2. Physical Conditions and Feedback in Intense Star Forming Environments J. Gallagher-U. Wisconsin L. J. Smith- Univ. College London R. W. O’Connell- U. Virginia May 2004 STScI Workshop

3. J. Gallagher & L. J. Smith M82F M82: 3.5-m WIYN Telescope I-band M82 view from the ground: A VERY disturbed galaxy- -bright with complex structure: dust and superimposed “stars” 1 arcsec ≈20 pc M82-A1 M82-F & L

4. Age = 60  20 Myr WHT spectroscopy: Gallagher & Smith 1999, MNRAS, 304, 540 25 arcsec HST angular resolution essential to measure sizes! 430 pc M82-F

5. Smith & Gallagher 2001, MNRAS, 326, 1027 M82-F: WHT Echelle Spectra & Mass: A Doomed SSC? SSCs have the mass and size of globular clusters. Star formation at the high density extreme of the interstellar gas cloud dissipation sequence. Roles of initial conditions & environment in survival?

6. Smith & Gallagher 2001, MNRAS, 326, 1027 L/M vs age of super star clusters Appears to lack low mass stars! 3 2 1 0.1 M_min M82-F

7. Cluster Dynamical Evolution: Mass Segregation Compact young star clusters may be unstable against mass segregation effects. Primordial mass segregation potentially amplified. IMF & survival complex relationship. M82-F as example. Appears likely candidate for disruption. Did low mass stars ever form?

8. M82-Chandra X-ray vs HST NIC IR: X-Ray Binaries & SSCs? Kaaret et al. 2004 MNRAS, 348, L28 XRBs not concentrated in SSCs: ejection? Implications for intermediate mass BH growth?

9. 10 x sharper view with HST: “Stars” brightest super star clusters- stellar energy inputs on scales too small to measure from the ground. Complex gas outflows & dust lanes; the violent atmosphere of a starburst STScI-PRC2001-08b R. de Grijs M82 A1 WFPC2 BVI+H 

10. STIS spectroscopy of starbursts: resolve compact clusters from background and each other--close projected packing in starburst clumps. high spectral resolution-advantage of diffraction-limited optics. Allows charting of substructures confused at ground-based resolutions. Access to key lines, e.g., [OII] and [OIII] for empirical emission line abundances and Balmer jump absorption edge for ages.

11. M82 A1: A luminous compact star cluster in region A--WFPC2 “V” Image 170 pc STIS slit position O’Connell et al. GO 9117 L. J. Smith et al. 2004 in prep

12. [NII]+H  [SII] STIS Cluster M82-A1 Smith et al 2004 in prep Wavelength -> Distance along slit -> Smooth line profiles: projected random velocity fields relatively uniform.

13. [NII]+H  [SII] STIS Cluster M82-A1 Smith et al 2004 in prep Distance along slit -> Compact HII around M82- A1 FWHM size of M82-A1continuum ~0.3 arcsec=5 pc HII region slightly larger, ~10 pc Example of luminous, evolved, but compact HII region

14. M82 STIS [SII] Emission Lines Nearly equal intensities-> n e ≈1000 cm -3 Moderate I([SII])/I(H  )=0.2 consistent with photoionization High mean thermal pressure: P/k ≈10 7

15. Starburst: Fragmented ISM Clouds embedded in low density hot, high pressure ISM: HII dominated by thin ionization fronts on dense, complex and often dusty clouds. ISM not static. Ionized gas has complex morphology and velocities.

16. M82 STIS H  + [NII] Emission Lines rather broad; fwhm observed =2.8 Å -> HII velocity dispersion ≈35 km/s. High turbulence=good environment for making SSCs Flux

17. H  FWHM (km/s) Type of Ionized Region (Hunter & Gallagher 1997, ApJ, 475, 65)

18. WFPC2-H  WFPC2-V

19. Shocked high pressure ISM Densit y bound edHII shell Radiation bounded O ++ zone Soft H- ionizing radiation Hot young SSC with stellar wind bubble A theoretical idea: Off center HII region from ISM superwind

20. Possibility: Compact star clusters=Positive Star Formation Feedback? To remain bound after star formation, require that ≥30% of mass in cloud center converted to stars. Normal star formation efficiencies are <10% Connection possible between intense star formation and high rates of star cluster formation? Cluster Dominated Star Formation = Efficient Star Formation  Higher SFR/Molecular Cloud Production Rate

21. Impacts of energy & mass outflows from starbursts  mass ejection vs. star formation rates  preferential loss of metals from SNe  structure of outflows--cooling rates  mixing into IGM vs. infall & recapture  stimulated star formation within & beyond starburst zones  ISM sweeping in companion galaxies

22. WIYN Narrow & broad band images: M82 Superwind Stellar disk continuum

23. New perspectives on M82 superwind from the combination of WIYN 3.5-m & HST broad- and narrow-band images HST: 0.05 arcsec resolution, moderate surface brightness sensitivity, especially in narrow band filters. WIYN: 0.5-1 arcsec resolution with excellent narrow band surface brightness sensitivity over wider FOV.

24. Dramatic?!! M. Westmoquette (UCL), J. Gallagher (UW), L. J. Smith (UCL) With NASA/ESA and WIYN Observatory/NSF M82: HST WFPC2 + WIYN

25. M. Westmoquette (UCL), J. Gallagher (UW), L. J. Smith (UCL) With NASA/ESA and WIYN Observatory/NSF M82: HST WFPC2 + WIYN

26. Connections between scales: Kpc-size winds driven by 10 pc massive, compact star clusters: energizing multiple nozzles=“shower head” wind Tenorio-Tagle, Silich, Munoz-Tunon 2003 ApJ, 597, 279

27. Radio VLA + MERLIN: Wills et al. 1999, MNRAS, 309, 395 HST P  NICMOS NIC GTO: Alonso-Herrero et al. 2003, AJ, 125, 1210 M82: The Multi-Wave Poster Galaxy

28. Chandra x-ray with H  + [NII] WIYN contour overlay-- approx alignment N E Not a simple wind in hollow cone--no limb brightening in optical emission, instead optical and x-ray emission nearly coincident. Multiple small flows escaping from ISM “tunnels” to form multi-stream cosmic “shower” vs. uniform wind?

29. NGC 3077: WFPC2 Studies-Stars, Gas & Feedback: Confined outflows? Where are the Shocks? D. Calzetti et al. 2004, AJ, 127, 1405 F300W HH

30. NGC3077: Shells & narrow shocks (black) from WFPC2 imaging emission line ratios. Shells: Martin (1998-- polygons); CO Walter et al. (2002--ellipses) Calzetti et al. 2004, AJ, 127,1405

31. Summary High angular resolution reveals super star clusters as common star formation mode in starbursts: formation of 100s-1000s of massive stars in <1 Myr maximum density star formation mode; requires <10 pc resolution focused inputs of UV & mechanical power sources positive feedback through dynamic, high pressure ISM? HST reveals small-large scale connections in starbursts starburst clumps sources of unsteady outflows traced in ionized gas shocks & compact ionization fronts; small intrinsic scale. chemical enrichment of surroundings--how does mixing occur?

32. Intense star formation is not a simple scale- up of processes commonly observed in galactic disks. Models exist and require observational tests. Only HST offers the combination of wavelength agility, angular resolution (WFPC3; HRC!+NIC), and spectroscopy STIS (+COS! For winds) to study critical small scale structures and processes in the nearest starbursts through optical photometric (r, L())& spectral line diagnostics (absorption [star clusters] & emission [nebulae] lines). A baseline for astrophysics of distant galaxies.