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Unveiling the faintest side of the Universe: discoveries, structure and open issues on ultra-diffuse galaxies

Unveiling the faintest side of the Universe: discoveries, structure and open issues on ultra-diffuse galaxies 08 MaggioMag 2025 14:30 - 23:55 UTC

SPEAKER: Enrichetta Iodice
Associate professor. INAF-Astronomical Observatory of Capodimonte – Naples
 
TITLE: Unveiling the faintest side of the Universe: discoveries, structure and open issues on ultra-diffuse galaxies
 
ABSTRACT: The subject of this talk is an intriguing class of objects: the ultra-diffuse galaxies (UDGs). UDGs are among the faintest and lowest- surface-brightness galaxies known in the Universe, having a central luminosity µg,0<24 mag/arcsec2, and effective radius (Re) larger than 1.5 kpc (see Fig.1). Even considering that low-surface brightness (LSB) galaxies were first recognized in the 80s (Sandage & Binggeli 1984; Impey+1988; Ferguson & Sandage 1988; Bothun+1991), UDGs were introduced as a new class of objects later in 2015, by van Dokkum+2015. They detected several extremely faint and diffuse galaxies in the Coma cluster, with an effective radius similar to that of the Milky Way (Re ~4.5 kpc), but with a ~100 times smaller stellar mass. Being so diffuse and faint, van Dokkum+2015 suggested that, to survive the tidal gravitational interactions in the cluster, UDGs should host a large amount of dark matter (DM). This brought ever-increasing attention to the detection and study of UDGs. Given the extremely low baryonic mass density, UDGs are indeed considered particularly suitable laboratories for testing the formation of galaxies in the standard Λ-cold dark matter (ΛCDM) scenario. This model postulates the existence of many low-mass DM haloes, and the baryons associated with them should be detected as dwarf galaxies. Therefore, the validity of the ΛCDM cosmological model relies also on our ability to find the baryonic counterparts of the predicted low-mass DM halos, which means deriving a complete census of the faintest, less massive stellar systems in the form of LSB galaxies and their relic globular clusters. Ten years after the first paper introducing UDGs (van Dokkum+2015), many efforts have been devoted to deriving the structural properties of this mysterious class of objects. In this talk I would like to i) review the state-of-the art on UDGs’ science, from both observational and theoretical sides, providing how much this field of research improved thanks to the advances in instrument developments, and ii) illustrate the groundbreaking results we are obtaining from two large projects that I am leading: 1) Looking into the faintEst WIth MUSE (LEWIS), focused on structural properties of UDGs from integral-field spectroscopy, and 2) Exploring the extreme universe: a preview of the galaxy Structure to be Unveiled from the Next geneRatIon aStronomical survEys (SUNRISE), focused on the detection and analysis of UDGs from deep imaging surveys.
 
BIO
 

‣ Personal details

Family name: Iodice, First name: Enrichetta

Researcher unique identifier(s): https://orcid.org/my-orcid?orcid=0000-0003-4291-0005

URL for web site: https://sites.google.com/inaf.it/enrichetta-iodice/home

‣ Education

26/10/2001 PhD

International School for Advanced Studies of Trieste, Italy.

Supervisors: Dr. M. Arnaboldi, Prof. L.S. Sparke and Prof. P. Salucci

Title: Formation Scenarios for Polar Ring Galaxies

13/11/1996 Master Degree in Physics, summa cum laude

University of Naples “Federico II”, Department of Physics, Italy

Supervisor: Prof. M. Capaccioli.

Title: Structure of Early-type galaxies

‣ Current position

2004 - present Associate professor, staff

INAF-Astronomical Observatory of Capodimonte, Naples, Italy

‣ Previous positions

2019 - 2020 Internship/science visitor as Associate Astronomer

European Southern Observatory, Garching, Germany

2001 - 2003 Post-doc Fellow

INAF-Astronomical Observatory of Capodimonte, Naples, Italy

1999 PhD visiting student

University of Wisconsin, Department of Astronomy, Madison, USA

‣ Research achievements

My scientific research is in the extragalactic field. It focuses on both observational and theoretical

aspects of the structure, formation, and evolution of galaxies, in groups and clusters, based on

imaging and spectroscopy, in the optical and near-infrared wavelength range. From 2014, I

became a leading expert in deep wide-field imaging and, from 2016, I gained similar experience

with spectroscopy, guiding several large projects. The major achievements are obtained in the LSB

science, i.e. structure of the stellar halos and intra-cluster light, detection and analysis of dwarf

galaxies and UDGs.

‣ Peer recognition

2025-ongoing: Chair of the INAF Scientific Committee

2024-ongoing: Euclid DR1 Local Universe (LU) Key Project (KP) Coordinator for the

KP-LU-DR1-3, titled "The Fornax Cluster: New Insights from Euclid

2023-2026: appointed as selected Italian representative on the ESO Users Committee. In

2025, I am chairing the UC

2023-ongoing: Head of the INAF Coordination Centre for the VST

‣ Science leadership

2023-2025: PI of the interdisciplinary (funded from MUR 2022) project entitled “Exploring

the extreme universe: a preview of the galaxy Structure to be Unveiled from the Next

geneRatIon aStronomical survEys (SUNRISE)”

2021-ongoing: PI of the ESO large program entitled "Looking into the faintEst WIth muSe

(LEWIS)", funded from INAF in 2022

2016-ongoing: PI of the deep imaging survey “VST survey of Early-type Galaxies

(VEGAS)"

2018-2022: co-PI of the deep imaging survey “Fornax Deep Survey at VST (FDS)"

2018-2022: co-PI of the spectroscopic survey “Fornax3D ( F3D)"

‣ Professorship

2021: University of Vienna. Course title: Assembly of galaxies in groups and clusters.

2024-ongoing: University “Vanvitelli” of Caserta, Physics department. Course title: i)

Introduction to Astrophysics, ii) Astrophysics of Galaxies.

DATE/TIME: Thursday 08 May 2025, at 2:30pm CET.
LOCATION: Accademia Pontaniana
The colloquium will also be broadcast online, on Zoom.
Meeting ID: 841 4421 2706    |    Passcode: 656302
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