scholarly journals Pulsars as probes of gravity and fundamental physics

2016 ◽  
Vol 25 (14) ◽  
pp. 1630029 ◽  
Author(s):  
Michael Kramer
Keyword(s):  
Strong Field ◽  
Direct Detection ◽  
Field Tests ◽  
Dense Matter ◽  
Experimental Tests ◽  
Fundamental Physics ◽  
Tests Of General Relativity ◽  
Pulsar Timing ◽  
Wide Range ◽  
Tests Of Gravity

Radio-loud neutron stars known as pulsars allow a wide range of experimental tests for fundamental physics, ranging from the study of super-dense matter to tests of General Relativity (GR) and its alternatives. As a result, pulsars provide strong-field tests of gravity, they allow for the direct detection of gravitational waves in a “pulsar timing array” (PTA), and they promise the future study of black hole properties. This contribution gives an overview of the on-going experiments and recent results.

OBSERVATIONAL CONSTRAINTS ON STRONG GRAVITY

2011 ◽  
Vol 20 (14) ◽  
pp. 2755-2760
Author(s):  
CHRIS DONE
Keyword(s):  
Black Hole ◽  
Event Horizon ◽  
Strong Field ◽  
Field Tests ◽  
High Energy ◽  
Observational Constraints ◽  
Tests Of General Relativity ◽  
Strong Gravity ◽  
Accretion Flows ◽  
Spacetime Curvature

Accretion onto a black hole transforms the darkest objects in the universe to the brightest. The high energy radiation emitted from the accretion flow before it disappears forever below the event horizon lights up the regions of strong spacetime curvature close to the black hole, enabling strong field tests of General Relativity. I review the observational constraints on strong gravity from such accretion flows, and show how the data strongly support the existence of such fundamental General Relativistic features of a last stable orbit and the event horizon. However, these successes also imply that gravity does not differ significantly from Einstein's predictions above the event horizon, so any new theory of quantum gravity will be very difficult to test.

scholarly journals Galactic center pulsar as a test of black hole existence and properties

1979 ◽  
Vol 84 ◽  
pp. 401-404
Author(s):  
B. Paczyński ◽  
V. Trimble
Keyword(s):  
General Relativity ◽  
Black Hole ◽  
Galactic Center ◽  
Strong Field ◽  
Field Tests ◽  
Central Black Hole ◽  
X Ray ◽  
Tests Of General Relativity ◽  
Period Orbit ◽  
Short Period

There is a reasonable chance of finding a (probably X-ray) pulsar in a short-period orbit around the galactic center. Such a pulsar can provide a test distinguishing a central black hole from a supermassive object or spinar. It also makes available a good clock in a region of space in which GM/Rc2 is much larger than solar system values, thus allowing strong-field tests of general relativity.

scholarly journals The Square Kilometre Array

2007 ◽  
Vol 3 (S248) ◽  
pp. 164-169 ◽  
Author(s):  
A. R. Taylor
Keyword(s):  
Large Scale ◽  
Angular Resolution ◽  
Strong Field ◽  
Field Tests ◽  
Field Of View ◽  
Origin And Evolution ◽  
Reference Design ◽  
Formation And Evolution ◽  
Tests Of Gravity ◽  
Global Project

AbstractThe SKA is a global project to plan and construct the next-generation international radio telescope operating at metre to cm wavelengths. More than 50 institutes in 19 countries are involved in its development. The SKA will be an interferometric array with a collecting area of up to one million square metres and maximum baseline of at least 3000 km. The SKA reference design includes field-of-view expansion technology that will allow instantaneous imaging of up to several tens of degrees. The SKA is being designed to address fundamental questions in cosmology, physics and astronomy. The key science goals range from the epoch or re-ionization, dark energy, the formation and evolution of galaxies and large-scale structure, the origin and evolution of cosmic magnetism, strong-field tests of gravity and gravity wave detection, the cradle of life, and the search for extraterrestrial intelligence. The sensitivity, field-of-view and angular resolution of the SKA will make possible a program to create a multi-epoch data base of wide-angle relative astrometry to a few μas precision for ~10,000,000 radio sources with S > 10 μJy.

