Mapping IFS Data

How to go about making maps of your data? This includes making into image single slices of a data-cube or mapping the output from spectral fits.

Turning your data into maps can be done either by displaying (and then making an image of) a slice or sum of slices of your data in while in cube format, or by fitting the spectra (e.g. the emission lines) while in RSS format and then plotting, as a greyscale or contour image, the fluxes vs. spatial position. Here are some tools for doing this:

  • IRAF:
      • wavextract IRAF task (from Jeremy Walsh). This takes data in standard data cube format and outputs a FITS image of the summed flux between two specified wavelength values. This is a very useful 'quick look' function. Click here for download and instructions page.
      • The NOAO sbands task can also be used in a similar way.
  • DAISY: This is a custom-made package written in perl and using the pgplot plotting routines that ingests ascii tables containing the results of spectral line fits, instrumental PSF, position table, etc., and outputs maps (greyscale/colour and/or contour) of flux, fwhm, velocity and line ratios. It was written by Katrina Exter (currently at KULeuven). Currently it runs on the command line and thus rather unwieldy to use. It is currently being converted to python and to be run as a GUI. (If you wanted a copy of Daisy, Katrina Exter is willing to provide it, once it has been converted to python.)
Electron density maps of the starburst galaxy M82 made with the Gemini GMOS-IFU (Westmoquette et al. 2009). This figure was created using a custom IDL script making use of the display_bins routine from Michele Cappellari, and illustrates how you can combine differently rotated offset fields into one figure with overlaid contours. Radial velocity maps for two Hα line components seen in four WIYN SparsePak positions across the face of the starburst galaxy NGC 1569 (Westmoquette et al. 2008). This illustrates how the maps are overlaid on a greyed out image to help identify where the fields are positioned.
Figure illustrating the use of overlaid filled circles scaled to represent the proportional to the excess in the [NII]λ6584/Hα line ratio in a VLT/FLAMES-ARGUS observation of NGC 5253. Other dashed and dotted lines delimit apertures used to extract spectra with Wolf-Rayet and nebular HeII features. The crosses mark the position of the three peaks of continuum emission (Monreal-Ibero et al. 2010).
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