OTELO survey: optimal emission-line flux determination with OSIRIS/GTC

Abstract

Emission-line galaxies are important targets for understanding the chemical evolution of galaxies in the universe. Deep, narrow-band imaging surveys allow to detect and study the flux and the equivalent widths (EW) 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 GTC 10.4m telescope located in La Palma, Spain, that will observe through selected atmospheric windows relatively free of sky emission lines. With a total survey area of 0.1 square degrees distributed in different fields, reaching a 5 σdepth of 10^-18 erg/cm^2/s and detecting objects of EW < 0.3 A, 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 Hαfrom [NII] lines by analyzing the flux errors obtained. We simulated the OTELO data by convolving a complete set of synthetic HII galaxies in EW with different widths of the OSIRIS TFs. We estimated relative flux errors of the recovered Hαand [NII]6583 lines. We found that, for the red TF, a FWHM of 12 A and a sampling of 5 A is an optimal combination that allow deblending Hαfrom the [NII]6583 line with a flux error lower than 20%. This combination will allow estimating SFRs and metallicities using the Hαflux and the N2 method, respectively.

16 pages, 9 figures. Some authors added. Accepted for publication in PASP

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Cited by in corpus (7)

• AGN-Host Galaxy Connection: Morphology and Colours of X-ray Selected AGN at z < 2
• The OTELO survey. I. Description, data reduction, and multi-wavelength catalogue
• The OTELO survey: Nature and mass-metallicity relation for H$\alpha$ emitters at $z\sim 0.4$
• GLACE survey: OSIRIS/GTC Tuneable Filter H$\alpha$ imaging of the rich galaxy cluster ZwCl 0024.0+1652 at z = 0.395. Part I -- Survey presentation, TF data reduction techniques and catalogue
• Filter Induced Bias in Lyα Emitter Surveys: A Comparison Between Standard and Tunable Filters. Gran Telescopio Canarias Preliminary Results
• Flux calibrated emission line imaging of extended sources using GTC/OSIRIS Tunable Filters
• GLACE survey: galaxy activity in ZwCl0024+1652 cluster from strong optical emission lines