Temperature Of Background Radiation Research Articles

Relativity with Hubble Constant as Velocity Equivalent of Position

Based on a plain belief that the cosmic space should be a unified whole with universal connection, rather than a patchwork of unconnected domain blocks, we reassess Hubble law as a short-range characterization of electromagnetic interaction and Hubble constant as velocity equivalent of position. If so, it is necessary to develop a matching transformation to work for relativity, which can ensure that the causal chain is not broken and the physical description is complete. To this end, we unify space and motion into a full-velocity concept and reshape Minkowski space into a pseudo-Minkowski one confined by an unreachable physical horizon. In the reshaped, all parts are physically allowed for unobstructed communication with each other, and the transformation that keeps physical laws including Hubble law invariant, is full-velocity Lorentz transformation, under which length contraction, time dilation and historization effect are discussed. Meanwhile, as a static solution of Einstein equation, the pseudo-Minkowski universe not only can reproduce the effective results of expansion model, but also derive the background radiation temperature and Hubble constant, etc.. Especially, it provides an analytic solution of gravitational field around mass without the singularity of event horizon.

The history of the Cosmos: Implications for the Hubble tension

Abstract In 2007, Storti predicted that the value of the cosmic microwave background radiation (CMBR) temperature may be improved: from the particle data group (PDG) value of [T 0 = 2.725 ± 0.001 K] to [T 0 = 2.7254 K]. In 2011, the PDG revised their value of CMBR to [T 0 = 2.7255 ± 0.006 K]. In 2008, Storti predicted a ΛCDM Hubble constant of [H 0 = 67.0843 km/s/Mpc]. In the same year, the PDG published their value as being [H 0 = 73 ± 3 km/s/Mpc]. In 2013, the PDG published a revised value of [H 0] as being considerably lower [H 0 = 67.3 ± 1.2 km/s/Mpc]. These predictions and experimental confirmations, in particular the value of [H 0] being successfully predicted 5 years in advance of the Planck collaboration and without Planck satellite instrumentation, demonstrate the power of the technique applied. We utilize the same technique to calculate the present values of ΛCDM [H 0], [ΩΛ], [ΩM], [q], and [Λ]. Subsequently, we describe the complete history of the cosmos from the instant of the Big Bang to the present epoch, in complete agreement with the standard model of cosmology. Moreover, we explicitly demonstrate that the Hubble tension does not exist, in a companion publication to this research article. This is achieved by utilizing a single equation to calculate both values of Hubble constant associated with the Hubble tension.

Indoor non-uniform environmental characteristics of local convection heating and its background radiation field correction

Insufficient partial heating based on the actual thermal demand of people or spaces becomes a revolutionary approach to reducing energy consumption. However, current research on local heating is case-specific and lacks standardized and unified guidelines for describing the formation of non-uniform indoor environments. In this paper, the local temperature imbalance rate and Part-Air Diffusion Performance Index (P-ADPI) parameters are proposed for multidimensional evaluation of indoor non-uniform environment characteristics. On the basis of the characteristic parameters, a unified indoor environment characterization partition was performed in the study. The results indicate that an increase in air supply temperature and air supply velocity could enlarge the characteristic core area and transition area. The intervention of background radiation conditions could intensify the inhomogeneity of the indoor environment, but it would have a minimal impact on the classification of the environment. The background radiation condition was incorporated into the characteristic boundary function model as a correction factor, and the correction factors for determining the background radiation temperature, position and the area fall within the ranges of 0.97–1.44, 0.82–1.01 and 0.98–1.10. This study has provided the groundwork for future studies on the local convection heating and the creation of a non-uniform indoor environment.

Temperature anisotropy of the CMBR and the nonzero cosmological constant

In this article, we analyze the effect of a spherically symmetrical clump on the anisotropy of the cosmic microwave background radiation temperature in the framework of the standard model of cosmology with a nonzero cosmological constant [Formula: see text] and we show that it weakens the Rees–Sciama effect.

