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
  • «Siamo lieti di annunciare che tutte le immagini di Osiris sono ora disponibili con una licenza Creative Commons», dice Holger Sierks, responsabile scientifico della fotocamera a bordo della sonda Rosetta che ha cambiato per sempre la nostra idea di cometa, a proposito del completamento dell'archivio di quasi 100mila immagini ottenute lungo tutti i 12 anni di missione

  • Esami di maturità in corso anche per il prototipo di ricevitore radio prodotto in Svezia dalla Chalmers University of Technology. Una volta completati con successo i test, verrà installato su tutte le antenne a parabola del progetto Square Kilometre Array

  • Dati raccolti con il telescopio spaziale Hubble e il Very Large Telescope confermano - ancora una volta - quanto previsto da Albert Einstein nella sua Teoria generale della relatività in merito al comportamento delle galassie su larga scala. Protagonista una lente gravitazionale

  • La tempesta di polvere su Marte che ha obbligato Opportunity a interrompere le sue attività si è estesa su scala globale, raggiungendo anche il rover Curiosity, dall’altra parte del pianeta rosso. Se fosse avvenuta sulla Terra, coprirebbe un’area più grande del Nord America e della Russia combinati

  • RemoveDEBRIS, una piccola sonda progettata per dimostrare la validità di tecnologie innovative per ripulire i cosiddetti detriti spaziali, è stata lanciata con successo dalla Stazione spaziale internazionale e presto comincerà a provare i suoi curiosi attrezzi da “pescatore”

  • Colleghi ed ex studenti ricordano Giorgio Palumbo, uno dei maggiori protagonisti dell'astrofisica delle alte energie, scomparso ieri. È stato professore al Dipartimento di Astronomia dell'Università di Bologna e molti ricordano «il giorno della sua ultima lezione in cui tanti suoi ex studenti entrarono in aula ad ascoltarlo, come se il tempo non fosse passato»

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