Attenuation proxy hidden in surface brightness – colour diagrams

A new strategy for the LSST era

¹ National Centre for Nuclear Research, Pasteura 7, 02-093 Warsaw, Poland
e-mail: katarzyna.malek@ncbj.gov.pl
² Aix-Marseille Univ., CNRS, CNES, LAM, Marseille, France
³ Astronomical Observatory of the Jagiellonian University, Orla 171, 30-244 Cracow, Poland
⁴ Instituto de Alta Investigación, Universidad de Tarapacá, Casilla 7D, Arica, Chile
⁵ Department of Astronomy, Indiana University, Bloomington, IN 47405, USA
⁶ School of Physics, University of New South Wales, Sydney, NSW 2052, Australia
⁷ Institute of Astrophysics, Facultad de Ciencias Exactas, Universidad Andrés Bello, Sede Concepción, Talcahuano, Chile
⁸ Centre for Astrophysics and Supercomputing, Swinburne University of Technology, Hawthorn, VIC 3122, Australia
⁹ Department of Physics and Astronomy, The University of Sheffield, Sheffield S3 7RH, UK
¹⁰ INAF – Osservatorio Astronomico di Padova, Vicolo dell’Osservatorio 5, 35122 Padova, Italy
¹¹ Instituto de Física, Pontificia Universidad Católica de Valparaíso, Casilla, 4059 Valparaíso, Chile
¹² Instituto de Estudios Astrofísicos, Facultad de Ingeniería y Ciencias, Universidad Diego Portales, Av. Ejército 441, Santiago, Chile
¹³ University of California, Riverside, 900 University Ave, Riverside, CA 92521, USA
¹⁴ INAF – Osservatorio Astrofisico di Catania, Via S. Sofia 78, 95123 Catania, Italy
¹⁵ SISSA, Via Bonomea 265, 34136 Trieste, Italy
¹⁶ Centro de Astronomía (CITEVA), Universidad de Antofagasta, Avenida Angamos 601, Antofagasta, Chile
¹⁷ Instituto de Astronomía, Universidad Nacional Autónoma de México, A.P. 70-264, 04510 México, DF, Mexico
¹⁸ INAF – Osservatorio Astronomico d’Abruzzo, Via Maggini SNC, 64100 Teramo, Italy
¹⁹ INAF – Osservatorio Astronomico di Capodimonte, Salita Moiariello 16, 80131 Napoli, Italy
²⁰ Kapteyn Astronomical Institute, University of Groningen, PO Box 800 9700 AV Groningen, The Netherlands
²¹ Departamento de Astrofísica, Universidad de La Laguna, 38206 La Laguna, Tenerife, Spain

Received: 30 October 2023
Accepted: 22 January 2024

Abstract

Aims. Large future sky surveys, such as the Legacy Survey of Space and Time (LSST), will provide optical photometry for billions of objects. Reliable estimation of the physical properties of galaxies requires information about dust attenuation, which is usually derived from ultraviolet (UV) and infrared (IR) data. This paper aims to construct a proxy for the far-UV (FUV) attenuation (A_FUVp) from the optical data alone, enabling the rapid estimation of the star formation rate (SFR) for galaxies that lack UV or IR data. This will accelerate and improve the estimation of key physical properties of billions of LSST–like observed galaxies (observed in the optical bands only).

Methods. To mimic LSST observations, we used the deep panchromatic optical coverage of the Sloan Digital Sky Survey (SDSS) Photometric Catalogue, Data Release 12, complemented by the estimated physical properties for the SDSS galaxies from the GALEX-SDSS-WISE Legacy Catalog (GSWLC) and inclination information obtained from the SDSS Data Release 7. We restricted our sample to the 0.025–0.1 spectroscopic redshift range and investigated relations among surface brightness, colours, and dust attenuation in the FUV range for star-forming galaxies obtained from the spectral energy distribution (SED).

Results. Dust attenuation is best correlated with colour measured between u and r bands (u − r) and the surface brightness in the u band (μ_u). We provide a dust attenuation proxy for galaxies on the star-forming main sequence. This relation can be used for the LSST or any other type of broadband optical survey. The mean ratio between the catalogue values of SFRs and those estimated using optical-only SDSS data with the A_FUVp prior calculated as ΔSFR = log(SFR_this work/SFR_GSWLC) is found to be less than 0.1 dex, while runs without priors result in an SFR overestimation larger than 0.3 dex. The presence or absence of the A_FUVp has a negligible influence on the stellar mass (M_star) estimation (with ΔM_star in the range from 0 to −0.15 dex).

Conclusions. We note that A_FUVp is reliable for low-redshift main sequence galaxies. Forthcoming deep optical observations of the LSST Deep Drilling Fields, which also have multi-wavelength data, will enable one to calibrate the obtained relation for higher redshift galaxies and, possibly, extend the study towards other types of galaxies, such as early-type galaxies off the main sequence.