MOND and the dynamics of NGC 1052−DF2

Famaey, Benoît; McGaugh, Stacy S.; Milgrom, Mordehai

doi:10.1093/mnras/sty1884

Cited by 68 publications

(81 citation statements)

References 34 publications

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“…This would challenge MOND with just over two-sigma confidence according to the velocity dispersion reported by van Dokkum et al (2018a,b) but is compatible within the three-sigma confidence range of the here obtained velocity dispersion using the same data. DF2 is thus most likely in a quasi-Newtonian state, confirming a central MOND prediction if it is indeed close to NGC 1052 Famaey et al 2018).…”

Section: Analytic Expectationssupporting

confidence: 66%

“…When a i ≈ a e < a 0 , the object is quasi-Newtonian i.e. Newton's law of Gravity applies with an effective gravitational constant G e f f ≥ G (Famaey & McGaugh 2012;McGaugh & Milgrom 2013;Famaey et al 2018;Müller et al 2019a). According to the Famaey & McGaugh (2012) formulation, the MOND acceleration a at the half-light radius is…”

Section: Comparison With Famaey and Mcgaugh (2012)mentioning

confidence: 99%

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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

Haghi

Kroupa

Banik

et al. 2019

Monthly Notices of the Royal Astronomical Society

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The ultra-diffuse dwarf galaxy NGC 1052-DF2 (DF2) has ten (eleven) measured globular clusters (GCs) with a line-of-sight velocity dispersion of σ = 7.8 +5.2 −2.2 km/s (σ = 10.6 +3.9 −2.3 km/s). Our conventional statistical analysis of the original ten GCs gives σ = 8.0 +4.3 −3.0 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.

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Section: Analytic Expectationssupporting

confidence: 66%

Section: Comparison With Famaey and Mcgaugh (2012)mentioning

confidence: 99%

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

Haghi

Kroupa

Banik

et al. 2019

Monthly Notices of the Royal Astronomical Society

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“…When the internal acceleration is larger than the external, g ex < g < a 0 , then we can apply the given formula for the isolated case. However, if g < g ex < a 0 the object is quasi-Newtonian, where Newton's law of Gravity applies with a renormalization of the gravitational constant G (McGaugh & Milgrom 2013a;Famaey et al 2018). The external acceleration can be approximated by g e = v 2 rot /D, where v rot is the rotation curve of the external galaxy and D is the separation between the two objects.…”

Section: The External Field Effect Calculationmentioning

confidence: 99%

Predicted MOND velocity dispersions for a catalog of ultra-diffuse galaxies in group environments

Müller

Famaey

Zhao

2019

A&A

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The possibility that ultra-diffuse galaxies lacking dark matter has recently stimulated interest to check the validity of Modified Newton Dynamics (MOND) predictions on the scale of such galaxies. It has been shown that the External Field Effect (EFE) induced by the close-by galaxy can suppress the velocity dispersion of these systems, so that they appear almost dark matter free in the Newtonian context. Here, following up on this, we are making a priori predictions for the velocity dispersion of 22 ultra-diffuse galaxies in the nearby Universe. This sample can be used to test MOND and the EFE with future follow-up measurements. We construct a catalog of nearby ultra-diffuse galaxies in galaxy group environments, and set upper and lower limits for the possible velocity dispersion allowed in MOND, taking into account possible variations in the mass-to-light ratio of the dwarf and in the distance to the galaxy group. The prediction for the velocity dispersion is made as a function of the three dimensional separation of the dwarf to its host. In 17 out of 22 cases, the EFE plays a crucial role in the prediction.

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“…A very low intrinsic velocity dispersion of around σ intr = 7.8 +5.2 −2.2 km s −1 (van Dokkum et al 2018a) of an isolated dwarf galaxy would be, according to van Dokkum et al (2018b), in major conflict with modified gravity theories such as Milgromian dynamics (MOND, Milgrom 1983). However, DF2 is close to the massive elliptical galaxy NGC 1052 and taking into account its external field (which is an important prediction of MOND), DF2 becomes well consistent with MOND (Famaey et al 2018;Kroupa et al 2018;Haghi et al 2019;Müller et al 2019). In fact, DF2 is extremely gas-depleted and could be therefore a satellite of NGC 1052, having lost its gas reservoir via ram-pressure stripping and tidal forces triggered by several close encounters (Chowdhury 2019;Sardone et al 2019).…”

Section: Introductionmentioning

confidence: 60%

The ultra-diffuse dwarf galaxies NGC 1052-DF2 and 1052-DF4 are in conflict with standard cosmology

Haslbauer

Banik

Kroupa

et al. 2019

Monthly Notices of the Royal Astronomical Society

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Recently van Dokkum et al. (2018b) reported that the galaxy NGC 1052-DF2 (DF2) lacks dark matter if located at 20 Mpc from Earth. In contrast, DF2 is a dark-matterdominated dwarf galaxy with a normal globular cluster population if it has a much shorter distance near 10 Mpc. However, DF2 then has a high peculiar velocity wrt. the cosmic microwave background of 886 km s −1 , which differs from that of the Local Group (LG) velocity vector by 1298 km s −1 with an angle of 117 • . Taking into account the dynamical M/L ratio, the stellar mass, half-light radius, peculiar velocity, motion relative to the LG, and the luminosities of the globular clusters, we show that the probability of finding DF2-like galaxies in the lambda cold dark matter (ΛCDM) TNG100-1 simulation is at most 1.0×10 −4 at 11.5 Mpc and is 4.8×10 −7 at 20.0 Mpc. At 11.5 Mpc, the peculiar velocity is in significant tension with the TNG100-1, TNG300-1, and Millennium simulations, but occurs naturally in a Milgromian cosmology. At 20.0 Mpc, the unusual globular cluster population would challenge any cosmological model. Estimating that precise measurements of the internal velocity dispersion, stellar mass, and distance exist for 100 galaxies, DF2 is in 2.6σ (11.5 Mpc) and 4.1σ (20.0 Mpc) tension with standard cosmology. Adopting the former distance for DF2 and assuming that NGC 1052-DF4 is at 20.0 Mpc, the existence of both is in tension at ≥ 4.8σ with the ΛCDM model. If both galaxies are at 20.0 Mpc the ΛCDM cosmology has to be rejected by ≥ 5.8σ.

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MOND and the dynamics of NGC 1052−DF2

Cited by 68 publications

References 34 publications

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

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

Predicted MOND velocity dispersions for a catalog of ultra-diffuse galaxies in group environments

The ultra-diffuse dwarf galaxies NGC 1052-DF2 and 1052-DF4 are in conflict with standard cosmology

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