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The Role of Dwarf Galaxy Interactions in Shaping the Magellanic System:

The Role of Dwarf Galaxy Interactions in Shaping the Magellanic System: Implications for Magellanic Irregulars & Dwarf Spheroidals. Gurtina Besla Columbia. Nitya Kallivayalil, Lars Hernquist, Roeland van der Marel, T.J. Cox & Dusan Keres. LMC. Milky Way. SMC.

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The Role of Dwarf Galaxy Interactions in Shaping the Magellanic System:

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  1. The Role of Dwarf Galaxy Interactions in Shaping the Magellanic System: Implications for Magellanic Irregulars & Dwarf Spheroidals Gurtina Besla Columbia Nitya Kallivayalil, Lars Hernquist, Roeland van der Marel, T.J. Cox & Dusan Keres

  2. LMC Milky Way SMC Image Credit: Miloslav Druckmuller (Brno University of Technology)

  3. Local Group & the Distance Morphology Relationship for Satellites The Local Group Antlia Milky Way Andromeda Tucana Cetus

  4. The LMC is the prototype for a class of dwarfs: Magellanic Irregulars Carlos Milovic F. - PixInsight Team http://www.pixinsight.com/ Biomedical Imaging Center - PUC “The Magellanic Clouds are not 'oddities' of Nature, but typical of a definite stage of the barred spiral sequence characterized by a specific kind of asymmetry” - de Vaucouleurs & Freeman 1972 Besla

  5. SMC: As a spheroidal galaxy? Zaritsky et al. 2000 See also Nidever et al. 2011 Stephane Guisard Besla

  6. Large Scale Morphology Leading Arm Bridge LMC Magellanic Stream SMC Nidever et al. 2010 Besla

  7. Dwarf Galaxy Evolution By studying the large scale gas morphology: What is the expected baryon loss rates from dwarf-dwarf tidal interactions? By studying the structure of the LMC: What is the dynamical state of the class of galaxies known as Magellanic Irregulars? By studying the structure of the SMC: What is the evolutionary relationship between gas rich, disk-like dwarfs and gas poor dwarf spheroidals? Besla

  8. NFW potential for the MW V LMC = 380 +/- 18 km/s Kallivayalil et al. 2006 Piatek et al. 2008 Besla et al. 2007 3rd Epoch of data: V ~ 320 +/- 25 km/s (Kalllivayalil, van der Marel, Besla et al. in prep; New Vcirc, Baseline, Kinematic models) New Orbital History First passage, or long period orbit (> 6 Gyr, e>0.7) (see also Shattow & Loeb 2009) STATIC MW MODEL Besla Image: Astronomy Magazine

  9. Kallivayalil, van der Marel, Anderson, Besla & Alcock 2012 in prep MW Mass Evolution Mass evolution following Fakhouri, Ma & Boylan-Kolchin 2010 Statistics from Millennium II : > 80% of surviving LMC’s about MW hosts at z=0 were accreted < 2 Gyr ago. (Boylan-Kolchin, Besla & Hernquist 2010) A First Infall is Favored in a LCDM Universe

  10. SMC in orbit about the LMC (no MW) • GADGET2 • (Springel 2005) • SPH simulations Rvir LMC tides remove an extended tail of gas from the SMC without the aid of MW tides

  11. Gas Morphology of the Magellanic System Besla et al. 2012, 2010 Leading Arm Bridge LMC Magellanic Stream SMC

  12. Magellanic IrregularNGC 4027 & 4027A ESO B,V,R wikisky Phookun et al. 1992 Besla

  13. MIPS Halpha (Bothun, Univ. Oregon) LMC in HI Kim et al 2001 R Band

  14. A recent LMC-SMC collisionBesla et al. 2012 arXiv: 1201.1299 Besla

  15. De-projected

  16. The Structure of the LMC and Magellanic Irregulars Besla

  17. DIrr - DSph Connection Tidal stripping/harrassment (Kazantzidis et al. 2011a, Lokas et al. 2012, Klimentowkski et al. 2009, Mayer et al 2005 Resonances -- D’Onghia, Besla et al 2010) but see Kirby talk Mergers with dark satellites (Starkenberg & Helmi in prep) But Rotation? Major Mergers of Disky Dwarfs (Kazantzidis, 2011b - But no gas - BCD Connection?) Direct Collisions in Dwarf Groups Besla

  18. Stanimirovic et al. 2004 SMC HI Gradient of 60 km/s NO rotation (< 8 km/s) To Bridge Zaritsky et al. 2000 See also Nidever et al. 2011 Stephane Guisard Besla

  19. SMC Structure: Herschel Gordon et al. 2009

  20. SMC Kinematics: Simulation Results 40 km/s Bridge

  21. Magellanic Irregular: NGC 4449 How Isolated is Isolated? Martinez-Delgado et al. 2011 Besla

  22. Summary Through these studies, we have shown that a picture in which the LMC and SMC are a binary pair of tidally interacting galaxies that has recently been accreted by the MW is consistent with - Cosmological expectations & HST PMs - The observed gas distribution of the system - The structure of the LMC: offset bar, characteristic of Magellanic Irregulars - The kinematics and structure of the SMC, establishing it as a transition object b/w a dIrr-dSph This process is expected to occur ubiquitously in small groups of low mass galaxies and may represent a generic mode of dwarf galaxy evolution that is independent of proximity to a massive host.

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