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Starbursts, Globular Clusters, and Dwarf Galaxies: What's Gone with the Winds?

Explore the formation and impact of dense star clusters in small galaxies, their role in powering outflows, and the connection to galaxy gas content. Study the feedback processes in starburst dwarf systems and the nature of stellar energetic feedback in galaxies.

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Starbursts, Globular Clusters, and Dwarf Galaxies: What's Gone with the Winds?

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  1. Starbursts, Globular Clusters, and Dwarf Galaxies: What's Gone with the Winds? NGC 1705--Tosi et al WFPC2 J. S. Gallagher University of Wisconsin-Madison J. S. Gallagher U. Michigan-Dwarfs + GCs

  2. WLM-dIrr Luminous GC MV=-8.8 WFPC2 study Hodge et al. 1999, ApJ, 521, 577 J. S. Gallagher U. Michigan-Dwarfs + GCs

  3. H1 NGC 147 WIYN V-band Hodge clusters: inner & outer locations Hodge 1977, AJ, 81, 25 H2 J. S. Gallagher U. Michigan-Dwarfs + GCs H3

  4. We conclude that---- • Long ago small galaxies made sufficient numbers of dense, massive star clusters for some to survive to the present. • These are found in the range of neabry dwarf systems from dIrrs to dEs to dSphs in a range of spatial and kinematic patterns. • Questions: • How did such small galaxies give birth to such clusters and what were the impacts? How does formation connect to chemistry and kinematics? • How important are GCs in powering outflows and reducing baryon content in low mass galaxies? Does this lead to very gas-poor galaxies? J. S. Gallagher U. Michigan-Dwarfs + GCs

  5. Observational approach to dwarf galaxy massive star clusters & gastrophysics-- • Nearby dwarf starbursts host young massive “super star clusters” (SSCs); structural analogs to globular clusters: • M ≥ 105 Msun • R(1/2) < 10 pc • Age < 30 Myr • SSCs--major power sources of L(Lyc) for [t<7-8 Myr] and L(mech) [t< 25-30 Myr]. • Observe feedback & cluster formation processes in action. J. S. Gallagher U. Michigan-Dwarfs + GCs

  6. NGC1569 & NGC5253: Two starburst dwarfs 10 Myr, 106Msun B A 10 NGC 1569: Gas-Rich Dwarf Starburst Galaxy, MV= -18 P. Anders, U. Goettingen; data HST: ESA/NASA J. S. Gallagher U. Michigan-Dwarfs + GCs

  7. Compact massive star cluster development & feedback: It’s the (re-)radiation! + Super molecular cloud core: n>105 cm-3, Vturb~10 km/s + Mm to sub-mm -> dusty molecular ISM + Efficient star formation; SF>30% + SFR>0.1Msun/yr for T~106 yr; Mcl≥105 Msun + Thermal IR & radio; super ultradense HII + Widespread photoionization + stellar wind cavity; supergiant HII region + UVOIR -> stars + HII & X-ray-shocked ISM + Starburst required for M*≤ 3x108 Msun, MV> -15 After Kelsey Johnson 2002, Science, 297, 776; Johnson & Kobulnicky 2003, ApJ, 597, 923 J. S. Gallagher U. Michigan-Dwarfs + GCs

  8. Inevitable Nature of Stellar Energetics Massive stars->> SNe II SSCs =>long lived supermassive star SNe II feedback: main mechanical power at low metals: Pmech~ (600km/s)2SN(SFR/dMW/dt) Mass-loading efficiency & galaxy ISM structure largely determine possible outflow speeds SNe key factor in lower mass galaxies with Vesc < 500 km/s J. S. Gallagher U. Michigan-Dwarfs + GCs

  9. More mechanical luminosity: DISK BLOWOUTS Supershells: Blowouts--vent into halos from disks. Hot interior partially confined by cooler shell Generally initial V(exp) << V(esc); P(z), n(z) critical Different physics than steady winds! Weaver et al. 1977, ApJ and later models Effects on HI vs fate of hot gas? Halo Photoionized surfaces Disk Mac Low et al. 1989, ApJ, 337, 141 J. S. Gallagher U. Michigan-Dwarfs + GCs

