The interaction-driven model for the starburst galaxies and AGNs

1. The interaction-driven modelfor 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 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 GOODS BzK COSMOS 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) Mullaney et al. (2012) Santini 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,… Baryonic processes SMBH growth DM merging trees • DM mergingtrees: Monte Carlo realizations • Dynamicalprocessesinvolvinggalaxieswithin DM haloes • Cooling, Disc properies, Star formation and SNae feedback • Starburststriggered by merging and fly-by events • Growth of SMBH from BH merging + accretion of galactic gas destabilized by galaxyencounters (merging and fly-by events) • Feedback from the AGN associated to the active, accretionphase (Menci et al. 04,05,06,08)

7. 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 Star formation and BH accretion Quiescient star formation Kennicutt 1998 Starburstdriven by (major+minor) merging and fly-by events SMBH accretion rate

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.