31 August 2026 to 4 September 2026
University of Malta
Europe/Malta timezone

Learning AGN multimodal characterization through optical, x-ray and host galaxy properties

2 Sept 2026, 10:20
20m
Aula Prima (University of Malta)

Aula Prima

University of Malta

Valletta Campus, St Paul Street Valletta VLT 1216, Malta

Speaker

Noemi Lery Borrelli

Description

Active Galactic Nuclei are powered by accretion onto supermassive black holes and exhibit a wide range of observed properties. While the Unified Model explains part of this diversity through orientation effects, growing observational evidence suggests that additional factors-such as evolutionary stage and host galaxy properties-also play a significant role.
In this context, we adopt a data-driven approach to investigate whether physical and evolutionary patterns can be identified across different AGN types. Our goal is to explore the relationships between optical spectral features, X-ray, and host galaxy properties, and to assess whether a unified representation can capture the intrinsic properties of AGN beyond traditional classification schemes.
To this end, we develop a multimodal machine learning framework integrating optical spectra, imaging, and tabular X-ray data. Each modality is modeled through a dedicated encoder, pre-trained independently on large, domain-specific datasets.
The encoders are then jointly fine-tuned on the eROSITA eFEDS dataset, enabling the construction of a shared latent space where different data modalities provide a consistent representation of the same underlying physical properties of AGN.
We analyze the learned representations using dimensionality reduction and clustering techniques, identifying structures, sub-populations, and potential evolutionary trends, along with correlations with known physical parameters.
Beyond its exploratory nature, the proposed framework provides a basis for downstream tasks such as AGN classification, redshift estimation, and the prediction of physical properties.

Presentation materials