scholarly journals Generalized Rastall's gravity and its effects on compact objects

2021 ◽  
Author(s):  
Clesio E. Mota ◽  
Luis C. N. Santos ◽  
Franciele M. da Silva ◽  
Guilherme Grams ◽  
Iarley P. Lobo ◽  
...  
Keyword(s):  
Compact Objects

scholarly journals Spin effects in the effective field theory approach to Post-Minkowskian conservative dynamics

2021 ◽  
Vol 2021 (6) ◽  
Author(s):  
Zhengwen Liu ◽  
Rafael A. Porto ◽  
Zixin Yang
Keyword(s):  
Field Theory ◽  
Effective Field Theory ◽  
Scattering Problem ◽  
Finite Size ◽  
Effective Field ◽  
Compact Objects ◽  
Scattering Data ◽  
Theory Approach ◽  
Spin Effects ◽  
Radial Action

Abstract Building upon the worldline effective field theory (EFT) formalism for spinning bodies developed for the Post-Newtonian regime, we generalize the EFT approach to Post-Minkowskian (PM) dynamics to include rotational degrees of freedom in a manifestly covariant framework. We introduce a systematic procedure to compute the total change in momentum and spin in the gravitational scattering of compact objects. For the special case of spins aligned with the orbital angular momentum, we show how to construct the radial action for elliptic-like orbits using the Boundary-to-Bound correspondence. As a paradigmatic example, we solve the scattering problem to next-to-leading PM order with linear and bilinear spin effects and arbitrary initial conditions, incorporating for the first time finite-size corrections. We obtain the aligned-spin radial action from the resulting scattering data, and derive the periastron advance and binding energy for circular orbits. We also provide the (square of the) center-of-mass momentum to $$ \mathcal{O}\left({G}^2\right) $$ O G 2 , which may be used to reconstruct a Hamiltonian. Our results are in perfect agreement with the existent literature, while at the same time extend the knowledge of the PM dynamics of compact binaries at quadratic order in spins.

scholarly journals Horizon radiation reaction forces

2020 ◽  
Vol 2020 (10) ◽  
Author(s):  
Walter D. Goldberger ◽  
Ira Z. Rothstein
Keyword(s):  
Black Hole ◽  
Equations Of Motion ◽  
Finite Size ◽  
Radiation Reaction ◽  
Effective Field ◽  
Compact Objects ◽  
Finite Size Effect ◽  
Binary Black Holes ◽  
Dissipative Effects ◽  
Reaction Forces

Abstract Using Effective Field Theory (EFT) methods, we compute the effects of horizon dissipation on the gravitational interactions of relativistic binary black hole systems. We assume that the dynamics is perturbative, i.e it admits an expansion in powers of Newton’s constant (post-Minkowskian, or PM, approximation). As applications, we compute corrections to the scattering angle in a black hole collision due to dissipative effects to leading PM order, as well as the post-Newtonian (PN) corrections to the equations of motion of binary black holes in non-relativistic orbits, which represents the leading order finite size effect in the equations of motion. The methods developed here are also applicable to the case of more general compact objects, eg. neutron stars, where the magnitude of the dissipative effects depends on non-gravitational physics (e.g, the equation of state for nuclear matter).

scholarly journals Ultra-compact objects from semi-classical gravity

2021 ◽  
Vol 103 (12) ◽  
Author(s):  
I. Prasetyo ◽  
H. S. Ramadhan ◽  
A. Sulaksono
Keyword(s):  
Compact Objects ◽  
Classical Gravity

scholarly journals Exploring a New Population of Compact Objects: X-ray and IR Observations of the Galactic Centre

2008 ◽  
Author(s):  
Reba M. Bandyopadhyay ◽  
Andrew J. Gosling ◽  
Stephen E. Eikenberry ◽  
Michael P. Muno ◽  
Katherine M. Blundell ◽  
...  
Keyword(s):  
Compact Objects ◽  
Galactic Centre ◽  
X Ray

scholarly journals Holographic equations of state and astrophysical compact objects

