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Probing the IMF

Probing the IMF. Star Formation in Massive Clusters. Probing the IMF: Goals. Quantify the IMF in rich, dense star-forming regions Understand the relationship between IMF; initial conditions locate the stellar birthline/region link to mass accretion rate

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Probing the IMF

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  1. Probing the IMF Star Formation in Massive Clusters

  2. Probing the IMF: Goals • Quantify the IMF in rich, dense star-forming regions • Understand the relationship between IMF; initial conditions • locate the stellar birthline/region • link to mass accretion rate • explore linkage to thermal + turbulent pressure • Critical to modeling star-formation in the early universe

  3. Probing the IMF: Measurements • JHK photometry • MCAO images at high Strehl (~0.5 at J-band) • IFU spectroscopy at R ~ 1000 • MCAO photometry can probe • 0.3 to 100 Msun in Arches cluster; R 136 • define birthline location + IMF • 5 to 100 Msun in clusters out to ~1 Mpc • quantify slope of upper IMF • IFU spectroscopy can probe brightest stars

  4. Probing the IMF: Measurements Galactic Center Superclusters: d = 10 kpc = 7” Stellar density ~ 100x Orion Nebula Cluster

  5. Probing the IMF: Measurements 20” R 136 LMC Massive Cluster: d = 200 kpc Stellar density ~ 10x Orion Nebula Cluster

  6. Probing the IMF: Measurements M82 Superclusters: d = 4 Mpc

  7. Probing the IMF: Measurements High dMacc/dt Low dMacc/dt Stellar Birthlines for Differing dMacc/dt How is dMacc/dt related to [Fe/H]; stellar density?

  8. Probing the IMF: Ancillary Science • Quantify the spatial distribution for stars of different masses & ages • Do massive stars form preferentially near the cluster center? • If so, does this imply a different formation mechanism? • Quantify stellar multiplicity in dense clusters • What role do dynamical interactions play in influencing multiplicity? • What are the relevant timescales and environmental conditions?

  9. Probing the IMF: Current Status With current 6-10m class telescopes + HST: • Crowding limits IMF probe to M > 2 Msun in Arches; R 136 • IMF probes in regions more distant than ~1 Mpc is precluded by crowding

  10. Probing the IMF: Need for GSMT Key issue is crowding (not photon collection) With a 30m GSMT, K-band diffraction limit is 0.015” • Arches clusters can be studied throughout the M33 disk • Probe birthlines; IMF for wide range of metallicities • R 136 clusters can be studied out to M82 (upper end of IMF)

  11. Probing the IMF: Requirements • MCAO-fed near IR imager with ~1’ FOV • Deliver Strehl ~ 0.5 at J-band • MCAO-fed IFU spectrograph with R ~ 3000

  12. Probing the IMF: Trades • Ability to probe IMF to larger distances; lower masses increases dramatically as aperture increases • Directly linked to reduced crowding • Adequate sampling of IMF may not require MCAO correction over maximum achievable field (~2’)

  13. 20” M 32 (Gemini/Hokupaa) GSMT with MCAO NGST Effects of Crowding on Photometry

  14. Probing the IMF: GSMT v NGST et al • NGST is limited by crowding (see previous slide) • ALMA could probe initial conditions in Galactic regions

  15. Probing the IMF: Needed Simulations • Quantify crowding vs aperture trade • Simulate variable extinction & nebular background • Understand Strehl vs photometric precision trade • Understand optimum field of view • Model time variations of Strehl during exposure

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