Constraining the orbital history of the Magellanic Clouds: a new bound scenario suggested by the tidal origin of the Magellanic Stream

Diaz, Jonathan; Bekki, Kenji

doi:10.1111/j.1365-2966.2011.18289.x

Cited by 86 publications

(107 citation statements)

References 34 publications

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“…It is also worth noting that the SMC has experienced at least two close encounters with the LMC, and is currently experiencing an ongoing encounter with the MW [44,55]. The relative strength of these interactions has varied as a function of time and orbital parameters of the three galaxies.…”

Section: Discussionmentioning

confidence: 99%

“…At low redshift, TCR nucleosynthesis could be important for low metallicity systems, which continue to experience tidal disruptions by their neighbors, such as the SMC [see eg. [44][45][46]. In these systems, at a given metallicity, one would thus expect to find a significantly higher 6 Li abundance and consequently, a lower 7 Li-to-6 Li ratio relative to that predicted by standard galactic chemical evolution models.…”

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confidence: 99%

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Galactic fly-bys: New source of lithium production

2013

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Observations of low-metallicity halo stars have revealed a puzzling result: the abundance of 7 Li in these stars is at least three times lower than their predicted primordial abundance. It is unclear whether the cause of this disagreement is a lack of understanding of lithium destruction mechanisms in stars or the non-standard physics behind the Big Bang Nucleosynthesis (BBN). Uncertainties related to the destruction of lithium in stars can be circumvented if lithium abundance is measured in the "pristine" gas of the low metallicity systems. The first measurement in one such system, the Small Magellanic Cloud (SMC), was found to be at the level of the pure expected primordial value, but is on the other hand, just barely consistent with the expected galactic abundance for the system at the SMC metallicity, where important lithium quantity was also produced in interactions of galactic cosmic rays (GCRs) and presents an addition to the already present primordial abundance. Due to the importance of the SMC lithium measurement for the resolution of the lithium problem, we here draw attention to the possibility of another post-BBN production channel of lithium, which could present an important addition to the observed SMC lithium abundance. Besides standard galactic cosmic rays, additional post-BBN production of lithium might come from cosmic rays accelerated in galaxy-galaxy interactions. This might be important for a system such is the SMC, which has experienced galaxy harassment in its history. Within a simplified but illustrative framework we demonstrate that large-scale tidal shocks from a few galactic fly-bys can possibly produce lithium in amounts comparable to those expected from the interactions of galactic cosmic-rays produced in supernovae over the entire history of a system. In case of the SMC, we find that only two such fly-bys could possibly account for as much lithium as the standard, GCR production channel. However, adding any a new mechanism for post-BBN production of lithium, like the one proposed here, would contribute to the observed SMC lithium abundance, causing this measurement to be more in tension with the primordial abundance predicted by the standard BBN.

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Section: Discussionmentioning

confidence: 99%

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confidence: 99%

Galactic fly-bys: New source of lithium production

2013

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“…Diaz & Bekki (2011) present a new tidal model in which, for the first time, structures resemble a clear bifurcation of the LA. Concerning LA4, we would like to note that the existence of this feature was predicted by Besla et al (2010), but their simulations fail to recover LA1.…”

Section: Discussionmentioning

confidence: 99%

The four leading arms of the Magellanic Cloud system

Venzmer¹,

Kerp²,

Kalberla³

2012

A&A

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Context. The Magellanic Cloud system (MCS) interacts via tidal and drag forces with the Milky Way galaxy. Aims. Using the Parkes Galactic All-Sky Survey (GASS) of atomic hydrogen we explore the role of drag on the evolution of the so-called Leading Arm (LA).Methods. We present a new image recognition algorithm that allows us to differentiate features within a 3D data cube (longitude, latitude, radial velocity) and to parameterize individual coherent structures. We compiled an Hi object catalog of LA objects within an area of 70 • × 85 • (1.6 sr) of the LA region. This catalog comprises information of location, column density, line width, shape and asymmetries of the individual LA objects above the 4-σ threshold of ΔT b 200 mK.Results. We present evidence of a fourth arm segment (LA4). For all LA objects we find an inverse correlation of velocities v GSR in Galactic Standard of Rest frame with Magellanic longitude. High-mass objects tend to have higher radial velocities than low-mass ones. About 1/4 of all LA objects can be characterized as head-tail (HT) structures. Conclusions. Using image recognition with objective criteria, it is feasible to isolate most of LA emission from the diffuse Milky Way Hi gas. Some blended gas components (we estimate 5%) escape detection, but we find a total gas content of the LA that is about 50% higher than previously assumed. These methods allow the deceleration of the LA clouds to be traced towards the Milky Way disk by drag forces. The derived velocity gradient strongly supports the assumption that the whole LA originates entirely in the Large Magellanic Cloud (LMC). LA4 is observed opposite to LA1, and we propose that both arms are related, spanning about 52 kpc in space. HT structures trace drag forces even at tens of kpc altitudes above the Milky Way disk.

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“…Nearly half a century ago, a giant stream of neutral hydrogen was discovered, attached to the LMC and the SMC on the sky (Wannier & Wrixon 1972;Mathewson et al 1974). Today, mapped in exquisite detail (see e.g., Putman et al 2003;Nidever et al 2008Nidever et al , 2010, the Magellanic Stream (MS) is yet to have a comprehensive model, but is generally explained as a result of tidal interaction between the Clouds and the Milky Way (see Besla et al 2007Besla et al , 2010Diaz & Bekki 2011, 2012. Note, however, that a ram-pressure origin of the MS has also been explored (see e.g., Moore & Davis 1994;Mastropietro et al 2005;Hammer et al 2015;Salem et al 2015).…”

Section: Introductionmentioning

confidence: 99%

To the Galactic Virial Radius with Hyper Suprime-Cam

Deason

Belokurov

Koposov

2018

ApJ

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The full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-prot purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.Please consult the full DRO policy for further details. AbstractWe exploit the exquisite, deep Hyper Suprime-Cam (HSC) imaging data to probe the Galactic halo out to 200 kpc. Using the ∼100 square degree, multiband photometry of the first HSC Wide survey data release, we identify blue horizontal branch (BHB) stars beyond 50 kpc in the halo. The presence of the Sagittarius (Sgr) stream in the HSC fields produces a notable excess of stars at the apocenter of the leading arm (∼50-60 kpc). For fields excluding Sgr, the BHB counts are consistent with a continuation of a −4 power law from the inner halo. However, we find that the majority of the non-Sgr BHB stars beyond 50 kpc reside in one 27 square degree HSC field called "VVDS." Curiously, this field is located close to the Magellanic plane, and we hypothesize that the excess of stars between 50 and 200 kpc could be associated with distant Magellanic debris. Indeed, without the VVDS, there are very few BHBs in the remaining portions of the Galaxy probed by the HSC. Accordingly, this scarcity of tracers is consistent with a significant decline in stellar density beyond 50 kpc, with a power law of −4 or steeper.

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Constraining the orbital history of the Magellanic Clouds: a new bound scenario suggested by the tidal origin of the Magellanic Stream

Cited by 86 publications

References 34 publications

Galactic fly-bys: New source of lithium production

Galactic fly-bys: New source of lithium production

The four leading arms of the Magellanic Cloud system

To the Galactic Virial Radius with Hyper Suprime-Cam

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