OTELO Survey: Optimal Emission-Line Flux Determination with OSIRIS/GTC
Emission-line galaxies are important targets for understanding the
chemical evolution of galaxies in the universe. Deep, narrowband imaging
surveys allow detection and study of the flux and the equivalent widths
(EWs) of the emission line studied. The present work has been developed
within the context of the OTELO project, an emission-line survey using
the tunable filters (TF) of OSIRIS, the first-generation instrument on
the Gran Telescopio Canarias (GTC) 10.4 m telescope located in La Palma,
Spain, that will observe through selected atmospheric windows that are
relatively free of sky emission lines. With a total survey area of 0.1
deg<SUP>2</SUP> distributed in different fields, reaching a 5σ
depth of 10<SUP>-18</SUP> ergs cm<SUP>-2</SUP>s<SUP>-1</SUP> and
detecting objects of EW < 0.3 Å , OTELO will be the deepest
emission-line survey to date. As part of the OTELO preparatory
activities, the objective of this study is to determine the best
combination of sampling and full width at half-maximum (FWHM) for the
OSIRIS tunable filters for deblending Hα from [N II] lines by
analyzing the flux errors obtained. We simulated the OTELO data by
convolving a complete set of synthetic H II galaxies in EWs, with
different widths of the OSIRIS TFs. We estimated relative flux errors of
the recovered Hα and [N II] λ6583 lines. We found that for
the red TF, a FWHM of 12 Å and a sampling of 5 Å is an
optimal combination that allows deblending Hα from the [N II]
λ6583 line with a flux error lower than 20%. This combination
will allow estimating SFRs and metallicities using the Hα flux and
the N2 method, respectively.