  With the availability of large integral-field unit (IFU) spectral surveys of
nearby galaxies, there is now the potential to extract spectral information
from across the bulges and discs of galaxies in a systematic way. This
information can address questions such as how these components built up with
time, how galaxies evolve and whether their evolution depends on other
properties of the galaxy such as its mass or environment. We present BUDDI, a
new approach to fit the two-dimensional light profiles of galaxies as a
function of wavelength to extract the spectral properties of these galaxies'
discs and bulges. The fitting is carried out using GalfitM, a modified form of
Galfit which can fit multi-waveband images simultaneously. The benefit of this
technique over traditional multi-waveband fits is that the stellar populations
of each component can be constrained using knowledge over the whole image and
spectrum available. The decomposition has been developed using commissioning
data from the SDSS-IV Mapping Nearby Galaxies at APO (MaNGA) survey with
redshifts z<0.14 and coverage of at least 1.5 effective radii for a spatial
resolution of 2.5 arcsec FWHM and field of view of >22 arcsec, but can be
applied to any IFU data of a nearby galaxy with similar or better spatial
resolution and coverage. We present an overview of the fitting process, the
results from our tests, and we finish with example stellar population analyses
of early-type galaxies from the MaNGA survey to give an indication of the
scientific potential of applying bulge-disc decomposition to IFU data.
