NGC 1705 Tosi et al WFPC 2 August

NGC 1705 --Tosi et al WFPC 2 August 28, 2007 J. S. Gallagher U. Michigan-Dwarfs + GCs

WLM-d. Irr Luminous GC MV=-8. 8 WFPC 2 study Hodge et al. 1999, Ap. J, 521, 577 August 28, 2007 J. S. Gallagher U. Michigan-Dwarfs + GCs

H 1 NGC 147 WIYN V-band Hodge clusters: inner & outer locations Hodge 1977, AJ, 81, 25 August 28, 2007 H 2 J. S. Gallagher H 3 U. Michigan-Dwarfs + GCs

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 d. Irrs to d. Es to d. Sphs 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? August 28, 2007 J. S. Gallagher U. Michigan-Dwarfs + GCs

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. August 28, 2007 J. S. Gallagher U. Michigan-Dwarfs + GCs

NGC 1569 & NGC 5253: Two starburst dwarfs 10 Myr, 106 Msun B A 10 NGC 1569: Gas-Rich Dwarf Starburst Galaxy, MV= -1 P. Anders, U. Goettingen; J. S. data HST: ESA/NASA Gallagher August 28, 2007 U. Michigan-Dwarfs + GCs

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. 1 Msun/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*≤ 3 x 108 Msun, MV> -15 After Kelsey Johnson 2002, Science, 297, 776; Johnson & Kobulnicky 2003, Ap. J, 597, 923 August 28, 2007 J. S. Gallagher U. Michigan-Dwarfs + GCs

Inevitable Nature of Stellar Energetics Massive stars->> SNe II SSCs =>long lived supermassive star SNe II feedback: main mechanical power at low metals: Pmech~ (600 km/s)2 SN(SFR/d. MW/dt) Mass-loading efficiency & galaxy ISM structure largely determine possible outflow speeds SNe key factor in lower mass galaxies with Vesc < 500 km/s August 28, 2007 J. S. Gallagher U. Michigan-Dwarfs + GCs

More mechanical luminosity: DISK BLOWOUTS Halo 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 Photoionized surfaces Different physics than steady winds! Weaver et al. 1977, Ap. J and later models Disk Effects on HI vs fate of hot gas? Mac Low et al. 1989, Ap. J, 337, 141 August 28, 2007 J. S. Gallagher U. Michigan-Dwarfs + GCs

NUCLEAR STARBURST WIND STRUCTURE Sustained mechanical energy inputs leads to galactic wind. Supersonic gas flow upstream of a critical point. Organized outflow M 82 as a nearby example--seen in larger galaxies; matter of scale? August 28, 2007 J. S. Gallagher U. Michigan-Dwarfs + GCs

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! SSCs 10 Feedback induced shift in SF A mode likely. B Superbubble from SSC A a likely dominant factor SFR declines as dense ISM exhausted-and ejected? GMC formation vs. destruction? August 28, 2007 J. S. Gallagher U. Michigan-Dwarfs + GCs

M. Westmoquette, K. Exter, L. Smith, J. Gallagher--2007 in prep Local views of NGC 1569 -- WIYN & HST: multiple super bub WIYN H +[NII] WFPC 2 H +[NII] August 28, 2007 J. S. Gallagher U. Michigan-Dwarfs + GCs

NGC 1569: SSCs important supershell drivers. HI Some likely to escape. HI M. Westmoquette et al. 2007 in prep C. Martin 1998, Ap. J, 506, 222 Kinematic supershells in NGC 1569 August 28, 2007 J. S. Gallagher U. Michigan-Dwarfs + GCs

High spatial concentration of massive stars powers hot gas outflow Martin, Kobulnicky, Heckman 2002, Ap. J, 574, 663 V(HII) ~ 100 km/s-Slow optical wind August 28, 2007 J. S. Gallagher U. Michigan-Dwarfs + GCs

NGC 1569 HI: starburst small scale relative to HI 2002, A&A, 392, 473 B A August 28, 2007 J. S. Gallagher U. Michigan-Dwarfs + GCs

Dwarf dichotomy: gas-rich, slowly evolving vs. gas free (e. g. Grebel, Gallagher & Harbeck 2003, AJ, 125, 1926) Nature vs. Nurture. NGC 5253 - gas deficient starburst HI/L ‹ 0. 1, MV≈-18 Starburst driving gas removal & transition to NGC 205 d. E-like structure? ? ? August 28, 2007 J. S. Gallagher U. Michigan-Dwarfs + GCs

NGC 5253 -ACS August 28, 2007 J. S. Gallagher U. Michigan-Dwarfs + GCs

Complex multi-phase ISM + persistent cool ISM in presence of intense star formation: Dellenbusch Wisconsin Ph. D Summers et al 2000 Harris et al. 2004 Kobulnicky & Skillman 1995 August 28, 2007 J. S. Gallagher U. Michigan-Dwarfs + GCs

SSC D>17 kpc from NGC 3310 starburst: MV= -11 ≈106 Msun Close to tidal debris but no HI GC formation mode? August 28, 2007 J. S. Gallagher U. Michigan-Dwarfs + GCs SDSS: Knapp et al. 2006, AJ Tidal debris: Wehner et al. 2006, MNRAS; 2005, Ap. JL

Globulars & Dwarfs: Now &Then • SSC formation --> starbursts: require Mbary≥ 108 Msun Triggers for SSCs? ? • SSCs in dwarfs usually centrally concentrated (NGC 3310!) • 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 Ph. D)? ? August 28, 2007 • 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 J. S. Gallagher U. Michigan-Dwarfs + GCs

August 28, 2007 J. S. Gallagher U. Michigan-Dwarfs + GCs