Voids form a prominent aspect of the Megaparsec distribution of galaxies and matter (Chincarini & Rood 1975; Gregory & Thompson 1978; Einasto, Joeveer & Saar 1980; Kirshner et al. 1981, 1987; de Lapparent, Geller & Huchra 1986; Colless et al. 2003; Tegmark et al. 2004; Guzzo et al. 2013, 2014). They are enormous regions with sizes in the range of 20 to 50 Mpc that are practically devoid of any galaxy, usually roundish in shape and occupying the major share of space in the Universe. Forming an essential and prominent aspect of the Cosmic Web (Bond, Kofman & Pogosyan 1996), they are instrumental in the spatial organization of the Cosmic Web (Einasto et al. 1980, Icke 1984; Sahni, Sathyaprakash & Shandarin 1994; Sheth & van de Weygaert 2004; Aragon-Calvo & Szalay 2013, Pisani et al. 2020). Surrounded by elongated filaments, sheetlike walls and dense compact clusters, they weave the salient web-like pattern of galaxies and matter pervading the observable Universe. The shape and evolution of voids are highly sensitive to the nature of dark energy, while their substructure and galaxy population provides a direct key to the nature of dark matter (Lee & Park 2008, Lavaux & Wandelt 2011, Bos et al. 2012, Pisani et al. 2015, 2020). Moreover, the pristine environment of void interiors is an important testing ground for our understanding of environmental influences on galaxy formation and evolution

This special session will address the large potential of cosmic voids for constraining key cosmological parameters, and to discuss and explore the information that galaxies in the interior and boundary of voids provides on the formation and evolution of galaxies. With the increasing realization that voids play a central role in our understanding of the cosmic structure formation process, it is timely and urgent to bring together experts on the various aspects of void related research. This is particularly so with the upcoming commissioning of large cosmological surveys - such as DESI, Euclid, the Vera Rubin Observatory, and SKA related surveys - and the availability of instruments that are opening up our insight into galaxy structure and dynamics over a large redshift range. ALMA and JWST will revolutionize our understanding of the connection between galaxy formation and cosmic environment.

This session will focus on three major related aspects of comsic voids. One is the cosmological role an significance of voids. To be able to optimally exploit the properties of voids, we should address the issue of defining and outlining voids based on a formalism that brings together geometric, topological and physical properties of voids. Observationally, voids are mainly defined through the spatial distribution of galaxies, Galaxies populating the boundary and interior of voids,void galaxies therefore constitute the third pillar of this special session.

Programme

• Voids and the Cosmos
• Detection and Classification of Voids
• Void Galaxies

Invited speakers

Confirmed speakers:
• Hélène Courtois (Lyon University)
• Francisco Kitaura (IAC)
• Kathryn Kreckel (Heidelberg University)
• Noam Libeskind (AIP)
• Alice Pisani (Princeton University)
• Michael Vogeley (Drexel University)

Scientific organisers

Isabel Pérez (Chair, Universidad de Granada), Rien van den Weijgaert (co-Chair, Kapteyn Astronomical Institute), Mamen Argudo (U. Pontificia de Valapraiso), Marie Aubert (U. de Lyon), Daniel Espada (U. de Granada), Ruben García-Benito (IAA), Ute Lisenfeld (U. de Granada), Alice Pisani (Pricenton University), Susana Planelles (U.de Valencia), Vicent Quilis (U. de Valencia), Tomás Ruiz-Lara (Kapteyn Astronomical Institute), Patricia Sánchez-Blázquez (U. Complutense de Madrid), Laura Sánchez-Menguiano (U. de Granada)

Contact

Isabel Pérez (isa @ ugr.es), Rien van den Weijgaert (weygaert @ astro.rug.nl)