A5036905644- Cosmology and Gravitation Theories
- Black Holes and Theoretical Physics
- Pulsars and Gravitational Waves Research
- Geophysics and Gravity Measurements
- Relativity and Gravitational Theory
- Galaxies: Formation, Evolution, Phenomena
- Advanced Differential Geometry Research
- Gamma-ray bursts and supernovae
- Solar and Space Plasma Dynamics
- Radio Astronomy Observations and Technology
- Particle physics theoretical and experimental studies
- Ionosphere and magnetosphere dynamics
- Astrophysical Phenomena and Observations
- Geophysics and Sensor Technology
- Dark Matter and Cosmic Phenomena
- Atmospheric Ozone and Climate
- Geomagnetism and Paleomagnetism Studies
- Quantum Electrodynamics and Casimir Effect
- Radio Wave Propagation Studies
- Advanced Frequency and Time Standards
- Environmental Sustainability and Education
- Engineering Education and Technology
- Engineering and Environmental Studies
- High-Energy Particle Collisions Research
- Noncommutative and Quantum Gravity Theories
Universidade Estadual Paulista (Unesp)
2015-2024
National Institute for Space Research
2007-2022
Universidade Federal de Itajubá
2011-2013
Academy of Athens
2011
There is a host of alternative theories gravitation in the literature, among them $f(R,T)$ recently elaborated by Harko and collaborators. In these $R$ $T$ are respectively Ricci scalar trace energy momentum tensor. already literature series studies different forms functions as well their cosmological consequences. However, there not so far related to gravitational waves gravity. Here we consider such an issue, particular studying putative extra polarization models that can appear theories....
The direct observation of gravitational waves (GW) in the near future, and corresponding determination number independent polarizations, is a powerful tool to test general relativity alternative theories gravity. In present work we use Newman–Penrose formalism characterize GWs quadratic gravity particular class f(R) Lagrangians. We find that both theory belong most invariant GWs, i.e., they can up six polarizations GWs. For combination parameters, five states. On other hand, if Palatini...
The direct observation of gravitational waves will provide a unique tool for probing the dynamical properties highly compact astrophysical objects, mapping ultrarelativistic regions space-time, and testing Einstein's general theory relativity. LISA (Laser Interferometer Space Antenna), joint National Aeronautics Administration European Agency mission to be launched in next decade, perform these scientific tasks by detecting studying low-frequency cosmic through their influence on phases six...
The direct detection of gravitational waves (GWs) opened a new chapter in the modern cosmology to probe possible deviations from general relativity (GR) theory. In present work, we investigate for first time modified GW form propagation inspiraling compact binary systems within context $f(T)$ gravity order obtain forecasts/constraints on free parameter First, show that waveform differs GR essentially due induced corrections GWs amplitude. Then, discuss forecasts assuming simulated sources as...
We investigate the propagation of primordial gravitational waves within context Horndeski theories; for this, we present a generalized transfer function quantifying subhorizon evolution wave modes after they enter horizon. compare theoretical prediction modified spectral density with aLIGO, Einstein telescope, LISA, gLISA and DECIGO sensitivity curves. Assuming reasonable different values free parameters theory (in agreement event GW170817 stability conditions theory), note that amplitude...
Pulsar timing experiments aimed at the detection of gravitational radiation have been performed for decades now. With forthcoming construction large arrays capable tracking multiple millisecond pulsars, it is very likely we will be able to make first in nano-Hertz band, and test Einstein's theory relativity by measuring polarization components detected signals. Since a wave predicted most general relativistic metric gravity accounts six modes (the usual two tensor polarizations as well...
Here we present a status report of the Schenberg antenna. In past three years it has gone to radical upgrading operation, in which have been installing 1K pot dilution refrigerator, cabling and amplifiers for nine transducer circuits, designing new suspension vibration isolation system microstrip antennas, developing full set transducers, oscillators. We are also studying an innovative approach, could transform into broadband gravitational wave detector.
Here we present a status report of the first spherical antenna project equipped with set parametric transducers for gravitational detection. The Mario Schenberg, as it is called, started its commissioning phase at Physics Institute University São Paulo, in September 2006, under full support FAPESP. We have been testing three preliminary transducer systems order to prepare detector next cryogenic run, when will be calibrated. are also developing sapphire oscillators that replace current ones...