Comparing the scalar-field dark energy models with recent observations

We focus on a class of scalar-field dark energy models (i.e., ϕCDM models) which behave like cosmological trackers at early times, and investigate the general properties of them. Particularly, we choose three ϕCDM models with typical potentials, i.e., V(ϕ)∝ϕ−α (inverse power-law (IPL) model), V(ϕ)∝cothαϕ (L-model) and V(ϕ)∝cosh(αϕ) (Oscillatory tracker model), where the latter two models are based on the α-attractors originated from the study of inflation. These models, which reduce to the ΛCDM model with α→0, are studied and compared with the recent observations, including the Pantheon sample of type Ia supernovae (SNe Ia), baryon acoustic oscillations (BAO) measurements extracted from 6dFGS, BOSS and eBOSS, as well as the temperature and polarization anisotropy power spectra data of cosmic microwave background radiation (CMB) from Planck 2018 results. The observational constraints from the combining sample (SNe Ia + BAO + CMB) indicate that none of the three ϕCDM models exclude the ΛCDM model at 68.3% confidence level. We find that the CMB anisotropy data have obvious advantages in constraining the dark energy models compared with other cosmological probes, which is particularly evident in the L-model. Furthermore, we apply the Bayesian evidence to compare the ϕCDM models and the ΛCDM model with the analysis of the combining sample. The concordance ΛCDM model is still the most supported one. In addition, among the three ϕCDM models, the IPL model is the most competitive one, while the L-model/Oscillatory tacker model is moderately/strongly disfavored.

Speeds of Wave Propagation in Ideal Gaseous Molecular and Neutrino Media.

The neutrino mass values extracted from the pioneering Nobel Prize winning measurements of Kajita and co-workers at Superkamiokande were used in the classical Newton-Laplace equation for computing the speed of propagation of acoustic waves in gases comprising neutrinos. It is found that, surprisingly, acoustic waves in the lightest neutrino environments proceed with the speed of light in vacuum, c. This allows for the computation of c in terms of the lightest neutrino mass within 1% and is consistent with the fact that gravitational waves have been recently found to propagate with the speed of light. It is also found that the rest energy, m1c2, of the lightest neutrinos coincides with the photon energy at the cosmic background radiation temperature (CMBR). These findings are discussed in terms of the dual nature of photons and its possible interrelation with the omnipresent neutrinos. The present results also confirm that neutrino gases behave as ideal gases with only one-half of a translational degree of freedom, consistent with their one-dimensional, and practically one-directional, degree of freedom.

Summation over the gravitational instantons and the temperature of the cosmic background radiation

In this paper, the contributions of gravitational instantons to the temperature of the cosmic background radiation are evaluated. The comoving number density in the radiation-dominated and matter-dominated eras is derived. In addition to the temperature resulting from expansion of the universe, the mass of the microscopic black holes required to create the thermal energy of the cosmic microwave background radiation is derived.

Deep learning of CMB radiation temperature

Focusing on an astrophysical scenario based on the variable polytropic gas (VPG) model, we mainly discuss evolution of the cosmic microwave background (CMB) radiation temperature from deep learning (DL) perspective. To reach this aim, we start with reconstructing a new formulation for the temperature-red shift relation of the CMB photons. Subsequently, with help of some astrophysical measurements given in literature for galaxy cluster and quasar samples, we obtain the best-fitting values of free model parameters via the genetic neural network (GNN) mechanism. Since, there is an important shortcoming for the GNN algorithm (it does not directly calculate the corresponding error on the derived best-fit value of a free parameter), we use the Fisher information matrix (FIM) approach to handle this issue. Finally, with the help of a DL algorithm including not only the long short-term memory (LSTM) cell approach but also the Dropout tool, which can remove the over-fitting problem raised in a DL study, we investigate an other numerical feature of our theoretical formulation from the machine learning perspective.

