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IFU observations of the high-z Universe Constraints on feedback from deep field observations with SAURON and VIMOS Joris Gerssen 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. • 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 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 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 – ... 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) Feedback • Galactic outflows driven by AGN and/or SNe – Resolve discrepancy between observed and predicted baryon fraction – Terminate star formation – Enrich IGM M82 (starburst) NGC 6240 (ULIRG) 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 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 SAURON observations: overview SSA22a SSA22b HB89 1738+350 SSA22b (z = 3.09) Wilman, Gerssen, Bower, Morris, Bacon, de Zeeuw & Davies (Nature, 14 July 2005) VolView rendering Ly- distribution 1.0 arcsec = 7.6 kpc 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 Model cartoon 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 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) SINFONI observations of SSA22b Constrain the stellar properties Link them to the superwind Scheduled for P77 (B) Foerster Schreiber et al. 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 Mean IGM transmission z~3 z ~ 2.5 Adelberger et al. 2003 Adelberger et al. 2005 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 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 VIMOS 'QSO2' z = 3.92, Texp = 9 hours LR mode Search by eye for candidates Need to identify/apply an automated procedure 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) 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 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) 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 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