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Authors: Bongiovanni, Ángel; Ramón-Pérez, Marina; Pérez García, Ana María; Cerviño, Miguel; Cepa, Jordi; Nadolny, Jakub; Pérez Martínez, Ricardo; Alfaro, Emilio J.; Castañeda, Héctor O.; Cedrés, Bernabé; de Diego, José A.; Ederoclite, Alessandro; Fernández-Lorenzo, Mirian; Gallego, Jesús; de Jesús González, José; González-Serrano, José Ignacio; Lara-López, Maritza A.; Oteo Gómez, Iván; Padilla Torres, Carmen P.; Pintos-Castro, Irene Pović, Mirjana; Sánchez-Portal, Miguel; Heath Jones, D.; Bland-Hawthorn, Joss; Cabrera-Lavers, Antonio, Context. The OSIRIS Tunable Filter Emission Line Object (OTELO) survey is a very deep, blind exploration of a selected region of the Extended Groth Strip and is designed for finding emission-line sources (ELSs). The survey design, observations, data reduction, astrometry, and photometry, as well as the correlation with ancillary data used to obtain a final catalogue, including photo-z estimates and a preliminary selection of ELS, were described in a previous contribution. Aims. Here, we aim to determine the main properties and luminosity function (LF) of the [O III] ELS sample of OTELO as a scientific demonstration of its capabilities, advantages, and complementarity with respect to other surveys. Methods. The selection and analysis procedures of ELS candidates obtained using tunable filter pseudo-spectra are described. We performed simulations in the parameter space of the survey to obtain emission-line detection probabilities. Relevant characteristics of [O III] emitters and the LF ([O III]), including the main selection biases and uncertainties, are presented. Results. From 541 preliminary emission-line source candidates selected around z = 0.8, a total of 184 sources were confirmed as [O III] emitters. Consistent with simulations, the minimum detectable line flux and equivalent width in this ELS sample are ∼5 × 10-19 erg s-1 cm2 and ∼6 Å, respectively. We are able to constrain the faint-end slope (α =-1.03ℓ ±ℓ 0.08) of the observed LF ([O III]) at a mean redshift of z = 0.83. This LF reaches values that are approximately ten times lower than those from other surveys. The vast majority (84%) of the morphologically classified [O III] ELSs are disc-like sources, and 87% of this sample is comprised of galaxies with stellar masses of M∗ < 1010 M· . © 2020 ESO., The authors thank the anonymous referee for her/his feedback and useful suggestions, and Terry Mahoney (at the IAC's Scientific Editorial Service) for his substantial improvements of the manuscript. AB thanks IAC researchers Begona Garcia Lorenzo, Julio Castro Almazan, and Jose A. Acosta Pulido for their useful comments. This work was supported by the Spanish Ministry of Economy and Competitiveness (MINECO) under the grants AYA2013 - 46724 - P, AYA2014 - 58861 - C3 - 1 - P, AYA2014 - 58861 - C3 - 2 - P, AYA2014 - 58861 - C3 - 3 - P, AYA2016 - 75808 - R, AYA2016 - 75931 - C2 - 1 - P, AYA2016 - 75931 - C2 - 2 - P and MDM-2017-0737 (Unidad de Excelencia Maria de Maeztu, CAB). This work was supported by the project Evolution of Galaxies, of reference AYA2017 - 88007 - C3 - 1 - P, within the "Programa estatal de fomento de la investigacion cientifica y tecnica de excelencia del Plan Estatal de Investigacion Cientifica y Tecnica y de Innovacion (2013-2016)" of the "Agencia Estatal de Investigacion del Ministerio de Ciencia, Innovacion y Universidades", and co-financed by the FEDER "Fondo Europeo de Desarrollo Regional". JAdD thanks the Instituto de Astrofisica de Canarias (IAC) for its support through the Programa de Excelencia Severo Ochoa and the Gobierno de Canarias for the Programa de Talento Tricontinental grant. MP acknowledges financial supports from the Ethiopian Space Science and Technology Institute (ESSTI) under the Ethiopian Ministry of Innovation and Technology (MInT), and from the State Agency for Research of the Spanish MCIU through the "Centre of Excellence Severo Ochoa" award for the Instituto de Astrofisica de Andalucia (SEV-2017-0709). EJA acknowledges financial support from the State Agency for Research of the Spanish MCIU through the "Centre of Excellence Severo Ochoa" award for the Instituto de Astrofisica de Andalucia (SEV-2017-0709). This article is based on observations made with the Gran Telescopio Canarias (GTC) at Roque de los Muchachos Observatory of the Instituto de Astrofisica de Canarias on the island of La Palma. This study makes use of data from AEGIS, a multi-wavelength sky survey conducted with the Chandra, GALEX, Hubble, Keck, CFHT, MMT, Subaru, Palomar, Spitzer, VLA, and other telescopes, and is supported in part by the NSF, NASA, and the STFC. Based on observations obtained with MegaPrime/MegaCam, a joint project of the CFHT and CEA/IRFU, at the Canada-France-Hawaii Telescope (CFHT) which is operated by the National Research Council (NRC) of Canada, the Institut National des Science de l'Univers of the Centre National de la Recherche Scientifique (CNRS) of France, and the University of Hawaii. This work is based in part on data products produced at Terapix available at the Canadian Astronomy Data Centre as part of the Canada-France-Hawaii Telescope Legacy Survey, a collaborative project of NRC and CNRS. Based on observations obtained with WIRCam, a joint project of CFHT, Taiwan, Korea, Canada, France, at the Canada-France-Hawaii Telescope (CFHT), which is operated by the National Research Council (NRC) of Canada, the Institute National des Sciences de l'Univers of the Centre National de la Recherche Scientifique of France, and the University of Hawaii. This work is based in part on data products produced at TERAPIX, the WIRDS (WIRcam Deep Survey) consortium, and the Canadian Astronomy Data Centre. This research was supported by a grant from the Agence Nationale de la Recherche ANR-07-BLAN-0228.

