1. 1 Carlo Nipoti Dipartimento di Astronomia Università di Bologna Thermal evaporation, AGN feedback and quenched star formation in massive galaxies Chandra NGC 4649 (Randall et al.) Carlo Nipoti - Vulcano, May 2008

2. 2 OUTLINE   Why are L>L* galaxies red and dead?   The role of AGN feedback & thermal evaporation   What happens at L<L*?   The origin of the core/cusp dichotomy of ellipticals Carlo Nipoti - Vulcano, May 2008

3. 3 BLUE CLOUD & RED SEQUENCE GALAXIES Colour <- Luminosity <- Truncation of the blue cloud Red sequence Blue cloud SDSS Baldry et al 2004 Carlo Nipoti - Vulcano, May 2008 L≈L *

4. 4 Why are L>L* galaxies red and dead? Carlo Nipoti - Vulcano, May 2008

5. 5 A critical halo mass Shock heating M shock > M shock ~ M crit (Binney 1977; Dekel & Birnboim 2003, Keres+ 2005) Trapping SN-heated gas M halo > M SN ~ M crit (Dekel & Silk 1986) Halos with M halo >M crit accumulate dense hot (T vir ) gas M crit = 10 12 M sun (M crit L * ) Carlo Nipoti - Vulcano, May 2008

6. 6 The role of (radio) AGN feedback Hot gas remains hot and does not form stars because: Carlo Nipoti - Vulcano, May 2008 - it can cool only in the centre - - in the centre it is re-heated by radio-AGN feedback From observations of cooling flows (e.g. Birzan et al. 2004; Binney 2004)

7. 7 The role of thermal evaporation In principle cosmic infall and gas-rich merging might restart star formation BUT Carlo Nipoti - Vulcano, May 2008 Cool gas can be eliminated via ablation and thermal evaporation by hot gas (Nipoti & Binney 2007) in M halo >M crit halos:

8. 8 MODELING OF THERMAL EVAPORATION IN GALAXIES (Nipoti & Binney 2007) Carlo Nipoti - Vulcano, May 2008 - - Cool (T≈10 4 K) clouds infalling in hot (T vir ≈10 6 -10 7 K) ISM - Minimum rate of ablation - The fate of a cool clouds depends on its mass (Cowie & McKee 1977) M cloud evaporation M cloud > M min => star formation

9. 9 TWO MODEL GALAXIES HIGH-MASS (HM) T=10 7 K M gal =3x10 11 M sun M halo >M crit LOW-MASS (LM) T=2.5x10 6 K M gal =3x10 10 M sun M halo <≈ M crit Model can be applied to any galaxy with known T(r) and n e (r) of ISM Carlo Nipoti - Vulcano, May 2008 (Nipoti & Binney 2007)

10. 10 MINIMUM CLOUD MASS TO SURVIVE EVAPORATION M halo >M crit ----> M halo Carlo Nipoti - Vulcano, May 2008 (Nipoti & Binney 2007)

11. 11 MINIMUM MASS NORMALIZED TO GALAXY MASS M min /M gal HIGH-MASS LOW-MASS CLOUD ELLIPTICITY Carlo Nipoti - Vulcano, May 2008 (Nipoti & Binney 2007) M halo >M crit M halo <≈ M crit

12. 12 WHY ARE L>L* GALAXIES RED AND DEAD? (summary) Galaxies with M halo >10 12 M sun accumulate hot (T vir ) gas T vir gas is kept hot Quenching of star-formationLack of cold gas Accreted cold gas is heated by radio-mode AGN feedback (+ other mechanisms?) by ablation & thermal evaporation (+ other mechanisms?) Carlo Nipoti - Vulcano, May 2008

13. 13 What happens at L<L*? Carlo Nipoti - Vulcano, May 2008

14. 14 AT L<L* ENVIRONMENT IS IMPORTANT Galaxies with M halo <10 12 M sun have lower-n, lower-T atmosphere Thermal evaporation by the ISM is not efficient Cold gas available in prmary haloes (field galaxies) Lack of cold gas in secondary haloes (cluster galaxies) Carlo Nipoti - Vulcano, May 2008 Red sequenceBlue cloud

15. 15 The cusp/core dichotomy within the red sequence Carlo Nipoti - Vulcano, May 2008

16. 16 A DICHOTOMY WITHIN THE RED SEQUENCE Colour <- Luminosity Core galaxiesPower-law galaxies (cuspy) SDSS Baldry et al 2004 Carlo Nipoti - Vulcano, May 2008 Truncation of the blue cloud Red sequence Blue cloud L≈L *

17. 17 CENTRAL SB PROFILE OF RED SEQUENCE GALAXIES Core galaxies (  <0.3) Graham et al (2003) Power-law galaxies (  >0.5) Carlo Nipoti - Vulcano, May 2008 - - Power law dissipation - Cores dissipationless dynamics (binary BHs?) Larson (1974) Begelman+ (1980)

18. 18 Carlo Nipoti - Vulcano, May 2008 Higher L B High L X /L B NO stellar nuclei NO central disks Radio-loud AGN Lower L/L Edd AGN Lower L B Stellar nuclei Central disks POWER-LAW GALAXIES Radio-quiet AGN Higher L/L Edd AGN Low L X /L B Faber et al. (1997) Pellergini (2005) Coté et al. (2006) Lauer et al. (2005) Capetti & Balmaverde (2006) De Reuter et al. (2005) CORE GALAXIES

19. 19 OPEN QUESTIONS 1) Why are CGs luminous and PLGs fainter? (no characteristic mass in purely stellar dynamical processes!) 2) Why does the central slope correlate with diffuse L X ? 3) Why does the central slope correlate with AGN properties? Carlo Nipoti - Vulcano, May 2008

20. 20 A SCENARIO FOR THE ORIGIN OF THE DICHOTOMY § All Es at some stage of evolution have central cores § All Es accrete cold gas § In hot-gas poor Es cold gas can form stars in the centre (=> core refilled => PLGs) § In hot-gas rich Es cold gas is evaporated (=> core preserved => CGs) Nipoti & Binney (2007) Carlo Nipoti - Vulcano, May 2008

21. 21 CENTRAL SLOPE vs CENTRAL AGE OF STARS data from Lauer et al. (2007), McDermid et al. (2006, SAURON) CGs PLGs Support from observations: new correlation for Es Carlo Nipoti - Vulcano, May 2008 Nipoti & Binney (2007)

22. 22 M gal <10 11 M sun (M halo <10 12 M sun ) X-ray faint no evaporation central starbursts cold gas available core refilled (PLG) stellar nucleus/disk cold mode AGN “higher” L/L Edd radio quiet AGN HIGH-MASS ELLIPTICALS M gal >10 11 M sun (M halo >10 12 M sun ) X-ray bright evaporation no central starbursts no cold gas available core preserved (GC) no stellar nucleus/disk hot-mode AGN “lower” L/L Edd radio loud AGN LOW-MASS ELLIPTICALS Carlo Nipoti - Vulcano, May 2008

23. 23 CONCLUSIONS 1) L>L*: Radio-mode feedback + thermal evaporation => “red and dead” 2) L cold gas available => blue cloud secondary halo => lack of cold => red sequence 3) Thermal evaporation can explain the core/cusp dichotomy of Ellipticals Carlo Nipoti - Vulcano, May 2008 Ultimately the energy for quenching star-formation comes from black holes, which act as thermostats for T vir gas