Rastall's theory is based on the nonconservation of energy-momentum tensor. We show that, in this theory, if we introduce a two-fluid model, one component representing vacuum energy whereas other pressureless matter (e.g. baryons plus cold dark matter), cosmological scenario same as for $\ensuremath{\Lambda}\mathrm{CDM}$ both at background and linear perturbation levels, except aspect: now may cluster. speculate that can lead to possibility distinguishing models nonlinear level.

ABSTRACT We test the possibility that black holes (BHs) detected by LIGO-Virgo-KAGRA (LVK) may be cosmologically coupled and grow in mass proportionally to cosmological scale factor some power k, which also act as dark energy source if k ≈ 3. This approach was proposed an extension of Kerr BHs embedded backgrounds possibly without singularities or horizons. In our analysis, we develop apply two methods these (CCBHs) either with connection energy. consider different scenarios for time between...

There are evidences that the cosmic microwave background (CMB) large-angle anomalies imply a departure from statistical isotropy and hence standard cosmological model. We propose $\ensuremath{\Lambda}\mathrm{CDM}$ model extension whose dark energy component preserves its nondynamical character but wields anisotropic vacuum pressure. Exact solutions for scale factors presented, upper bounds deformation parameter evaluated value is estimated considering elliptical universe proposal to solve...

We review the difficulties of generalized Chaplygin gas model to fit observational data, due tension between background and perturbative tests. argue that such issues may be circumvented by means a self-interacting scalar field representation model. However, this proposal seems successful only if has non-canonical form. The latter can implemented in Rastall's theory gravity, which is based on modification usual matter conservation law. show that, besides its application model, other...

We perform a post-Newtonian (PN) solar system analysis for Palatini $f(R)$ theories considering finite volume nonspherical planets and with emphasis to functions that are analytical about $R=0$. First we consider the Will-Nordtvedt parametrized (PPN) formalism, from which metric is shown depend, in general, on terms not covered by standard PPN potentials. Hence, full of PN equations motion performed. From latter conclude that, apart redefinitions internal energy pressure, cannot be...

Abstract Rastall introduced a stress-energy tensor whose divergence is proportional to the gradient of Ricci scalar. This proposal leads change in form field equations General Relativity, but it preserves number degrees freedom. Rastall’s can be either interpreted as GR with redefined SET, or imply different physical consequences inside matter sector. We investigate limits under which directly derived from an action, particular two f ( R )-gravity extensions: $$f(R,\mathcal L_m)$$ <mml:math...

We consider tensor-multiscalar representations for several types of modified gravity actions. The first example is the theory with action representing an arbitrary smooth function scalar curvature $R$ and $\ensuremath{\square}R$, integrand Gauss-Bonnet term square Weyl tensor. present a simple procedure leading to equivalent space-time metric four auxiliary scalars especially discuss calibration cosmological constant condition existence de Sitter-like solutions in case empty universe....

We study, by means of the model proposed in Del Popolo (2009), effect baryon physics on small scale problems CDM model. show that, using this model, cusp/core problem, missing satellite problem (MSP), Too Big to Fail (TBTF) and angular momentum catastrophe can be reconciled with observations. Concerning interaction among dark matter (DM) baryonic clumps 1% mass halo, through dynamical friction (DF), is able flatten inner cusp density profiles. moreover assume that haloes form primarily...

Abstract We investigate the cosmological coupling of spherical, local astrophysical systems. derive a general formula quantifying Misner-Sharp mass these objects. show that, in weak-field limit, is only allowed if there are pressure anisotropies. also apply our results to galaxies, modelling them with Navarro-Frenk-White and Einasto profiles. that galactic can be coupled dynamics examine its dependence on scale factor universe.

ABSTRACT The population of compact objects both Galactic and extragalactic can now be studied verified observationally with increasing efficiency, the latter thanks to detection object mergers through gravitational waves. formation channels merging binaries are, however, not yet fully understood, may even vary over cosmic time. We address this problem a synthesis approach, including BOSSA, new initial sampling code, deal variation conditions evaluate its consequences.

