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Mapping the HI Neighborhood Around Starburst Dwarf Galaxies

Mapping the HI Neighborhood Around Starburst Dwarf Galaxies. Megan Johnson NRAO, Green Bank. Tully-Fisher Workshop, April 2012. Outline. Introduction NGC 1569 Review of stellar and gas kinematics from LITTLE THINGS GBT map NGC 4163/NGC 4214 Future Work Summary. Introduction.

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Mapping the HI Neighborhood Around Starburst Dwarf Galaxies

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  1. Mapping the HI Neighborhood Around Starburst Dwarf Galaxies Megan Johnson NRAO, Green Bank Tully-Fisher Workshop, April 2012

  2. Outline • Introduction • NGC 1569 • Review of stellar and gas kinematics from LITTLE THINGS • GBT map • NGC 4163/NGC 4214 • Future Work • Summary Megan Johnson - TF 35

  3. Introduction • Starburst = short-lived intense period of star formation that is unsustainable over the Hubble time due to the limited supply of gas within a galaxy (McQuinn + 2010);generally, interactions/mergers are triggers • Dwarf Galaxy = low luminosity, low mass system, contained in a dark matter halo; believed to be the “Building Blocks” of larger galaxies • Starburst Dwarf Galaxy = possibly a “Building Block” in action? What is the role of interactions/mergers between dwarf galaxies? Megan Johnson - TF 35

  4. Introduction • Can HI environment around starburst dwarf galaxies provide clues to their interaction/merger history? Megan Johnson - TF 35

  5. NGC 1569 – What is its shape? • Stellar and Gas Kinematics Vmax/σz A B • Member of IC 342 Galaxy Group • D =3.36Mpc(Grocholski+ 2008) • MV =-17.57 • SFR = 0.24 M/yr • HI mass = 2.5 x 108 M • Stellar mass =2.8 x 108 M Megan Johnson - TF 35

  6. Previous Work: “HI Companion,” “HI Bridge,” Stil & Israel (1998) and “NCM HI Cloud” – Stil & Israel (2002) - HV3 “Chimney” - Hunter et al. (1993); Mühle et al. (2005); Westmoquette et al. (2008) Megan Johnson - TF 35

  7. Stellar Kinematics Megan Johnson - TF 35

  8. Position-Velocity Diagrams – Stars and Gas Megan Johnson - TF 35

  9. Ionized Gas in NGC 1569 B A Megan Johnson - TF 35

  10. Stellar Velocity Dispersions <σz> = 21 ± 4 km/s Constant SSC A SSC B Megan Johnson - TF 35

  11. Bulk Motion Extraction Megan Johnson - TF 35

  12. Bulk Motion Extraction Strong NCM Bulk VF Vmax = 50 ± 10 km/s Weak NCM Strong + Weak Megan Johnson - TF 35

  13. Rotation Curve of NGC 1569 Vmax = 50 ± 10 km/s Megan Johnson - TF 35

  14. Baryonic TF Relation – Trachternach+ 2009 Total Baryonic Mass = 6.8 x 108 M ★ NGC 1569 Megan Johnson - TF 35

  15. -113.17 km/s GBT Map around NGC 1569 NGC 1569 Southern HI Extension UGCA 92 Megan Johnson - TF 35

  16. -110.76 km/s GBT Map around NGC 1569 NGC 1569 Intergalactic Filaments UGCA 92 MW Cloud Megan Johnson - TF 35

  17. NGC 4163 • Member of Canes VenaticiCloud • D = 2.8 Mpc • MV = -14.37 • SFR = 9.1 x 10-4M/yr • HI mass = 1.4 x 107 M • Stellar mass = 2.7 x 107 M Megan Johnson - TF 35

  18. NGC 4163 – IWM Velocity Field Megan Johnson - TF 35

  19. NGC 4214 • D = 2.9 Mpc • MV = -17.56 • SFR = 0.13 M/yr • HI mass = 5.8 x 108 M • Stellar mass = 4.8 x 108 M • Member of Canes Venatici Cloud Megan Johnson - TF 35

  20. NGC 4214 – IWM Velocity Field Megan Johnson - TF 35

  21. Integrated HI GBT Map UGCA 7605 RMS = 25 mK, (at 1σ in a 1 km/s channel) UGCA 7559 UGCA 7599 NGC 4214 NGC 4163 NGC 4190 NGC 4244 Megan Johnson - TF 35

  22. What about field dwarfs? • Are nearby dwarf irregular galaxies still assembling? • GBT proposal to map all LITTLE THINGS dwarfs Megan Johnson - TF 35

  23. IC 1613 – Local Group Member Megan Johnson - TF 35

  24. DDO 165 – M81 Group Member Megan Johnson - TF 35

  25. DDO 46 – No Known Group Megan Johnson - TF 35

  26. Summary • NGC 1569 is a thick disk • Vmax/σz = 2.4 ± 0.7 • Stars and gas kinematically follow each other • Extended HI emission to south and northeast of NGC 1569 in VLA map stretching in the direction of UGCA 92 and confirmed with GBT • NGC 4163/4214 • “Unsettled” HI in VLA maps • Possible extendedemission detected in GBT map …stay tuned … • LITTLE THINGS - ?? Megan Johnson - TF 35

  27. Megan Johnson - TF 35

  28. Ultra-dense HI Cloud (UDHIC) Hα tail – Velocity ~ -90 km/s (Tomita et al. 1994)

  29. Integrated HI Intensity Contour Map Megan Johnson - TF 35

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