Evolution of CMB temperature in a Chaplygin gas model from deep learning perspective

Evolution of the cosmic microwave background (CMB) radiation temperature is investigated in the context of modified generalized Chaplygin gas (mgCG) model with a Deep Neural Network (DNN) analysis. First, we reconstruct a new formulation for the temperature-red shift relation of the CMB photons and then find out the best-fitting values of the arbitrary parameters introduced in the model via the help of a neural network mechanism including the genetic algorithm (GA) and the Fisher information matrix (FIM) approach (we name this mechanism as the genetic Fisher algorithm or shortly the GFA) by considering astrophysical measurements given in literature for some galaxy cluster and quasar samples. Subsequently, we apply the long short-term memory plus Dropout (LSTMD) neural network approach, which is emerging as a solution for problematic issues in the DNN investigations (e.g. the over-fitting), to well-known astrophysical parameters. In view of the presented conclusions, the whole mechanism comes forward as a new up and coming step on how one can cultivate a new neural network that can calculate its own confidence region. In addition to this, it is significant to emphasize here that the promising approach helps to decrease the computational load of pricey codes for astrophysical models and probes the necessity of alternative CMB radiation temperature models. As a result, we prove that the fitted form of our model is in very good agreement with the observational data. • We constructed a new theoretical model for the evolution CMB radiation temperature. • New model was fitted by making use of the recent observational data. • The fitting process was improved with the help of deep learning analysis. • The fitted model agrees with the current experimental data and the Λ CDM cosmology. • We showed that deep learning algorithms can take crucial roles in astrophysics.

Pentagonal prism spherical hohlraums for OMEGA

A new configuration is proposed for spherical hohlraums on OMEGA in which seven laser entrance holes (LEHs) are used—five around the equator and one at each pole [Farmer et al., Phys. Plasmas 26, 032701 (2019)]. This is known as the PEPR (pentagonal prism) hohlraum. A new view-factor code LORE is used to model the PEPR hohlraum and compare its performance with tetrahedral hohlraums shot on OMEGA. With optimization of beam pointings, the PEPR hohlraum produces a nonuniformity ranging from 1.1% (rms) at low albedos to 0.6% at high albedos. The tradeoffs between hohlraum-to-capsule ratio, uniformity, and background radiation temperature have been explored, and it has been shown that larger LEH radii on the poles can result in a modest improvement in uniformity. The seven-hole PEPR hohlraum is well matched to the OMEGA symmetry and promises to provide insight into the performance of spherical hohlraums including octahedral (six-LEH) hohlraums.

Cosmological constraints on Hořava gravity revised in light of GW170817 and GRB170817A and the degeneracy with massive neutrinos

We revise the cosmological bounds on Ho\v{r}ava gravity taking into accounts the stringent constraint on the speed of propagation of gravitational waves from GW170817 and GRB170817A. In light of this we also investigate the degeneracy between massive neutrinos and Ho\v{r}ava gravity. We show that a luminal propagation of gravitational waves suppresses the large-scale Cosmic Microwave Background (CMB) radiation temperature anisotropies and the presence of massive neutrinos increases this effect. On the contrary large neutrinos mass can compensate the modifications induced by Ho\v{r}ava gravity in the lensing, matter and primordial B-mode power spectra. Another degeneracy is found, at theoretical level, between the tensor-to-scalar ratio $r$ and massive neutrinos as well as with the model's parameters. We analyze these effects using CMB, supernovae type Ia (SNIa), galaxy clustering and weak gravitational lensing measurements and we show how such degeneracies are removed. We find that the model's parameters are constrained to be very close to their General Relativity limits and we get a two orders of magnitude improved upper bound, with respect to the Big Bang Nucleosynthesis constraint, on the deviation of the effective gravitational constant from the Newtonian one. The deviance information criterion suggests that in Ho\v{r}ava gravity $\Sigma m_\nu>0$ is favored when CMB data only are considered, while the joint analysis of all datasets prefers zero neutrinos mass.

World-Universe Model Predictions

In 2013, World-Universe Model (WUM) proposed a principally different way to solve the problem of Newtonian Constant of Gravitation measurement precision. WUM revealed a self-consistent set of time-varying values of Primary Cosmological parameters of the World: Gravitation parameter, Hubble’s parameter, Age of the World, Temperature of the Microwave Background Radiation, and the concentration of Intergalactic plasma. Based on the inter-connectivity of these parameters, WUM solved the Missing Baryon problem and predicted the values of the following Cosmological parameters: gravitation G, concentration of Intergalactic plasma, relative energy density of protons in the Medium, and the minimum energy of photons, which were experimentally confirmed in 2015-2018. Between 2013 and 2018, the relative standard uncertainty of G measurements decreased x6. The set of values obtained by WUM was recommended for consideration in CODATA Recommended Values of the Fundamental Physical Constants 2014.

