Intergalactic Matter and the Galaxy.

Kahn, F. D.; Waltjer, L.

doi:10.1086/146762

Cited by 428 publications

(369 citation statements)

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“…The total mass of the group has been determined with a number of empirical methods including the classic model of Kahn & Woltjer (1959; see also Einasto & Lynden-Bell 1982), the virial theorem (see a review by van den Bergh 1999), and the zero-velocity estimate (cf. a recent paper by Karachentsev et al 2009 and references therein).…”

Section: The Very Local Environmentmentioning

confidence: 99%

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Local dark matter and dark energy as estimated on a scale of ~1 Mpc in a self-consistent way

Chernin¹,

Teerikorpi²,

Valtonen³

et al. 2009

A&A

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Context. Dark energy was first detected from large distances on gigaparsec scales. If it is vacuum energy (or Einstein's Λ), it should also exist in very local space. Here we discuss its measurement on megaparsec scales of the Local Group. Aims. We combine the modified Kahn-Woltjer method for the Milky Way-M 31 binary and the HST observations of the expansion flow around the Local Group in order to study in a self-consistent way and simultaneously the local density of dark energy and the dark matter mass contained within the Local Group. Methods. A theoretical model is used that accounts for the dynamical effects of dark energy on a scale of ∼1 Mpc. Results. The local dark energy density is put into the range 0.8−3.7ρ v (ρ v is the globally measured density), and the Local Group mass lies within 3.1−5.8 × 10 12 M . The lower limit of the local dark energy density, about 4/5× the global value, is determined by the natural binding condition for the group binary and the maximal zero-gravity radius. The near coincidence of two values measured with independent methods on scales differing by ∼1000 times is remarkable. The mass ∼4 × 10 12 M and the local dark energy density ∼ρ v are also consistent with the expansion flow close to the Local Group, within the standard cosmological model. Conclusions. One should take into account the dark energy in dynamical mass estimation methods for galaxy groups, including the virial theorem. Our analysis gives new strong evidence in favor of Einstein's idea of the universal antigravity described by the cosmological constant.

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Section: The Very Local Environmentmentioning

confidence: 99%

“…Fifty years ago, Kahn & Woltjer (1959) used a simple linear two body dynamics to describe the relative motion of the Milky Way (MW) and M 31 galaxies. The motion of the galaxies was described (in the reference frame of the binary's center of mass) by the equation of motion,…”

Section: Modified Kahn-woltjer (Mkw) Modelmentioning

confidence: 99%

Local dark matter and dark energy as estimated on a scale of ~1 Mpc in a self-consistent way

Chernin¹,

Teerikorpi²,

Valtonen³

et al. 2009

A&A

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show abstract

“…One example is the 'numerical action' method developed by Peebles et al (2001) to reconstruct the peculiar velocities of nearby galaxies which, when applied to the LG, predicts a fairly large circular velocity for the MW (Peebles, Tully & Shaya 2011). A simpler, but nonetheless useful, example is provided by the 'timing argument' (Kahn & Woltjer 1959), where the MW-M31 system is approximated as a pair of isolated point masses that expand radially away after the big bang but decelerate under their own gravity until they turn around and start approaching. Assuming that the age of the Universe is known, that the orbit is strictly radial, and that the pair is on first approach, this argument leads to a robust and unbiased estimate of the total mass of the system (Li & White 2008).…”

mentioning

confidence: 99%

The apostle project: Local Group kinematic mass constraints and simulation candidate selection

Fattahi

Navarro

Sawala

et al. 2016

Mon. Not. R. Astron. Soc.

215

268

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We use a large sample of isolated dark matter halo pairs drawn from cosmological N-body simulations to identify candidate systems whose kinematics match that of the Local Group of Galaxies (LG). We find, in agreement with the "timing argument" and earlier work, that the separation and approach velocity of the Milky Way (MW) and Andromeda (M31) galaxies favour a total mass for the pair of ∼ 5 × 10 12 M ⊙ . A mass this large, however, is difficult to reconcile with the small relative tangential velocity of the pair, as well as with the small deceleration from the Hubble flow observed for the most distant LG members. Halo pairs that match these three criteria have average masses a factor of ∼ 2 times smaller than suggested by the timing argument, but with large dispersion, spanning more than a decade in mass. Guided by these results, we have selected 12 halo pairs with total mass in the range 1.6-3.6 × 10 12 M ⊙ for the APOSTLE project (A Project Of Simulations of The Local Environment), a suite of resimulations at various numerical resolution levels (reaching up to ∼ 10 4 M ⊙ per gas particle) that use the hydrodynamical code and subgrid physics developed for the EA-GLE project. These simulations reproduce, by construction, the main kinematics of the MW-M31 pair, and produce satellite populations whose overall number, luminosities, and kinematics are in good agreement with observations of the MW and M31 companions. These diagnostics are sensitive to the total mass assumed for the MW-M31 pair; indeed, the LG satellite population would be quite difficult to reproduce for pair masses as high as indicated by the timing argument. The APOSTLE candidate systems thus provide an excellent testbed to confront directly many of the predictions of the ΛCDM cosmology with observations of our local Universe.

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“…The next essential step in the dark matter story was made by Kahn & Woltjer (1959). They noticed that the Andromeda galaxy and our Galaxy approach each other, whereas almost all other galaxies recede from us.…”

Section: History Of the Dark Matter Conceptmentioning

confidence: 99%

Dark Matter in Groups and Clusters of Galaxies

Einasto

2000

International Astronomical Union Colloquium

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Abstract.We compare the characteristics of stellar populations with those of dark halos. Dark matter around galaxies, and in groups, clusters and voids is discussed. Modern data suggest that the overall density of matter in the Universe is Ω M = 0.3 ± 0.1, about 80 % of this matter is nonbaryonic dark matter, and about 20 % is baryonic, mostly in the form of hot intra-cluster and intragroup gas, the rest in stellar populations of galaxies. All bright galaxies are surrounded by dark matter halos of external radii 200 − 300 kpc; halos consist mostly of non-baryonic matter with some mixture of hot gas. The Universe is dominated by dark energy (cosmological constant) term. Dark matter dominates in the dynamical evolution of galaxies in groups and clusters.

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Intergalactic Matter and the Galaxy.

Cited by 428 publications

References 0 publications

Local dark matter and dark energy as estimated on a scale of ~1 Mpc in a self-consistent way

Local dark matter and dark energy as estimated on a scale of ~1 Mpc in a self-consistent way

The apostle project: Local Group kinematic mass constraints and simulation candidate selection

Dark Matter in Groups and Clusters of Galaxies

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