MEGARA MEGARA. Instituto de Astrofísica de Canarias. David Barrado y Navascúes. University of Florida Rafael Guzmán Robotics, mechanics

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1 A proposed wide-field optical IFU for GTC They build as if they are to live forever; they live as if they are to die tomorrow (old Greek proverb on the inhabitants of the city of Megara) Science Team Consortium Armando Gil de Paz (PI), Artemio Herrero (IAC), Africa Castillo Morales (UCM), Carmen Sánchez Contreras (CAB-LAM), Casiana Muñoz-Tuñon (IAC), David Barrado y Navascúes (CAB-LAEX), Esperanza Carrasco (INAOE), Javier Cenarro (CEFCA), Jesús Gallego (UCM), Jorge Iglesias-Paramo (IAA), José M. Vílchez (IAA), Lola Sabau (INTA- LINES), Marisa García Vargas (Fractal), Mercedes Mollá (CIEMAT), Nacho Trujillo (IAC), Nicolas Cardiel (UCM), Pablo G. Pérez-González (UCM), Rafael Guzmán (UoF), Sebastían Sánchez (CEFCA) Institution Representative Area of expertise / interests Universidad Complutense de Madrid Instituto de Astrofísica de Canarias INTA/Laboratorio de Instrumentación Espacial INTA/Centro de Astrobiología Armando Gil de Paz Artemio Herrero Lola Sabau David Barrado y Navascúes Management, detectors, software Detectors, optics, mechanics, integration, verification Fiber optics, spectrograph verification Robotics, mechanics, management University of Florida Rafael Guzmán Robotics, mechanics INAOE Esperanza Carrasco Fiber optics and main optics Participating companies: Fractal (optical and mech. design), AVS (positioner robot), SEDI (fiber bundles),...

2 Outline i) Main characteristics of ii) Science drivers iii) Optical & mechanical design iv) Spectral setups & response v) Timeline Main characteristics IFU FOV (in 4 dith. ptgs.) 1.2x1.2 arcmin 2 (1 x1 minimum) MOS (simultaneous w. IFU) ~90 objects in 3.5x3.5 arcmin 2 Spaxel (fiber) size Wavelength range Spectral resolution arcsec Å R= # of spectrographs 8 (7 IFU + 1 MOS) (6 minimum) # of spaxels / multiplexing 5400 (4000 minimum) GTC station Budget (for all 8 spectrogr.) Folded-Cass Nasmyth) 7.5 M (5.8 M minimum = 6 spectrogr.) Delivery date 2014 (1 st spectrograph by 2013)

3 Science Drivers: Motivation: Recent results show that radial stellar migration in spirals is quite important At some radii only 25% of the stars may have formed in-situ! Implications: Most of what we know (or thought we knew) about the Star Formation History of spiral galaxies might be quite wrong. Science Drivers: Compelling obs. evidence! and beyond! (Bakos et al. 2008) In our own MW (e.g. Roskar et al. 2008) (Muños-Mateos et al. 2009)

4 Science Drivers: and theoretical! and full cosmological ones! From idealized N-body simulations (Sánchez-Blázquez et al. 2009) (Roskar et al. 2008) Science Drivers: Possible causes for the stellar migration (& radial mixing): i)disk heating by scattering by spiral arms and mol. clouds. Stars born in circular orbits move towards more inclined and eccentric orbits. ii)transient arms lead to scattering of stars beyond corotation to stillcircular orbits (because its transient nature it happens throughout the entire disk) (Sellwood & Binney 2002). iii)satellite accretion (e.g. Young et al. 2007) iv)magnetic fields (when gas transforms into stars the equilibrium between gravity, rotation, and B dissapears) (Battaner et al. 2002) v)bars (e.g. Foyle et al. 2008)

5 Science Drivers: Possible causes for the stellar migration (& radial mixing): i)disk heating by scattering by spiral arms and mol. clouds. Stars born in circular orbits move towards more inclined and eccentric orbits. ii)transient arms lead to scattering of stars beyond corotation to stillcircular orbits (because its transient nature it happens throughout the entire disk) (Sellwood & Binney 2002). iii)satellite accretion (e.g. Young et al. 2007) iv)magnetic fields (when gas transforms into stars the equilibrium between gravity, rotation, and B dissapears) (Battaner et al. 2002) v)bars (e.g. Foyle et al. 2008) What is the mechanism that dominates? Are all relevant (if any) for any disk morphology or mass? Science Drivers: What do we know already? i)disk heating is well correlated with z, which can be measured with highresolution spectroscopy (R~10,000) in face-on galaxies. ii)the determination of the velocity ellipsoid (using a high-res IFU) provides clues on whether cloud or spiral-arm scattering heat the disk. iii)the efficiency of transient spiral arms is a function of the disk-mass fraction (Sellwood & Binney 2002). iv)transient arms have been also proposed to be responsible of the higher velocity dispersion found in older stars (Lacey 1991) v)the effective Star Formation History is partly driven by these effects. vi)these mechanisms result in different abundance gradients for stars (or stellar populations) of different ages and for the gas.

