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, Hosein; Kroupa, Pavel; Banik, Indranil; Wu, Xufen; Zonoozi, Akram Hasani; Javanmardi, Behnam; Ghari, Amir; Müller, Oliver; Dabringhausen, J.; Zhao, Hongsheng

doi:10.1093/mnras/stz1465

Cited by 53 publications

(81 citation statements)

References 88 publications

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“…NGC 1052-DF2 and DF4 (van Dokkum et al 2018(van Dokkum et al , 2019. Some of the controversy has centred on whether DF2 Contact e-mail: dforbes@swin.edu.au and DF4 lie in the NGC 1052 group at ∼20 Mpc or much closer at ∼13 Mpc Haghi et al 2019); the closer distance would imply a more typical dark matter content. Also debated in the literature is whether DF2 is inconsistent with Modified Newtonian Dynamics (MOND) (van Dokkum et al 2018) or consistent (Haghi et al 2019).…”

Section: Introductionmentioning

confidence: 99%

Dark matter and no dark matter: on the halo mass of NGC 1052

Forbes

Alabi

Brodie

et al. 2019

Monthly Notices of the Royal Astronomical Society

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The NGC 1052 group, and in particular the discovery of two ultra diffuse galaxies with very low internal velocity dispersions, has been the subject of much attention recently. Here we present radial velocities for a sample of 77 globular clusters associated with NGC 1052 obtained on the Keck telescope. Their mean velocity and velocity dispersion are consistent with that of the host galaxy. Using a simple tracer mass estimator, we infer the enclosed dynamical mass and dark matter fraction of NGC 1052. Extrapolating our measurements with an NFW mass profile we infer a total halo mass of 6.2 (±0.2) × 10 12 M . This mass is fully consistent with that expected from the stellar mass-halo mass relation, suggesting that NGC 1052 has a normal dark matter halo mass (i.e. it is not deficient in dark matter in contrast to two ultra diffuse galaxies in the group). We present a phase space diagram showing the galaxies that lie within the projected virial radius (390 kpc) of NGC 1052. Finally, we briefly discuss the two dark matter deficient galaxies (NGC 1052-DF and DF4) and consider whether MOND can account for their low observed internal velocity dispersions.

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Section: Introductionmentioning

confidence: 99%

Dark matter and no dark matter: on the halo mass of NGC 1052

Forbes

Alabi

Brodie

et al. 2019

Monthly Notices of the Royal Astronomical Society

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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: 65%

“…However, their conclusion of the discovery of a dark-matter-deficient galaxy relies on a distance of D = 20 Mpc from Earth. DF2 and also DF4 may be satellites of NGC 1052 and the whole system may be located at a much shorter distance of ≈ 10 Mpc, making their GC populations comparable to those of other galaxies (Haghi et al 2019). In the here presented analysis, we showed that finding similar galaxies in standard cosmology is extremely rare regardless of its actual distance from Earth.…”

Section: Resultsmentioning

confidence: 99%

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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“…Throughout this letter we use the Bayesian framework to describe uncertainties using probabilities and probability distributions (O'Hagan & Forster 2004;Gregory 2005), noting that this approach has been used previously in assessing the veracity of dynamical models of stellar systems (Diakogiannis et al 2014;Mackey et al 2019b). The posterior distribution for parameters Λ given data D is given by…”

Section: Bayesian Inferencementioning

confidence: 99%

“…Nusser 2018), as well as for alternative models of gravity (e.g. Famaey et al 2018;Haslbauer et al 2019;Haghi et al 2019).…”

Section: Introductionmentioning

confidence: 99%

The globular cluster population of NGC 1052-DF2: evidence for rotation

Lewis

Brewer

Wan

2019

Monthly Notices of the Royal Astronomical Society: Letters

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Based upon the kinematics of ten globular clusters, it has recently been claimed that the ultra-diffuse galaxy, NGC 1052-DF2, lacks a significant quantity of dark matter. Dynamical analyses have generally assumed that this galaxy is pressure supported, with the relatively small velocity dispersion of the globular cluster population indicating the deficit of dark matter. However, the presence of a significant rotation of the globular cluster population could substantially modify this conclusion. Here we present the discovery of such a signature of rotation in the kinematics of NGC 1052-DF2's globular clusters, with a velocity amplitude of ∼ 12.44 +4.40 −5.16 km/s, which, through Bayesian model comparison, represents a marginally better fit to the available kinematic data; note that this rotation is distinct from, and approximately perpendicular to, the recently identified rotation of the stellar component of NGC 1052-DF2. Assuming this truly represents an underlying rotation, it is shown that the determined mass depends upon the inclination of the rotational component and, with a moderate inclination, the resultant mass to light ratio can exceed M/L ∼ 10.

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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

Cited by 53 publications

References 88 publications

Dark matter and no dark matter: on the halo mass of NGC 1052

Dark matter and no dark matter: on the halo mass of NGC 1052

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

The globular cluster population of NGC 1052-DF2: evidence for rotation

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