TY - JOUR
T1 - UV LIGHTS
T2 - New tools for revealing the low surface brightness regime in the ultraviolet
AU - Ruiz Cejudo, Ignacio
AU - Trujillo, Ignacio
AU - Golini, Giulia
AU - Sedighi, Nafise
AU - Montes, Mireia
AU - Guerra Arencibia, Sergio
AU - D'onofrio, Mauro
AU - Zaritsky, Dennis
AU - Raji, Samane
AU - Chamba, Nushkia
AU - Chuang, Chen Yu
AU - Donnerstein, Richard
AU - Eskandarlou, Sepideh
AU - Hosseini-Shahisavandi, S. Zahra
AU - Infante-Sainz, Raúl
AU - Kaboud, Ouldouz
AU - Martin, Garreth
AU - Román, Javier
AU - Sharbaf, Zahra
N1 - Publisher Copyright:
© 2025 The Authors.
PY - 2025/5
Y1 - 2025/5
N2 - Ultra-deep optical imaging surveys have reached unprecedented depths (≳30 mag arcsec-2; 3σ, 10″ × 10″), thus facilitating the study of very faint galactic structures. However, the ultraviolet bands, which are key to the study of stellar populations, remain essentially unexplored at these depths. In this paper, we present a detailed surface brightness and color analysis of the outermost regions of 20 nearby galaxies in the LBT Imaging of Galactic Haloes and Tidal Structues (LIGHTS) fields observed by GALEX in the far-UV and near-UV. We adapted and applied a low surface brightness oriented methodology that has proven effective in ultra-deep optical surveys. We propose a novel approach to background subtraction for UV imaging. Instead of subtracting a constant value from the background, we subtract a Poisson distribution that transforms the background into a pseudo-Gaussian distribution centered at zero. Furthermore, the point spread function (PSF) deconvolution algorithms developed for optical data are applied to our sample, using a novel set of very extended (R = 750″) PSFs for the GALEX bands. This methodology allowed us to obtain depths ranging from 28.5 to 30 mag arcsec-2 (3σ; 10″ × 10″) with reliable surface brightness profiles up to 31 mag arcsec-2. This is about 1 mag deeper than with standard UV techniques. We used the surface brightness and color profiles to show that the application of PSF deconvolution, especially in the far-UV, effectively mitigates the excess of light present in the outer regions of certain galaxies compared to the standard GALEX pipeline. This finding is crucial for any accurate stellar population inference from the color profiles. Additionally, a qualitative analysis of the results is presented, with particular emphasis on the surface brightness and color properties of the galaxies beyond their optical edges. Our work highlights the importance of developing innovative low surface brightness methods for UV surveys.
AB - Ultra-deep optical imaging surveys have reached unprecedented depths (≳30 mag arcsec-2; 3σ, 10″ × 10″), thus facilitating the study of very faint galactic structures. However, the ultraviolet bands, which are key to the study of stellar populations, remain essentially unexplored at these depths. In this paper, we present a detailed surface brightness and color analysis of the outermost regions of 20 nearby galaxies in the LBT Imaging of Galactic Haloes and Tidal Structues (LIGHTS) fields observed by GALEX in the far-UV and near-UV. We adapted and applied a low surface brightness oriented methodology that has proven effective in ultra-deep optical surveys. We propose a novel approach to background subtraction for UV imaging. Instead of subtracting a constant value from the background, we subtract a Poisson distribution that transforms the background into a pseudo-Gaussian distribution centered at zero. Furthermore, the point spread function (PSF) deconvolution algorithms developed for optical data are applied to our sample, using a novel set of very extended (R = 750″) PSFs for the GALEX bands. This methodology allowed us to obtain depths ranging from 28.5 to 30 mag arcsec-2 (3σ; 10″ × 10″) with reliable surface brightness profiles up to 31 mag arcsec-2. This is about 1 mag deeper than with standard UV techniques. We used the surface brightness and color profiles to show that the application of PSF deconvolution, especially in the far-UV, effectively mitigates the excess of light present in the outer regions of certain galaxies compared to the standard GALEX pipeline. This finding is crucial for any accurate stellar population inference from the color profiles. Additionally, a qualitative analysis of the results is presented, with particular emphasis on the surface brightness and color properties of the galaxies beyond their optical edges. Our work highlights the importance of developing innovative low surface brightness methods for UV surveys.
KW - Galaxies: evolution
KW - Galaxies: photometry
KW - Galaxies: stellar content
KW - Methods: data analysis
KW - Ultraviolet: galaxies
UR - https://www.scopus.com/pages/publications/105005197134
U2 - 10.1051/0004-6361/202452836
DO - 10.1051/0004-6361/202452836
M3 - Article
AN - SCOPUS:105005197134
SN - 0004-6361
VL - 697
JO - Astronomy & Astrophysics
JF - Astronomy & Astrophysics
M1 - A91
ER -