The Local Group Mass in the light of Gaia

Abstract

High accuracy proper motions (PMs) of M31 and other Local Group satellites have now been provided by the {\it Gaia} satellite. We revisit the Timing Argument to compute the total mass $M$ of the Local Group from the orbit of the Milky Way and M31, allowing for the Cosmological Constant. We rectify for a systematic effect caused by the presence of the Large Magellanic Cloud (LMC). The interaction of the LMC with the Milky Way induces a motion towards the LMC. This contribution to the measured velocity of approach of the Milky Way and M31 must be removed. We allow for cosmic bias and scatter by extracting correction factors tailored to the accretion history of the Local Group. The distribution of correction factors is centered around $0.63$ with a scatter $\pm 0.2$, indicating that the Timing Argument significantly overestimates the true mass. Adjusting for all these effects, the estimated mass of the Local Group is $M=3.4_{-1.1}^{+1.4}\times 10^{12}{M}_{\odot }$ (68 % CL) when using the M31 tangential velocity $82_{-35}^{+38}$ km/s. Lower tangential velocity models with $59_{-38}^{+42}$ km/s (derived from the same PM data with a flat prior on the tangential velocity) lead to an estimated mass of $M=3.1_{-1.0}^{+1.3}\times 10^{12}{M}_{\odot }$ (68 % CL). By making an inventory of the total mass associated with the 4 most substantial LG members (the Milky Way, M31, M33 and the LMC), we estimate the known mass is in the range $3.7_{-0.5}^{+0.5}\times 10^{12}{M}_{\odot }$.

Accepted in ApjL. Only minor textual changes in this version

References in corpus (12)

• The M31 Velocity Vector. II. Radial Orbit Towards the Milky Way and Implied Local Group Mass
• M31 Transverse Velocity and Local Group Mass from Satellite Kinematics
• Measuring the Mass of the Large Magellanic Cloud with Stellar Streams Observed by $S^5$
• Detection of the Milky Way reflex motion due to the Large Magellanic Cloud infall
• Dynamical signatures of a LCDM-halo and the distribution of the baryons in M33
• The Need for Speed: Escape velocity and dynamical mass measurements of the Andromeda galaxy
• Balancing mass and momentum in the Local Group
• Orbital masses of nearby luminous galaxies
• Constraining the mass of the Local Group
• Local Group timing argument and virial theorem mass estimators from cosmological simulations
• The M31/M33 tidal interaction: A hydrodynamic simulation of the extended gas distribution
• The Local Group as a test system for Modified Newtonian Dynamics

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