Stellar populations of galaxies in the ALHAMBRA survey up to z ∼ 1

II. Stellar content of quiescent galaxies within the dust-corrected stellar mass–colour and the UVJ colour–colour diagrams^⋆⋆⋆

¹ Centro de Estudios de Física del Cosmos de Aragón (CEFCA), Plaza San Juan 1, Floor 2, 44001 Teruel, Spain
² Academia Sinica Institute of Astronomy & Astrophysics (ASIAA), 11F of Astronomy-Mathematics Building, AS/NTU, No. 1, Section 4, Roosevelt Road, Taipei 10617, Taiwan
e-mail: ladiaz@asiaa.sinica.edu.tw, ladg84@gmail.com
³ Centro de Estudios de Física del Cosmos de Aragón (CEFCA) – Unidad Asociada al CSIC, Plaza San Juan 1, Floor 2, 44001 Teruel, Spain
⁴ Mullard Space Science Laboratory, University College London, Holmbury St Mary, Dorking, Surrey RH5 6NT, UK
⁵ IAA-CSIC, Glorieta de la Astronomía s/n, 18008 Granada, Spain
⁶ Instituto de Astrofísica de Canarias, Vía Láctea s/n, 38200 La Laguna, Tenerife, Spain
⁷ Instituto de Física de Cantabria (CSIC-UC), 39005 Santander, Spain
⁸ Unidad Asociada Observatorio Astronómico (IFCA-UV), 46980 Paterna, 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, 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 Departamento de Astrofísica, Facultad de Física, Universidad de La Laguna, 38206 La Laguna, Spain
¹⁵ Instituto de Astrofísica, Universidad Católica de Chile, Av. Vicuna Mackenna 4860, 782-0436 Macul, Santiago, Chile
¹⁶ Centro de Astro-Ingeniería, Universidad Católica de Chile, Av. Vicuna Mackenna 4860, 782-0436 Macul, Santiago, Chile
¹⁷ Observatori Astronòmic, Universitat de València, C/ Catedràtic José Beltrán 2, 46980 Paterna, Spain
¹⁸ Departament d’Astronomia i Astrofísica, Universitat de València, 46100 Burjassot, Spain
¹⁹ Instituto de Astronomía, Geofísica e Ciéncias Atmosféricas, Universidade de São Paulo, São Paulo, Brazil

Received: 7 February 2018
Accepted: 27 August 2019

Abstract

Aims. Our aim is to determine the distribution of stellar population parameters (extinction, age, metallicity, and star formation rates) of quiescent galaxies within the rest-frame stellar mass–colour diagrams and UVJ colour–colour diagrams corrected for extinction up to z ∼ 1. These novel diagrams reduce the contamination in samples of quiescent galaxies owing to dust-reddened galaxies, and they provide useful constraints on stellar population parameters only using rest-frame colours and/or stellar mass.

Methods. We set constraints on the stellar population parameters of quiescent galaxies combining the ALHAMBRA multi-filter photo-spectra with our fitting code for spectral energy distribution, MUlti-Filter FITting (MUFFIT), making use of composite stellar population models based on two independent sets of simple stellar population (SSP) models. The extinction obtained by MUFFIT allowed us to remove dusty star-forming (DSF) galaxies from the sample of red UVJ galaxies. The distributions of stellar population parameters across these rest-frame diagrams are revealed after the dust correction and are fitted by LOESS, a bi-dimensional and locally weighted regression method, to reduce uncertainty effects.

Results. Quiescent galaxy samples defined via classical UVJ diagrams are typically contaminated by a ∼20% fraction of DSF galaxies. A significant part of the galaxies in the green valley are actually obscured star-forming galaxies (∼30–65%). Consequently, the transition of galaxies from the blue cloud to the red sequence, and hence the related mechanisms for quenching, seems to be much more efficient and faster than previously reported. The rest-frame stellar mass–colour and UVJ colour–colour diagrams are useful for constraining the age, metallicity, extinction, and star formation rate of quiescent galaxies by only their redshift, rest-frame colours, and/or stellar mass. Dust correction plays an important role in understanding how quiescent galaxies are distributed in these diagrams and is key to performing a pure selection of quiescent galaxies via intrinsic colours.