Estimating Fixed-Frame Galaxy Magnitudes in the Sloan Digital Sky Survey


Blanton MR, Brinkmann J, Csabai I, Doi M, Eisenstein D, Fukugita M, Gunn JE, Hogg DW, Schlegel DJ. Estimating Fixed-Frame Galaxy Magnitudes in the Sloan Digital Sky Survey. The Astronomical Journal. 2003;125 :2348-2360.

Date Published:

May 1, 2003


Broadband measurements of flux for galaxies at different redshiftsmeasure different regions of the rest-frame galaxy spectrum. Certainastronomical questions, such as the evolution of the luminosity functionof galaxies, require transforming these inherently redshift-dependentmagnitudes into redshift-independent quantities. To prepare to addressthese astronomical questions, investigated in detail in subsequentpapers, we fit spectral energy distributions (SEDs) to broadbandphotometric observations in the context of the optical observations ofthe Sloan Digital Sky Survey (SDSS). Linear combinations of fourspectral templates can reproduce the five SDSS magnitudes of allgalaxies to the precision of the photometry. Expressed in theappropriate coordinate system, the locus of the coefficients multiplyingthe templates is planar and, in fact, nearly linear. The resultingreconstructed SEDs can be used to recover fixed-frame magnitudes over arange of redshifts. This process yields consistent results in the sensethat, within each sample, the intrinsic colors of similar type galaxiesare nearly constant with redshift. We compare our results with simplerinterpolation methods and galaxy spectrophotometry from the SDSS. Thesoftware that generates these results is publicly available and easilyadapted to handle a wide range of galaxy observations.Based on observations obtained with the Sloan Digital Sky Survey.