222 research outputs found
Self-force via a Green's function decomposition
The gravitational field of a particle of small mass \mu moving through curved
spacetime is naturally decomposed into two parts each of which satisfies the
perturbed Einstein equations through O(\mu). One part is an inhomogeneous field
which, near the particle, looks like the \mu/r field distorted by the local
Riemann tensor; it does not depend on the behavior of the source in either the
infinite past or future. The other part is a homogeneous field and includes the
``tail term''; it completely determines the self force effects of the particle
interacting with its own gravitational field, including radiation reaction.
Self force effects for scalar, electromagnetic and gravitational fields are all
described in this manner.Comment: PRD, in press. Enhanced emphasis on the equivalence principl
Perturbative Approach to an orbital evolution around a Supermassive black hole
A charge-free, point particle of infinitesimal mass orbiting a Kerr black
hole is known to move along a geodesic. When the particle has a finite mass or
charge, it emits radiation which carries away orbital energy and angular
momentum, and the orbit deviates from a geodesic.
In this paper we assume that the deviation is small and show that the
half-advanced minus half-retarded field surprisingly provides the correct
radiation reaction force, in a time-averaged sense, and determines the orbit of
the particle.Comment: accepted for publication in the Physical Revie
Mass loss by a scalar charge in an expanding universe
We study the phenomenon of mass loss by a scalar charge -- a point particle
that acts a source for a noninteracting scalar field -- in an expanding
universe. The charge is placed on comoving world lines of two cosmological
spacetimes: a de Sitter universe, and a spatially-flat, matter-dominated
universe. In both cases, we find that the particle's rest mass is not a
constant, but that it changes in response to the emission of monopole scalar
radiation by the particle. In de Sitter spacetime, the particle radiates all of
its mass within a finite proper time. In the matter-dominated cosmology, this
happens only if the charge of the particle is sufficiently large; for smaller
charges the particle first loses some of its mass, but then regains it all
eventually.Comment: 11 pages, RevTeX4, Accepted for Phys. Rev.
Seismic interpretation and generation of depth surfaces for Late Palaeozoic strata in the Irish Sea Region
This report describes the methodology and results of a regional seismic interpretation of the
basins of the Irish Sea. It does not review the basins of the Celtic Sea. The aim of the
interpretation was to map the distribution of Palaeozoic basins and highs, interpreting the key
Devonian-Carboniferous surfaces and main structural elements of the area. About 40,000 km
of 2D seismic reflection data have been interpreted and tied to key released wells in the
project area. The seismic and well data were augmented by donated reports from sponsor
companies.
A set of 8 depth structure maps of key horizons have been produced for the pre-Permian
succession. These maps provide a key dataset to aid assessment of the petroleum systems of
the Palaeozoic strata within the study area. The surfaces, supplied digitally at a grid spacing
of 5000 m, give a regional view of the topography of the horizons, and comprise:
âUVARâ (Variscan Unconformity) beneath Permian and Triassic strata
Base Warwickshire Group (late Westphalian - ?Stephanian)
Top Namurian (Base Pennine Coal Measures Group)
Top Intra-Namurian (Top Bowland Shale in south, Base Millstone Grit elsewhere)
Top Visean (Lower Carboniferous)
Intra-Visean (amalgamated with Top Middle Border Group in north)
Base Carboniferous (amalgamated with Base Clyde Plateau lavas in the North
Channel to South-West Arran Sub-Basin)
âUCALâ Acadian (Caledonian) Unconformity)
It is important to note that the variable data quality and sparsity of deep wells leads to a
seismic interpretation which is strongly driven by regional geological models, themselves
heavily dependent on inference from the onshore area. This is particularly the case with the
deeper Carboniferous horizons which are not penetrated by any well and which may be only
weakly reflective. In such cases, picks from better quality data may be interpolated through
areas with poor quality data, as a modelled surface, to ensure a continuous surface for
gridding.
The well dataset has been re-interpreted (Wakefield et al., 2016) before integration with the
seismic interpretation.
The following general observations are made:
The present study has confirmed the Permian-Mesozoic structural framework for the region
established by Jackson and Mulholland (1993) and Jackson et al. (1995, 1996, 1997).
The basin recognised in Quadrant 109 by Jackson and co-workers (op. cit.) is
reinterpreted as a major Carboniferous half-graben structure controlled by a
syndepositional fault on its NW side. It continues beneath thin Permo-Triassic cover
into the Eubonia Basin and Ogham Platform, preserving a thick Westphalian
succession, including inferred Warwickshire Group strata. It is inferred to have
continued eastward into the Lagman Basin prior to its tectonic dissection by a
combination of Variscan inversion and Permo-Mesozoic graben development along
the Keys Fault.
A belt of Variscan fold/thrust inversion structures on the Godred Croven Platform is
correlated with structures on the Formby Platform and Ribblesdale Foldbelt onshore.
CR/16/041 Last modified: 2016/05/30 09:37
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The area of Carboniferous (undivided) subcrop depicted on mapping by BGS (1994)
to north and west of the Isle of Man has been reclassified into Visean and Namurian
elements.
The presence of significant thicknesses of Carboniferous strata in the southern part of
the North Channel is regarded as doubtful, but farther north, in the Larne, Rathlin and
South-West Arran Sub-basins, greater thicknesses may be present.
A detailed description of tectono-stratigraphic development based on the seismic
interpretation is given in Pharaoh et al. (2016b), integrated with the petroleum system
analysis
Massive-Field Approach to the Scalar Self Force in Curved Spacetime
We derive a new regularization method for the calculation of the (massless)
scalar self force in curved spacetime. In this method, the scalar self force is
expressed in terms of the difference between two retarded scalar fields: the
massless scalar field, and an auxiliary massive scalar field. This field
difference combined with a certain limiting process gives the expression for
the scalar self-force. This expression provides a new self force calculation
method.Comment: 23 pages, few modification
Cosmic Censorship, Area Theorem, and Self-Energy of Particles
The (zeroth-order) energy of a particle in the background of a black hole is
given by Carter's integrals. However, exact calculations of a particle's {\it
self-energy} (first-order corrections) are still beyond our present reach in
many situations. In this paper we use Hawking's area theorem in order to derive
bounds on the self-energy of a particle in the vicinity of a black hole.
Furthermore, we show that self-energy corrections {\it must} be taken into
account in order to guarantee the validity of Penrose cosmic censorship
conjecture.Comment: 11 page
Reconstruction of Black Hole Metric Perturbations from Weyl Curvature
Perturbation theory of rotating black holes is usually described in terms of
Weyl scalars and , which each satisfy Teukolsky's complex
master wave equation and respectively represent outgoing and ingoing radiation.
On the other hand metric perturbations of a Kerr hole can be described in terms
of (Hertz-like) potentials in outgoing or ingoing {\it radiation
gauges}. In this paper we relate these potentials to what one actually computes
in perturbation theory, i.e and . We explicitly construct
these relations in the nonrotating limit, preparatory to devising a
corresponding approach for building up the perturbed spacetime of a rotating
black hole. We discuss the application of our procedure to second order
perturbation theory and to the study of radiation reaction effects for a
particle orbiting a massive black hole.Comment: 6 Pages, Revtex
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