The OTELO survey

II. The faint-end of the Hα luminosity function at z ∼ 0.40

¹ Instituto de Astrofísica de Canarias (IAC), 38200 La Laguna, Tenerife, Spain
e-mail: bongio@iac.es
² Departamento de Astrofísica, Universidad de La Laguna (ULL), 38205 La Laguna, Tenerife, Spain
³ Asociación Astrofísica para la Promoción de la Investigación, Instrumentación y su Desarrollo, ASPID, 38205 La Laguna, Tenerife, Spain
⁴ Centro de Astrobiología (CSIC/INTA), 28850 Torrejón de Ardoz, Madrid, Spain
⁵ ISDEFE for European Space Astronomy Centre (ESAC)/ESA, PO Box 78, Villanueva de la Cañada 28690, Madrid, Spain
⁶ Dark Cosmology Centre, Niels Bohr Institute, University of Copenhagen, Juliane Maries Vej 30, 2100 Copenhagen Ø, Denmark
⁷ Instituto de Astronomía, Universidad Nacional Autónoma de México, México D.F., Mexico
⁸ Instituto de Astrofísica de Andalucía, CSIC, 18080 Granada, Spain
⁹ Departamento de Física, Escuela Superior de Física y Matemáticas, Instituto Politécnico Nacional, México D.F., Mexico
¹⁰ Departamento de Astrofísica, Facultad de CC. Físicas, Universidad Complutense de Madrid, 28040 Madrid, Spain
¹¹ Instituto de Física de Cantabria (CSIC-Universidad de Cantabria), 39005 Santander, Spain
¹² Institute for Astronomy, University of Edinburgh, Royal Observatory, Blackford Hill, Edinburgh EH9 3HJ, UK
¹³ European Southern Observatory, Karl-Schwarzschild-Str. 2, 85748 Garching, Germany
¹⁴ Department of Astronomy & Astrophysics, University of Toronto, Canada
¹⁵ Ethiopian Space Science and Technology Institute (ESSTI), Entoto Observatory and Research Center (EORC), Astronomy and Astrophysics Research Division, PO Box 33679, Addis Abbaba, Ethiopia
¹⁶ European Southern Observatory, Alonso de Córdova 3107, Vitacura Casilla 19001, Santiago, Chile
¹⁷ Joint ALMA Observatory, Alonso de Córdova 3107, Vitacura Casilla 763 0355, Santiago, Chile

Received: 24 April 2018
Accepted: 30 November 2018

Abstract

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 log₁₀L_lim = 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 ρ_SFR = 0.012 ± 0.005 M_⊙ yr⁻¹ Mpc⁻³.