Arrays of Annular Antennas With SINIS Bolometers

For improving the dynamic range and sensitivity at high power load, we have integrated superconductor-insulator-normal metal-insulator-superconductor (SINIS) bolometers with a frequency selective surface (FSS)-based distributed absorber formed by a series and parallel array consisting of 25 annular antenna elements, each containing two SINIS bolometers. By using a design with 50 bolometers, we reduce incident power load on each bolometer, increase sensitivity and saturation power which is important for ground-based and balloon-borne telescopes with high background power loads. Our main detector pixel is optimized for a frequency band centered at 345GHz. The detectors are matched to incoming telescope beam by a back-to-back horn with a back reflector. Such a configuration improves both the efficiency and the bandwidth of the receiver. Measured voltage responsivity approaches 210(9) VW with an amplifier-limited voltage noise of 20nVHz(12), which corresponds to a NEP 10(-17) WHz(12). The linear voltage response for incoming power is observed for absorbed power of about 5 pW. The current responsivity for parallel array is 210(4) AW and the shot noise limited intrinsic noise equivalent power is NEP 510(-18)WHz(12). The noise equivalent temperature difference is NETD 100 KHz(12) at 2.7-K background radiation temperature.

APD optimal bias voltage compensation method based on machine learning

The signal-to-noise ratio (SNR) of avalanche photodiode (APD) in optical detection system is greatly influenced by background radiation and operating temperature, so an APD optimal bias voltage compensation method based on machine learning is designed to accurately judge the current laser emission state and APD working state so that dichotomy compensation can be carried out to make APD work in optimal state. By means of cross-verification, the accuracy of judging laser emission state and APD working state is as high as 100% and 99.3% separately, then the number of input variables in the model is reduced appropriately by experiment and the prediction speed of the algorithm is further improved. Finally, road detection application is taken as the experimental background and comparison between the proposed method and the most widely used signal amplitude feedback compensation method is carried out. The results of this study suggest that the proposed APD optimal bias voltage compensation method based on machine learning offers a new and promising approach.

The Possibility of Converting Energy in Space with the Aid of a Chain Heat Machine Operating on Methane and Nitrogen

An analysis has been made of the useful mechanical work done in space with the aid of a heat machine, in which the working body consists of liquids with a superlow boiling temperature (methane and nitrogen). The use of nitrogen and methane is facilitated by the low temperature of the cosmic background radiation making it possible to cool nitrogen and methane to very low temperatures. The investigation is carried out on the basis of modeling the chain heat machine consisting of two units. The setting of the stationary regime of machine operation takes several hours. The scattering of energy into the outer space requires a condenser of large area.

On the possible enhancement of the global 21-cm signal at reionization from the decay of cosmic string cusps

We consider cosmic string cusp annihilations as a possible source of enhancement to the global background radiation temperature in 21-cm photons at reionization. A soft photon spectrum is induced via the Bremsstrahlung and Synchrotron emission of electrons borne out of QCD jets formed off the cusp. The maximal energy density background comes from synchrotron induced photons with a string tension of Gμ ∼ 10−18. In this instance, the radiation background at reionization is heated up by 5 · 10−3 K. We find that the depth of the absorption trough (δ Tb) in 21-cm at reionization is altered by one part in 104 from the strings, requiring high precision measurements to be detectable. This mechanism cannot explain the δ Tb observed by the EDGES experiment.

An absorption profile centred at 78 megahertz in the sky-averaged spectrum.

