Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The Local Group Mass in the light of Gaia   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^{+1.4}_{-1.1} \times 10^{12} M_{\odot}$ (68 % CL) when using the M31
tangential velocity $ 82^{+38}_{-35}$ km/s. Lower tangential velocity models
with $59^{+42}_{-38}$ 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^{+1.3}_{-1.0}
\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 $3.7^{+0.5}_{-0.5} \times
10^{12} \, M_{\odot}$.

2
The categories of this paper are: math
16
The categories of this paper are: stat
28
The categories of this paper are: alg-geom
31
The categories of this paper are: ao-sci
8
The categories of this paper are: hep-ex
19
The categories of this paper are: eess
33
The categories of this paper are: plasm-ph
18
The categories of this paper are: econ
30
The categories of this paper are: q-alg
14
The categories of this paper are: math-ph
24
The categories of this paper are: dg-ga
4
The categories of this paper are: cond-mat
23
The categories of this paper are: solv-int
36
The categories of this paper are: cmp-lg
17
The categories of this paper are: q-fin
22
The categories of this paper are: chao-dyn