from CMB lensing

2020 ◽  
Vol 501 (2) ◽  
pp. 1823-1835
Author(s):  
Eric J Baxter ◽  
Blake D Sherwin
Keyword(s):  
Power Spectrum ◽  
Cold Dark Matter ◽  
High Redshift ◽  
Hubble Constant ◽  
New Physics ◽  
Data Sets ◽  
Density Parameter ◽  
Acoustic Oscillations ◽  
The Galaxy ◽  
Local Measurements

ABSTRACT Measurements of the Hubble constant, H0, from the cosmic distance ladder are currently in tension with the value inferred from Planck observations of the cosmic microwave background (CMB) and other high-redshift data sets if a flat Λ cold dark matter (ΛCDM) cosmological model is assumed. One of the few promising theoretical resolutions of this tension is to invoke new physics that changes the sound horizon scale in the early Universe; this can bring CMB and baryon acoustic oscillations (BAO) constraints on H0 into better agreement with local measurements. In this paper, we discuss how a measurement of the Hubble constant can be made from the CMB without using information from the sound horizon scale, rs. In particular, we show how measurements of the CMB lensing power spectrum can place interesting constraints on H0 when combined with measurements of either supernovae or galaxy weak lensing, which constrain the matter density parameter. The constraints arise from the sensitivity of the CMB lensing power spectrum to the horizon scale at matter–radiation equality (in projection); this scale could have a different dependence on new physics than the sound horizon. From an analysis of current CMB lensing data from Planck and Pantheon supernovae with conservative external priors, we derive an rs-independent constraint of $H_0 = 73.5\pm 5.3\, {\rm km}\,{\rm s}^{-1}\,{\rm Mpc}^{-1}$. Forecasts for future CMB surveys indicate that improving constraints beyond an error of $\sigma (H_0) = 3\, {\rm km}\,{\rm s}^{-1}\,{\rm Mpc}^{-1}$ will be difficult with CMB lensing, although applying similar methods to the galaxy power spectrum may allow for further improvements.

scholarly journals A combined analysis of the H0 late time direct measurements and the impact on the Dark Energy sector

2021 ◽  
Vol 502 (2) ◽  
pp. 2065-2073
Author(s):  
Eleonora Di Valentino
Keyword(s):  
Dark Energy ◽  
Time Delay ◽  
Surface Brightness ◽  
Hubble Constant ◽  
New Physics ◽  
Late Time ◽  
Direct Measurements ◽  
Phantom Dark Energy ◽  
Surface Brightness Fluctuations ◽  
The Impact

ABSTRACT We combine 23 Hubble constant measurements based on Cepheids-SN Ia, TRGB-SN Ia, Miras-SN Ia, Masers, Tully Fisher, Surface Brightness Fluctuations, SN II, Time-delay Lensing, Standard Sirens and γ-ray Attenuation, obtaining our best optimistic H0 estimate, that is H0 = 72.94 ± 0.75 km s–1 Mpc–1 at 68 per cent CL. This is in 5.9σ tension with the ΛCDM model, therefore we evaluate its impact on the extended Dark Energy cosmological models that can alleviate the tension. We find more than 4.9σ evidence for a phantom Dark Energy equation of state in the wCDM scenario, the cosmological constant ruled out at more than 3σ in a w0waCDM model and more than 5.7σ evidence for a coupling between Dark Matter and Dark Energy in the IDE scenario. Finally, we check the robustness of our results; and we quote two additional combinations of the Hubble constant. The ultra-conservative estimate, H0 = 72.7 ± 1.1 km s–1 Mpc–1 at 68 per cent CL, is obtained removing the Cepheids-SN Ia and the Time-Delay Lensing based measurements, and confirms the evidence for new physics.

scholarly journals General cosmography model with spatial curvature

2019 ◽  
Vol 491 (4) ◽  
pp. 4960-4972 ◽  
Author(s):  
En-Kun Li ◽  
Minghui Du ◽  
Lixin Xu
Keyword(s):  
Taylor Series ◽  
High Redshift ◽  
Hubble Constant ◽  
Acoustic Oscillation ◽  
New Physics ◽  
Basic Function ◽  
Closed Universe ◽  
Spatial Curvature ◽  
Tension Level ◽  
Bayesian Evidence

ABSTRACT We adopt a cosmographic approach in order to determine spatial curvature (i.e. ΩK), combining the latest release of cosmic chronometer (CC) data, the Pantheon sample of Type Ia supernovae observations and baryon acoustic oscillation measurements. We use the expanded transverse comoving distance DM($z$) as a basic function for deriving H($z$) and other cosmic distances. In this scenario, ΩK can be constrained only by CC data. To overcome the convergence issues at high-redshift domains, two methods are applied: the Padé approximants and the Taylor series in terms of the new redshift y = $z$/(1 + $z$). Adopting the Bayesian evidence, we find that there is positive evidence for the Padé approximant up to order (2,2) and weak evidence for the Taylor series up to third order against the ΛCDM + ΩK model. The constraint results show that a closed Universe is preferred by present observations under all the approximations used in this study. Also, the tension level of the Hubble constant H0 has less than 2σ significance between different approximations and the local distance ladder determination. For each assumed approximation, H0 is anticorrelated with ΩK and the sound horizon at the end of the radiation drag epoch, which indicates that the H0 tension problem can be slightly relaxed by introducing ΩK or any new physics that can reduce the sound horizon in the early Universe.

