The collision velocity of the bullet cluster in conventional and modified dynamics

Angus, Garry W.; McGaugh, Stacy S.

doi:10.1111/j.1365-2966.2007.12403.x

Cited by 60 publications

(65 citation statements)

References 71 publications

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“…As clusters merge, their halos overlap and dark matter constraints should be taken into account, as shown in Nusser (2008). Finally, we also ignored the gravitational interaction of the infalling matter outside the cluster pair, which could affect the assumption that masses are constant since their formation time (Angus & McGaugh 2008). All these points may modify the results presented in section 5.2.…”

Section: Caveats About the Methodsmentioning

confidence: 95%

Dynamical analysis of the cluster pair: A3407 + A3408

Nascimento

Ribeiro

Trevisan

et al. 2016

Mon. Not. R. Astron. Soc.

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We carried out a dynamical study of the galaxy cluster pair A3407 & A3408 based on a spectroscopic survey obtained with the 4 meter Blanco telescope at the CTIO, plus 6dF data, and ROSAT All-Sky-Survey. The sample consists of 122 member galaxies brighter than m R = 20. Our main goal is to probe the galaxy dynamics in this field and verify if the sample constitutes a single galaxy system or corresponds to an ongoing merging process. Statistical tests were applied to clusters members showing that both the composite system A3407 + A3408 as well as each individual cluster have Gaussian velocity distribution. A velocity gradient of ∼ 847 ± 114 km s −1 was identified around the principal axis of the projected distribution of galaxies, indicating that the global field may be rotating. Applying the KMM algorithm to the distribution of galaxies we found that the solution with two clusters is better than the single unit solution at the 99% c.l. This is consistent with the X-ray distribution around this field, which shows no common X-ray halo involving A3407 and A3408. We also estimated virial masses and applied a two-body model to probe the dynamics of the pair. The more likely scenario is that in which the pair is gravitationally bound and probably experiences a collapse phase, with the cluster cores crossing in less than ∼1 h −1 Gyr, a pre-merger scenario. The complex X-ray morphology, the gas temperature, and some signs of galaxy evolution in A3408 suggests a post-merger scenario, with cores having crossed each other ∼ 1.65h −1 Gyr ago, as an alternative solution.

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Section: Caveats About the Methodsmentioning

confidence: 95%

Dynamical analysis of the cluster pair: A3407 + A3408

Nascimento

Ribeiro

Trevisan

et al. 2016

Mon. Not. R. Astron. Soc.

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“…Furthermore, the high galaxy-cluster-galaxy-cluster velocities required to obtain the features of the Bullet cluster have been shown to be extremely unlikely in the CCM (Sect. 1), but these velocities are found to naturally occur in MOND (Angus & McGaugh 2008). Last but not least, the time-delay problem of the CCM mentioned in Sect.…”

Section: Non-newtonian Weak-field Gravitymentioning

confidence: 99%

“…The velocity of the sub-cluster relative to the large cluster has since been calculated to be about 3000 km s −1 so that the observed morphology can arise (Mastropietro & Burkert 2008). But according to Angus & McGaugh (2008) and Lee & Komatsu (2010), such high velocities between a sub-cluster and a main galaxy cluster are virtually excluded in the CCM. Near the centre of lens-galaxies, the observed delay times between the multiple images of strongly lensed background sources cannot be understood if the galaxy has a standard (NFW or isothermal) DM content and if, at the same time, the Hubble constant has a classical value of 70 km s −1 Mpc −1 : the solution is either to decrease the Hubble constant (in disagreement with other observations), or to consider the known baryonic matter (with constant mass-to-light ratio) as the one and only source of the lensing (Kochanek & Schechter 2004).…”

Section: Introductionmentioning

confidence: 99%

Local-Group tests of dark-matter concordance cosmology

Kroupa

Famaey

Boer

et al. 2010

A&A

229

301

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Predictions of the concordance cosmological model (CCM) of the structures in the environment of large spiral galaxies are compared with observed properties of Local Group galaxies. Five new, most probably irreconcilable problems are uncovered: 1) A wide variety of published CCM models consistently predict some form of relation between dark-matter-mass and luminosity for the Milky Way (MW) satellite galaxies, but none is observed.2) The mass function of luminous sub-haloes predicted by the CCM contains too few satellites with dark matter (DM) mass ≈10 7 M within their innermost 300 pc than in the case of the MW satellites.3) The Local Group galaxies and data from extragalactic surveys indicate there is a correlation between bulge-mass and the number of luminous satellites that is not predicted by the CCM. 4) The 13 new ultra-faint MW satellites define a disc-of-satellites (DoS) that is virtually identical to the DoS previously found for the 11 classical MW satellites, implying that most of the 24 MW satellites are correlated in phase-space. 5) The occurrence of two MW-type DM halo masses hosting MW-like galaxies is unlikely in the CCM. However, the properties of the Local Group galaxies provide information leading to a solution of the above problems. The DoS and bulge-satellite correlation suggest that dissipational events forming bulges are related to the processes forming phase-space correlated satellite populations. These events are well known to occur since in galaxy encounters energy and angular momentum are expelled in the form of tidal tails, which can fragment to form populations of tidal-dwarf galaxies (TDGs) and associated star clusters. If Local Group satellite galaxies are to be interpreted as TDGs then the substructure predictions of the CCM are internally in conflict. All findings thus suggest that the CCM does not account for the Local Group observations and that therefore existing as well as new viable alternatives have to be further explored. These are discussed and natural solutions for the above problems emerge.

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“…If a Milgromian cosmology is allowed to have a hot DM component then the Bullet Cluster is well explainable (Angus & McGaugh 2008;. We know that neutrinos oscillate, therefore they must have a mass.…”

Section: The Bullet and Train-wreck Clustersmentioning

confidence: 99%

The Dark Matter Crisis: Falsification of the Current Standard Model of Cosmology

Kroupa¹

2012

Publ. – Astron. Soc. Aust

243

275

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Abstract:The current standard model of cosmology (SMoC) requires The Dual Dwarf Galaxy Theorem to be true according to which two types of dwarf galaxies must exist: primordial dark-matter (DM) dominated (type A) dwarf galaxies, and tidal-dwarf and ram-pressure-dwarf (type B) galaxies void of DM. Type A dwarfs surround the host approximately spherically, while type B dwarfs are typically correlated in phasespace. Type B dwarfs must exist in any cosmological theory in which galaxies interact. Only one type of dwarf galaxy is observed to exist on the baryonic Tully-Fisher plot and in the radius-mass plane. The Milky Way satellite system forms a vast phase-space-correlated structure that includes globular clusters and stellar and gaseous streams. Other galaxies also have phase-space correlated satellite systems. Therefore, The Dual Dwarf Galaxy Theorem is falsified by observation and dynamically relevant cold or warm DM cannot exist. It is shown that the SMoC is incompatible with a large set of other extragalactic observations. Other theoretical solutions to cosmological observations exist. In particular, alone the empirical mass-discrepancyacceleration correlation constitutes convincing evidence that galactic-scale dynamics must be Milgromian. Major problems with inflationary big bang cosmologies remain unresolved.

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The collision velocity of the bullet cluster in conventional and modified dynamics

Cited by 60 publications

References 71 publications

Dynamical analysis of the cluster pair: A3407 + A3408

Dynamical analysis of the cluster pair: A3407 + A3408

Local-Group tests of dark-matter concordance cosmology

The Dark Matter Crisis: Falsification of the Current Standard Model of Cosmology

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