The number of satellite galaxies connected to the Milky Way and to the Andromeda galaxy respectively, are comparable in number to the number of planets, dwarf planets, moons, and large asteroids in the solar system.
Sadly, the preprint does not have an indexed table listing all of them and their properties, although it does analyze the properties of these satellite galaxies from a variety of perspectives. But, Wikipedia does have a list of satellite galaxies for the Milky Way, and for the Andromeda galaxy.
At the time of writing, there are 88 confirmed satellite galaxies in the LG [i.e the Local Group] (49 in the MW [i.e. the Milky Way galaxy] and 39 in M31 [i.e. the Andromeda galaxy]) and a further 15 candidate galaxies (14 in the MW and 1 in M31).
From Amandine Doliva-Dolinsky, Michelle L. M. Collins, Nicolas F. Martin, "The satellite galaxies of the Milky Way and Andromeda" arXiv:2502.06948 (February 10, 2025) (to be published as a chapter in the forthcoming Encyclopedia of Astrophysics).
The abstract of the pre-print states:
The satellite galaxies of the Local Group provide us with an important probe of galaxy formation, evolution, and cosmology. The two large spirals that dominate this group -- the Milky Way and Andromeda -- are each host to tens of satellites, ranging in stellar mass from M∗=3×109M⊙ down to as little as M∗∼1000M⊙. In this review, we (1) provide an overview of the known satellite population of the Milky Way and Andromeda, including how they are discovered and their observed properties; (2) discuss their importance in understanding the nature of dark matter, star formation in the early Universe, the assembly histories of their massive hosts, and the impact of reionisation on the lowest mass galaxies; and (3) highlight the coming revolution and challenges of this field as new observatories and facilities come online. In the coming decades, the study of Local Group satellites should allow us to place competitive constraints on both dark matter and galaxy evolution.
Low-Acceleration Gravitational Anomaly from Bayesian 3D Modeling of Wide Binary Orbits: Methodology and Results with Gaia DR3
ReplyDeleteAuthors: Kyu-Hyun Chae
Abstract: Isolated wide binary stars provide natural laboratories to directly test or measure weak gravity for Newtonian acceleration gN≲10−9 m s−2. Recent statistical analyses of wide binaries have been performed only with sky-projected relative velocities vp in the pairs. A new method of Bayesian orbit modeling exploiting three relative velocity components including the radial (line-of-sight) component vr is developed to measure a gravitational anomaly parameter Γ≡log10Geff/GN−−−−−−−√ where Geff is the effective gravitational constant for pseudo-Newtonian elliptical orbits, while GN is Newton's constant. The method infers individual probability distributions of Γ and then combines the independent distributions to obtain a consolidated distribution in a specific range of gN. Here the method is described and applied to a sample of 312 wide binaries in a broad dynamic range 10−11.0≲gN≲10−6.7 m s−2 with vr uncertainties in the range 168<σvr<380 m s−1 selected from the Gaia DR3 database. The following results are obtained: Γ=0.000±0.011 (Nbinary=125) for a high acceleration regime (10−7.9≲gN≲10−6.7 m s−2) agreeing well with Newton, but Γ=0.085±0.040 (35) for a MOND regime (10−11.0≲gN≲10−9.5 m s−2) and Γ=0.063±0.015 (111) for a MOND+transition regime (10−11.0≲gN≲10−8.5 m s−2). These results show that gravitational anomaly is evident for gN≲10−9 m s−2 and Γ in the MOND regime (≲10−9.5 m s−2) agrees with the first-tier prediction (≈0.07) of MOND gravity theories. △ Less
Submitted 13 February, 2025; originally announced February 2025.
Comments: 34 pages, 24 figures, 3 tables (submitted to the AAS journals)