Browsing Astronomy and Astrophysics by Title
Now showing items 120-139 of 195
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Observational Constraints on the Completeness of Space near Astrophysical Objects
We consider the observational effects of a deficit angle, w, in the topology of the solar system and in the 'double pulsar' system PSR J0737-3039A/B. Using observations of the perihelion precession of Mercury, and the ... -
Observational Cosmology in Macroscopic Gravity
We discuss the construction of cosmological models within the framework of Macroscopic Gravity (MG), which is a theory that models the effects of averaging the geometry of space-time on large scales. We find new exact ... -
On -symmetric Fixed Points and Superconformality
(2011-05) -
On Regular Hypergraphs of High Girth
(2014-03-10)We give lower bounds on the maximum possible girth of an r-uniform, d-regular hypergraph with at most n vertices, using the definition of a hypergraph cycle due to Berge. These differ from the trivial upper bound by an ... -
On the absence of the usual weak-field limit, and the impossibility of embedding some known solutions for isolated masses in cosmologies with f(R) dark energy
(2012-10-02)The problem of matching different regions of spacetime in order to construct inhomogeneous cosmological models is investigated in the context of Lagrangian theories of gravity constructed from general analytic functions ... -
On the Emergence of Accelerating Cosmic Expansion in f(R) Theories of Gravity
We consider cosmological modelling in $f(R)$ theories of gravity, using both top-down and bottom-up constructions. The top-down models are based on Robertson-Walker geometries, and the bottom-up constructions are built by ... -
On the superconformal index of Argyres–Douglas theories
(2016-01-08) -
Opto-mechanical design of a new cross dispersion unit for the CRIRES+ high resolution spectrograph for the VLT
(2014-01-01)© 2014 SPIE. CRIRES is one of the few IR (0.92-5.2 μm) high-resolution spectrographs in operation at the VLT since 2006. Despite good performance it suffers a limitation that significantly hampers its ability: a small ... -
The Parameterised Post-Newtonian Limit of Bimetric Theories of Gravity
We consider the post-Newtonian limit of a general class of bimetric theories of gravity, in which both metrics are dynamical. The established parameterised post-Newtonian approach is followed as closely as possible, although ... -
The Parameterised Post-Newtonian Limit of Fourth-Order Theories of Gravity
We determine the full post-Newtonian limit of theories of gravity that extend general relativity by replacing the Ricci scalar, R, in the generating Lagrangian by some analytic function, f(R). We restrict ourselves to ... -
The partition function of ABJ theory
(2013-05) -
Perturbation Theory in Lemaitre-Tolman-Bondi Cosmology
The Lemaitre-Tolman-Bondi solution has received much attention as a possible alternative to Dark Energy, as it is able to account for the apparent acceleration of the Universe without any exotic matter content. However, ... -
Phosphorus-bearing molecules in solar-type star forming regions: First PO detection
(Blackwell Publishing Inc., 2016-11-11) -
Photoevaporation obfuscates the distinction between wind and viscous angular momentum transport in protoplanetary discs
(2024-01-01)How protoplanetary discs evolve remains an unanswered question. Competing theories of viscosity and magnetohydrodynamic disc winds have been put forward as the drivers of angular momentum transport in protoplanetary discs. ... -
Photosynthesis Under a Red Sun: Predicting the absorption characteristics of an extraterrestrial light-harvesting antenna
(Oxford University Press (OUP), 2023)Here, we discuss the feasibility of photosynthesis on Earth-like rocky planets in close orbit around ultracool red dwarf stars. Stars of this type have very limited emission in the photosynthetically active region of the ... -
Piecewise Silence in Discrete Cosmological Models
We consider a family of cosmological models in which all mass is confined to a regular lattice of identical black holes. By exploiting the reflection symmetry about planes that bisect these lattices into identical halves, ...