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Galaxy Formation and Evolution

Tracing the assembly history of galaxies over cosmic time remains a primary goal for observational and theoretical studies of the Universe. Photometric and redshift surveys provide key informations.  They allow to follow the evolution of galaxies from high-z to the local universe to understand their nature: how they formed, how they evolve. From the comparison  with models of galaxy formation and evolution it is possible to understand what are the main physical mechanism at play and the associated timescales.




Researchers Involved:  S. Bardelli, M. Bolzonella, F. Calura, A. Cappi, P. Ciliegi, C. Gruppioni, R. Merighi, M. Mignoli,L. Pozzetti, E. Vanzella, G. Zamorani, E. Zucca (staff at INAF-OABo), A. Cimatti, F. Pozzi (staff at UniBo)

Post docs: O. Cucciati (OABo), S. de Barros (OABo), A. Gargiulo (cofin UNIBo), G. Lanzuisi (OABo), M. Moresco (UNIBo), V. Sommariva (UNIBo), M. Talia (UniBo), L. Vallini (cofin UNIBo)

PhD Students: A. Citro (UNIBo), N. Malavasi (UNIBo), S. Quai (UNIBo)

Referred papers: ~150 (since 2013) with more than 2000 citations in total. Recent (>=2013) publications

Grants awarded in the last 3 years: 2 PRIN-INAF-2010; 2 PRIN-INAF-2011; 2 PRIN-INAF-2012; PICS CNRS-INAF 2012;  PRIN-MIUR-2012; ASI-COFIS;  ASI;  2 ASI-Herschel; 5 ASI-Euclid;  Accordi-Italia/Brasile, … 

Main activities at OABO

The main aim of this group is the study of the galaxy evolution from the local universe to the re-ionization’s epoch, for various galaxy types and in different environments.  In this context we are involved in several international collaborations, developing photometric and spectroscopic surveys, selected at different wavelengths, from the optical to the Far-IR (VVDS, zCOSMOS, VIPERS, zCOSMOS/SINS, VUDS, GOODS, CANDELS, PEP-Herschel). From these studies we are reconstructing a coherent picture of galaxy formation and evolution, both for the star formation and for the galaxy assembly history, as well as the re-ionization epoch. The main aim of these studies is to understand which re the main mechanisms guiding galaxy evolution (mergers, star formation activity, gas accreation, etc …) and which are the role of metallicity and dust content.

Furthermore we are deeply involved in the studies and in the definiton of the scientific objectives of Euclid, a Dark Energy ESA mission, and SAFARI, an ESA contribution to the infrared mission SPICA.

Recent results:

Davidzon, Cucciati, Bolzonella et al. 2016: “The VIMOS Public Extragalactic Redshift Survey (VIPERS). Environmental effects shaping the galaxy stellar mass function”

Vallini, Gruppioni et al. 2016: “CO luminosity function from Herschel-selected galaxies and the contribution of AGN”

Malavasi, Pozzetti et al. 2016: “Reconstructing the galaxy density field with photometric redshifts. I. Methodology and validation on stellar mass functions”

de Barros, Vanzella et al. 2016: “An extreme [O III] emitter at z = 3.2: a low metallicity Lyman continuum source”

Calura et al. 2015: “Feedback from Massive Stars and Gas Expulsion from Proto-Globular Clusters”

Talia, Cimatti, Pozzetti et al. 2015: “The star formation rate cookbook at 1 < z < 3: Extinction-corrected relations for UV and [OII]λ3727 luminosities”

Gruppioni et al. 2015: “Star formation in Herschel’s Monsters versus semi-analytic models”

Cappi et al. 2015: “The VIMOS Public Extragalactic Redshift Survey (VIPERS). Hierarchical scaling and biasing”

Pozzi, Calura et al. 2015: “Are the Bulk of z > 2 Herschel Galaxies Proto-Spheroids?”

Galaxy surveys at OABO:


The VIMOS VLT Deep Survey  (VVDS) is an imaging and redshift survey of the deep universe based on more than 150,000 redshifts in four fields. VVDS was observed with the  VIMOS instrument at  ESO-VLT, from magnitude selected samples of galaxies picked from the imaging survey:

  • A sample of 100,000 redshifts for sources up to AB = 22.5.
  • A sample of 50,000 redshifts for objects up to AB = 24
  • A sample of 1,000 redshifts for objects up to AB = 26


GMASS (“Galaxy Mass Assembly ultra-deep Spectroscopic Survey”), based on an ESO Large Programme (PI A. Cimatti), performed ultra-deep ESO VLT+FORS2 multi-object spectroscopy with very long integration times (15-40 hours per mask) of infrared-selected galaxies at z>1.4 (based on high-quality photometric redshifts).  The GMASS target field (about 50 square arcminutes) is located in the GOODS-South/CDFS area and includes most of the Hubble Ultra deep Field and a fraction of the K20 field.