  10. NUCLEAR STARBURST WIND STRUCTURE Sustained mechanical energy inputs leads to galactic wind. Supersonic gas flow upstream of a critical point. Organized outflow M82 as a nearby example--seen in larger galaxies; matter of scale? J. S. Gallagher U. Michigan-Dwarfs + GCs

  11. NGC 1569 - NIR with WIYN 3.5-m Telescope; Natural Seeing: SF Patterns: SSCs Embedded in Young Star Clouds NGC 1569--3 SSCs in ~10 Myr-- Large jump in L(mech) associated with SSCs! Feedback induced shift in SF mode likely. Superbubble from SSC A a likely dominant factor SFR declines as dense ISM exhausted-and ejected? GMC formation vs. destruction? SSCs10 A B J. S. Gallagher U. Michigan-Dwarfs + GCs

  12. WFPC2 H +[NII] Local views of NGC 1569-- WIYN & HST: multiple super bubbles WIYN H +[NII] M. Westmoquette, K. Exter, L. Smith, J. Gallagher--2007 in prep J. S. Gallagher U. Michigan-Dwarfs + GCs

  13. NGC1569: SSCs important supershell drivers. Some likely to escape. HI HI M. Westmoquette et al. 2007 in prep C. Martin 1998, ApJ, 506, 222 Kinematic supershells in NGC 1569 J. S. Gallagher U. Michigan-Dwarfs + GCs

  14. High spatial concentration of massive stars powers hot gas outflow Martin, Kobulnicky, Heckman 2002, ApJ, 574, 663 V(HII) ~ 100 km/s-- Slow optical wind J. S. Gallagher U. Michigan-Dwarfs + GCs

  15. NGC1569 HI: starburst small scale relative to HI 2002, A&A, 392, 473 B A J. S. Gallagher U. Michigan-Dwarfs + GCs

  16. Dwarf dichotomy: gas-rich, slowly evolving vs. gas free (e.g. Grebel, Gallagher & Harbeck 2003, AJ, 125, 1926) Nature vs. Nurture. NGC5253 - gas deficient starburst HI/L ‹ 0.1, MV≈-18 Starburst driving gas removal & transition to NGC205 dE-like structure??? J. S. Gallagher U. Michigan-Dwarfs + GCs

  17. NGC5253-ACS J. S. Gallagher U. Michigan-Dwarfs + GCs

  18. Summers et al 2000 Harris et al. 2004 Kobulnicky & Skillman 1995 Complex multi-phase ISM + persistent cool ISM in presence of intense star formation: Dellenbusch Wisconsin PhD J. S. Gallagher U. Michigan-Dwarfs + GCs

  19. SSC D>17 kpc from NGC3310 starburst: MV= -11 ≈106 Msun Close to tidal debris but no HI GC formation mode? SDSS: Knapp et al.2006, AJ Tidal debris: Wehner et al. 2006, MNRAS; 2005, ApJL J. S. Gallagher U. Michigan-Dwarfs + GCs

  20. SSC formation --> starbursts: require Mbary≥108 Msun Triggers for SSCs?? SSCs in dwarfs usually centrally concentrated (NGC3310!) Multiple supershells--inefficient ISM mass loss. More efficient bleeding of metals Gas poor starbursts with central clusters (disks)--a final collapse phase of the ISM. Why & how (Kate Dellenbusch PhD)?? GC formation REQUIRES starbursts in small galaxies GCs have wide spatial distribution in dwarfs, not always centrally concentrated; ISM energy deposition reduced GC formation not strictkly associated with gas loss--SF extends past GC era Denser IGM surroundings may choke winds--affect metal evolution and radiation escape Globulars & Dwarfs: Now &Then J. S. Gallagher U. Michigan-Dwarfs + GCs

  21. J. S. Gallagher U. Michigan-Dwarfs + GCs

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