Este artigo trata-se de um estudo do tipo Revisão Literatura, cujo objetivo é reunir e analisar publicações científicas sobre as Mudanças Climáticas Doenças Tropicais em Manaus: Desafios para a Enfermagem na Prevenção Cuidado. A metodologia adotada visa proporcionar uma visão ampla atualizada o tema, com base evidências publicadas. Para coleta dados, foram selecionados artigos disponíveis nas bases Scientific Electronic Library Online (SCIELO), Literatura Latino-Americana Ciências da Saúde...

We consider the application of quantum corrections computed using renormalization group arguments in astrophysical domain and show that, for most natural interpretation scale parameter, a gravitational coupling parameter G varying 10−7 its value across galaxy (which is roughly variation 10−12 per light-year) sufficient to generate rotation curves agreement with observations. The quality resulting fit similar Isothermal profile once both shape curve mass-to-light ratios are considered...

We develop and apply new techniques in order to uncover galaxy rotation curves (RC) systematics. Considering that an ideal dark matter (DM) profile should yield RCs have no bias towards any particular radius, we find the Burkert DM satisfies test, while Navarro-Frenk-While (NFW) has a tendency of better fitting region between one two disc scale lengths than inner length region. Our sample indicates this behaviour happens more 75% galaxies fitted with NFW halo. Also, does not weaken by...

We show that a class of bigravity theories contain solutions describing dark matter. A particular member this is also shown to be equivalent the Eddington-Born-Infeld gravity, recently proposed as candidate for Bigravity have cosmological de Sitter backgrounds and we find interpolating between matter acceleration eras.

The N-body dark matter (DM) simulations point that DM density profiles, e.g. the NFW halo, should be cuspy in its center, but observations disfavour this kind of profile. Here we consider whether observed rotation curves "close" to galactic centre can favour modified gravity models comparison and how quantify such difference. Two explicit are considered, MOND a more recent approach called RGGR (in reference Renormalization Group effects General Relativity). It is also purpose work...

The Radial Acceleration Relation (RAR) shows a strong correlation between two accelerations associated to galaxy rotation curves. relation these is given by nonlinear function which depends on an acceleration scale $a_\dagger$. Some have interpreted this as evidence for gravity model, such Modified Newtonian Dynamics (MOND), posits fundamental $a_0$ common all the galaxies. However, it was later shown, using Bayesian inference, that seems not be case: credible intervals individual galaxies...

We show that Renormalization Group extensions of the Einstein-Hilbert action for large scale physics are not, in general, a particular case standard Scalar-Tensor (ST) gravity. present new class ST actions, which potential is not necessarily fixed at level, and this extended theory formally contains case. also propose here setting identification explicitly covariant valid arbitrary relativistic fluids.

Palatini [Formula: see text] gravity is probably the simplest extension of general relativity (GR) and realization a metric-affine theory. It has same number degrees freedom as GR and, in vacuum, it straightforwardly mapped into with cosmological constant. The mapping between inside matter possible but at expense reinterpreting meaning fields. physical consequences such will depend on context. Here, we consider three cases within weak field limit: solar system dynamics, planetary internal...

There are some approaches, either based on General Relativity (GR) or modified gravity, that use galaxy rotation curves to derive the matter density of corresponding galaxy, and this procedure would indicate a partial complete elimination dark in galaxies. Here we review these clarify difficulties inverted procedure, present method for evaluating them, it test two specific approaches GR: Cooperstock-Tieu (CT) Balasin-Grumiller (BG) approaches. Using new method, find neither tested can...

Massive Brans-Dicke (BD) theory is among the simplest general relativity extensions. It commonly found as weak-field limit of other gravitational theories. Here we do a detailed post-Newtonian analysis massive BD We start by expanding field equations following Will-Nordtvedt parametrized (PPN) formalism, without point-particle approximations. A single potential that not present in standard PPN formalism found. This new hinders immediate conclusions. To proceed, complete first-order and...