Sökning: "modified gravity"

Visar resultat 1 - 5 av 32 uppsatser innehållade orden modified gravity.

  1. 1. Gravitational Collapse of a Massless Scalar Field in a Theory of Minimally Modified Gravity

    Master-uppsats, KTH/Fysik

    Författare :Atabak Fathe Jalali; [2024]
    Nyckelord :Theoretical physics; astrophysics; modified gravity; minimally modified gravity; gravitational collapse; VCDM; scalar collapse; apparent horizon; numerical relativity; Teoretisk fysik; astrofysik; modifierad gravitation; minimalt modifierad gravitation; gravitationskollaps; VCDM; skalär kollaps; uppenbar horisont; numerisk relativitet;

    Sammanfattning : This thesis explores the spherically symmetric gravitational collapse of a massless scalar field in a minimally modified gravity theory denoted VCDM (V replaces $\Lambda$ in the $\Lambda$CDM abbreviation), a class of theories propagating the same degrees of freedom as general relativity at the expense of broken 4D diffeomorphism invariance. Numerical evolution of the equations of motion reveals that for small initial scalar profile amplitudes, no black hole forms from the collapse. LÄS MER

  3. 2. Gravity water waves over constant vorticity flows: from laminar flows to touching waves

    Master-uppsats, Lunds universitet/Matematik (naturvetenskapliga fakulteten); Lunds universitet/Matematikcentrum

    Författare :Francisco Gonçalves Jorge Dias de Carvalho; [2023]
    Nyckelord :Partial differential equations; Water waves; Euler equations; Free boundary problem; Bifurcation theory; Nonlinear functional analysis; Hilbert transform; Mathematics and Statistics;

    Sammanfattning : In a recent paper, Hur and Wheeler proved the existence of periodic steady water waves over an infinitely deep, two-dimensional and constant vorticity flow and subject to gravity whose profile overhangs, among which, waves whose surface touches at a point, enclosing a bubble of air. We take this further, proving the existence of a continuous curve of water waves from a laminar flow up to a touching wave for fixed non-zero gravity. LÄS MER

  4. 3. Planes of satellite galaxies

    Kandidat-uppsats, Lunds universitet/Astronomi - Genomgår omorganisation

    Författare :Jessica Laura Erika Kocher; [2022]
    Nyckelord :Physics and Astronomy;

    Sammanfattning : The Planes of Satellites Problem is an open question within the field of galaxy formation. It is based on the observations that the Milky Way's satellites, as well as those around the Andromeda (M31) galaxy, align in planes. LÄS MER

  5. 4. Markov Chain Monte Carlo (MCMC) and Bayesian Inference for Gravitational Waves

    Kandidat-uppsats, Lunds universitet/Astronomi - Genomgår omorganisation

    Författare :Christine Andersson; [2021]
    Nyckelord :Gravitational Waves; LISA; LISA mission; Bayesian Inference; Markov Chain Monte Carlo; MCMC; Bayes’ Theorem; stochastic sampling; Metropolis Hastings; histograms; Physics and Astronomy;

    Sammanfattning : The Laser Interferometer Space Antenna (LISA) is a space borne gravitational wave detec- tor set to launch in 2034, with the objective of detecting and studying the Gravitational Waves (GWs) of our universe. So far, ground-based detectors such as the Laser Interferometer Gravitational-Wave Observatory (LIGO) have been successful in detecting GWs, but the limitations of ground based detectors is what makes LISA so special. LÄS MER

  7. 5. Multiple fly-by for interplanetary missions

    Master-uppsats, Luleå tekniska universitet/Rymdteknik

    Författare :Javier Chivite Sierra; [2021]
    Nyckelord :;

    Sammanfattning : Current state-of-the-art of propulsion system for space vehicles does not allow to deliver therequired payload for the mission to all bodies in the Solar System. Therefore, alternatives havebeen developed to reach those bodies without having the necessary technology. LÄS MER