High redshift galaxies in the ALHAMBRA survey^⋆

II. Strengthening the evidence of bright-end excess in UV luminosity functions at 2.5 ≤ z≤ 4.5 by PDF analysis

¹ Centro de Estudios de Física del Cosmos de Aragón, Unidad Asociada al CSIC, Plaza San Juan 1, 44001 Teruel, Spain
e-mail: kerttu@cefca.es
² APC, AstroParticule et Cosmologie, Université Paris Diderot, CNRS/IN2P3, CEA/lrfu, Observatoire de Paris, Sorbonne Paris Cité, 10 rue Alice Domon et Léonie Duquet, 75205 Paris CEDEX 13 France
³ IAA-CSIC, Glorieta de la Astronomía s/n, 18008 Granada, Spain
⁴ Instituto de Física de Cantabria (CSIC-UC), 39005 Santander, Spain
⁵ Unidad Asociada Observatorio Astronómico (IFCA-UV), 46980 Paterna, Spain
⁶ Ethiopian Space Science and Technology Institute (ESSTI), Entoto Observatory and Research Centre (EORC), Astronomy and Astrophysics Research Division, Addid Ababa, Ethiopia
⁷ Instituto de Astrofísica de Canarias, Vía Láctea s/n, 38200 La Laguna, Tenerife, Spain
⁸ Departamento de Astrofísica, Facultad de Física, Universidad de La Laguna, 38206 La Laguna, Spain
⁹ Observatório Nacional-MCT, Rua José Cristino, 77, CEP 20921-400 Rio de Janeiro, RJ, Brazil
¹⁰ Department of Theoretical Physics, University of the Basque Country UPV/EHU, 48080 Bilbao, Spain
¹¹ IKERBASQUE, Basque Foundation for Science, María Díaz Haroko Kalea, 3, 48013 Bilbao, Spain
¹² Departamento de Física Atómica, Molecular y Nuclear, Facultad de Física, Universidad de Sevilla, 41012 Sevilla, Spain
¹³ Institut de Ciències de l’Espai (IEEC-CSIC), Facultat de Ciències, Campus UAB, 08193 Bellaterra, Spain
¹⁴ Instituto de Astrofísica, Universidad Católica de Chile, Av. Vicuna Mackenna 4860, 782-0436, Macul, Santiago, Chile
¹⁵ Centro de Astro-Ingeniería, Universidad Católica de Chile, Av. Vicuna Mackenna 4860, 782-0436, Macul, Santiago, Chile
¹⁶ Observatori Astronòmic,Universitat de València, C/ Catedràtic José Beltrán 2, 46980 Paterna, Spain
¹⁷ Departament d’Astronomia i Astrofísica, Universitat de València, 46100 Burjassot, Spain
¹⁸ Instituto de Astronomía, Geofísica e Ciéncias Atmosféricas, Universidade de São Paulo, São Paulo, Brazil

Received: 18 August 2017
Accepted: 3 February 2018

Abstract

Context. Knowing the exact shape of the ultraviolet (UV) luminosity function (LF) of high-redshift galaxies is important to understand the star formation history of the early Universe. However, the uncertainties, especially at the faint and bright ends of the LFs, remain significant.

Aims. In this paper, we study the UV LF of redshift z = 2.5 – 4.5 galaxies in 2.38 deg² of ALHAMBRA data with I ≤ 24. Thanks to the large area covered by ALHAMBRA, we particularly constrain the bright end of the LF. We also calculate the cosmic variance and the corresponding bias values for our sample and derive their host dark matter halo masses.

Methods. We have used a novel methodology based on redshift and magnitude probability distribution functions (PDFs). This methodology robustly takes into account the uncertainties due to redshift and magnitude errors, shot noise, and cosmic variance, and models the LF in two dimensions (z, M_UV).

Results. We find an excess of bright * M^*_UV galaxies as compared to the studies based on broad-band photometric data. However, our results agree well with the LF of the magnitude-selected spectroscopic VVDS data. We measure high bias values, b ~ 8 – 10, that are compatible with the previous measurements considering the redshifts and magnitudes of our galaxies and further reinforce the real high-redshift nature of our bright galaxies.

Conclusions. We call into question the shape of the LF at its bright end; is it a double power-law as suggested by the recent broad-band photometric studies or rather a brighter Schechter function, as suggested by our multi-filter analysis and the spectroscopic VVDS data.