A new method showing the impact of pulp refining on fiber-fiber interactions in wet webs

2016 ◽  
Vol 31 (2) ◽  
pp. 205-212 ◽  
Author(s):  
Belle Jürgen ◽  
Kleemann Stephan ◽  
Odermatt Jürgen ◽  
Olbrich Andrea
Keyword(s):  
New Method ◽  
The Impact

scholarly journals Quasi-equilibrium models of high-redshift disc galaxy evolution

2020 ◽  
Vol 500 (3) ◽  
pp. 3394-3412
Author(s):  
Steven R Furlanetto
Keyword(s):  
Star Formation ◽  
Galaxy Evolution ◽  
Galaxy Formation ◽  
High Redshift ◽  
Formation Rate ◽  
New Physics ◽  
Small Scale ◽  
Quasi Equilibrium ◽  
Mass Relation ◽  
Disc Galaxy

ABSTRACT In recent years, simple models of galaxy formation have been shown to provide reasonably good matches to available data on high-redshift luminosity functions. However, these prescriptions are primarily phenomenological, with only crude connections to the physics of galaxy evolution. Here, we introduce a set of galaxy models that are based on a simple physical framework but incorporate more sophisticated models of feedback, star formation, and other processes. We apply these models to the high-redshift regime, showing that most of the generic predictions of the simplest models remain valid. In particular, the stellar mass–halo mass relation depends almost entirely on the physics of feedback (and is thus independent of the details of small-scale star formation) and the specific star formation rate is a simple multiple of the cosmological accretion rate. We also show that, in contrast, the galaxy’s gas mass is sensitive to the physics of star formation, although the inclusion of feedback-driven star formation laws significantly changes the naive expectations. While these models are far from detailed enough to describe every aspect of galaxy formation, they inform our understanding of galaxy formation by illustrating several generic aspects of that process, and they provide a physically grounded basis for extrapolating predictions to faint galaxies and high redshifts currently out of reach of observations. If observations show violations from these simple trends, they would indicate new physics occurring inside the earliest generations of galaxies.

scholarly journals A new method of inferring the size, number density, and charge of mesospheric dust from its in situ collection by the DUSTY probe

2019 ◽  
Vol 12 (3) ◽  
pp. 1673-1683 ◽  
Author(s):  
Ove Havnes ◽  
Tarjei Antonsen ◽  
Gerd Baumgarten ◽  
Thomas W. Hartquist ◽  
Alexander Biebricher ◽  
...  
Keyword(s):  
New Method ◽  
Production Model ◽  
Dust Particles ◽  
Bottom Plate ◽  
Charged Dust ◽  
Fundamental Parameters ◽  
Dust Charge ◽  
Analysis Technique ◽  
June July ◽  
The Impact

Abstract. We present a new method of analyzing measurements of mesospheric dust made with DUSTY rocket-borne Faraday cup probes. It can yield the variation in fundamental dust parameters through a mesospheric cloud with an altitude resolution down to 10 cm or less if plasma probes give the plasma density variations with similar height resolution. A DUSTY probe was the first probe that unambiguously detected charged dust and aerosol particles in the Earth's mesosphere. DUSTY excluded the ambient plasma by various biased grids, which however allowed dust particles with radii above a few nanometers to enter, and it measured the flux of charged dust particles. The flux measurements directly yielded the total ambient dust charge density. We extend the analysis of DUSTY data by using the impact currents on its main grid and the bottom plate as before, together with a dust charging model and a secondary charge production model, to allow the determination of fundamental parameters, such as dust radius, charge number, and total dust density. We demonstrate the utility of the new analysis technique by considering observations made with the DUSTY probes during the MAXIDUSTY rocket campaign in June–July 2016 and comparing the results with those of other instruments (lidar and photometer) also used in the campaign. In the present version we have used monodisperse dust size distributions.

scholarly journals The Impact of the Quality Assessment of Optimal Assignment for Data Association in a Multitarget Tracking Context