Cosmological Gravitational Waves (GWs) are usually associated with the transverse-traceless part of metric perturbations in context theory cosmological perturbations.These modes just usual polarizations '+' and '×' which appear general relativity theory.However, majority alternative theories gravity, GWs can present more than these two polarization states.In this context, Newman-Penrose formalism is particularly suitable for evaluating number non-null GW modes.In work we intend to take into...
The determination of the polarization modes gravitational waves (GWs) and their dispersion relations is a crucial task for scrutinizing viability extended theories gravity. A tool to investigate states GWs well-known formalism developed by Eardley, Lee, Lightman [Phys. Rev. D 8, 3308 (1973).] which uses Newman-Penrose (NP) coefficients determine content in metric However, if speed smaller than light, number NP greater polarizations. To overcome this inconvenience we use Bardeen describe six...
We discuss the dynamics of Universe within framework massive graviton cold dark matter scenario (MGCDM) in which gravitons are geometrically treated as particles. In this modified gravity theory, main effect is to alter density evolution component such a way that evolves an accelerating expanding regime, presently observed. Tight constraints on cosmological parameters MGCDM model derived by performing joint likelihood analysis involving recent supernovae type Ia data, cosmic microwave...
An unified cosmological model for an Universe filled with a mass dimension one (MDO) fermionic field plus the standard matter fields is considered. After primordial quantum fluctuation slowly rolls down to bottom of symmetry breaking potential, driving inflationary regime that increases scale factor about 71 e-folds. end inflation, starts oscillate and can transfer its energy particles through reheating mechanism. Such process briefly discussed in terms admissible couplings MDO...
Abstract Problems with the concordance cosmology $$\Lambda $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mi>Λ</mml:mi> </mml:math> CDM as cosmological constant problem, coincidence problems and Hubble tension has led to many proposed alternatives, (t)$$ <mml:mrow> <mml:mo>(</mml:mo> <mml:mi>t</mml:mi> <mml:mo>)</mml:mo> </mml:mrow> CDM, where now called term is allowed vary due an interaction pressureless matter. Here, we analyze one class of these proposals, namely,...
Abstract The near‐Earth interplanetary environment conditions affect the dynamics of relativistic electron population quasitrapped in radiation belts. A complex chain processes observed magnetosphere can contribute to variability these populations when structures, such as counterpart a solar coronal mass ejection (ICME), and high‐speed wind streams interact with magnetosphere. However, coexist, it is hard untangle relative contribution each process loss particles eventual repopulation. Here...
We analyze the trajectories of three geostationary satellites forming GEOstationary GRAvitational Wave Interferometer (GEOGRAWI)~\cite{tinto}, a space-based laser interferometer mission aiming to detect and study gravitational radiation in ($10^{-4} - 10$) Hz band. The combined effects gravity fields Earth, Sun Moon make deviate from their nominally stationary, equatorial equilateral configuration. Since changes relative distances orientations could negatively affect precision heterodyne...
Theories of gravity for which gravitons can be treated as massive particles have presently been studied realistic modifications General Relativity, and tested with cosmological observations. In this work, we study the ability a recently proposed theory gravitons, so-called Visser theory, to explain measurements luminosity distance from Union2 compilation, most recent Type-Ia Supernovae (SNe Ia) dataset, adopting current ratio total density non-relativistic matter critical ($\Omega_m$) free...
It is believed that soon after the Planck era, spacetime should have a semi-classical nature. Therefore, it unavoidable to modify theory of general relativity or look for alternative theories gravitation. An interesting possibility found in literature considers two geometric counter-terms regularize divergences effective action. These are responsible higher-order derivative metric In present paper, we investigate how isotropization occurs. For this reason single solution chosen throughout...
Among the various possibilities to probe theory behind recent accelerated expansion of universe, energy conditions (ECs) are particular interest, since it is possible confront and constrain many models, including different theories gravity, with observational data. In this context, we use ECs any alternative whose extra term acts as a cosmological constant. For purpose, apply model-independent approach reconstruct universe. Using Type Ia supernova, baryon acoustic oscillations...