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
  • Un telegramma astronomico pubblicato ieri dal team del satellite Agile dà notizia di un improvviso incremento nell’emissione gamma della Nebulosa del Granchio. Ce ne parla Marco Tavani dell’Inaf Iaps di Roma, responsabile scientifico della missione

  • Serena è la suite di strumenti dedicata allo studio delle particelle presenti nell'ambiente attorno a Mercurio, pronta per decollare a bordo della missione BepiColombo. A lei il compito di raccogliere informazioni sulla tenue atmosfera del pianeta e su come questa interagisca con l'attività del vicino Sole. L'intervista a Stefano Orsini, dell'Inaf, responsabile scientifico di Serena

  • Grazie alla potenza del radiotelescopio Alma, una nuova ricerca britannica ha individuato un segno distintivo negli anelli di polvere dei dischi protoplanetari che indica lo spostamento in corso di un pianeta verso una sistemazione gravitazionalmente più consona. Secondo lo studio guidato dall'Università di Warwick, a fare la differenza è la dimensione dei grani di polvere

  • Attraverso collisioni fra ioni di xeno, prodotte al Cern con Lhc e analizzate con l'esperimento Alice, è stato possibile ricostruire proprietà fondamentali del plasma di quark e gluoni che costituiva la materia dell'universo all'epoca del Big Bang

  • Con il telescopio spaziale Hubble gli studiosi cercano di capire come l’intensa emissione di raggi ultravioletti da parte delle stelle nane rosse influenzi i pianeti nella zona abitabile. Fra gli autori dello studio, Isabella Pagano dell’Inaf di Catania

  • Si chiama More, acronimo per Mercury Orbiter Radioscience Experiment, e riflettendo come uno specchio complessi segnali radio ad altissima frequenza, inviati da due enormi antenne terrestri, permetterà alla missione Esa BepiColombo di tracciare una sorta di tomografia dell’interno di Mercurio. E di mettere alla prova la Relatività generale di Einstein

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