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CALZ_UNRED

CALZ_UNRED

Name


    CALZ_UNRED

Purpose


    Deredden a galaxy spectrum using the Calzetti et al. (2000) recipe

Explanation


    Calzetti et al. (2000, ApJ 533, 682) developed a recipe for dereddening
    the spectra of galaxies where massive stars dominate the radiation output,
    valid between 0.12 to 2.2 microns. (CALZ_UNRED extrapolates between
    0.12 and 0.0912 microns.)

Calling Sequence


    CALZ_UNRED, wave, flux, ebv, [ funred, R_V = ]

Input


      WAVE - wavelength vector (Angstroms)
      FLUX - calibrated flux vector, same number of elements as WAVE
              If only 3 parameters are supplied, then this vector will
              updated on output to contain the dereddened flux.
      EBV - color excess E(B-V), scalar. If a negative EBV is supplied,
              then fluxes will be reddened rather than deredenned.
              Note that the supplied color excess should be that derived for
              the stellar continuum, EBV(stars), which is related to the
              reddening derived from the gas, EBV(gas), via the Balmer
              decrement by EBV(stars) = 0.44*EBV(gas)

Output


      FUNRED - unreddened flux vector, same units and number of elements
              as FLUX. FUNRED values will be zeroed outside valid domain
              Calz_unred (0.0912 - 2.2 microns).
         

Optional Input Keyword


      R_V - Ratio of total to selective extinction, default = 4.05.
            Calzetti et al. (2000) estimate R_V = 4.05 +/- 0.80 from optical
            -IR observations of 4 starbursts.

Example


      Estimate how a flat galaxy spectrum (in wavelength) between 1200 A
      and 3200 A is altered by a reddening of E(B-V) = 0.1.
      IDL> w = 1200 + findgen(40)*50 ;Create a wavelength vector
      IDL> f = w*0 + 1 ;Create a "flat" flux vector
      IDL> calz_unred, w, f, -0.1, fnew ;Redden (negative E(B-V)) flux vector
      IDL> plot,w,fnew

Notes


      Use the 4 parameter calling sequence if you wish to save the
              original flux vector.

Procedure Calls


      POLY()

Revision History


      Written W. Landsman Raytheon ITSS December, 2000



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