6 How will we address this? i) Kinematics: Ionized-gas and stellar kinematics out to the disks edges. Both H +Mgb (intermediate-mass MS) and CaT (giants) regions will be analyzed. ii) Science Drivers: Effective Star formation History from R=5000 full-optical-range spectroscopy. iii) Abundances: Ionized-gas abundances and stellar abundances from spectral indices (sensitive to different stellar populations) and full-spectrum fitting. Sanchez et al. (2009, in prep.) Science Drivers: Study of galactic winds in nearby Star Forming Galaxies (Leads: C. Muñoz-Tuñón & A. Castillo-Morales) Jiménez-Vicente et al. (2007) Objective: Using both NaD absorption and H emission to identify and characterize (velocities & fate) outflows in nearby SFGs.

7 Science Drivers: High-z line emitters: Evolution of SF dwarfs & LAE/LABs (Leads: A. Gil de Paz & S. Sánchez + Pérez-González, Guzmán, Gallego) Objective: Study the evolution of the faint-end slope of the ELGs LF (dwarf SFG) at 0<z<1.3 Gil de Paz et al. (2009, in prep.) from Magellan 6.5m M B,0 =-16.1 mag 6h with three R=5000 VPH (covering Å) for a total field of 2.4 x2.4 ( obj. in 30 nights). Science Drivers: Nebular shaping and acceleration beyond the AGB: (Lead: C. Sánchez Contreras) Objective: Characterize the interaction of post-agb winds with the envelopes of AGBs to unveil the nature and origin of these winds. (Figure: H image and spectra of PPN OH and best-fitting spatio-kinematical model)

8 Science Drivers: Nebular shaping and acceleration beyond the AGB (Lead: C. Sánchez Contreras) Post-AGB winds are the drivers of the fast transition from the spherically symmetric AGBs to the bipolar or multipolar PNe. (Figure: Keck ESI spectra of 2 PPNs showing P-Cygni profiles, evidence for pristine post-agb winds in these objects ; Sánchez-Contreras et al. 2008) Focal-plane layout Minimum: 1 x1 (~4x682 fibers)

9 Compact bundle ~682 fibers with minimum fiber pitch FOV~16x16 arcsec mm x 13.6 mm (f/17) 2.4 mm x 2.4 mm (f/3) Use: Study of the central regions of (i) extended or (ii) clustered targets and (iii) for calibration purposes. Sparse bundle 1.2 Compact bundle 6x682 fibers in rows and columns separated by ~1.6 x diam. FOV~1.2x1.2 arcmin 2 (1 x1 minimum) 60.6 mm x 60.6 mm (f/17) 10.7 mm x 10.7 mm (f/3) Use: (i) Sparse study of extended targets or (ii) full spatial coverage with 4 dith. pointings.

10 Sparse bundle Dithering tecnique for covering the whole 1.2x1.2 arcmin 2 FOV in 4 pointings. Minimum overlap & full coverage! Dispersed bundle (aka MOS) Sparse bundle AVS (Added Value Solutions) design Compact bundle AVS design allows ~90 objects in the 3.5x3.5 arcmin 2 non-curved, non-vignetted Folded-Cass FOV (~7x90 fibers to trace AD). Use: (i) Study of low-density fields & (ii) IFU sky subtraction.

11 Optical design (by FRACTAL) Pupil Position: VPH-type Fibers Pseudo-Slit Collimator, f# F3 i) Collimator+camera design in Littrow with optimized VPH incidence angle ii) Pupil size is 170 mm; disperser element is a VPH grating embedded in two prisms. Lens diameter is <240 mm. Materials are CaF 2 & Schott blanks. Camera f# F1.5 Detector Mechanical design (by FRACTAL) spectrograph: Weight: 320 kg Dimensions: 1850 mm long x 1350 mm width x 500 mm height

12 Spectral setups Note that given that the spectral range is fixed for each VPH: i) A set of eight R~ VPHs ~ 8x30 k = 240,000 ii) A set of eight R~15,000 VPHs ~ 8x100 k = 800,000 But one high-res VPH (100 k ) would already provide: 16 x16 IFU (Compact Bundle) or 3.5 x3.5 MOS Spectral response x10-1 Fiber attenuation (db/km) (Polymicro UV enhanced) lambda 3700 Å 4500 Å 6000 Å 8000 Å Fibers 73% 88% 95% 95% Fibers (length = 20m) Spectrogr. +CCD 15% 34% 43% 53% Collimator + filter + VPH + deep-depleted CCD Total 11% 30% 41% 50% Total

13 Pipeline & quick-analysis tool Both the reduction pipeline and quick-analysis software will be based on R3D and E3D (Sánchez 2004, 2006) but adapted to the GTC standards.