scholarly journals Slowly rotating topological neutron stars: universal relations and epicyclic frequencies

2020 ◽  
Vol 80 (9) ◽  
Author(s):  
Victor I. Danchev ◽  
Daniela D. Doneva ◽  
Stoytcho S. Yazadjiev
Keyword(s):  
General Relativity ◽  
Neutron Stars ◽  
Strong Field ◽  
Compact Objects ◽  
X Ray ◽  
Tests Of General Relativity ◽  
New Type ◽  
Theories Of Gravity ◽  
Scalar Theories ◽  
The Moment

AbstractIn the modern era of abundant X-ray detections and the increasing momentum of gravitational waves astronomy, tests of general relativity in strong field regime become increasingly feasible and their importance for probing gravity cannot be understated. To this end, we study the characteristics of slowly rotating topological neutron stars in the tensor-multi-scalar theories of gravity following the static study of this new type of compact objects by two of the authors. We explore the moment of inertia and verify that universal relations known from general relativity hold for this new class of compact objects. Furthermore, we study the properties of their innermost stable circular orbits and the epicyclic frequencies due to the latter’s hinted link to observational quantities such as quasi-periodic X-ray spectrum features.

scholarly journals The confrontation between general relativity and experiment

2009 ◽  
Vol 5 (S261) ◽  
pp. 198-199
Author(s):  
Clifford M. Will
Keyword(s):  
General Relativity ◽  
Gravitational Wave ◽  
Equivalence Principle ◽  
Gamma Ray ◽  
Strong Field ◽  
Weak Field ◽  
X Ray ◽  
Spacetime Geometry ◽  
Tests Of General Relativity ◽  
Laser Interferometric

AbstractWe review the experimental evidence for Einstein's general relativity. A variety of high precision null experiments confirm the Einstein Equivalence Principle, which underlies the concept that gravitation is synonymous with spacetime geometry, and must be described by a metric theory. Solar system experiments that test the weak-field, post-Newtonian limit of metric theories strongly favor general relativity. Binary pulsars test gravitational-wave damping and aspects of strong-field general relativity. During the coming decades, tests of general relativity in new regimes may be possible. Laser interferometric gravitational-wave observatories on Earth and in space may provide new tests via precise measurements of the properties of gravitational waves. Future efforts using X-ray, infrared, gamma-ray and gravitational-wave astronomy may one day test general relativity in the strong-field regime near black holes and neutron stars.

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 LOFT: the Large Observatory For X-ray Timing

2012 ◽  
Vol 8 (S290) ◽  
pp. 163-170
Author(s):  
Tomaso M. Belloni ◽  
Enrico Bozzo ◽  
Keyword(s):  
General Relativity ◽  
Strong Field ◽  
Compact Objects ◽  
High Time Resolution ◽  
General Description ◽  
X Ray ◽  
Equation Of States ◽  
Wide Range ◽  
First Time ◽  
New Discovery

AbstractLOFT, the large observatory for X-ray timing, is a new mission concept competing with other four candidates for a launch opportunity in 2022-2024. LOFT will be performing high-time resolution X-ray observations of compact objects, combining for the first time an unprecedented large collecting area for X-ray photons and a spectral resolution approaching that of CCD-based X-ray instruments (down to 200 eV FWHM at 6 keV). The operating energy range is 2-80 keV. The main science goals of LOFT are the measurement of the neutron stars equation of states and the test of General Relativity in the strong field regime. The breakthrough capabilities of the instruments on-board LOFT will permit to open also new discovery windows for a wide range of Galactic and extragalactic X-ray sources.In this contribution, we provide a general description of the mission concept and summarize its main scientific capabilities.

scholarly journals Recent LIGO-Virgo discoveries

2021 ◽  
pp. 2130010
Author(s):  
Maximiliano Isi
Keyword(s):  
Black Holes ◽  
General Relativity ◽  
Black Hole ◽  
Neutron Star ◽  
Neutron Stars ◽  
Gravitational Wave ◽  
Compact Objects ◽  
Tests Of General Relativity ◽  
Mass Gap ◽  
Cosmic History