http://www.iac.es/proyecto/otelo Aims. We take advantage of the capability of the OTELO survey to obtain the Hα luminosity function (LF) at z ∼ 0.40. Because of the deepest coverage of OTELO, we are able to determine the faint end of the LF, and thus better constrain the star formation rate and the number of galaxies at low luminosities. The AGN contribution to this LF is estimated as well. Methods. We make use of the multiwavelength catalogue of objects in the field compiled by the OTELO survey, which is unique in terms of minimum flux and equivalent width. We also take advantage of the pseudo-spectra built for each source, which allow the identification of emission lines and the discrimination of different types of objects. Results. The Hα luminosity function at z ∼ 0.40 is obtained, which extends the current faint end by almost 1 dex, reaching minimal luminosities of log10Llim = 38.5 erg s−1 (or ∼0.002 M⊙ yr−1). The AGN contribution to the total Hα luminosity is estimated. We find that no AGN should be expected below a luminosity of log10L = 38.6 erg s−1. From the sample of non-AGN (presumably, pure SFG) at z ∼ 0.40 we estimated a star formation rate density of ρSFR = 0.012 ± 0.005 M⊙ yr−1 Mpc−3. This work was supported by the Spanish Ministry of Economy and Competitiveness (MINECO) under the grants AYA2013- 46724- P, AYA2014 58861-C3-1- P, AYA2014-58861-C3-2-P, AYA2014-58861-C3-3- P, AYA2016 -75808-R, AYA2016-75931-C2-2-P, AYA2017-88007-C3-1-P, and AYA2017 -88007-C3-2- P. Based on observations made with the Gran Telescopio Canarias installed in the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofisica de Canarias, in the island of La Palma. The authors thanks the anonymous referee for her/his feedback and suggestions; With funding from the Spanish government through the "María de Maeztu Unit of Excellence" accreditation (MDM-2017-0737). Peer review

The evolution of galaxies through cosmic time is studied observationally by means of extragalactic surveys. The OTELO survey aims to provide the deepest narrow-band survey to date in terms of minimum detectable flux and emission line equivalent width in order to detect the faintest extragalactic emission line systems. In this way, OTELO data will complements other broad-band, narrow-band, and spectroscopic surveys. The red tunable filter of the OSIRIS instrument on the 10.4 m Gran Telescopio Canarias (GTC) is used to scan a spectral window centred at $9175 \AA$, which is free from strong sky emission lines, with a sampling interval of $6 \AA$ and a bandwidth of $12 \AA$ in the most deeply explored Extended Groth Strip region. Careful data reduction using improved techniques for sky ring subtraction, accurate astrometry, photometric calibration, and source extraction enables us to compile the OTELO catalogue. This catalogue is complemented with ancillary data ranging from deep X-ray to far-infrared, including high resolution HST images, which allow us to segregate the different types of targets, derive precise photometric redshifts, and obtain the morphological classification of the extragalactic objects detected. The OTELO multi-wavelength catalogue contains 11237 entries and is 50\% complete at AB magnitude 26.38. Of these sources, 6600 have photometric redshifts with an uncertainty $z_{phot}$ better than $0.2 (1+z_{phot})$. A total of 4336 of these sources correspond to preliminary emission line candidates, which are complemented by 81 candidate stars and 483 sources that qualify as absorption line systems. The OTELO survey products were released to the public on 2019., Comment: v1: 29 pages, 29 figures. Published in Astronomy \& Astrophysics. v2: author's affiliation and final statement in Abstract updated

There is a typographical error in the first paragraph of Sect. 5.3: the formula “[O III]⊥4959/[O III]⊥4959 → 0.3” should read “[O III]⊥4959/[O III]⊥5007 → 0.3”.

We take advantage of the capabilities of the OTELO survey to select and study the AGN population in the field. We performed an analysis of the properties of these objects, including their demography, morphology, and IR luminosity. Focusing on the population of H$\alpha$ emitters at $z \sim 0.4$, we also aim to study the environments of AGN and non-AGN galaxies at that redshift. We make use of the multiwavelength catalog of objects in the field compiled by the OTELO survey, unique in terms of minimum line flux and equivalent width. The OTELO pseudo-spectra allow the identification of emission lines and the spectral classification of the sources. We obtained a sample of 72 AGNs in the field of OTELO, selected with four different methods in the optical, X-rays, and mid-infrared bands. We find that using X-rays is the most efficient way to select AGNs. An analysis was performed on the AGN population of OTELO in order to characterize its members. At $z \sim 0.4$, we find that up to 26\% of our H$\alpha$ emitters are AGNs. At that redshift, AGNs are found in identical environments to non-AGNs, although they represent the most clustered group when compared to passive and star-forming galaxies. The majority of our AGNs at any redshift were classified as late-type galaxies, including a 16\% proportion of irregulars. Another 16\% of AGNs show signs of interactions or mergers. Regarding the infrared luminosity, we are able to recover all the luminous infrared galaxies (LIRGs) in the field of OTELO up to $z\sim 1.6$. We find that the proportion of LIRGs and ultra-luminous infrared galaxies (ULIRGs) is higher among the AGN population, and that ULIRGs show a higher fraction of AGNs than LIRGs., Comment: 31 pages, 32 figures. Published in Astronomy \& Astrophysics