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Integral field spectroscopy
 

Integral field spectroscopy

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Conferencia impartida por Sebastián Sánchez en los Viernes Científicos organizada por la Facultad de Ciencias Experimentales de la Universidad de Almería el 14 de enero de 2011.

Conferencia impartida por Sebastián Sánchez en los Viernes Científicos organizada por la Facultad de Ciencias Experimentales de la Universidad de Almería el 14 de enero de 2011.

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    Integral field spectroscopy Integral field spectroscopy Presentation Transcript

    • Integral Field Spectroscopy Universidad de Almeria Viernes de Ciencia 14 January 2011 S.F.Sánchez (CAHA)
    • IFS or 3D Spectroscopy
      • Is the spectroscopic technique that samples a quasi-continous area in the sky (FOV).
      • The FOV is sampled by small aperture elements named spaxels, which correspond to pixels of an image.
      • Light coming through each spaxel is transported to the entrance of an spectrograph.
      • The image/plane and focal/plane are completely decoupled: Lot of software is required to reconstruct the orginal spatial shape at each wavelength.
    • Different kind of spaxels.
      • Is the spectroscopic technique that samples a quasi-continous area in the sky (FOV).
      • The FOV is sampled by small aperture elements named spaxels, which correspond to pixels of an image.
      • Light coming through each spaxel is transported to the entrance of an spectrograph.
      • The image/plane and focal/plane are completely decoupled: Lot of software is required to reconstruct the orginal spatial shape at each wavelength.
    • How to send the light to the Spectrograph?
      • Image Slicers: Light is “sliced” in small continous pseudo-slits: SINFONI, MUSE...
      • Lensarrays: Continous lensarray is focused in separated apertures: SAURON, TIGER...
      • Fiber-Bundles (+lensarrays): Lights is conducted by fibers: PMAS/PPAK, VIMOS, GMOS...
    • Fiber Feed IFS technique
    • The Raw data of FF IFUs
    • The Raw data of FF IFUs
    • FF IFU: Data Reduction (I)
      • Continuum exposure used to find and trace the location of the spectra in the CCD.
      • The FWHM of the spectra projected in the cross-dispersion axis determined.
      • Gaussian extraction performed.
      • Comparison Arc used to determine the distorsion correction and wavelength solution, latter applied to the data.
    • FF IFU: Data Reduction (II)
      • Sky-frames taken during the twilight used to correct for the differentical transmission fiber to fiber (wavelength dependent).
      • Spectrophotometric calibration standard star exposure used to determine the flux calibration, applied to the science frames.
      • Science (331), Sky (36) and calibration spectra (15) are separated in different frames, once reduced.
      • Sky spectrum is derived for each frae (median+3sigma clipping of the 36 sky-spectra) and the subtracted to the data.
    • FF IFU: Data Reduction (III)
      • Re-arrange the dithered pointings in a single row-stacked spectra frame, plus the complementary Position Table.
      • Mask the spectral pixel strongly affected by the vignetting.
      • Interpolate the final Mosaic into a common grid datacube of 1”/pixel.
      • When available, perform a flux recalibration based on broad-band photometry.
    • The Raw data of FF IFUs
    • Tracing process (I)
    • Tracing process (II)
    • Extraction: How to Add flux?
    • Extraction: cross-talk?
    • Extraction: The final product
    • Distorsions: Shifting lines.
    • Dispersion:Which line are you?
    • Fiber-to-Fiber transmission
    • Sky subtraction... If possible.
    • Where my spectra comes from?.
    • PMAS/PPAK: Dithering.
      • 3 position dither pattern per pointing.
      • Complete spatial covering of the FOV.
      • Increase of the spatial resolution.
      • Fully implemented in R3D.
    • WF-IFS Mosaics Experiment
    • Matching the pointings.
      • The pointings overlap, in at least 11 spectra.
      • The change in transparency is critical
      • Accuracy of the telescope offsets is also critical.
    • Results: Orion (Sánchez et al. 2006)
    • Results: M74 (Sánchez et al. 2010)
    • CALIFA: Summary I
      • Calar Alto Legacy Integral Field Area survey.
      • Survey of ~600 Galaxies in the Local Universe (0.0005<z<0.003), i.e., D<40Mpc.
      • IFS using [email_address] Calar Alto.
      • Mid-resolution (R~1000/2000) spectroscopic data between 3700-7000AA.
      • Covering a 90% of the size of the galaxies.
    • CALIFA: Summary II
      • Proposed by 47 researchers from 5 countries:
        • PI:S.F.Sánchez.
        • co-PI: R.Kennicutt & A.Gil de Paz).
      • It will consume ~200 dark nights in 3 years.
      • Starting the 1 st of July 2010 (NOW!!!).
      • Already on-going:
        • Runs scheduled.
        • ~40 galaxies already observed.
    • CALIFA: Science Goals
      • Model the resolved stellar population in galaxies of any kind and trace the star formation history.
      • Determine the nature of the ionized gas and its chemical abundance gradients.
      • Determine the 2D kinematic structure of galaxies in the local Universe.
    • CALIFA: Mother Sample
      • Proposal: 937 galaxies, diameter selected, at 0.005<z<0.03 from SDSS imaging survey, covering the full CM down to Mb<-18 mag.
      • 572/937 have 2MASS data.
      • 339/937 have IRAS data (24 with L FIR >10 10.5 L Sun ).
      • 261/937 have FIRST data.
      • All included in NYU (n sersic , scale-length).
      • All included in the GalaxyZoo.
      • 537/937 have SDSS spectra:
        • 162 with few or no gas.
        • 184 AGN candidates.
        • 277 galaxies with SF ionization.
    • CALIFA: PILOT Studies
    • CALIFA: Pilot Study.
      • Work in process:
        • Data reduced.
        • Integrated and central spectra derived.
        • Automatic analysis on the Integrated Spectra Performed.
        • Gradients studied for a reduced sample.
      • To be done:
        • Fully automatic 2D analysis.
        • Detail comparison with SDSS.
    • 3D Spectroscopy Summary
      • IFS is a common user technique (40% of the observations done with the 3.5m at CAHA, 80% of one of the UT/VLT).
      • Many of proposed or new generations instruments are IFUs (MUSE, MEGARA).
      • JWST will include an IFU.
      • There is science that can only be done with IFUs.
      • Any future astronomer should be prepared to use it.