A new formulation of the external field effect in MOND and numerical simulations of ultra-diffuse dwarf galaxies $-$ application to NGC 1052-DF2 and NGC 1052-DF4

Abstract

The ultra-diffuse dwarf galaxy NGC 1052-DF2 (DF2) has ten (eleven) measured globular clusters (GCs) with a line-of-sight velocity dispersion of $\sigma =7.8_{-2.2}^{+5.2}$km/s ($\sigma =10.6_{-2.3}^{+3.9}$km/s). Our conventional statistical analysis of the original ten GCs gives $\sigma =8.0_{-3.0}^{+4.3}$km/s. The overall distribution of velocities agrees well with a Gaussian of this width. Due to the non-linear Poisson equation in MOND, a dwarf galaxy has weaker self-gravity when in close proximity to a massive host. This external field effect is investigated using a new analytic formulation and fully self-consistent live $N$-body models in MOND. Our formulation agrees well with that of Famaey and McGaugh (2012). These new simulations confirm our analytic results and suggest that DF2 may be in a deep-freeze state unique to MOND. The correctly calculated MOND velocity dispersion agrees with our inferred dispersion and that of van Dokkum et al. (2018b) if DF2 is within 150 kpc of NGC 1052 and both are 20 Mpc away. The GCs of DF2 are however significantly brighter and larger than normal GCs, a problem which disappears if DF2 is significantly closer to us. A distance of 10-13 Mpc makes DF2 a normal dwarf galaxy even more consistent with MOND and the 13 Mpc distance reported by Trujillo et. al. (2019). We discuss the similar dwarf DF4, finding good agreement with MOND. We also discuss possible massive galaxies near DF2 and DF4 along with their distances and peculiar velocities, noting that NGC 1052 may lie at a distance near 10 Mpc.

14 pages, 9 figures, 2 Tables, accepted for publication in MNRAS

References in corpus (15)

• The Baryon Content of Extremely Low Mass Dwarf Galaxies
• Kinematics of the Local Universe XIII. 21-cm line measurements of 452 galaxies with the Nançay radiotelescope, JHK Tully-Fisher relation and preliminary maps of the peculiar velocity field
• A second galaxy missing dark matter in the NGC1052 group
• Galaxies as simple dynamical systems: observational data disfavor dark matter and stochastic star formation
• From Spitzer Galaxy Photometry to Tully-Fisher Distances
• Still Missing Dark Matter: KCWI High-Resolution Stellar Kinematics of NGC1052-DF2
• Velocity anti-correlation of diametrically opposed galaxy satellites in the low redshift universe
• The optimally-sampled galaxy-wide stellar initial mass function - Observational tests and the publicly available GalIMF code
• Phantom of RAMSES (POR): A new Milgromian dynamics N-body code
• Southern GEMS Groups I: Dynamical Properties
• Galactic rotation curves, the baryon-to-dark-halo-mass relation and space-time scale invariance
• Stellar streams as gravitational experiments II. Asymmetric tails of globular cluster streams
• The chemical evolution of galaxies with a variable IGIMF
• Predicted MOND velocity dispersions for a catalog of ultra-diffuse galaxies in group environments
• Constraints on the HI Mass of NGC 1052-DF2

Cited by in corpus (29)

• From galactic bars to the Hubble tension: weighing up the astrophysical evidence for Milgromian gravity
• Galaxies lacking dark matter produced by close encounters in a cosmological simulation
• A Tip of the Red Giant Branch Distance of $22.1\pm 1.2$ Mpc to the Dark Matter Deficient Galaxy NGC1052-DF2 from 40 Orbits of Hubble Space Telescope Imaging
• The distribution and morphologies of Fornax Cluster dwarf galaxies suggest they lack dark matter
• A spectroscopic study of MATLAS-2019 with MUSE: an ultra-diffuse galaxy with an excess of old globular clusters
• Testing the Strong Equivalence Principle. II. Relating the External Field Effect in Galaxy Rotation Curves to the Large-Scale Structure of the Universe
• Asymmetrical tidal tails of open star clusters: stars crossing their cluster's prah challenge Newtonian gravitation
• 3D hydrodynamic simulations for the formation of the Local Group satellite planes
• Models of modified-inertia formulation of MOND
• Numerical Solutions of the External Field Effect on the Radial Acceleration in Disk Galaxies
• Probing the radial acceleration relation and the strong equivalence principle with the Coma cluster ultra-diffuse galaxies
• The properties of dwarf spheroidal galaxies in the Cen A group: Stellar populations, internal dynamics, and a heart-shaped Halpha ring
• On the tension between the Radial Acceleration Relation and Solar System quadrupole in modified gravity MOND
• On the functional form of the radial acceleration relation
• The underlying radial acceleration relation
• The phenomenology of the external field effect in cold dark matter models
• Scale-invariant dynamics in the Solar System
• Testing non-local gravity through Ultra-Diffuse Galaxies kinematics
• Simulations of cluster ultra-diffuse galaxies in MOND
• The kinematics of star clusters undergoing gas expulsion in Newtonian and Milgromian dynamics
• Velocity dispersion of dark matter deficient ultra-diffuse galaxies: A case for modified gravity
• Evolution of globular-cluster systems of ultra-diffuse galaxies due to dynamical friction in MOND gravity
• Formation of collisional ring galaxies in Milgromian dynamics
• Measuring Mass of Gas in Central Galaxies using weak lensing and satellite kinematics in MOND
• DHOST gravity in Ultra-diffuse galaxies -- Part I: the case of NGC1052-DF2
• The Cen A galaxy group: dynamical mass and missing baryons
• Comparing dark matter and MOND hyphotheses from the distribution function of A, F, early-G stars in the solar neighbourhood
• Examining Baryonic Faber-Jackson Relation in Galaxy Groups
• The tidal features of the classical Milky Way satellites: Expected in MOND but inconsistent with cold dark matter models