Inferring the gravitational binding energy and moment of inertia of PSR J0030+0451 and PSR J0740+6620 from new universal relations

The Neutron Star Interior Composition Explorer (NICER) recently simultaneously measured the gravitational mass (Mg) and radius (R) of PSR J0030+0451 and PSR J0740+6620, respectively. Inspired by the groundbreaking observations, we establish two high accuracy universal relations (with the relative error at 1% level) related to Mg and R to infer the gravitational binding energy (Eg) and moment of inertia (I) of the two pulsars. By combining these universal relations with the data of (Mg, R) released by NICER collaboration, the gravitational binding energy and moment of inertia of PSR J0030+0451 can be constrained within |Eg| = 0.21+0.03−0.03M⊙ and I = 1.95+0.70−0.50×1045g cm2at 68% credible level, respectively. The gravitational binding energy and moment of inertia of PSR J0740+6620 can be constrained within |Eg| = 0.47+0.09−0.12M⊙ and I = 4.65+1.16−0.82 × 1045g cm2at 68% credible level, respectively.

Gravitational Lensing and Wormhole Shadows

The problem of bending and scattering of light rays passing outside the entrance of a wormhole with zero gravitational mass is considered. The process of ray capture by a wormhole, as well as the formation process of a shadow when illuminated by a standard screen, is investigated. These mechanisms are also compared to the case of light ray motion in the vicinity of the Schwarzschild black hole.

Maximum baryon masses for static neutron stars in f(R) gravity

We investigate the upper mass limit predictions of the baryonic mass for static neutron stars in the context of f(R) gravity. We use the most popular f(R) gravity model, namely the R2gravity, and calculate the maximum baryon mass of static neutron stars adopting several realistic equations of state and one ideal equation of state, namely that of causal limit. Our motivation is based on the fact that neutron stars with baryon masses larger than the maximum mass for static neutron star configurations inevitably collapse to black holes. Thus with our analysis, we want further to enlighten the predictions for the maximum baryon masses of static neutron stars in R2gravity, which, in turn, further strengthens our understanding of the mysterious mass-gap region. As we show, the baryon masses of most of the equations of states studied in this paper, lie in the lower limits of the mass-gap region M ∼ 2.5 − 5M⊙, but intriguingly enough, the highest value of the maximum baryon masses we found is of the order of M ∼ 3M⊙. This upper mass limit also appears as a maximum static neutron star gravitational mass limit in other contexts. Combining the two results which refer to baryon and gravitational masses, we point out that the gravitational mass of static neutron stars cannot be larger than three solar masses, while based on maximum baryon masses results of the present work, we can conspicuously state that it is highly likely the lower mass limits of astrophysical black holes in the range of M ∼ 2.5 − 3M⊙. This, in turn, implies that maximum neutron star masses in the context of R2gravity are likely to be in the lower limits of the range of M ∼ 2.4 − 3M⊙.

Geological-geotechnical risk mapping of gravitational mass movements in an urban area in Colombo, Brazil

This work presents a geological-geotechnical risk map of gravitational mass movements and a susceptibility map to shallow translational slides to Vila Nova community, located in the municipality of Colombo, Brazil. The first map was created through a qualitative mapping methodology and the second one was elaborated using a deterministic method of slope stability. An aerial photogrammetric survey with UAV technology was performed, as well as field reconnaissance, laboratory testing, and geoprocessing techniques. Seven slope failures were identified as well as a range of other evidences of instability associated with the predisposition of the terrain to erosive and gravitational movements linked to human intervention without urban planning and engineering techniques. Moreover, the qualitative and quantitative analyses pointed out that 13% to 9% of the study area, respectively, are in a very high-risk condition for landslides. Thus, the resulting cartographic products are presented as an important technical contribution for landslide risk management as well as land use planning for reducing the geotechnical problems faced on site.

