The High-Z Universe

Understanding the physics and tracing the cosmic history of the galaxy mass assembly is one of the main open questions of galaxy formation and evolution. Despite the tremendous progress in observational cosmology, the accuracy in the estimate of cosmological parameters and the successful convergence on the LambdaCDM cosmological model, the mechanisms leading to the birth and the evolution of galaxies are still poorly known.

The empirical approach adopted is the investigation of galaxy formation and evolution to search for and to study the populations of distant galaxies.
Samples selected in the optical bands allow to cull star-forming galaxies where the redshifted ultraviolet (UV) radiation is dominated by hot, massive and short-lived stars. However, optical samples are affected by severe biases due to the strong influence of dust extinction and to the wide range of shapes of the spectral energy distributions (SEDs) depending on the level of star formation activity and on the age of the galaxy.
At longer wavelengths, the above problems are alleviated, as the rest-frame near-infrared radiation is dominated by low mass, long-lived stars. Also, the shapes of the SEDs in such a spectral range are very similar for all galaxy types, and the effects of dust extinction become less severe.

In addition, the rest-frame near-IR luminosity is known to correlate with the galaxy mass. The above advantages make galaxy samples selected in the near- (e.g. K-band at 2.2mum) or, even better, in the mid-IR (e.g. 4-8mum, now possible with the Spitzer Space Telescope) more suitable than optical samples to investigate galaxy evolution and, particularly, the history of galaxy stellar mass assembly.

At OAPd we are deeply involved in many ongoing survey projects as GOODS, GMASS, COSMOS and others, aimed at mapping the galaxy populations as a function of redshift and environment. These projects are establishing the observational facts that theoretical modelling will try to reproduce, ensuring full multiwavelength coverage from X-rays to radio making use of all main observational facilities worldwide, both on the ground and in space. Moreover, data from previous IR mission, i.e., the ISO mission which also involved people from OAPd, are now reduced and published.
These observations allowed us to deep our knowledge on the IR and far-IR luminosity functions (LF), which have long been used to constrain galaxy formation models and to quantify star formation and evolution both in luminosity and in density. Thanks to our ISOCAM, optical/near-IR observations and spectroscopy we presented the 60 micron LF and the bi-variate 15 micron LF, one of the few determinations based on ISO data, of a sample of galaxies on which numerous study of galaxy evolution still rely. Despite the fact that our redshift range exceeds 0.3, and our 60micron LF extends up to log(L60)=12, does not show any evidence of evolution.

The high-z Universe -PAST STUDIES

News – MEDIA INAF

Il notiziario online dell'Istituto Nazionale di Astrofisica
  • La stazione spaziale cinese TianGong 1 è ormai prossima al rientro incontrollato in atmosfera, previsto attorno alla prima metà di marzo. Ne parliamo con Alberto Buzzoni, coordinatore scientifico del progetto Prisma, la cui rete italiana di camere per lo studio delle meteore tenterà di seguire l’evento

  • Il satellite cinese Micius ha permesso di dimostrare la fattibilità concreta di un collegamento internet intercontinentale ultra-sicuro facendo comunicare Pechino con Graz, in Austria, attraverso un sistema di crittografia quantistica basato sulla trasmissione di un singolo fotone

  • Lo spettacolo ”Starlight”, opera teatrale sulla storia dell'astrofisica in Italia di e con Filippo Tognazzo, sarà per la prima volta a Milano il 27 e 28 gennaio al Pacta dei teatri durante il festival ”Scienza in scena Atto 1”

  • Quanto può essere massiccia una stella di neutroni? Lo ha stabilito Luciano Rezzolla, dell’Istituto di studi avanzati di Francoforte, combinando le osservazioni delle onde gravitazioni prodotte dalla fusione di un sistema binario di stelle di neutroni con le relazioni quasi-universali presentate dallo stesso autore nel 2016. Media Inaf lo ha intervistato

  • Uno studio internazionale, a cui ha partecipato Sandro Scandolo dell’Ictp di Trieste, ha identificato con precisione il processo attraverso il quale - dal quarzo sottoposto ad alte pressioni nel mantello terrestre - si forma la coesite. Questo minerale si origina anche a seguito di impatti meteorici, contribuendo quindi a identificare l’origine dei crateri

  • Un nuovo studio guidato da Antonino Petralia dell'Inaf di Palermo presenta i risultati di recenti simulazioni d’un evento di pioggia coronale, osservato il 4 novembre 2015, allo scopo di comprendere il meccanismo alla base del processo di frammentazione e ricaduta del plasma

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