@article{10902/4538,
year = {2013},
month = {10},
url = {http://hdl.handle.net/10902/4538},
abstract = {Lyα emitter (LAE) surveys have successfully used the excess in a narrowband filter compared to a nearby broadband image to find candidates. However, the odd spectral energy distribution (SED) of LAEs combined with the instrumental profile has important effects on the properties of the candidate samples extracted from these surveys. We investigate the effect of the bandpass width and the transmission profile of the narrowband filters used for extracting LAE candidates at redshifts z sime 6.5 through Monte Carlo simulations, and we present pilot observations to test the performance of tunable filters to find LAEs and other emission-line candidates. We compare the samples obtained using a narrow ideal rectangular filter, the Subaru NB921 narrowband filter, and sweeping across a wavelength range using the ultra-narrow-band tunable filters of the instrument OSIRIS, installed at the 10.4 m Gran Telescopio Canarias. We use this instrument for extracting LAE candidates from a small set of real observations. Broadband data from the Subaru, Hubble Space Telescope, and Spitzer databases were used for fitting SEDs to calculate photometric redshifts and to identify interlopers. Narrowband surveys are very efficient in finding LAEs in large sky areas, but the samples obtained are not evenly distributed in redshift along the filter bandpass, and the number of LAEs with equivalent widths <60 Å can be underestimated. These biased results do not appear in samples obtained using ultra-narrow-band tunable filters. However, the field size of tunable filters is restricted because of the variation of the effective wavelength across the image. Thus, narrowband and ultra-narrow-band surveys are complementary strategies to investigate high-redshift LAEs.},
organization = {This research has been partially funded by the UNAMDGAPA-PAPIIT IN110013 Program. J.A.D. and M.A.D. are grateful for support from CONACyT grant CB-128556. J.A.D. is grateful for support from grant SAB2010-0011 awarded by the Spanish MIED through the “Programa Nacional de Movilidad de Recursos Humanos” included in the Plan Nacional de I-D+i 2008-2011. T.V. acknowledges support from CONACYT grant 165365 through the program “Estancias posdoctorales y sabáticas al extranjero para la consolidación de grupos de investigación.” This work has been partially funded by the Spanish Ministry of Science and Innovation (MICINN) under the Consolider-Ingenio 2010 Program grant CSD2006-00070: First Science with the GTC (http://www.iac.es/consolider-ingenio-gtc), AYA2011-29517-C03-01, and AYA2011-29517-C03-02. Observations presented in this paper were made with the Gran Telescopio Canarias (GTC), installed in the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofísica de Canarias, on the island of La Palma. The authors are thankful to the anonymous referee for the critical and constructive suggestions},
publisher = {American Astronomical Society},
publisher = {Institute of Physics},
publisher = {Astronomical Journal, 2013, 146 (4), A96},
title = {Filter-induced bias in Lyα emitter surveys: a comparison between standard and tunable filters. gran telescopio Canarias preliminary results},
author = {Diego, J.A. de and Leo, M.A. de and Cepa, Jordi and Bongiovanni, Ángel and Verdugo, T. and Sánchez Portal, Miguel and González Serrano, José Ignacio},
}