2,539 research outputs found
Implementation of standard testbeds for numerical relativity
We discuss results that have been obtained from the implementation of the
initial round of testbeds for numerical relativity which was proposed in the
first paper of the Apples with Apples Alliance. We present benchmark results
for various codes which provide templates for analyzing the testbeds and to
draw conclusions about various features of the codes. This allows us to sharpen
the initial test specifications, design a new test and add theoretical insight.Comment: Corrected versio
Pathway to the Square Kilometre Array - The German White Paper -
The Square Kilometre Array (SKA) is the most ambitious radio telescope ever
planned. With a collecting area of about a square kilometre, the SKA will be
far superior in sensitivity and observing speed to all current radio
facilities. The scientific capability promised by the SKA and its technological
challenges provide an ideal base for interdisciplinary research, technology
transfer, and collaboration between universities, research centres and
industry. The SKA in the radio regime and the European Extreme Large Telescope
(E-ELT) in the optical band are on the roadmap of the European Strategy Forum
for Research Infrastructures (ESFRI) and have been recognised as the essential
facilities for European research in astronomy.
This "White Paper" outlines the German science and R&D interests in the SKA
project and will provide the basis for future funding applications to secure
German involvement in the Square Kilometre Array.Comment: Editors: H. R. Kl\"ockner, M. Kramer, H. Falcke, D.J. Schwarz, A.
Eckart, G. Kauffmann, A. Zensus; 150 pages (low resolution- and colour-scale
images), published in July 2012, language English (including a foreword and
an executive summary in German), the original file is available via the MPIfR
homepag
CompF2: Theoretical Calculations and Simulation Topical Group Report
This report summarizes the work of the Computational Frontier topical group
on theoretical calculations and simulation for Snowmass 2021. We discuss the
challenges, potential solutions, and needs facing six diverse but related
topical areas that span the subject of theoretical calculations and simulation
in high energy physics (HEP): cosmic calculations, particle accelerator
modeling, detector simulation, event generators, perturbative calculations, and
lattice QCD (quantum chromodynamics). The challenges arise from the next
generations of HEP experiments, which will include more complex instruments,
provide larger data volumes, and perform more precise measurements.
Calculations and simulations will need to keep up with these increased
requirements. The other aspect of the challenge is the evolution of computing
landscape away from general-purpose computing on CPUs and toward
special-purpose accelerators and coprocessors such as GPUs and FPGAs. These
newer devices can provide substantial improvements for certain categories of
algorithms, at the expense of more specialized programming and memory and data
access patterns.Comment: Report of the Computational Frontier Topical Group on Theoretical
Calculations and Simulation for Snowmass 202
Rapid determination of LISA sensitivity to extreme mass ratio inspirals with machine learning
Gravitational wave observations of the inspiral of stellar-mass compact
objects into massive black holes (MBHs), extreme mass ratio inspirals (EMRIs),
enable precision measurements of parameters such as the MBH mass and spin. The
Laser Interferometer Space Antenna is expected to detect sufficient EMRIs to
probe the underlying source population, testing theories of the formation and
evolution of MBHs and their environments. Population studies are subject to
selection effects that vary across the EMRI parameter space, which bias
inference results if unaccounted for. This bias can be corrected, but
evaluating the detectability of many EMRI signals is computationally expensive.
We mitigate this cost by (i) constructing a rapid and accurate neural network
interpolator capable of predicting the signal-to-noise ratio of an EMRI from
its parameters, and (ii) further accelerating detectability estimation with a
neural network that learns the selection function, leveraging our first neural
network for data generation. The resulting framework rapidly estimates the
selection function, enabling a full treatment of EMRI detectability in
population inference analyses. We apply our method to an astrophysically
motivated EMRI population model, demonstrating the potential selection biases
and subsequently correcting for them. Accounting for selection effects, we
predict that LISA will measure the MBH mass function slope to a precision of
8.8%, the CO mass function slope to a precision of 4.6%, the width of the MBH
spin magnitude distribution to a precision of 10% and the event rate to a
precision of 12% with EMRIs at redshifts below z=6.Comment: 12 pages, 4 figure
The numerical relativity breakthrough for binary black holes
The evolution of black-hole binaries in vacuum spacetimes constitutes the
two-body problem in general relativity. The solution of this problem in the
framework of the Einstein field equations is a substantially more complex
exercise than that of the dynamics of two point masses in Newtonian gravity,
but it also presents us with a wealth of new exciting physics. Numerical
methods are likely the only method to compute the dynamics of black-hole
systems in the fully non-linear regime and have been pursued since the 1960s,
culminating in dramatic breakthroughs in 2005. Here we review the methodology
and the developments that finally gave us a solution of this fundamental
problem of Einstein's theory and discuss the breakthrough's implication for the
wide range of contemporary black-hole physics.Comment: 34 pages, 5 figures; Invited article for Classical and Quantum
Gravity's "Milestones of General Relativity" series; to match published
versio
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