A dynamical model of the local cosmic expansion

  title={A dynamical model of the local cosmic expansion},
  author={Jorge Pe{\~n}arrubia and Yinzhe Ma and Matthew G. Walker and Alan W. McConnachie},
  journal={Monthly Notices of the Royal Astronomical Society},
We combine the equations of motion that govern the dynamics of galaxies in the local volume with Bayesian techniques in order to fit orbits to published distances and velocities of galaxies within $\sim 3$ Mpc. We find a Local Group (LG) mass $2.3\pm 0.7\times 10^{12}{\rm M}_\odot$ that is consistent with the combined dynamical masses of M31 and the Milky Way, and a mass ratio $0.54^{+0.23}_{-0.17}$ that rules out models where our Galaxy is more massive than M31 with $\sim 95\%$ confidence. The… Expand
Cosmic flow around local massive galaxies
Aims. We use accurate data on distances and radial velocities of galaxies around the Local Group, as well as around 14 other massive nearby groups, to estimate their radius of the zero-velocityExpand
The Local Group as a test system for Modified Newtonian Dynamics
The Local Group (LG) is {an appropriate} test system for Modified Newtonian Dynamics, since the acceleration of M31 galaxy is fully in the deep MOND regime $a \ll a_0$. We model the LG as a two bodyExpand
What galaxy masses perturb the local cosmic expansion
We use 12 cosmological $N$-body simulations of Local Group systems (the Apostle models) to inspect the relation between the virial mass of the main haloes ($M_{\rm vir,1}$ and $M_{\rm vir,2}$), theExpand
Dynamical history of the Local Group in ΛCDM
The positions and velocities of galaxies in the Local Group (LG) measure the gravitational field within it. This is mostly due to the Milky Way (MW) and Andromeda (M31). We constrain their massesExpand
Dynamical history of the Local Group in $\Lambda$CDM – II. Including external perturbers in 3D
We attempt to fit the observed radial velocities (RVs) of ${\,{\sim}\,}30$ Local Group (LG) galaxies using a 3D dynamical model of it and its immediate environment within the context of the standardExpand
A plane of high-velocity galaxies across the Local Group
We recently showed that several Local Group (LG) galaxies have much higher radial velocities (RVs) than predicted by a 3D dynamical model of the standard cosmological paradigm. Here, we show that 6Expand
Milky Way and Andromeda past-encounters in different gravity models: the impact on the estimated Local Group mass
The Two-body problem of $M31$ and the Milky Way (MW) galaxies with a Cosmological Constant background is studied, with emphasis on the possibility that they experienced Past Encounters. ByExpand
Local Group Analogs in ΛCDM Cosmological Simulations
We use semi-analytic galaxy catalogs based on two high-resolution cosmological $N$-body simulations, Millennium-WMAP7 and Millennium-II, to investigate the formation of the Local Group (LG) analogs.Expand
The APOSTLE simulations: solutions to the Local Group's cosmic puzzles
The Local Group of galaxies offer some of the most discriminating tests of models of cosmic structure formation. For example, observations of the Milky Way (MW) and Andromeda satellite populationsExpand
Planets in Other Universes: Habitability constraints on density fluctuations and galactic structure
Motivated by the possibility that different versions of the laws of physics could be realized within other universes, this paper delineates the galactic parameters that allow for habitable planetsExpand


Balancing mass and momentum in the Local Group
In the rest frame of the Local Group (LG), the total momentum of the Milky Way (MW) and Andromeda (M31) should balance to zero. We use this fact to constrain new solutions for the solar motion withExpand
The formation of Local Group planes of galaxies
The confinement of most satellite galaxies in the Local Group to thin planes presents a challenge to the theory of hierarchical galaxy cl ustering. The PAndAS collaboration has identified aExpand
Weighing the Local Group in the presence of dark energy
We revise the mass estimate of the Local Group (LG) when Dark Energy (in the form of the Cosmological Constant) is incorporated into the Timing Argument (TA) mass estimator for the Local Group (LG).Expand
The Local Hubble flow: A Manifestation of dark energy
Our local environment at $r<10$ Mpc expands linearly and smoothly, as if ruled by a uniform matter distribution, while observations show the very clumpy local universe. This is a long standing enigmaExpand
Inferring the Andromeda Galaxy's mass from its giant southern stream with Bayesian simulation sampling
M31 has a giant stream of stars extending far to the south and a great deal of other tidal debris in its halo, much of which is thought to be directly associated with the southern stream. We modelExpand
The Solar Motion Relative to the Local Group
New data on the membership of the Local Group (LG) are used, in conjunction with new and improved radial velocity data, to refine the derivation of the motion of the Sun relative to the LG. The SunExpand
The RAVE survey: constraining the local Galactic escape speed
New constraints on the local escape speed of the Galaxy are reported, finding that the escape velocity lies within the range 498 <v(esc) <608 km s (-1) (90 per cent confidence), with a median likelihood of 544 km s(-1). Expand
Local kinematics and the local standard of rest
We re-examine the stellar kinematics of the solar neighbourhood in terms of the velocity υ� of the Sun with respect to the local standard of rest. We show that the classical determination of itsExpand
Mass models of the Milky Way
We present a simple method for fitting parametrized mass models of the Milky Way to observational constraints. We take a Bayesian approach which allows us to take into account input from photometricExpand
The Masses of the Milky Way and Andromeda galaxies
We present a family of robust tracer mass estimators to compute the enclosed mass of galaxy haloes from samples of discrete positional and kinematical data of tracers, such as halo stars, globularExpand