Overview

The discovery of the accelerated Universe has represented one of the major scientific breakthroughs of the past century. This finding has driven, in the last decades, a major effort to study effective methods to measure and characterize the cosmic expansion, and to develop new ground- and space-based facilities able to provide the large amounts of high-quality data required to characterize it. 

The current disagreement between the measured expansion rate and that inferred from the best-fit version of the Lambda cold dark matter cosmological model derived from cosmic microwave background fluctuations is now greater than 5σ (the Hubble tension). Resolving this discrepancy is one of the pressing issues in modern cosmology. 

The Surface Brightness Fluctuations (SBF) method is one of the most powerful tools to determine galaxy distances, a fundamental requirement for characterizing the expansion of the Universe. 

In addition to being one of the methods that robustly constrains the local value of the Hubble parameter, the SBF technique offers the opportunity to determine galaxy group membership and dwarf galaxy associations in targets and distance regimes where few (if any) other standard candles are applicable.

The method measures the intrinsic variance in a galaxy surface brightness distribution to determine its distance with an accuracy down to about 5%, currently for galaxies out to distances of ∼200 Mpc (potentially 300 Mpc with JWST).

The outstanding quality and quantity of data expected from next-generation facilities (LSST, EUCLID, JWST, Roman, etc.) offer a promising route to derive even more precise and accurate cosmological SBF distances for potentially tens of thousands of galaxies, independent of and complementary to Type Ia supernovae and Cepheids. However, the volume of data expected from these facilities also poses significant challenges for the use of the method, requiring SBF analyses to be carried out in a fast, robust, and automated way, compared to the classical SBF measurement procedures based on extensive user intervention.

Objectives of the meeting

The primary goal of the workshop is to provide researchers with the skills needed to measure extragalactic distances using the SBF method. The intent is to provide a description of the theoretical and observational bases of the SBF technique, and to present the fast and automated pipeline named FAST-SBF for the SBF analysis of images, newly developed by a team of researchers led by the INAF–Observatory of Abruzzo.

Participants will actively engage with the code during hands-on, group collaboration and interactive learning sessions. They will face and manage concrete problems in deriving SBF measurements by applying the pipeline to actual images from public LSST and Euclid survey data, for which the pipeline has been specifically optimized.

SOC 

• John Blakeslee
• Enzo Brocato
• Michele Cantiello
• Matteo Canzari
• Rebecca Habas
• Joe Jensen
• Gabriella Raimondo
• Gabriele Riccio

Participation

Participation in the meeting is open to everyone and free of charge and is limited to about 30 participants.

Participants are expected to have:

• a basic knowledge of Python programming;
• familiarity with astronomical image handling;
• a basic understanding of photometry.

Organizers

This meeting has been organized by INAF Osservatorio Astronomico d'Abruzzo  and supported by the INAF “Astrofisica Fondamentale” Mini-grant 2024 n.17/RSN1 (PI G. Riccio) and the INAF GO grant 12/2024 "Advancing Cosmological Distance Measurements through JWST: Stellar Population Distance Indicators - TRGB and SBF Setting the Standard (PI M. Cantiello). 

In collaboration with INAF-OA Roma (Italy), NOIRLab (AZ, USA), and Utah Valley University (UT, USA).