1 / 41

Starbursts & Super Star Clusters

Starbursts & Super Star Clusters. J. Gallagher U. Wisconsin-Madison with L. J. Smith, M. Westmoquette (UCL), R. O’Connell (UVa), R. de Grijs (U. Sheffield) . MODEST-6 Workshop- 29 August 2005 .

yanni
Download Presentation

Starbursts & Super Star Clusters

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Starbursts & Super Star Clusters J. Gallagher U. Wisconsin-Madison with L. J. Smith, M. Westmoquette (UCL), R. O’Connell (UVa), R. de Grijs (U. Sheffield) MODEST-6 Workshop- 29 August 2005

  2. Super Star Clusters (SSCs):Upper Mass Range for Young Compact Clusters--Densest Single Generation Stellar Systems--Endpoint of Star Formation Dissipational Sequence • Stellar mass >104 Msun • Half light radius R1/2 ≤ 5-7 pc • Within R1/2 N*(1 Msun) ~104 - 106 pc-3 • Ages << globular clusters 0-few 100 Myr • Common in starbursts--sometimes tightly packed in starburst “clumps”

  3. Possible Starburst Scale-Intensity ULIRGs high 1012 L Starbursts N1275 M82 M83 1010 L Intensity Starbursts are not simply scaled-up versions of normal galactic disks. NGC1569 108 L Main SFR density starburst contribution from moderate mass galactic starbursts: “downsizing”. Orion OB Assoc low Spiral arm 0.01 1 0.1 Starburst Scale (kpc)

  4. Measuring Parameters • Linear size R--high angular resolution, 0.1 arcsec or better needed for D<10 Mpc; half light radius. • Age tcl--spectral energy distributions; colors okay if broad wavelength coverage; NIR alone difficult • Luminosity Lcl()--photometry & extinction correction; zone of radiative influence for ionization and mechanical luminosities • Chemical abundances Z*--stellar or HII spectra • Dynamical mass--stellar velocity dispersion, requires cool stars (tssc > 6-7 Myr) • Stellar mass function--resolved cluster or Mdyn/L with age & model from measured Lcl(, Z*, tcl, Mcl*)

  5. Hunter et al. 1995 ApJ, 448, 179 R136 Radial Profile Archetype: 30 Doradus: small super star cluster or “SSC” Berstein & Novaki 1999, APOD

  6. NGC 1569: SSCS in a dwarf starburst

  7. A = Double Cluster De Marchi et al. 1997, ApJ, 479, L27 B A 10 NGC 1569: Dwarf Starburst Galaxy P. Anders, U. Goettingen; data HST: ESA/NASA

  8. Composite spectra: Mixture of ages--high mass stars, >30-40 Msun present in SSCs; RSGs in optical of cluster A WR* Cluster A Cool star Ho & Filippenko 1996, ApJ, 466, L83

  9. Smith & Gallagher 2001, MNRAS, 326, 1027

  10. 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-- Feedback induced shift in SF mode? Increased pressure of SSC A a dominant factor? SFR declines as dense ISM exhausted-and ejected? GMC formation vs. destruction? SSCs10 A B

  11. Is the formation of SSCs a statistical process as the stellar IMF appears to be: More clusters= higher upper mass limit? (Yes in Antennae--but are these compact SSCs? (M82 ??) OR Is SSC formation in some cases a result of a feedback enhanced mode of star formation? (NGC1569?)

  12. NGC1569 SSCs NOT detected as luminous X-ray sources: L(x) ≤ 2 x 1036 erg/s Martin, Kobulnicky, Heckman, 2002, ApJ, 574,663

  13. M82-nearby giant starburst Stellar disk M. Westmoquette (UCL), J. Gallagher (UW), L. J. Smith (UCL) With NASA/ESA and WIYN Observatory/NSF M82: HST WFPC2 + WIYN

  14. M82 view from the ground: A VERY disturbed galaxy-- bright starburst clumps: dust and superimposed SSC “stars” D=3.6 MPC 1 arcsec ≈19 pc M82: 3.5-m WIYN Telescope I-band M82-SSCs F & L M82F M82- clump A M82- clump B J. Gallagher & L. J. Smith

  15. Melo et al. 2005, ApJ M82 SSCs & Starburst Clumps: V-band WFPC2 M82-A1 SSC: 106 M - r1/2~2-3 pc - t<10 Myr >> L. Smith Talk for Details! << Starburst Clump A ~10 Myr

  16. NGC 7673 starburst-WFPC2 Homeier, Gallagher, Pasquali ~8 kpc Clumping of compact young star clusters-a step beyond super OB associations? Characteristic of unstable gas-rich disks subject to intense star formation? Background galaxy D=40 Mpc; MV=-20