The zCOSMOS project  is a major treasury redshift survey in the COSMOS field. This project consist in two parallel surveys:

  • the bright survey, aiming at observing ~ 20 000 magnitude selected galaxies with IAB ≤ 22.5 and 0.1≤ z ≤ 1.2 over 1.7 deg2;
  • the deep survey, with approximately 10 000 galaxies selected through color-selection criteria expected to be at 1.4 < z < 3.0, within the central 1 deg2.




The “VIMOS Public Extragalactic Redshift Survey” (VIPERS) is an ongoing ESO Large Program to map in detail the spatial distribution of normal galaxies over an unprecedented volume of the z~1 Universe. VIPERS is using VIMOS at the VLT to measure 100,000 redshifts for galaxies with red magnitude I(AB) brighter than 22.5 over an area of 24 square degrees.





The VIMOS Ultra Deep Survey (VUDS) is a Legacy survey of ~10,000 galaxies observed with VLT/VIMOS to make a complete census of the star-forming galaxy population at 2≤z≤ 6.7. Galaxies are selected in a total area of 1 deg2spread in the COSMOS, ECDFS and VVDS-02h fields to minimise cosmic variance. Galaxies are selected using deep multi-band photometry, and multi-slit spectroscopic observations are conducted with VIMOS on the VLT with 14h integrations over 3600 < Lambda < 9500A.


CANDELS (Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey), is the largest project in the history of Hubble, with 902 assigned orbits of observing time. It is designed to document the first third of galactic evolution from z ~ 9 to 1.5 via deep imaging of more than 250,000 galaxies with WFC3/IR and ACS. Five premier multi-wavelength sky regions are selected; each has multi-wavelenght data from Spitzer and other facilities, and has extensive spectroscopy of the brighter galaxies. The use of five widely separated fields (including both GOODS North and South) mitigates cosmic variance and yields statistically robust and complete samples of galaxies down to 109 solar masses out to z ~ 8.



VANDELS is an ESO public spectroscopic survey targeting high-redshift galaxies within the Chandra Deep Field South (CDFS) and UKIDSS Ultra Deep Survey (UDS) survey fields. Specifically, VANDELS will use the VIMOS multi-object spectrograph to obtain ultra-deep, medium resolution, optical spectra (0.48μm-1.0μm) of around 2500 high-redshift galaxies, the majority of which will be selected from the HST imaging of the CDFS and UDS fields provided by the CANDELS survey. Combining the ultra-deep VANDELS spectroscopy with the best available optical+nearIR+Spitzer imaging will produce a unique legacy dataset, capable of unveiling the physics underpinning high-redshift galaxy evolution.


An ESO Large Programme spectroscopic survey (“Dark Matter Mass Distributions of Hubble Treasury Clusters and the Foundations of LambdaCDM Structure Formation Models“, PI Rosati) at the VLT with the VIMOS instrument is ongoing. One of the scientific goals is to exploit galaxy clusters as “gravitational telescopes” to study the physical properties of high redshift faint galaxies (sub-L*) in the range 2<z<7.


PACS Evolutionary Probe (PEP) is a Herschel guaranteed time key programme survey of the extragalactic sky, aimed to study the restframe far-infrared emission of galaxies up to redshift ~3, as a function of environment. The PEP survey includes six among the most widely studied blank fields across the sky (COSMOS, Lockman Hole, GOODS-S, GOODS-N, E-CDFS, Groth Stripes), two high-redshift galaxy clusters and ten lensing clusters.





Future Surveys and missions


Euclid is an  ESA medium class astronomy and astrophysics space mission. It was selected by ESA in October 2011 after a selection process started in 2005. Euclid will explore how the Universe evolved over the past 10 billion years to address questions related to fundamental physics and cosmology on the nature and properties of dark energy, dark matter and gravity, as well as on the physics of the early universe and the initial conditions which seed the formation of cosmic structure.

At OABo we are deeply involved in Euclid science activity (science working groups),  as well as in Organitation Units, which define and implement methods and algorithms for Euclid data reductions and analysis.


SPICA is a next-generation infrared astronomy mission, lead by JAXA (Japan) with important contributions foreseen from ESA and a European consortium.
SAFARI (SpicA FAR-infrared Instrument) is one of the three instruments planned for the SPICA payload. SAFARI is the FIR imaging spectrometer (30 – 210 μm, spectral resolution of 10 to 10000), next to two mid-infrared instruments, namely the MIR coronograph (3.5/5 – 27 μm)  and the MIR camera/spectrometer (5 – 38 μm).

At OABo we are deeply involved in Safari science activity,  as well as in the definition of the strategy for future extragalactic surveys.


Available Master Theses

Theses are available. Please contact staff researchers at OABo listed above.











by Lucia Pozzetti
Last update: November 27, 2013