Does the dwarf galaxy system of the Milky Way originate from Andromeda?

Fouquet, Sylvain; Hammer, François; Yang, Yanbin; Puech, Mathieu; Flores, Hector

doi:10.48550/arxiv.1209.4077

Cited by 4 publications

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“…It was argued [6] that the kinematical and morphological properties of M31 can be explained by assuming a single major merger event at the M31 location about 8.7 Gyr ago during which TDGs have been formed. Further studies revealed that the Milky Way disk of dwarf satellites, the so called Vast Polar Structure, also can be explained through the tidal tail of this ancient merger event [7]. The Vast Thin Disk of Satellites (VTDS) around M31 could have been predicted before its discovery by Ibata et al [1] (see also [8]).…”

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confidence: 96%

Thin disk of co-rotating dwarfs: A fingerprint of dissipative (mirror) dark matter?

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2013

Physics of the Dark Universe

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Recent observations indicate that about half of the dwarf satellite galaxies around M31 orbit in a thin plane approximately aligned with the Milky Way. It has been argued that this observation along with several other features can be explained if these dwarf satellite galaxies originated as tidal dwarf galaxies formed during an ancient merger event. However if dark matter is collisionless then tidal dwarf galaxies should be free of dark matter -a condition that is difficult to reconcile with observations indicating that dwarf satellite galaxies are dark matter dominated. We argue that dissipative dark matter candidates, such as mirror dark matter, offer a simple solution to this puzzle.Recently the discovery of a vast, thin plane of co-rotating dwarf galaxies orbiting the Andromeda galaxy [1] has been reported. It was found that about half of the satellites of the Andromeda M31 galaxy belong to a vast extremely thin planar structure (about 400 kpc in diameter but only about 14 kpc in thickness). The structure is co-planar with the Milky Way to M31 position vector and is almost perfectly aligned with the pole of the Milky Way's disk. Of the 15 satellites in this thin plane, 13 of these were found to be co-rotating sharing the same direction of angular momentum. A similar planar structure but not so extremely thin and not so numerous (nine satellites with one counter-orbiting) was found earlier among Milky Way's dwarf satellites [2]. Such vast coherent planar structures constitutes an interesting puzzle from the point of view of the standard Concordance Cosmology [3].Such structures can be understood if the satellite galaxies originated as tidal dwarf galaxies. It was suggested by Zwicky long ago that new dwarf galaxies can be formed as a result of violent disruptions of galaxies during close encounters [4]. When two galaxies interact, tidal forces rip out matter from the galactic discs thus providing enough intergalactic tidal debris from which new dwarf galaxies (TDGs -Tidal Dwarf Galaxies) are formed. In such a tidal scenario planar distribution of newly formed TDGs as well as their correlated orbital moments are a natural outcome as the TDGs are formed from a common tidal tail in a plane defined by the orbit of the interaction [2]. Interestingly, it was shown that significant amount of counter-orbiting material emerges quite naturally in tidal interactions of disc galaxies [5]. Therefore, a tidal scenario can explain even the existence of the satellites orbiting counter to the bulk of other dwarf galaxies in the planar structure.It was argued [6] that the kinematical and morphological properties of M31 can be explained by assuming a single major merger event at the M31 location about 8.7 Gyr ago during which TDGs have been formed. Further studies revealed that the Milky Way disk of dwarf satellites, the so called Vast Polar Structure, also can be explained through the tidal tail of this ancient merger event [7]. The Vast Thin Disk of Satellites (VTDS) around M31 could have been predicted before its discovery by...

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confidence: 96%

Thin disk of co-rotating dwarfs: A fingerprint of dissipative (mirror) dark matter?

