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Low-mass galaxies At high-redshift, cold gas effectively expelled by feedback

High-mass galaxies At high z>2, SF proceeds at extremely high rates Feedback is ineffective in suppressing star formation Rapid gas consumption Cold gas exhausting at z ~2 Star formation drops thereafter Local galaxies are gas poor with old stars. Low-mass galaxies

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Low-mass galaxies At high-redshift, cold gas effectively expelled by feedback

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  1. High-mass galaxies At high z>2, SF proceeds at extremely high rates Feedback is ineffective in suppressing star formation Rapid gas consumption Cold gas exhausting at z~2 Star formation drops thereafter Local galaxies are gas poor with old stars Low-mass galaxies At high-redshift, cold gas effectively expelled by feedback Suppressed SF at high –z At lower z, haloes grow and feedback becomes less effective Cold gas left available at low-z Star formation still active at low z Smooth SF history

  2. large mass small mass

  3. Observations show: A sharp transition in the physical properties of galaxies at M*~ 3 1010 Mʘ(see, e.g., Kauffmann et al. 2003)

  4. Tully, Mould, Aaronson 1982 • Massive galaxies are redder • Contain older stars • star formation much larger at high • redshitfs

  5. Bimodal Color Distribution Bright Red Galaxies Faint BlueGalaxies Baldry et al. 2004

  6. Color Distribution Dependence on luminosity BLUE RED

  7. The cold gas fraction log Number log Number Local galaxies with u-r<1 Local galaxies with u-r>1.5 -20.5 < Mr <-19.5

  8. M=109 Mʘ at z=4.5 Mprog=109 Mʘ

  9. Colore Distribution: Dependence on the environment

  10. t1 t2 t3 Large mass halo small mass halo Z=0 The star formation histories of the population contained (today) in dense environments (groups/clusters) peaks at higher redshift compared to that of smaller galaxies. Galaxies endng up in clusters originate from the merging of clumps which have collapsed in biased, high-density regions of the density field, hence at higher redshift.

  11. Bimodality extends at least up to z ≈ 0.8 Bell et al. 03

  12. The Evolution of luminosity and mass functions i) density evolution, typical of hierarchical clustering, (mass of galaxies increases with time) ii) luminosity evolution (SFR increasing with z from z=1 to z=2.5, flat at higher z) i) density evolution, typical of hierarchical clustering (mass of galaxies increases with time) estimates from Glazebrook et al. (GDDS) Rudnick et al. (FIRES) Dickinson et al. (HDFN) Fontana et al. (K20) Bell et al. (COMBO)

  13. The Luminosity Evolution

  14. I:Luminosity evolution: B and UV • B-band and UV luminosity ~ • instanteneous star form. rate - The number of massive objects decreases with z (hierarchical clustering) - Star Formation strongly increases with z Z=3 Z=0 N M

  15. II: Luminosity evolution: K MZ<25 • K-band luminosity ~ total mass in stars formed at current time At z ~ 1.5 simple models underpredict the total amount of stars formed in massive haloes Additional mechanism MUST BE triggering star formation at z≥4 Pozzetti et al. 2003 Starbursts Data: Fontana et al 03

  16. ‘”tidal forces during encounters cause otherwise stable disks to develop bars, and the gas in such barred disks, subjected to strong gravitational torques, flows toward the central regions “ Mihos & Hernquist 1996 See also Noguchi 1987 Barnes & Hernquist 1991 Part of the available galactic cold gas is detabilized and funnelled toward the centre Cavaliere Vittorini 2000 Gas Angular Momentum Rate: Duration:

  17. Part of the available cold gas is detabilized and funnelled toward the centre Cavaliere Vittorini 2000 (Sanders & Mirabel 96) Starbursts Freqency Starbursts Mass Conversion rate Strongly increases with z Larger r/R ratio Smaller tr~(1+z)-1/2 Strongly increases with z larger m’/m ratios Larger vd/V ratio Smaller tr~(1+z)-1/2 Larger cold gas mass Larger f ≥ 0.01

  18. The Bursts EROs

  19. AGN activity triggered by destabilization of gas during encounters: • Would naturally explain • They are already in place at high z • (at least at z=2, see McLure talk) • while the stellar content of galaxies • is still growing • II) Their activity drops at lower z Burst constitute only one mode of star formation addig to quiescent star formation BUT for AGN constitute the whole feeding mechanism

