Scientific rationale

Observations from the James Webb Space Telescope (JWST) have identified a unique population of compact, extreme red sources known as "Little Red Dots" (LRDs). These objects exhibit red optical and blue UV continua, faint blue UV features, and often broad Balmer lines, suggesting the presence of Active Galactic Nuclei (AGNs). Despite spectroscopic follow-ups revealing strong AGN signatures, interpreting their spectral energy distributions (SEDs) remains challenging, as traditional galaxy or AGN models fail to reconcile their UV and optical properties. These sources can be game changers in the quest for understanding galaxy evolution.

The goal of this Focus Week is to bring together researchers working on observations and simulations  to share findings and enhance our understanding of LRDs. This will also reinforce the link between observers and galaxy formation theorists across continents, strengthening international collaborations.

In particular, observers are now examining a vast sample of LRDs at z > 4 using exquisite photometric and spectroscopic JWST data to understand their nature, taking advantage of gravitational lensing to probe bright and intrinsically faint populations. This involves analyzing their spectral properties and fitting SEDs to infer galaxy characteristics such as stellar mass, metallicity, and dust attenuation, while also exploring whether LRDs are a population comprising both star-forming and AGN-hosting galaxies, with unique physical properties.

To complement over hundreds hrs of observations, simulations and models offer insights into galaxy formation, AGN feedback, and the role of dust attenuation. These simulations, paired with radiative transfer calculations, help make predictions of the multi-wavelength emission from galaxies hosting black holes at high redshifts, providing critical input for comparing theoretical models with real data.

Main organizers:

R. Tripodi (INAF-OAR, IFPU)

F. Di Mascia (SNS)

Participants:

Yoshihisa Asada (University of Toronto)

Maulik Bhatt (Scuola Normale Superiore)

Maruša Bradač (University of Ljubljana) 

Saksham Chandna (Scuola Normale Superiore)

Simona Gallerani (Scuola Normale Superiore)

Anishya Harshan (University of Cambridge) 

Kohei Inayoshi (Peking University)

Xihan Ji (University of Cambridge)

Jon Judez (University of Ljubljana) 

Alessandro Lupi (Como Lake Center for Astrophysics, University of Insubria)

Vladan Markov (University of Ljubljana) 

Nicholas Martis (University of Ljubljana) 

Rosi Mérida (Saint Mary's University)

Giada Quadri (University of Milano-Bicocca)

Gregor Rihtaršič (University of Ljubljana) 

Vadim Rusakov (University of Manchester)

Jan Scholtz (Cambridge University)

Darach Watson (Niels Bohr Institute, University of Copenhagen) 

Tommaso Zana (Sapienza, University of Rome)