2015 ◽  
Vol 15 (7) ◽  
pp. 88-98
Author(s):  
J. Dezert ◽  
A. Tchamova ◽  
P. Konstantinova
Keyword(s):  
Quality Assessment ◽  
Data Association ◽  
New Method ◽  
Multitarget Tracking ◽  
Belief Functions ◽  
Tracking Systems ◽  
Optimal Assignment ◽  
The Individual ◽  
The Impact

Abstract The main purpose of this paper is to apply and to test the performance of a new method, based on belief functions, proposed by Dezert et al. in order to evaluate the quality of the individual association pairings provided in the optimal data association solution for improving the performances of multisensor-multitarget tracking systems. The advantages of its implementation in an illustrative realistic surveillance context, when some of the association decisions are unreliable and doubtful and lead to potentially critical mistake, are discussed. A comparison with the results obtained on the base of Generalized Data Association is made.

scholarly journals NLO QCD corrections to off-shell $${t{\bar{t}}W^\pm }$$ production at the LHC: correlations and asymmetries

2021 ◽  
Vol 81 (7) ◽  
Author(s):  
Giuseppe Bevilacqua ◽  
Huan-Yu Bi ◽  
Heribertus Bayu Hartanto ◽  
Manfred Kraus ◽  
Jasmina Nasufi ◽  
...  
Keyword(s):  
Top Quark ◽  
Charge Asymmetry ◽  
New Physics ◽  
Atlas Collaboration ◽  
Narrow Width Approximation ◽  
Theoretical Predictions ◽  
Top Quark Decay ◽  
Quark Decay ◽  
Precision Observables ◽  
The Impact

AbstractRecent discrepancies between theoretical predictions and experimental data in multi-lepton plus b-jets analyses for the $$t{\bar{t}}W^\pm $$ t t ¯ W ± process, as reported by the ATLAS collaboration, have indicated that more accurate theoretical predictions and high precision observables are needed to constrain numerous new physics scenarios in this channel. To this end we employ NLO QCD computations with full off-shell top quark effects included to provide theoretical predictions for the $$\mathcal{R}= \sigma _{t{\bar{t}}W^+}/\sigma _{t{\bar{t}}W^-}$$ R = σ t t ¯ W + / σ t t ¯ W - cross section ratio at the LHC with $$\sqrt{s}=13$$ s = 13 TeV. Depending on the transverse momentum cut on the b-jet we obtain 2–3% theoretical precision on $$\mathcal{R}$$ R , which should help to shed some light on new physics effects that can reveal themselves only once sufficiently precise Standard Model theoretical predictions are available. Furthermore, triggered by these discrepancies we reexamine the charge asymmetry of the top quark and its decay products in the $$t{\bar{t}}W^\pm $$ t t ¯ W ± production process. In the case of charge asymmetries, that are uniquely sensitive to the chiral nature of possible new physics in this channel, theoretical uncertainties below 15% are obtained. Additionally, the impact of the top quark decay modelling is scrutinised by explicit comparison with predictions in the narrow-width approximation.

scholarly journals 3D Finite Element Model Simulating the Behaviour of Filling Soils Used to Set Up a New Placement Method for Separate Sewer Systems

2019 ◽  
Vol 8 (3) ◽  
pp. 87-98
Author(s):  
Alaa Abbas ◽  
Felicite Ruddock ◽  
Rafid Alkhaddar ◽  
Glynn Rothwell ◽  
Iacopo Carnacina ◽  
...  
Keyword(s):  
Finite Element ◽  
Soil Properties ◽  
Model Simulation ◽  
New Method ◽  
Traffic Load ◽  
Scale Model ◽  
Fe Model ◽  
Fe Method ◽  
Buried Pipes ◽  
The Impact

The use of a finite element (FE) method and selection of the appropriate model to simulate soil elastoplastic behaviour has confirmed the importance and sensitivity of the soil properties on the accuracy when compared with experimental data. The properties of the filling soil play a significant role in determining levels of deformation and displacement of both the soil and subterranean structures when using the FE model simulation. This paper investigates the impact of the traffic load on the filling soil deformation when using the traditional method, one pipe in a trench, and a new method, two pipes in a single trench one over the other, for setting up a separate sewer system. The interaction between the buried pipes and the filling soils has been simulated using an elastoplastic FE model. A modified Drucker–Prager cap constitutive model was used to simulate the stress-strain behaviours of the soil. A series of laboratory tests were conducted to identify the elastoplastic properties of the composite soil used to bury the pipes. The FE models were calibrated using a physical lab model for testing the buried pipes under applied load. This allows the FE model to be confidently upgraded to a full-scale model. The pipe-soil interactions were found to be significantly influenced by the soil properties, the method of placing the pipes in the trench and the diameters of the buried pipes. The deformation of the surface soil was decreased by approximately 10% when using the new method of setting up the separate sewer.

Sign in / Sign up

Export Citation Format

Share Document