Research activities

Galaxies and cosmology

This research line focuses on studying the origin and evolution of the observable Universe, and the formation and evolution of galaxies and the large-scale structures they inhabit. Investigations carried out in this framework span from the early conditions in the very young Universe 13.8 billion years ago and the formation of the first elements to the physical laws across cosmic space and time, the nature of the major constituents of the Universe and the way they determine its evolution and fate, the formation and evolution of galaxies and of the cosmic web they inhabit, made of groups and clusters of galaxies, and of the filamentary structures connecting them.

Researchers at the INAF Observatory of Trieste (OATS) pursue a broad range of these research lines, blending a unique combination of advanced theoretical models and multi-wavelength observations from worldwide ground-based as well as space observatories.

Physical cosmology studies the evolution of the observable Universe, from a state of nearly homogeneous density at early times to the formation of the structures characterising the distribution of both visible and dark matter at later times.


Indeed, the most direct information we have on the early Universe is given by the Cosmic Microwave Background radiation. It provides a snapshot of the matter and radiation density some 300,000 years after the Big Bang. This appears to be largely isotropic, with tiny fluctuations corresponding to the “seeds” that will eventually give rise to the distribution of galaxies we observe today: a large-scale structure reflecting the underlying distribution of dark matter, looking like a huge web of filaments and sheets, intersecting in massive, dense knots corresponding to groups and clusters of galaxies. Measurements based on astrophysical systems that are believed to have approximately constant luminosity have demonstrated that the Universe’s expansion started accelerating about 5 billion years ago.

The standard ΛCDM model, based on a cosmological constant Λ and Cold Dark Matter (CDM) as main drivers of this late-time expansion, is extremely successful in describing a wide range of observations. This general picture, however, is still missing crucial ingredients with direct implications for our understanding of fundamental physics. What is responsible for the generation of primordial fluctuations? What is “dark matter”? How is it related to the Standard Model of particle physics? What is the physical mechanism responsible for the late-time cosmic acceleration discovered over 20 years ago? Is it due to some form of “dark energy” or a hint of a theory of gravity different from Einstein's general relativity? Some recent discrepancies between theoretical predictions and observations might lead to the solution of some of these problems or possibly pose new and more challenging ones.

Large-Scale Structure



At large scales, perturbations in the galaxy distribution trace directly the perturbations in the dark matter density and also provide a probe of the primordial fluctuations. In addition, the growth of matter perturbations across cosmic time provides important tests of alternative models of dark energy or modified gravity, constraints on the mass of neutrinos and on general properties of dark matter and dark interactions. At OATS, we probe the large-scale structure by studying the 3D distribution of galaxies, as measured from their angular positions in the sky and their redshifts (galaxy clustering). In particular, we develop analytical and numerical models for the measurement of the galaxy clustering from spectroscopic galaxy surveys and are heavily involved with building the analysis pipeline Euclid, an ESA mission that has been successfully launched in July 2023. Other probes of the large-scale structure that we actively study are (i) the 21cm intensity mapping that probes the large-scale structure of the Universe by using the integrated 21cm line emission from unresolved galaxies and (ii), the Lyman-α forest, that traces density perturbations using the absorption lines in the spectra of distant quasars imprinted by the distribution of neutral hydrogen along the line of sight.

Staff: Pierluigi Monaco (UniTS), Emiliano Sefusatti (OATS), Matteo Viel (SISSA)

Postdocs: Emilio Bellini (IFPU/UNG), Isabella Carucci (OATS), Yousry Elkhashab (UniTs), Chiara Moretti (SISSA), Federico Rizzo (OATS), Elena Sarpa (SISSA)

Students: Marius Lepinzan (UniTs), Jacopo Salvalaggio (UniTs), Francesco Verdiani (SISSA)

Links: Webpage of the large-scale structure group in Trieste

Image

Le quattro unità del Very Large Telescope (credit ESO).
Image

Rappresentazione artistica del disco di una galassia con getti gassosi espulsi dal nucleo (credit Nature).
For the public
Contacts

INAF-Astronomical Observatory of Trieste
Via G.B. Tiepolo, 11 I-34143 Trieste, Italy

Tel. +39 040 3199 111
info.oats@inaf.it

C.F. 97220210583

We use cookies to ensure that we give you the best experience on our website.
If you continue to use this site we will assume that you are happy with it.

Login