N-body simulations of the Small Magellanic Cloud and the Magellanic Stream

Abstract

An extensive set of N-body simulations has been carried out on the gravitational interaction of the Small Magellanic Cloud (SMC) with the Galaxy and the Large Magellanic Cloud (LMC). The SMC is assumed to have been a barred galaxy with a disc-to-halo mass ratio of unity before interaction and modelled by a large number of self-gravitating particles, whereas the Galaxy and LMC have been represented by rigid spherical potentials. Our more advanced numerical treatment has enabled us to obtain the most integrated and systematic understanding to date of numerous morphological and kinematical features observed in the Magellanic system (excluding the LMC), which have been dealt with more or less separately in previous studies. The best model we have found succeeded in reproducing the Magellanic Stream (MS) as a tidal plume created by the SMC-LMC-Galaxy close encounter 1.5 Gyr ago. At the same time, we see the formation of a leading counterpart to the Magellanic Stream (the leading arm), on the opposite side of the Magellanic Clouds to the Stream, which mimicks the overall distribution of several neutral hydrogen clumps observed in the corresponding region of the sky. A close encounter with the LMC 0.2 Gyr ago created another tidal tail and bridge system, which constitutes the inter-Cloud region in our model. The elongation of the SMC bar along the line-of-sight direction suggested by Cepheid observations has been partially reproduced, alongside its projected appearance on the sky. The model successfully explains some major trends in the kinematics of young populations in the SMC bar and older populations in the 'halo' of the SMC, as well as the overall velocity pattern for the gas, young stars, and carbon stars in the inter-Cloud region.

The Magellanic Stream, High‐Velocity Clouds, and the Sculptor Group

“…To begin with, the column density distribution does not gradually drop off toward the Stream's tail in the tidal simulations (e.g., Gardiner & Noguchi 1996;hereafter GN96). Although the HIPASS observations show the Stream to be extremely clumpy, there is still a systematic decrease in the mean column density from MS I to MS VI (see Table 2) which should be explained.…”

H [CSC]i[/CSC] Fine Structure in Magellanic Tidal Debris

“…Figure 1 shows the velocity field and distribution of brightness temperature for these clouds based on the high-velocity component list of Morras et al (2000), with the positions of the Gardiner & Noguchi (1996) tidal model particles overlaid. Population EP is defined as the gas in the region l ¼ 250 330 , b ¼ À30 to 30 with v LSR > 150 km s À1 .…”

High‐resolution absorption spectroscopy of the circumgalactic medium of the Milky Way

“…The Stream represents a massive (∼ 10 8 − 10 9 M ⊙ ) gaseous structure consisting of both neutral and ionized gas and is believed to be a result of the interaction of the two Magellanic Clouds as they approach the Milky Way (e.g., Wannier & Wrixon 1972;Gardiner & Noguchi 1996;Weiner & Williams 1996;Putman et al 2003;Brüns et al 2005). Although the MS has a relatively large distance of ∼ 50 − 60 kpc, it covers about 4 percent of the 21cm high-velocity sky (see Wakker 2004).…”

“…Tidal models indicate that the main body of the Stream most likely was stripped from its parent galaxy ∼ 1 − 2 Gyr ago (e.g., Gardiner & Noguchi 1996;Connors et al 2006;Besla et al 2010Besla et al ,2012 To further increase the accuracy of the metallicity determination of the Stream towards Fairall 9 and other background targets and to study in detail the chemical composition of the gas and dust in the MS, more accurate spectral data are needed. As part of our ongoing project to www.an-journal.org Fig.…”