The LIGO and Virgo gravitational-wave detectors carried out the first half of their third observing run from April through October 2019. During this period, they detected 39 new signals from the coalescence of black holes or neutron stars, more than quadrupling the total number of detected events. These detections included some unprecedented sources, like a pair of black holes with unequal masses (GW190412), a massive pair of neutron stars (GW190425), a black hole potentially in the supernova pair-instability mass gap (GW190521), and either the lightest black hole or the heaviest neutron star known to date (GW190814). Collectively, the full set of signals provided astrophysically valuable information about the distributions of compact objects and their evolution throughout cosmic history. It also enabled more constraining and diverse tests of general relativity, including new probes of the fundamental nature of black holes. This review summarizes the highlights of these results and their implications.

scholarly journals From fundamental physics to tests with compact objects in metric-affine theories of gravity

2020 ◽  
Vol 29 (11) ◽  
pp. 2041007
Author(s):  
Diego Rubiera-Garcia
Keyword(s):  
Black Holes ◽  
General Relativity ◽  
Strong Field ◽  
Compact Objects ◽  
Fundamental Physics ◽  
Theories Of Gravity

This paper provides a short but comprehensible overview of some relevant aspects of metric-affine theories of gravity in relation to the physics and astrophysics of compact objects. We shall highlight the pertinence of this approach to supersede General Relativity on its strong-field regime, as well as its advantages and some of its difficulties. Moreover, we shall reflect on the present and future opportunities to test its predictions with relativistic and nonrelativistic stars, black holes, and other exotic horizonless compact objects.

The stellar graveyard

2019 ◽  
pp. 177-206
Author(s):  
Nils Andersson
Keyword(s):  
Black Holes ◽  
General Relativity ◽  
Neutron Stars ◽  
Gravitational Wave ◽  
Stellar Evolution ◽  
White Dwarfs ◽  
Supermassive Black Holes ◽  
Compact Objects ◽  
Fermi Gases ◽  
The 1950S

This chapter introduces the different classes of compact objects—white dwarfs, neutron stars, and black holes—that are relevant for gravitational-wave astronomy. The ideas are placed in the context of developing an understanding of the likely endpoint(s) of stellar evolution. Key ideas like Fermi gases and the Chandrasekhar mass are discussed, as is the emergence of general relativity as a cornerstone of astrophysics in the 1950s. Issues associated with different formation channels for, in particular, black holes are considered. The chapter ends with a discussion of the supermassive black holes that are found at the centre of galaxies.

scholarly journals Accretion onto Relativistic Objects

1974 ◽  
Vol 64 ◽  
pp. 194-212
Author(s):  
M. J. Rees
Keyword(s):  
Black Holes ◽  
Interstellar Medium ◽  
Neutron Stars ◽  
Binary Systems ◽  
Compact Object ◽  
Stellar Mass ◽  
Supermassive Black Holes ◽  
Compact Objects ◽  
X Ray ◽  
Intergalactic Space

The physics of spherically symmetrical accretion onto a compact object is briefly reviewed. Neither neutron stars nor stellar-mass black holes are likely to be readily detectable if they are isolated and accreting from the interstellar medium. Supermassive black holes in intergalactic space may however be detectable. The effects of accretion onto compact objects in binary systems are then discussed, with reference to the phenomena observed in variable X-ray sources.

scholarly journals High-Mass X-ray Binaries: progenitors of double compact objects

2018 ◽  
Vol 14 (S346) ◽  
pp. 1-13
Author(s):  
Edward P. J. van den Heuvel
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Neutron Stars ◽  
Compact Objects ◽  
High Mass ◽  
X Ray ◽  
Future Evolution ◽  
Short Period ◽  
Orbital Periods ◽  
X Ray Binaries

AbstractA summary is given of the present state of our knowledge of High-Mass X-ray Binaries (HMXBs), their formation and expected future evolution. Among the HMXB-systems that contain neutron stars, only those that have orbital periods upwards of one year will survive the Common-Envelope (CE) evolution that follows the HMXB phase. These systems may produce close double neutron stars with eccentric orbits. The HMXBs that contain black holes do not necessarily evolve into a CE phase. Systems with relatively short orbital periods will evolve by stable Roche-lobe overflow to short-period Wolf-Rayet (WR) X-ray binaries containing a black hole. Two other ways for the formation of WR X-ray binaries with black holes are identified: CE-evolution of wide HMXBs and homogeneous evolution of very close systems. In all three cases, the final product of the WR X-ray binary will be a double black hole or a black hole neutron star binary.

Sign in / Sign up

Export Citation Format

Share Document