Abstract
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 (Kallivayalil et al. 2006a,b). Given the new velocities, cosmological simulations of structure formation favor a scenario where the Magellanic Clouds (MCs) are currently on their first infall towards our Galaxy (Boylan-Kolchin et al. 2011, Busha et al. 2011). We illustrate here that the observed irregular morphology and internal kinematics of the MCs (in gas and stars) are naturally explained by interactions between the LMC and SMC, rather than gravitational interactions with the MW. This picture further supports a first infall scenario (Besla et a. 2007). In particular, we demonstrate that the Magellanic Stream, a band of HI gas trailing behind the MCs 150 degrees 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-center, warped stellar bar of the LMC and its one-armed spiral, can be naturally explained by a recent direct collision with the SMC. Such structures are key morphological characteristics of a class of galaxies referred to as Magellanic Irregulars (de Vaucouleurs & Freeman 1972), 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 important not only for the evolution of dwarf galaxies but also have direct consequences for the buildup of baryons in our own MW, as LMC-mass systems are believed to be the dominant building blocks of MW-type halos.
Highlights
The Large Magellanic Cloud (LMC) is the prototype for a class of dwarf galaxies known as Magellanic Irregulars
We have explored two models for the possible interaction history of the LMC and Small Magellanic Cloud (SMC) in an effort to simultaneously reproduce both the large scale gaseous distribution of the Magellanic System and the internal structure and morphology of the LMC
The resulting kinematics and structure of the LMC strongly favor a scenario in which the Magellanic Clouds (MCs) have recently (100-300 Myr) experienced a direct collision
Summary
The Large Magellanic Cloud (LMC) is the prototype for a class of dwarf galaxies known as Magellanic Irregulars. There are numerous examples of Magellanic Irregulars in our Local Volume, they are rarely found about massive spirals This has been confirmed by recent studies of the frequency of LMC analogs about Milky Way (MW) type galaxies in the SDSS DR7 catalog (Liu et al 2011; Tollerud et al 2011). Recent studies indicate that the LMC is much bluer in color relative to analogs in its magnitude range (Tollerud et al 2011; James & Ivory 2011) This fact is difficult to reconcile with the expected gas loss and quenching of star formation the LMC should have incurred if it were a long-term companion of the MW (Grcevich & Putman 2009). The MW cannot have been the driver of its morphological evolution
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
