Sökning: "black hole"

Visar resultat 1 - 5 av 84 uppsatser innehållade orden black hole.

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. The visibility of stellar transients in the Galactic Centre

   Kandidat-uppsats, Lunds universitet/Fysiska institutionen; Lunds universitet/Astrofysik

   Författare :Jonathan Ström; [2024]
   Nyckelord :Physics and Astronomy;

   Sammanfattning : A semi-analytical simulation was developed to evaluate the K-band magnitudes of Red Giants [0.96 - 1.02 M⊙] orbiting the supermassive black hole in the galactic centre. The model assumed star formation between 10-12 Gyrs ago and by following the IMF and applying a random age condition, a stellar population was created. LÄS MER

4. 3. The black hole information paradox and holography

   Master-uppsats, Uppsala universitet/Teoretisk fysik

   Författare :Ona Mola Bertran; [2023]
   Nyckelord :information paradox; semiclassical physics; holography; AdS CFT correspondence; island formula; entanglement entropy;

   Sammanfattning : Hawking theorized in 1974 that black holes emit particles as a quantum effect. It follows from this fact that a black hole that emits particles while absorbing none ends up evaporating. The process of black hole evaporation studied from semiclassical gravity violates quantum mechanics leading to serious problems. LÄS MER

5. 4. Cosmological Horizons and the Unruh Effect

   L3-uppsats, Uppsala universitet/Teoretisk fysik

   Författare :Niklas Engelhardt Önne; [2023]
   Nyckelord :Unruh effect; quantum scalar fields; Bogoliubov transformations; accelerated observers; Minkowski spacetime; cosmological horizons; Rindler observers; special relativity; QFT; Unruh-effekten; skalära kvantfält; Bogoliubov-transformationer; accelererande referenssystem; Minkowski rumtid; kosmologiska horisonter; Rindlerobservatörer; speciell relativitetsteori; QFT;

   Sammanfattning : The black hole information paradox, which states that the evaporation of black holes due to Hawking radiation results in a violation of the conservation of quantum information, is arguably one of the most fundamental problems in all of modern physics. Through the equivalence principle, the essence of the problem can be understood and studied in the context of much simpler flat spacetime (described by the theory of special relativity); in this context the Hawking radiation takes the form of the so-called Unruh effect, a thermal effect in the vacuum of a Minkowski quantum field theory that can be measured by accelerated observers. LÄS MER

7. 5. Intermediate-mass black hole binary as an origin of super-massive black holes

   Kandidat-uppsats, Lunds universitet/Astrofysik; Lunds universitet/Fysiska institutionen

   Författare :Isabelle Signe Maj Maria Thord; [2023]
   Nyckelord :Intermediate-mass black holes; binary; merger; hardening; encounters; Physics and Astronomy;

   Sammanfattning : Galactic nuclei contain super-massive black holes (SMBHs), nuclear stellar clusters (NSCs), or both. In the NSC, intermediate-mass black holes (IMBHs) are likely to reside and form highly eccentric binaries. Over time, the orbit of a binary could harden via interaction with surrounding low-mass stars. LÄS MER