The role of dwarf galaxy interactions in shaping the Magellanic System and implications for Magellanic Irregulars

By G. Besla, N. Kallivayalil, L. Hernquist, R. P. van der Marel, Thomas J. Cox, D. Keres̆. 2012

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We present a novel pair of numerical models of the interaction history between the Large and Small Magellanic Clouds (LMC and SMC, respectively) and our Milky Way (MW) in light of recent high-precision proper motions from the Hubble Space Telescope. Given the updated velocities, cosmological simulations of hierarchical structure formation favour a scenario where the Magellanic Clouds (MCs) are currently on their first infall towards our Galaxy. We illustrate here that the observed irregular morphology and internal kinematics of the Magellanic System (in gas and stars) are naturally explained by interactions between the LMC and SMC, rather than gravitational interactions with the MW. These conclusions provide further support that the MCs are completing their first infall to our system. In particular, we demonstrate that the Magellanic Stream, a band of H i gas trailing behind the Clouds 150° across the sky, can be accounted for by the action of LMC tides on the SMC before the system was accreted by the MW. We further demonstrate that the off-centre, warped stellar bar of the LMC, and its one-armed spiral can be naturally explained by a recent direct collision with its lower mass companion, the SMC. Such structures are key morphological characteristics of a class of galaxies referred to as Magellanic Irregulars, the majority of which are not associated with massive spiral galaxies. We infer that dwarf–dwarf galaxy interactions are important drivers for the morphological evolution of Magellanic Irregulars and can dramatically affect the efficiency of baryon removal from dwarf galaxies via the formation of extended tidal bridges and tails. Such interactions are not only important for the evolution of dwarf galaxies but also have direct consequences for the build-up of baryons in our own MW, as LMC-mass systems are believed to be the dominant building blocks of MW-type haloes.

Subfields: Astronomy and Astrophysics, Instrumentation

View Paper: https://www.semanticscholar.org/paper/6d7194cb8d5fc9192382cc54eb4f9143f193004d

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Citations in the corpus

Moving mesh cosmology: tracing cosmological gas accretion (2013, background): “The importance in separating different gas origins in the simulations can be seen by reference to observations of our local environment, in which the Magellanic Stream is a large reservoir of cold, neutral gas thought to arise from the tidal interaction of dwarf satellites (Besla et al. 2010, 2012).”
THIRD-EPOCH MAGELLANIC CLOUD PROPER MOTIONS. II. THE LARGE MAGELLANIC CLOUD ROTATION FIELD IN THREE DIMENSIONS (2013, background): “However, more recent numerical simulations in which the morphology of the LMC is highly disturbed due to interactions with the SMC have shown that the dynamical centers of the gas and stars often stay closely aligned (Besla et al. 2012).”
Hunting for the Dark Matter Wake Induced by the Large Magellanic Cloud (2019, methodology): “…massive LMC halo models (1011M ) have also been shown to reproduce several observations, such as the global properties of the Magellanic System (Besla et al. 2010, 2012, 2013; Salem et al. 2015; Pardy et al. 2018), the morphology of the MW’s HI disk and its resulting line of nodes (Weinberg &…”
The total mass of the Large Magellanic Cloud from its perturbation on the Orphan stream (2018, background): “However, attempts to model the Magellanic stream seen in HI (Putman et al. 2003) have found that the SMC has likely had multiple pericentric passages with the LMC (e.g. Besla et al. 2012).”
A timing constraint on the (total) mass of the Large Magellanic Cloud (2015, methodology): “Interestingly, N-body simulations of Besla et al. (2012) illustrate the SMC needs to complete 2–3 orbits about the LMC within the past ∼ 3Gyr in order to produce the main components of the Magellanic System which, given the high relative speed of the SMC with respect to the LMC (∼ 130kms−1;…”
Dwarf galaxy planes: the discovery of symmetric structures in the Local Group (2013, background): “This lead Besla et al. (2010, 2012) to suggest that the MS might have been formed by the tidal interaction of LMC and SMC before they were accreted onto the MW.”
Stellar Streams Discovered in the Dark Energy Survey (2018, background): “The proximity between Elqui and the Magellanic Stream suggests that Elqui may in fact be stellar ejecta from a past collision between the LMC and SMC (Besla et al. 2010, 2012).”
Galaxies as simple dynamical systems: observational data disfavor dark matter and stochastic star formation (2014, background): “dwarf spheroidal satellite galaxies. Today this is known as the DoS or VPOS (Sec. 5.1.1). The most recent work on the orbital evolution of the Large and Small Magellanic Clouds by Besla et al. (2012, [206]) studies, for the very ﬁrst time, the two galaxies selfconsistently within the SMoC. Therewith”
THIRD-EPOCH MAGELLANIC CLOUD PROPER MOTIONS. I. HUBBLE SPACE TELESCOPE/WFC3 DATA AND ORBIT IMPLICATIONS (2013, methodology): “…of the large scale gaseous structures of the Magellanic System (Stream, Bridge and Leading Arm) and the internal structure and kinematics of the Clouds are a result of interactions between the LMC and SMC in a first infall scenario, rather than interactions with the MW (Besla et al. 2010, 2012).”
THE STAR FORMATION HISTORIES OF LOCAL GROUP DWARF GALAXIES. I. HUBBLE SPACE TELESCOPE/WIDE FIELD PLANETARY CAMERA 2 OBSERVATIONS (2014, background): “…a massive galaxies can result in several effects, including the temporary enhancement of star-formation, as is thought to be the case of the SMC and LMC (e.g., Besla et al. 2007, 2012; Weisz et al. 2013) and the eventual quenching of star-formation (e.g., Teyssier et al. 2012; Slater & Bell 2013).”