Probing the Birth of Super Star Clusters
Kelsey Johnson
With help from: Alan Aversa, Crystal Brogan, Rosie Chen, Jeremy Darling, Miller Goss, Remy Indebetouw, Amanda Kepley, Chip Kobulnicky, Amy Reines, Bill Vacca, David Whelan NOAO Summer Program 1995
Remy Regina Indebetouw Jorgenson
Angelle Tanner
Seth Redfield Reed Riddle
Kelsey Johnson
Amy Winebarger Super Star Clusters: Cluster forma on in the Extreme
• Plausibly proto‐globular clusters
• Forma on common in early universe
• Impact on the ISM & IGM
1) What physical conditions are required to form these clusters?
2) Does this extreme environment affect affect the SF process itself? Strategy: Look for sources with similar SEDs to Ultracompact HII regions
Compact, “inverted spectrum” sources Very dense HII regions non-thermal
Sn free-free
optically-thick free-free 100 1 l (cm)
Wood & Churchwell 1989 NGC 4449 II ZW 40 NGC 4490
Aversa et al.sub Image credit: Michael Gariepy/ Kepley et al. in prep, Beck et et al. Adam Block/NOAO/AURA/NSF Reines et al. 08
NGC 2537 NGC 5253 NGC 3125
Aversa et al. sub Turner et al. 00 Aversa et al. sub Image Credit: Sloan Digital Sky Survey Image credit: Angel Lopez-Sanchez
Haro 3 IC 4662 NGC 4214
Beck et al. 00 Image Credit: NASA and Hubble Heritage Team (STScI) Johnson et al. 03 Johnson et al. 04 Natal Clusters are rare! (i.e. short‐lived)
Recent radio survey of nearby “star-forming” galaxies: Only 9/28 have detected thermal sources
Aversa, Johnson, et al.submitted Henize 2-10
ACS optical, Vacca et al. in prep NICMOS Pa a, Reines et al. prep Early Universe Analog?
SBS 0335‐052 ultra‐low metallicity: 12 + log(O/H) = 7.25
VLA + Pie Town X‐band, HST op cal
10,000 O-type* stars
HST ACS Ha, V‐band, UV Johnson, Hunt, & Reines 09 What can we learn from the radio continuum?
Radii of HII regions as small as a few pc
7 Electron densi es Pressures > 10 kB Ionizing flux Stellar Masses: up to 1000s O7‐type stars Radio recombination lines - a better tool? (e.g. Mohan, Anantharamaiah, & Goss 2001)
4 -3 • Densities: ne > 10 cm • Radii: r ~ 2-10 pc 52 • Ionizing Flux: Nlyc > 10
Nearly perfect agreement with simple models! Example: prediction for H92a line
a a a a a a a a a a H63 H70 H69 H62 H67 H68 H64 H65 H71 H66 (1s, 12 hours)
Don’t forget the EVLA!
EVLA + GBT Radio Recombination Line survey being led by Amanda Kepley Stay tuned! Ubiquitous Water Masers!
Darling, Brogan, & Johnson 08 Water masers!
All maser sources appear to be extremely young
Brogan, Johnson & Darling in prep. Natal SSCs are really darn bright in the IR!
He 2-10
The radio sources alone account for at least 60% of the mid-IR flux from the entire galaxy
VLA 2 cm, Gemini 10um (Vacca, Johnson, & Conti 2002) • Electron densities • Hardness of radiation field • Ionizing flux
Spitzer ch1,ch4, 24um (b,g,r) Radio 3.6cm contours
Johnson, Whelan, Indebetouw, & Reines in prep Panchromatic data is essential: stars, dust, and gas all contributing
Infrared excess ® Hot dust
Reines, Johnson, & Hunt 08
Nebular continuum Paschen break
Reines et al. 2010 Breaking the age-extinction degeneracy
NGC4449 VLA 3.6cm HST V-band Reines, Johnson, & Goss 08 Modeling the observable proper es of natal star clusters
Near‐IR Spitzer IRAC Spitzer MIPS J, H, K 3.6, (4.5+5.8), 8.0 m 24, 70, 160 m
Indebetouw, Whitney, Johnson, & Wood, ApJ 2006 Whelan, Johnson, et al. in prep ALMA early science simula on
Amanda Kepley, Rosie Chen, et al. in prep Summary
• Super star clusters are important • Natal clusters are rare • Extreme pressures and densities • Possibly ubiquitous masers • Clumps are important • Panchromatic observations are essential • At least some super star clusters are special • We will know more soon …