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2013

Physics of the Dark Universe

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“…Moreover, the location of the Giant Stream further limits the volume swept by the tidal tail, that still includes the MW. The MW could be presently reached by the tidal tail, whose modeling predicts a velocity consistent with that of the LMC 63 .…”

Section: Merger Imprints In Observations Of Nearby Spiralsmentioning

confidence: 88%

“…If such progenitors of MW satellites have reached the MW potential at the same time along a few specific orbits, they may reproduce most of their intrinsic kinematics and surface brightness 71 . Our simulations of M31 tidal tails 63,74 provide realistic TDGs that are far less compact than assumed in the previous work 72,73 and are more easily disrupted after a single passage. Completing such a study 74 is mandatory to verify whether or not the large mass-to-light ratios of the MW dwarfs falsify the M31 scenario.…”

Section: Merger Imprints In Observations Of Nearby Spiralsmentioning

confidence: 97%

“…The nature of MW dwarfs A major merger, that occurred five to six billion years ago at the M31 location, may have affected the whole content of the Local Group, because two-third of its baryons lie in this galaxy. In fact gas-rich major mergers are efficient in forming tidal dwarfs 63 (TDGs) with baryonic masses up to that of the Large Magellanic Cloud. The proximity of the Magellanic Clouds (MCs) near the MW is quite exceptional 64 : only 0.4% of local galaxies display such an environment, and those are found in a double galaxy system such as the Local Group with M31 and the MW.…”

Section: Merger Imprints In Observations Of Nearby Spiralsmentioning

confidence: 99%

“…The above scenario could appear speculative and is far from being proved. First, MW dwarfs, with the noticeable exception of MCs, are gas-free objects while TDGs expelled by the M31 merger are 90% gas-rich 63 . Second it has been argued that, due to their large velocity dispersions, MW dwarves are largely dominated by dark matter 67,68 , while TDGs are DM free.…”

Section: Merger Imprints In Observations Of Nearby Spiralsmentioning

confidence: 99%

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The Formation of Large Galactic Disks Through the Hierarchical Scenario: Further Consequences

et al. 2012

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Using the deepest and most complete observations of distant galaxies, we investigate the progenitors of present-day large spirals. Observations include spatially-resolved kinematics, detailed morphologies and photometry from UV to mid-IR. Six billions years ago, half of the present-day spirals were starbursts experiencing major mergers, evidence for this is provided by their anomalous kinematics and morphologies. They are consequently modeled using hydrodynamics models of mergers and it perfectly matches with merger rate predictions by state-of-the-art-ΛCDM semi-empirical models. Furthermore imprints in the halo of local galaxies such as M31 or NGC5907 are likely caused by major merger relics. This suggests that the hierarchical scenario has played a major role in shaping the massive galaxies of the Hubble sequence. Linking galaxy properties at different epochs is the best way to fully understand galaxy formation processes and we have tested such a link through generated series of simulations of gas-rich mergers. Mergers have expelled material in galactic haloes and beyond, possibly explaining 60% of the missing baryons in Milky-Way (MW) mass galaxies. A past major merger in M31 might drastically affect our understanding of Local Group galaxies, including MW dwarfs. We also propose future directions to observationally constrain the necessary ingredients in galaxy simulations.

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On the spin bias of satellite galaxies in the local group-like environment

Lee

Lemson

2013

J. Cosmol. Astropart. Phys.

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Abstract. We utilize the Millennium-II simulation databases to study the spin bias of dark subhalos in the Local Group-like systems which have two prominent satellites with comparable masses. Selecting the group-size halos with total mass similar to that of the Local Group (LG) from the friends-of-friends halo catalog and locating their subhalos from the substructure catalog, we determine the most massive (main) and second to the most massive (submain) ones among the subhalos hosted by each selected halo. When the dimensionless spin parameter (λ) of each subhalo is derived from its specific angular momentum and circular velocity at virial radius, a signal of correlation is detected between the spin parameters of the subhalos and the main-tosubmain mass ratios of their host halos at z = 0: The higher main-to-submain mass ratio a host halo has, the higher mean spin parameter its subhalos have. It is also found that the correlations exist even for the subhalo progenitors at z = 0.5 and 1. Our interpretation of this result is that the subhalo spin bias is not a transient effect but an intrinsic property of a LG-like system with higher main-to-submain mass ratio, caused by stronger anisotropic stress in the region. A cosmological implication of our result is also discussed.

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Does the dwarf galaxy system of the Milky Way originate from Andromeda?

Cited by 4 publications

References 0 publications

Thin disk of co-rotating dwarfs: A fingerprint of dissipative (mirror) dark matter?

Thin disk of co-rotating dwarfs: A fingerprint of dissipative (mirror) dark matter?

The Formation of Large Galactic Disks Through the Hierarchical Scenario: Further Consequences

On the spin bias of satellite galaxies in the local group-like environment

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