2011 ◽  
Vol 2011 (10) ◽  
Author(s):  
Youngman Kim ◽  
Chang-Hwan Lee ◽  
Ik Jae Shin ◽  
Mew-Bing Wan
Keyword(s):  
Equations Of State ◽  
Compact Objects

scholarly journals Numerical methods for General Relativistic particles

2018 ◽  
Vol 14 (S342) ◽  
pp. 19-23
Author(s):  
Fabio Bacchini ◽  
Bart Ripperda ◽  
Alexander Y. Chen ◽  
Lorenzo Sironi
Keyword(s):  
Numerical Methods ◽  
Gravitational Lensing ◽  
Complex Dynamics ◽  
Equations Of Motion ◽  
Numerical Algorithms ◽  
Relativistic Effects ◽  
Compact Objects ◽  
Light Rays ◽  
Massive Particles ◽  
External Forces

AbstractWe present recent developments on numerical algorithms for computing photon and particle trajectories in the surrounding of compact objects. Strong gravity around neutron stars or black holes causes relativistic effects on the motion of massive particles and distorts light rays due to gravitational lensing. Efficient numerical methods are required for solving the equations of motion and compute i) the black hole shadow obtained by tracing light rays from the object to a distant observer, and ii) obtain information on the dynamics of the plasma at the microscopic scale. Here, we present generalized algorithms capable of simulating ensembles of photons or massive particles in any spacetime, with the option of including external forces. The coupling of these tools with GRMHD simulations is the key point for obtaining insight on the complex dynamics of accretion disks and jets and for comparing simulations with upcoming observational results from the Event Horizon Telescope.

scholarly journals Gamma-ray astrophysics in the MeV range

2021 ◽  
Author(s):  
Alessandro De Angelis ◽  
Vincent Tatischeff ◽  
Andrea Argan ◽  
Søren Brandt ◽  
Andrea Bulgarelli ◽  
...  
Keyword(s):  
High Efficiency ◽  
Gamma Ray ◽  
Earth Science ◽  
Technological Development ◽  
Cosmic Ray ◽  
Space Mission ◽  
Compact Objects ◽  
Medium Size ◽  
Cosmic Ray Interactions ◽  
Silicon Microstrip Detectors

AbstractThe energy range between about 100 keV and 1 GeV is of interest for a vast class of astrophysical topics. In particular, (1) it is the missing ingredient for understanding extreme processes in the multi-messenger era; (2) it allows localizing cosmic-ray interactions with background material and radiation in the Universe, and spotting the reprocessing of these particles; (3) last but not least, gamma-ray emission lines trace the formation of elements in the Galaxy and beyond. In addition, studying the still largely unexplored MeV domain of astronomy would provide for a rich observatory science, including the study of compact objects, solar- and Earth-science, as well as fundamental physics. The technological development of silicon microstrip detectors makes it possible now to detect MeV photons in space with high efficiency and low background. During the last decade, a concept of detector (“ASTROGAM”) has been proposed to fulfil these goals, based on a silicon hodoscope, a 3D position-sensitive calorimeter, and an anticoincidence detector. In this paper we stress the importance of a medium size (M-class) space mission, dubbed “ASTROMEV”, to fulfil these objectives.

scholarly journals Mass-radius relation of compact objects

2019 ◽  
Vol 15 (S356) ◽  
pp. 383-384
Author(s):  
Seman Abaraya ◽  
Tolu Biressa
Keyword(s):  
Numerical Analysis ◽  
Equation Of State ◽  
Compact Objects ◽  
Mass Limit ◽  
Einstein Field Equations ◽  
Field Equations ◽  
Formation And Evolution ◽  
Active Research ◽  
Compact Sources ◽  
Astrophysical Research

AbstractCompact objects are of great interest in astrophysical research. There are active research interests in understanding better various aspects of formation and evolution of these objects. In this paper we addressed some problems related to the compact objects mass limit. We employed Einstein field equations (EFEs) to derive the equation of state (EoS). With the assumption of high densities and low temperature of compact sources, the derived equation of state is reduced to polytropic kind. Studying the polytropic equations we obtained similar physical implications, in agreement to previous works. Using the latest version of Mathematica-11 in our numerical analysis, we also obtained similar results except slight differences in accuracy.

Aspects of the Collapse of Compact Objects

1980 ◽  
Vol 4 (1) ◽  
pp. 49-50
Author(s):  
R. A. Gingold ◽  
J. J. Monaghan
Keyword(s):  
Neutron Star ◽  
Neutron Stars ◽  
White Dwarf ◽  
Compact Objects ◽  
Dwarf Star

Misner Thorne and Wheeler (1973), (page 629) suggested that a freshly formed White Dwarf star of several solar masses would, if slowly — rotating, collapse to form a neutron star pancake which would become unstable and eventually produce several, possibly colliding, neutron stars.

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