After stars formed in the early Universe, their ultraviolet light is expected, eventually, to have penetrated the primordial hydrogen gas and altered the excitation state of its 21-centimetre hyperfine line. This alteration would cause the gas to absorb photons from the cosmic microwave background, producing a spectral distortion that should be observable today at radio frequencies of less than 200 megahertz. Here we report the detection of a flattened absorption profile in the sky-averaged radio spectrum, which is centred at a frequency of 78 megahertz and has a best-fitting full-width at half-maximum of 19 megahertz and an amplitude of 0.5 kelvin. The profile is largely consistent with expectations for the 21-centimetre signal induced by early stars; however, the best-fitting amplitude of the profile is more than a factor of two greater than the largest predictions. This discrepancy suggests that either the primordial gas was much colder than expected or the background radiation temperature was hotter than expected. Astrophysical phenomena (such as radiation from stars and stellar remnants) are unlikely to account for this discrepancy; of the proposed extensions to the standard model of cosmology and particle physics, only cooling of the gas as a result of interactions between dark matter and baryons seems to explain the observed amplitude. The low-frequency edge of the observed profile indicates that stars existed and had produced a background of Lyman-α photons by 180 million years after the Big Bang. The high-frequency edge indicates that the gas was heated to above the radiation temperature less than 100 million years later.

MeV dark matter complementarity and the dark photon portal

We discuss the phenomenology of an MeV-scale Dirac fermion coupled to the Standard Model through a dark photon with kinetic mixing with the electromagnetic field. We compute the dark matter relic density and explore the interplay of direct detection and accelerator searches for dark photons. We show that precise measurements of the temperature and polarization power spectra of the Cosmic Microwave Background Radiation lead to stringent constraints, leaving a small window for the thermal production of this MeV dark matter candidate. The forthcoming MeV gamma-ray telescope e-ASTROGAM will offer important and complementary opportunities to discover dark matter particles with masses below ∼ 10 MeV . Lastly, we discuss how a late-time inflation episode and freeze-in production could conspire to yield the correct relic density while being consistent with existing and future constraints.

Cosmic transparency and acceleration

In this paper, by considering an absorption probability independent of photon wavelength, we show that current type Ia supernovae (SNe Ia) and gamma ray burst (GRBs) observations plus high-redshift measurements of the cosmic microwave background (CMB) radiation temperature support cosmic acceleration regardless of the transparent-universe assumption. Two flat scenarios are considered in our analyses: the $\Lambda$CDM model and a kinematic model. We consider $\tau(z)=2\ln(1+z)^{\varepsilon}$, where $\tau(z)$ denotes the opacity between an observer at $z=0$ and a source at $z$. This choice is equivalent to deforming the cosmic distance duality relation as $D_LD^{-1}_A = (1 + z)^{2+\varepsilon}$ and, if the absorption probability is independent of photon wavelength, the CMB temperature evolution law is $T_{CMB}(z)=T_0(1+z)^{1+2\varepsilon/3 }$. By marginalizing on the $\varepsilon$ parameter, our analyses rule out a decelerating universe at 99.99 \% c.l. for all scenarios considered. Interestingly, by considering only SNe Ia and GRBs observations, we obtain that a decelerated universe indicated by $\Omega_{\Lambda} \leq 0.33$ and $q_0 > 0$ is ruled out around 1.5$\sigma$ c.l. and 2$\sigma$ c.l., respectively, regardless of the transparent-universe assumption.

Note on the initial conditions within the effective field theory approach of cosmic acceleration

By using the effective field theory approach, we investigate the role of initial condition for the dark energy or modified gravity models. In details, we consider the constant and linear parametrization of the effective Newton constant models. Firstly, under the adiabatic assumption, the correction from the extra scalar degree of freedom in the beyond $\Lambda$CDM model is found to be negligible. The dominant ingredient in this setup is the primordial curvature perturbation originated from inflation mechanism, and the energy budget of the matter components is not very crucial. Secondly, the iso-curvature perturbation sourced by the extra scalar field is studied. For the constant and linear model of the effective Newton constant, there is no such kind of scalar mode exist. For the quadratic model, there is a non-trivial one. However, the amplitude of the scalar field is damped away very fast on all scales. Consequently, it could not support a reasonable structure formation. Finally, we study the importance of the setup of the scalar field starting time. By setting different turn-on time, namely $a=10^{-2} $ and $a=10^{-7} $, we compare the cosmic microwave background radiation temperature, lensing deflection angle auto-correlation function as well as the matter power spectrum in the constant and linear model. We find there is an order of $\mathcal{O}(1\%)$ difference in the observable spectra for constant model, while for the linear model, it is smaller than $\mathcal{O}(0.1\%)$.