Related papers: A new line on the wide binary test of gravity
The empirical distribution of projected rotational velocities (vsini) in massive O-type stars is characterized by a dominant slow velocity component and a tail of fast rotators. Binary interaction has been proposed to play a dominant role…
We consider the process of stellar binaries tidally disrupted by a supermassive black hole. For highly eccentric orbits, as one star is ejected from the three-body system, the companion remains bound to the black hole. Hypervelocity stars…
The accelerating expansion of the Universe at recent epochs has called into question the validity of general relativity on cosmological scales. One probe of gravity is a comparison of expansion history of the Universe with the history of…
The gravitational wave (GW) detection of a binary neutron star inspiral made by the Advanced LIGO and Advanced Virgo paves the unprecedented way for multi-messenger observations. The propagation speed of this GW can be scrutinized by…
To calibrate stellar velocity dispersion measurements from optical and near-IR stellar lines, and to improve the black hole mass (MBH)- stellar velocity dispersion (sigma) relation, we measure stellar velocity dispersions based on high…
Gravitational wave (GW) observations of binary neutron star (BNS) mergers can be used to measure luminosity distances and hence, when coupled with estimates for the mergers' host redshifts, infer the Hubble constant, $H_0$. These…
Modifications to GR generically predict time and scale-dependent effects which may be probed by observations of strong lensing by galaxies. Measurements of the stellar velocity dispersion determine the dynamical mass whereas measurements of…
The line of sight velocity dispersion of the ultra-diffuse galaxies (UDGs) NGC1052-DF2 and NGC1052-DF4 have been reasonably explained only with the baryonic matter, without requiring any dark matter contribution. The comparable ratio…
We estimated the contribution of binary systems to the velocity dispersion inside OB-associations derived from Gaia DR2 proper motions. The maximum contribution to the velocity dispersion is given by the systems with the period of…
The velocity dispersion profile in globular clusters (GCs) is explained here without having to rely on dark matter or a modification of Newtonian dynamics (MOND). The flattening of the velocity dispersion at large radii in certain Milky Way…
We investigate the feasibility of determining the pairwise velocity dispersion (PVD) for Lyman Break Galaxies (LBGs), and of using this quantity as a discriminator among theoretical models. We find that when the Two Point Correlation…
Within the weak-field approximation of general relativity, new exact solutions are derived for the gravitational field of a mass moving with arbitrary velocity and acceleration. A mass having a constant velocity greater than 3^-1/2 times…
We report on the current status of the radial velocity monitoring of nearby OB stars to look for binaries with small mass ratios. The combined data of radial velocities using the domestic 1-2 m-class telescopes seems to confirm the…
Nowadays, thanks to the improved precision of cosmological data, it has been possible to search for deviation from the general relativity theory with tests on large cosmic scales. Particularly, there is a class of modified gravity theories…
The observed stellar kinematics of dispersion-supported galaxies are often used to measure dynamical masses. Recently, several analytical relationships between the stellar line-of-sight velocity dispersion, the projected (2D) or deprojected…
We use the kinematic data of the stars in eight dwarf spheroidal galaxies to assess whether $f(R)$ gravity can fit the observed profiles of the line-of-sight velocity dispersion of these systems without resorting to dark matter. Our model…
We study the orbital evolution of wide binary stars in the solar neighborhood due to gravitational perturbations from passing stars. We include the effects of the Galactic tidal field and continue to follow the stars after they become…
The total mass of a distant star cluster is often derived from the virial theorem, using line-of-sight velocity dispersion measurements and half-light radii, under the implicit assumption that all stars are single (although it is known that…
The most simple observed cases of gravitational lensing of distant quasars and galaxies by galaxies and clusters of galaxies are used to test Einstein's theory of General Relativity and Newtonian Gravity over galactic and intergalactic…
The velocity distribution of galaxies in clusters is not universal; rather, galaxies are segregated according to their spectral type and relative luminosity. We examine the velocity distributions of different populations of galaxies within…