Strong-field tests of gravity with the double pulsar

2006 ◽  
Vol 15 (1-2) ◽  
pp. 34-42 ◽  
Author(s):  
M. Kramer ◽  
I.H. Stairs ◽  
R.N. Manchester ◽  
M.A. McLaughlin ◽  
A.G. Lyne ◽  
...  
Keyword(s):  
Strong Field ◽  
Field Tests ◽  
Tests Of Gravity

scholarly journals EXPERIMENTAL TESTS OF A BEARING CAPACITY OF «FUNDEX» PILES AFTER THE LONG “RELAXATION” IN CLAY SOILS THE DEAD PRESSING AND PULLING-OUT LOADS

2019 ◽  
Vol 10 (2) ◽  
pp. 13-29
Author(s):  
A. V Savinov ◽  
V. E Frolov ◽  
Y. N Brovikov ◽  
M. P Kozhinskiy
Keyword(s):  
Bearing Capacity ◽  
Field Tests ◽  
Experimental Tests ◽  
Soil Conditions ◽  
Field Methods ◽  
Technical Science ◽  
Pull Out ◽  
Geological Conditions ◽  
Wide Range ◽  
The Dead

In the article analyzes the results of experimental tests of new “Fundex” piles for The City of Saratov. Сlassification of piles based on their interplay with the pile base has been devised by Doctor of Technical Science, Professor F.K. Lapshin. Changes introduced in 2016 into SP 24.13330.2011 “Pile foundations” concerning calculation of the displacing stuffed concrete piles. The short analysis of history of creation of tables SP 24.13330 by determination of rated resistance on a lateral area and under the lower end of piles is carried out. It is shown that these sizes are not the limit resistances at exhaustion of a carrying capacity of a soil at “failure”, and are accepted with some stock at achievement by a pile of “predetermined” settling. There has been noted the existence of a large number of piles testing methods by means of incrementally increasing load different from methodology GOST 5686-2012 “Soils. Methods of field trials of piles” by various assessment criteria of the ultimate pile bearing capacity. Two identical piles have been manufactured in identical soils and after a long (3 months) “relaxation” without load tests have been conducted under GOST 5686 with static indenting and pull out loads. Engineering-geological conditions of the platform and distance between piles excluded their interference at manufacture and tests. the dead pressing and pulling-out loads. Comparison of results of field tests of “Fundex” piles to design values of a bearing capacity of the displacing piles determined by the recommendations of SP 24.13330 is carried out. The essential divergence of the experimental and estimated values at assessment of a bearing capacity of a heel of a pile is noted. Conclusions are drawn on need of additional experimental research of the basis of “Fundex” piles for the wide range of soil conditions by laboratory and field methods with parallel tests static indenting and pull out loads.

scholarly journals Post-Newtonian gravitational and scalar waves in scalar-Gauss-Bonnet gravity

2021 ◽  
Author(s):  
Banafsheh Shiralilou ◽  
Tanja Hinderer ◽  
Samaya Nissanke ◽  
Nestor Ortiz ◽  
Helvi Witek
Keyword(s):  
General Relativity ◽  
Black Hole ◽  
Gravitational Wave ◽  
Strong Field ◽  
Field Tests ◽  
Theoretical Modelling ◽  
Bonnet Gravity ◽  
Weak Coupling Approximation ◽  
Tests Of Gravity ◽  
The Impact

Abstract Gravitational waves emitted by black hole binary inspiral and mergers enable unprecedented strong-field tests of gravity, requiring accurate theoretical modelling of the expected signals in extensions of General Relativity. In this paper we model the gravitational wave emission of inspiralling binaries in scalar Gauss-Bonnet gravity theories. Going beyond the weak-coupling approximation, we derive the gravitational waveform to relative first post-Newtonian order beyond the quadrupole approximation and calculate new contributions from nonlinear curvature terms. We also compute the scalar waveform to relative 0.5PN order beyond the leading -0.5PN order terms. We quantify the effect of these terms and provide ready-to-implement gravitational wave and scalar waveforms as well as the Fourier domain phase for quasi-circular binaries. We also perform a parameter space study, which indicates that the values of black hole scalar charges play a crucial role in the detectability of deviation from General Relativity. We also compare the scalar waveforms to numerical relativity simulations to assess the impact of the relativistic corrections to the scalar radiation. Our results provide important foundations for future precision tests of gravity.

scholarly journals Strong-field tests of gravity using pulsars and black holes

2004 ◽  
Vol 48 (11-12) ◽  
pp. 993-1002 ◽  
Author(s):  
M. Kramer ◽  
D.C. Backer ◽  
J.M. Cordes ◽  
T.J.W. Lazio ◽  
B.W. Stappers ◽  
...  
Keyword(s):  
Black Holes ◽  
Strong Field ◽  
Field Tests ◽  
Tests Of Gravity
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