  20. The effect of Starbursts on the Galaxy Lum. Function. Cold Gas destabilization from Fly-by interactions strongly decreases from z=3 to z=0 Somerville Primack & Faber 2001 At high z a large amount of cold gas is destabilized MZ < 25.5 L > 0.2 L* Strong starbursts are expected at z > 3-4 Data from Giavalisco et al. 03

  21. K-band Lumin. Functions The effect of Starbursts induced by fly-by events in the K-band observables NM et al 2004 K-band z-counts

  22. Stellar Mass function at high z z=1-1.6 z=1.6-2 z=2-3

  23. The Big Picture • At z > 2.5 – 3 • -Effective cooling (low virial T≈105 K, high densities) • -rapid merging, frequent encounters allow continuous refueling of gas in the growing galactic haloes. • -High SFR (≈102 Mʘ/yr), especially in clumps formed in BIASED regions of the density field • (progenitors of large-mass galaxies / cluster members. • -Self-regulated SF: in small-mass clumps (M<109 Mʘ) feedback yields a self-regulated star-formation • -Frequent encounters continuously destabilize an appreciable fraction of such a gas triggering: • - fast BH accretion: QSO at full Eddington rate • Powerful starbursts(up to 103 Mʘ / yr) • Building-up of the stellar mass conent • At z < 2. • i) Construction of galaxies and merging rate decline • ii) Accretion of smaller lumps by major progenitors • iii) decline of fractionf ≈ Dj / j of gas accreted by BH or converted in SBursts • iv) exaustion of cold gas in massive galaxies • (originated from the merging of clumps collapsed in biased, • high-density regions where most of the gas has already been • converted into stars) • v) Lower-mass haloes (MDM> 5 1011 Mʘ) still star forming • vi)Starbursts activity drops especially in massive systems • - QSO only occasionally refueled by encounters • - Emission drops down to L~ 10-2 LEddington • - QSO Lum. Funct. steepens at bright end Large B/ UV Emission Ly-break glxs preferentially in massive haloes with larger cross section for interactions. 1/3 of the stellar mass in galaxies with M*>1010 Mʘ is in place at by z≈2 What about z≈3 ? Arising of bimodality in the properties of galaxy pop. • Massive galaxies (MDM> 1013 Mʘ) undergo an almost passive evolutionredder colors. • Residual star formation in less massive galaxies (rates 0.1 – 1 Mʘ/yr) still retaining part of theircold gas reservoir (blue colors)

  24. BibliografiaI. Evoluzione delle Perturbazioni Cosmologiche1.    E. Bertschinger, Annu. Rev. Astron. Astrophys. 1998. 36: 599-6542.    Coles, P., Lucchin, F."Cosmology - The origin and evolution of Cosmic Structure", 1995, Wiley, Chichester.3.    Efstathiou, G., Silk, J.I., 1983, Foundamental Cosmic Phys., 9, 14.    Lucchin, F. "Introduzione alla cosmologia", 1998, Zanichelli, Bologna.5.    Peebles, P.J.E., 1981, Astrophys. Journ., 248, 8856.    Peebles, P.J.E., 1982, Astrophys. Journ., 258, 4157.    Peebles, P.J.E. "The large-scale structure of the Universe", 1980, Princeton University Press, Princeton.8.    Peebles P.J.E. 1993. Principles of Physical Cosmology. Princeton: Princeton Univ. Press   9.    Padmanabhan, T. "Structure formation in the Universe", Cambridge Univ. Press, 1993.10.  Sahni, V. & Coles, P., 1995. Approximation Methods for Nonlinear Gravitational Clustering, Phys. Rep., 262, 1II. Statistica degli Aloni di Materia Oscura-Merging Trees1.    Vedi testi sez. I. 2.    Bardeen, J.M., Bond, J.R., Kaiser, N., Szalay, A.S., 1986, Astrophys. Journ., 304, 153.    Lacey, C., Cole, S., 1993, MNRAS, 262, 6274.    Press, W., Schechter, P. 1974, Astrophys. Journ., 187, 425III. Proprieta’ Aloni di Materia Oscura - Dinamica Galattica1.    Vedi testi sez. I. 2.    Binney J. and Tremaine S., 1987, Galactic Dynamics (Princeton Univ. Press, Princeton, NJ, USA)3.    Navarro, J.F., Frenk, C.S., White, S.D.M., 1997, Astrophys. Journ., 490, 4934.    Saslaw, W.C., 1985, "Gravitational Physics of Stellar and Galactic Systems"  (Cambridge: Cambridge Univ. Press)IV. Formazione Gerarchica delle Galassie1.    Cole, S., Lacey, C.G., Baugh, C.M., Frenk, C.S., 2000, Monthly Not. Roy. Astron. Soc., 319, 1682.    Fall, S., Efstathiou, G., 1980, Monthly Not. Roy. Astron. Soc., 193, 1893.    Kauffmann, G., White, S.D.M., Guiderdoni, B., 1993, Monthly Not. Roy. Astron. Soc., 264, 2014.    Cole, S., Aragon-Salamanca, A., Frenk, C.S., Navarro, J.F., Zepf, S.E., 1994, Monthly Not. Roy. Astron. Soc., 271, 7815.    Menci et al. 2002, Astrophys. Journ., 578, 186.    Mo, H., Mao, S., White, S.D:M., 1998, Monthly Not. Roy. Astron. Soc.,  295, 3197.    Rees, M.J., Ostriker, J.P., 1977, Monthly Not. Roy. Astron. Soc., 179, 5418.    Somerville, R.S., Primack, J.R., 1999 Monthly Not. Roy. Astron. Soc, 310, 1087 9.    Somerville, R.S., Primack, J.R., Faber, S.M., 2001, Monthly Not. Roy. Astron. Soc, 320, 50410.  White, S.D.M., Frenk, C.S. 1991, Astrophys. Journ., 379, 52

