1. The interaction-driven model for the starburst galaxies and AGNs
Alessandra Lamastra
Collaborators:
N. Menci, F. Fiore, P. Santini, A. Bongiorno

2. Outline
The interaction-driven model for the starburst galaxies and AGNs
The contribution of the SB galaxies to the cosmic SFRD
SFR in AGN host

3. The SFR-M* relation Disk-like systems Extended SF
Star forming galaxies follow a tight correlation (σ≈0.3 dex) between their stellar mass and the SFR from z=0 to z=6 (Brinchmann et al. 2004, Noeske et al. 2007, Elbaz et al. 2007, Daddi et al. 2007, Santini et al. 2009, Salim et al. 2007, Strak et al. 2009, Gonzalez et al. 2011)
Z≈0
Rodighiero et al. (2011)
Elbaz et al. (2011)
Elbaz et al. (2011)
Disk-like systems
Extended SF
Large gas depletion time scale (2 Gyr)
“Main sequence” galaxies
Interacting systems
SF in the nuclear region
low gas depletion time scale (10-few Myr)
Starburst galaxies

4. The contribution of starburst galaxies to the SFRD at z≈2
Herschel-PACS COSMOS
Herschel-PACS GOODS
BzK COSMOS
BzK GOODS
Rodighiero et al. (2011)
SB account for ≈10% of the cosmic SFRD at z≈2
Starburst galaxies: SSFR> 4×SSFRMS

5. The SFR-M* relation of AGN hosts
Rovilos et al. (2012)
Santini et al. (2012)
Mullaney et al. (2012)
Angela’s talk
AGN hosts follow the distribution of SF inactive galaxies

6. The semi-analytic model
gas cooling, star formation
SN feedback,… + +
DM merging trees
Baryonic processes
SMBH growth
DM merging trees: Monte Carlo realizations
Dynamical processes involving galaxies within DM haloes
Cooling, Disc properies, Star formation and SNae feedback
Starbursts triggered by merging and fly-by events
Growth of SMBH from BH merging + accretion of galactic gas destabilized by galaxy encounters (merging and fly-by events)
Feedback from the AGN associated to the active, accretion phase
(Menci et al. 04,05,06,08)

7. Star formation and BH accretion
Kennicutt 1998
Quiescient star formation
Starburst driven by (major+minor) merging and fly-by events
SMBH accretion rate
Frequent galaxy interactions
Rapid cooling (high gas density)
Starbursts with large fraction of
gas converted into stars
Drop of interaction rate
Decline of cooling rate
Quiescent and declining star formation
z>2
z<2

8. The predicted SFR-M* relation
Rodighiero et al. (2011)
GOODS /COSMOS
Herschel-PACS/BzK galaxies
Santini et al. (2009)
GOODS-MUSIC catalog
SAM
Offset between the observed and predicted SFR-M* relation
(see also Daddi et al. 2004, Davè 2008, Fontanot et al. 2009, Santini et al. 2009)

9. The SSFR distribution SFRq>SFRb SFRb>SFRq SSFR>tH-1
SSFR>SSFRMS/4
SSFR-cut used by Rodighiero et al. (2011) to identify starburst galaxies: SSFR > 4 x SSFRMS

10. The contribution of MS and SB galaxies to the cosmic SFRD
1.5<z<2.5
Quiescent SF
Burst-like SF
Rodighiero et al. (2011)
The interaction-driven scenario for the starburst galaxies is consistent with the observational constraints indicating that starburst galaxies contribute for ≈ 10% of the cosmic SFRD at 1.5<z<2.5
The contribution of the burst-dominated SF systems increases with redshift, rising from 1%-5% at z≈0 to 25%-27% at z=5-6

11. AGNs in starburst galaxies
The fraction of AGN hosted in starburst galaxies is an increasing function of the AGN luminosity

12. Summary
The interaction-driven scenario for the starburst galaxies is consistent with the observational constraints indicating that starburst galaxies contribute for ≈ 10% of the cosmic SFRD at 1.5<z<2.5.
The interaction-driven model provides strict predictions for the evolution of the starburst contribution to the cosmic SFRD and for the number of AGN hosted in starburst galaxies as a function of the AGN luminosity.