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IFU observations of the high-z Universe

Constraints on feedback from deep field observations with SAURON and VIMOS. IFU observations of the high-z Universe. Joris Gerssen. Overview. Until a decade ago only extreme objects were known in the distant universe

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IFU observations of the high-z Universe

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  1. Constraints on feedback from deep field observations with SAURON and VIMOS IFU observations of the high-z Universe Joris Gerssen

  2. Overview • Until a decade ago only extreme objects were known in the distant universe • Since then photometric redshift surveys and narrow band surveys identified ( at z ~2 to ~4) • Lyman Break Galaxies • Ly-alpha galaxies • Observational constraints on galaxy formation and evolution • e.g. morphology, star formation history, luminosty functions, etc.

  3. Among the drivers behind this advancement are • The 10m class telescopes and instruments • Hubble Space Telescope • Theoretical understanding of structure formation • Integral Field Spectropscopy (IFS) is a recent development with great potential to further galaxy evolution studies

  4. Integral Field Spectroscopy Data cube: f(x, y, lambda) • VIMOS • SINFONI • MUSE • SAURON • PMAS • … Typical properties: Field-of-View few (tens) of arcsec Spectral resolution: R ~200 to ~2500

  5. High-redshift science with IFUs • (e.g. list of MUSE science drivers) • Formation and evolution of galaxies: • High-z Ly- emitters • Feedback • Luminosity functions (PPAK, VIRUS) • Reionization • ...

  6. Feedback • A longstanding problem in galaxy formation is to understand how gas cools to form galaxies • Discrepancy between observed baryon fraction (~8%) and predicted fraction (> 50% ) • To solve this “cosmic cooling crisis” the cooling of gas needs to be balanced by the injection of energy (SNe/AGN)

  7. Feedback • Galactic outflows driven by AGN and/or SNe • Resolve discrepancy between observed and predicted baryon fraction • Terminate star formation • Enrich IGM NGC 6240 (ULIRG) M82 (starburst)

  8. IFU Deep Field Observations • Deep SAURON & VIMOS observations of blank sky • But in practice centered on QSOs/high-z galaxies • observe extended Ly- halo emission • serendipitous detections

  9. SAURON Deep Fields • The SAURON IFU is optimized for the study of internal kinematics in early type galaxies • DF observations of: SSA22a, SSA22b, HB89 • Redshift range 2.9 - 3.3 (4900 - 5400 Angstrom) • Texp ~10 hours • FoV: 33 x 41 arcsec, R ~ 1500

  10. SAURON observations: overview SSA22a SSA22b HB89 1738+350

  11. SSA22b (z = 3.09) Wilman, Gerssen, Bower, Morris, Bacon, de Zeeuw & Davies (Nature, 14 July 2005) VolView rendering

  12. Ly- distribution 1.0 arcsec = 7.6 kpc

  13. Line profiles • Emission lines ~ 1000 km/s wide • Emission peaks shift by a few 100 km/s • Absorption minima differ by at most a few tens of km/s • Ly alpha is resonant scattered, naturally double peaked • Yet, absorption by neutral gas is a more straighforward explanation

  14. Model cartoon

  15. SSA22b results • Assuming shock velocities of several 100 km/s • Shell travels ~100 kpc in a few 108yr • Shell can cool to ~104 K in this time • Implied by the Voigt profile b parameter • Required to be in photoionization equilibrium • Implied shell mass of 1011 M • Kinetic energy of the shell ~1058 erg • About 1060 erg available (IMF) • Superwind model provides a consistent, and energetically feasible description

  16. Comparison with SSA22a • SSA22a • Kinematical structure more irregular • Luminous sub-mm source • Suggests that a similar outflow may have just begun • Probe a wider range of galaxies: • SCUBA galaxy (observed last year) • Radio galaxy (observed one last week) • LBG (a few hours last week)

  17. SINFONI observations of SSA22b Constrain the stellar properties Link them to the superwind Scheduled for P77 (B) Foerster Schreiber et al.

  18. Serendipitous emitters • The correlation of Ly-alpha emitters with the distribution of intergalactic gas provides another route to observationally constrain feedback • Based on Adelberger et al (2003) who find that the mean transmission increases close to a QSO • This result is derived from 3 Ly- sources only

  19. Mean IGM transmission z ~ 2.5 z ~ 3 Adelberger et al. 2003 Adelberger et al. 2005

  20. Advantage of IFUs • IFUs cover a smaller FOV then narrow band imaging, but • IFUs are better matched to Ly-alpha line width • Do not require spectroscopic follow-up • Directly probe the volume around a central QSO • Thus, IFUs should be more efficient than narrow band surveys

  21. IFU observations • Search the data cube for emitters • Use the QSO spectrum to measure the gas distribution • Likely require the UVES spectra • Available: • One SAURON data cube • 2 of 4 VIMOS IFU data cubes SAURON example: HB89 +1738+350

  22. VIMOS 'QSO2' z = 3.92, Texp = 9 hours LR mode

  23. Search by eye for candidates Need to identify/apply an automated procedure

  24. Detection algorithms • Matched kernel search • Many false detections • IDL algorithm (van Breukelen & Jarvis 2005) • FLEX: X-ray based technique (Braito et al. 2005) • ELISE-3D: sextractor based (Foucaud 2005)

  25. van Breukelen & Jarvis (MNRAS 2005) • Similar data set: • Radio galaxy at z = 2.9 • same instrumental set up • similar exposure time • Yet, they find more (14) and brighter Ly- emitters • Using an automated source finder

  26. In progress • A direct comparison with the van Breukelen results • Obtained their data from ESO archive • And reduced and analyzed it with our procedures • Preliminary results are in reasonably good agreement • ‘Our’ data appears somwhat more noisy • Find their emitters and their new type-II quasar (Jarvis et al 2005)

  27. Preliminary results • Number density of Ly alpha emitters agrees with model predictions (fortuitous) • The VIMOS fields contain 5 - 14 emitters • Models (Deliou 2005) predict 9 in a similar volume • IFUs are sensitive to at least a few 10E-18 erg/s/cm2

  28. Summary • IFUs provide a uniquely powerful way to study the haloes around high redshift proto-galaxies • Volumetric data are an efficient way to search for Ly-alpha galaxies • An alternative method to constrain feedback • IFUs are a very valuable new tool to study the formation and evolution of galaxies

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