  25. V. Confronto con Proprieta’ Osserv. delle Galassie1.    Vedi anche testi sez. IV2.    Cimatti et al. 1999, Astron. Astrophys., 352, L453.    Cimatti, A., et al. 2002, Astron. Astrophys., 392, 3954.    Ellis, R. 1998, Nature, 395, 3 (supplement to No 6701, October 1, 1998)5.    Fontana, A., et al 2003, Astrophys. Journ., 587, 5446.    Fontana, A. et al.,  2003, Astrophys. Journal, 594, L97.    Ghigna et al. 2000, Astrophys. Journal., 544, 6168.    Kauffmann, G., Charlot, S., 1998, Monthly Not. Roy. Astron. Soc,, 294, 7059.    Kennicut, R.C., 1998, Astrophys. Journ., 498, 54110.  Menci N. et al. 2003, astro-ph/031149611.  Renzini, A., The formation of galactic bulges, edited by C.M. Carollo, H.C. Ferguson, R.F.G. Wyse. Cambridge, U.K. ;          New York : Cambridge University Press, 1999. (Cambridge contemporary astrophysics), p.9 (astro-ph/9902108)12.  Poli, F. et al., 2003, Astrophysical Journal Letters, 593, L113.  Pozzetti, L. et al. 2003, Astron. Astrophys., 402, 83714.  Steidel, C.C., Adelberger, K.L., Giavalisco, M., Dickinson, M., Pettini, M. 1999, Astrophys. Journ., 519, 1VI. Evoluzione Cosmologica dei Nuclei Galattici Attivi1.    Di Matteo, T., et al. 2003, Astrophys. Journ., 593, 562.    Ferrarese, L. Merritt, D., 2000, Astrophys. Journ., 539, L93.    Gebhardt, K. et al., 2000, Astrophys. Journ., 539, L134.    Kauffmann, G., Haehnelt, M., 2000, Monthly Not. Roy. Astron. Soc., 311, 5765.    Menci, N. et al. 2003, Astrophys. Journ. 587, L636.    Rees, M.J., 1984, ARAA, 22, 471VII. Ammassi di Galassie1.    Sarazin, C., 1986, Rev. Mod. Phys., 58, 12.    Cavaliere, A. et al. 1997, Astrophysical Journal, 484, L213.    Cavaliere, A. et al. 1999, Monthly Not. Roy. Astron. Soc., 308, 5994.    Menci, N., Cavaliere, A.,  1999, Monthly Not. Roy. Astron. Soc., 311, 505.    Ponman, T. J.; Cannon, D. B.; Navarro, J. F., 1999, Nature, 397, 135

  26. Part of the available cold gas is detabilized and funnelled toward the centre Cavaliere Vittorini 2000 (Sanders & Mirabel 96) 3/4 feeds circumnuclear starbursts QSO Properties Starbursts Properties