Stress anisotropy in natural debris flows during impacting a monitoring structure

The frictional resistance of rock and debris is supposed to induce stress anisotropy in the unsteady, non-uniform flow of gravitational mass flows, including debris flows. Though widely used in analytical models and numerical simulation tools, concurrent measurements of stresses in different directions are not yet available for natural flow events. The present study aims to investigate the relation of longitudinal and bed-normal stress exerted by two natural debris flows impacting a monitoring barrier in the Gadria creek, Italy. For that, a force plate in front of a barrier was used to continuously record forces normal to the channel bed, whereas load cells mounted on the vertical wall of the barrier recorded forces in flow direction. We observed an anisotropic stress state during most of the flow events, with stress ratios ranging between 0.1 and 3.5. Video recordings reveal complex deposition and re-mobilization patterns in front of the barrier during surges and highlight the unsteady nature of debris flows. These first-time in-situ measurements confirm the assumption of stress anisotropy in natural debris flows for gravitational mass flows, and provide data for model testing.

Unification of gravitation and electromagnetic force(First Portion)

Since electron has been discovered, people have been thinking it possess one electric charge, the nuclear possess contrary charge. Based on the provided new discovery that moving photons do create force, I have calculated the number Z of elements, discovered that the number Z of elements can be calculated by frequency of x-ray, and the atomic weight can also be calculated by frequency of x-ray. This method of calculated way shows the essence of electric charge, and shows the essence of gravitational mass, from this way, here in first time provide one way show the unification of gravitation and electromagnetic force.

Unification of gravitation and electromagnetic force(First Portion)

Since electron has been discovered, people have been thinking it possess one electric charge, the nuclear possess contrary charge. Based on the provided new discovery that moving photons do create force, I have calculated the number Z of elements, discovered that the number Z of elements can be calculated by frequency of x-ray, and the atomic weight can also be calculated by frequency of x-ray. This method of calculated way shows the essence of electric charge, and shows the essence of gravitational mass, from this way, here in first time provide one way show the unification of gravitation and electromagnetic force.

Modified Gravity and Dark Matter

At present there is a renewed interest in theories of ”modified” gravity. Here, under a more drastic modification enforced by Galilei group, we obtain a completely new gravitational structure, and which exists in addition to the already available general relativity of today. Correlated with this, we show that in addition, there is a new ”modified” quantum mechanics, in as much as it exists as an independent and new ”pure” non-relativistic quantum me- chanics, and which has no relativistic counterpart. This is in addition to the present quantum mechanics, where the relativistic and non-relativistic structures are counterparts of each other. The above holds, firstly due to the correlation between Galilei group and quantum mechanics. These math- ematical conclusions are consolidated by the fact that there exists a physical Majorana interaction between each neutron- proton pairs in nuclei. Galilei invariance of Majorana exchange in Majorana interaction, shows that the mass here is of pure gravitational nature, and which is immune to the other three forces. This makes an amazing connection between the gravitational force and the quantum mechanics. This pure gravitational mass would man- ifest itself as dark matter of the universe. It is our new modified gravity that generates the dark matter.

Application of The AHP Method For Prioritizing Actions To Reduce Risk Associated With Gravitational Mass Movements In Areas Along The Margins of Watercourses of The City of Rio Branco, Brazil.

Problems related to gravitational mass movements at the margins of water courses are present in different parts of the world, but in the Amazon, whose hydrological regime has unique characteristics, and whose socioeconomic situation may be considered as underdeveloped, such problems come into sharp focus. Rotational landslides and creeps on the ground are present with high frequency and magnitude in several municipalities in the Western Amazon. Such processes act in association and annually cause significant losses and material damage. In this context, this study proposes the structuring of a decision-making process that aims to assist in the indication of critical areas, as well as proposing possible actions to mitigate risks. The criteria and procedures adopted for risk-mapping in a portion of the urban center of Rio Branco-AC are described, herein. Risk was measured, based on the multicriteria analysis of attributes related to the physical, anthropic environment and the characteristics of the processes considered. The Hierarchical Analysis Method (AHP), was the technique adopted to structure the risk assessment model, which was later integrated into the GIS environment, to allow spatial analysis. The results were presented in the form of cartograms, descriptive tables and graphs, and aim to help control the mapped risks.