  17. Hubble Ultradeep Field: High-z clumpy & compact starbursts--a key early star formation mode

  18. Chandra X-ray contours: wind mass loading + thermalization

  19. Basic astronomy: Astrometry key to IDs, especially as distance increases… Chandra vs clusters in Antennae: Fabbiano et al. 2002, ApJ, 577, 710 1 arcsec= 73(D/15 Mpc) pc

  20. 1 arcsec M82-Chandra X-ray vs HST NIC IR: X-Ray Shocked Winds & Binaries in SSCs? Most SSCs not luminous X-ray sources. Wind thermalization low within clusters (clumpy winds???) BH binaries ejected Implications for intermediate mass BH growth--nuclei vs. “field” Kaaret et al. 2004 MNRAS, 348, L28

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

  22. 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? SFE vs Mcl? Smith & Gallagher 2001, MNRAS, 326, 1027

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

  24. ? ? 5 pc “Using PSF-fitting photometry, we derive the cluster’s light-to-mass (L/M) ratio in both near-IR and optical light and compare to population-synthesis models. The ratios are inconsistent with a normal stellar initial mass function for the adopted age of 40–60Myr, suggesting a deficiency of low-mass stars within the volume sampled.King model light profile fits to new Hubble Space Telescope ACS images ofM82-F, in combination with fits to archival near-IR images, indicate mass segregation in the cluster. As a result, the virial mass represents a lower limit on the mass of the cluster.” McCrady, Graham, & Vacca 2005, ApJ, 621, 278

  25. ComplexStar Cluster Ecology: AffectsSurvivalRates! Low M/L in an older SSC--signature of impending disruption? Why do GCs survive when mortality rates seem high in nearby SSC systems? Extra binding (DM???)--Special Formation Conditions?? Gallagher & Grebel 2003, IAU 217

  26. Starburst field FUV spectra systematically “older” than SSCs --> substantial cluster dissolution within ~10 Myr? Chandar et al. 2005, ApJ, 628, 210

  27. BUT Many M82 region B star clusters have colors consistent with ages of near 1 gyr. (also Parmentier, de Grijs & Gilmore 2003, MNRAS, 342, 208) ->> Evidence of long lived clusters and multiple bursts associated with orbital period of M82. de Grijs, O’Connell, Gallagher (2001)

  28. M82 Starburst Clump B ~1000 Myr clusters But where are the 2000 Myr clusters?

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

  30. Summary • SSCs are commonly produced in intense star forming events with masses up to and beyond 106 Msun and R1/2 ~ 2-5 pc. • Densest stellar cluster--an extreme of star formation. • SSCs cluster to make “starburst clumps” where SSC-SSC interactions are possible and which drive galactic winds. • SSCs contain a full range of intermediate-high mass stars. • Central stellar densities can exceed 105 stars/pc3. • Mass segregation may have a major influence on the observed properties (low M/L ratios) and evolution (dissolution) of SSCs. PDMFs thus are uncertain. • Statistics of SSCs suggest high early disruption rates in starbursts, although in some cases significant numbers of clusters reach ~1 Gyr in age. • SSCs do not appear to generally host strong X-ray sources, suggesting that SNe II binaries are ejected.

  31. M82--11.7 microns--compact star forming regions Lipscy & Plavchan 2004, ApJ, 603, 82

  32. NGC1569-photo ages: Anders et al. 2004, MNRAS, 347, 17

  33. 2002 A&A, 381, 825 SNRs in NGC1569: Triggered SF? Merlin: compact radio sources

  34. McCrady, Gilbert, & Graham 2003, ApJ, 596, 240

  35. Cluster Dynamical Evolution: Crossing Time Cluster crossing times typically 1% or less of galactic orbital periods and 10% or less of massive star evolutionary time scales. We are dealing with systems that experience substantial dynamical evolution: SSCs not durable?

  36. Clusters & Dynamical Evolution: Two Body Relaxation Time scale for two-body relaxation to become important--a fundamental reference time in a star cluster: But time scale varies with position and mass: Cluster cores evolve rapidly, especially if massive stars Preferentially form near the cluster center. O. Gerhard 2000, Massive Stellar Clusters, p12

  37. X-ray sources & clusters--diffuse hot gas backgrounds Martin, Kobulnicky, Heckman 2002, ApJ, 574, 663 V(HII) ~ 100 km/s-- Slow optical wind

  38. M82 - SUPERWIND ! A C H +[NII] HST/WFPC2

  39. Smith & Gallagher 2001, MNRAS, 326, 1027

  40. Tosi et al WFPC2 Pasquali et al. WFPC2 Dwarf starbursts: NGC1705 Harris et al WFPC2 Nuclear starbursts: M83 Major mergers: NGC6240 Interactions: M82 Gallagher et al. WIYN

  41. M82: Radio (Rodriguiz-Rico et al. 2004, ApJ, 616, 783) vs. HST F160W NICMOS Image OR Perils of 1 arcsec rms positions + SNR x HII region

More Related