  27. Pre-collisionD t ~ 0.01(rinit/h)3/2 trot As the galaxies fall in towards each other for the first time, they move on simple parabolic orbits until they are close enough that they have entered each others' dark halos, and the gravitational force becomes non-Keplerian. During this infall, the galaxies hardly respond to one another at all, save for their orbital motion. Impact D t ~ 0.3 (rp/h)3/2 trot As the galaxies reach perigalacticon, they feel the strong tidal force from one another. The galaxies become strongly distorted, and the tidal tails are launched from their back sides. Strong shocks are driven in the galaxies' ISM due to tidal caustics in the disks as well as direct hydrodynamic compression of the colliding ISM. Gravitational ResponseD t ~trot As the galaxies separate from their initial collision, the disk self-gravity can amplify the tidal distortions into a strong $m=2$ spiral or bar pattern. This self-gravitation response is strongly coupled to the internal structure of the galaxies as well as their orbital motion, resulting in a variety of dynamical responses

  28. z=3 z=1 z=0.4 Menci et al. 04 MBH~s4 Cold gas mass ~ s2.5 Interactions favour large galact. masses s3.5 SN feedback disfavours small galact. masses s4 Data from Gebhardt et al. 2000 (circles) Ferrarese & Merrit 2000 (squares)

  29. -21< Mr < -19 Local Blue Galaxy Pop. u-r < 1.3 Local Red Galaxy Pop. u-r >1.8

  30. log MBH (Mʘ )

  31. Thenormalizationof the QSO LFs - increases from z=0 to z=2 - decreases for z>2 Theshapeof the QSO LFs progressively flattens for z>2.5 z=1.2 z=0.5 z=2 The rise with z of the normalization is due to the increasing fraction of destabilized cold gas feeding the BH z=3 z=4.2 BECAUSE The encounter rate and the hence the accretion rate increases with z Data from Hartwick & Shade 1990, Boyle et al 2000, Fan et al 2001 The flattening is due to the rapid exaustion of galactic cold gas in larger galaxies, whose star formation is peaked at higher z

  32. The rapid decrease at z<2.5 is due to 3 concurring factors 1) The decrease with time of the merging rate of galaxies 2) The decrease with time of the galactic cold gas left available for accretion 3) The decrease with time of the encounter rate stimulating the cold gas funneling toward the nucleus Previous works adopting SAMs treated the accreted fraction f as a free parameter constant with z (missed process #3) Data from Hartwick & Shade 1990, Warren, Hewitt, Osmer 1994, Goldschmidt & Miller 1998, Boyle et al 2000, Fan et al 2001

  33. The effect of Starbursts on the Galaxy Lum. Function. Cold Gas destabilization from Fly-by interactions strongly decreases from z=3 to z=0 At high z a large amount of cold gas is destabilized Strong starbursts are expected at z > 3-4 NM et al. 2004 Data from Steidel et al. 99

  34. K-band Lumin. Functions The effect of Starbursts induced by fly-by events in the K-band observables NM et al 2004 K-band z-counts

  35. The stellar Mass Function (Fontana et al. 04) Data from Fontana et al. 03

  36. The Global Picture • At z > 2.5 - 3 • rapid merging, frequent encounters allow continuous refueling of gas in the growing galactic haloes. • Frequent encounters continuously destabilize an appreciable fraction of such a gas triggering: • fast BH accretion: QSO at full Eddington rate • - powerful starbursts • Such processes are produced preferentially in massive haloes due to their larger cross section for interactions. • At z < 2.5 - 3 • i) Construction of galaxies and merging rate decline • ii) decline of accreted fractionf ≈ Dj / j • iii) exaustion of cold gasparticulary in massive galaxies (originated from the merging of clumps collapsed in biased, high-density regions where most of the gas has already been converted into stars) • - QSO only occasionally refueled by encounters • - Emission drops down to L~ 10-2 LEddington • - QSO Lum. Funct. steepens at bright end • Starbursts activity drops • Massive galaxies (MDM > 1013 M⊙) undergo an almost passive evolution redder colors • Residual star formation in less massive galaxies which still retain part of their cold gas Evolutinary Tracks Galaxies with DM mass of: M=1013 M⊙ M=1012 M⊙ M=2.5 1011 M⊙ M=5 1010 M⊙

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