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

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

*

* m

mhigh

*

* owm

ml

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

small masslarge mass

Observations show:

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

Tully, Mould, Aaronson 1982

• Massive galaxies are redder• Contain older stars • star formation much larger at high redshitfs

Bimodal Color Distribution

Baldry et al. 2004

BrightRed Galaxies

FaintBlue Galaxies

Color Distribution Dependence on luminosity

BLUE

RED

log Numberlog Number

Local galaxies with u-r<1 Local galaxies with u-r>1.5-20.5 < Mr <-19.5

The cold gas fraction

Mprog=109 Mʘ

skmEv SNfeedbackc /10002

M=109 Mʘ at z=4.5

Colore Distribution: Dependence on the environment

t1

t2

t3

Z=0

Large masshalo

small masshalo

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.

The star formation histories of the population contained (today) in dense environments (groups/clusters) peaks at higher redshift compared to that of smaller galaxies.

Bimodality extends at least up to z ≈ 0.8

Bell et al. 03

estimates fromGlazebrook et al. (GDDS)Rudnick et al. (FIRES)Dickinson et al. (HDFN)Fontana et al. (K20)Bell et al. (COMBO)

The Evolution of luminosity and mass functionsi) 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)

The Luminosity Evolution

I:Luminosity evolution: B and UV- B-band and UV luminosity ~ instanteneous star form. rate

- Star Formation strongly increases with z

- The number of massive objects decreases with z (hierarchical clustering)

M

NZ=0Z=3

*mLB

II: Luminosity evolution: K

- K-band luminosity ~ total mass in stars formed at current time

*

0

*

0

*

')'( )'(

')'()'(

mdtttmSconstt

dttttmS

t

t

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

StarburstsPozzetti et al. 2003

MZ<25

Data: Fontana et al 03

Mihos & Hernquist 1996See also Noguchi 1987 Barnes & Hernquist 1991

Gas Angular Momentum

‘”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 “

mbV

vrm

j

jVvf dd'

2

1

2

1),(

Part of the available galactic cold gas is detabilized and funnelled toward the centre

Cavaliere Vittorini 2000

Rate:

tidalrelr rV /1 Duration:

reltidal VrnFlyBy

)( 21

mbV

vrm

j

jVvf dd'

2

1

2

1),(

Part of the available cold gas is detabilized and funnelled toward the centre

Cavaliere Vittorini 2000

(Sanders & Mirabel 96)

Starbursts Mass Conversion rate

r

coldmftvm

4

3),(*

Strongly increases with z

larger m’/m ratios

Larger vd/V ratio

Smaller r~(1+z)-1/2

Larger cold gas mass

Larger f ≥ 0.01

Starbursts Freqency

reltidal VrnFlyBy

)( 21

Strongly increases with z

Larger r/R ratio

Smaller r~(1+z)-1/2

3/1 Rn

122

1

dynFlyBy R

r

R

V

R

r rel

The Bursts

EROs

AGN activity triggered by destabilization of gas during encounters:

Would naturally explain

1) 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 formationBUT for AGN constitute the whole feeding mechanism

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

The effect of Starbursts on the Galaxy Lum. Function.

MZ < 25.5

L > 0.2 L*

Data from Giavalisco et al. 03

Somerville Primack & Faber 2001

The effect of Starbursts induced by fly-by events in the K-band observables

K-band Lumin. Functions

K-band z-counts

NM et al 2004

z=1-1.6

z=1.6-2

z=2-3

Stellar Mass function at high z

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 declineii) Accretion of smaller lumps by major progenitors iii) decline of fraction f ≈ j / j of gas accreted by BH or converted in SBurstsiv) 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

Arising of bimodality in the properties of galaxy pop.

• Massive galaxies (MDM > 1013 Mʘ) undergo an almost passive evolution redder colors.• Residual star formation in less massive galaxies (rates 0.1 – 1 Mʘ/yr) still retaining part of theircold gas reservoir (blue colors)

preferentially in massive haloes with larger cross section for interactions.

Large B/ UV EmissionLy-break glxs

1/3 of the stellar mass in galaxies with M*>1010 Mʘ is in place at by z≈2

What about z≈3 ?

The Big Picture

Bibliografia

I. Evoluzione delle Perturbazioni Cosmologiche 1.    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, 1

II. Statistica degli Aloni di Materia Oscura-Merging Trees

1.    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, 425

III. Proprieta’ Aloni di Materia Oscura - Dinamica Galattica

1.    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 Galassie

1.    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

V. Confronto con Proprieta’ Osserv. delle Galassie

1.    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, 1

VI. Evoluzione Cosmologica dei Nuclei Galattici Attivi

1.    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, 471

VII. Ammassi di Galassie

1.    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

mbV

vrm

j

jVvf dd'

2

1

2

1),(

Part of the available cold gas is detabilized and funnelled toward the centre

r

coldacc

mftvm

4

1),(

accmc

tvL

2

),(

')',()1(0

dttvmmt

accBH

Cavaliere Vittorini 2000

(Sanders & Mirabel 96)

3/4 feeds circumnuclear starbursts

t

dttttmS0

* ')'()'(

QSO Properties Starbursts Properties

r

coldmftvm

4

3),(*

Pre-collision 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 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 Response t ~trot

As the galaxies separate from their initial collision, the disk self-gravity canamplify the tidal distortions into a strong $m=2$ spiral or bar pattern. Thisself-gravitation response is strongly coupled to the internal structure of the galaxies as well as their orbital motion, resulting in a variety of dynamicalresponses

z=0.4

z=1

z=3

MBH~4

Cold gas mass ~ 2.5

Interactions favour large galact. masses 3.5

SN feedback disfavours small galact. masses 4

Data from Gebhardt et al. 2000 (circles)Ferrarese & Merrit 2000 (squares)

Menci et al. 04

Local Blue Galaxy Pop.u-r < 1.3

Local Red Galaxy Pop.u-r >1.8

-21< Mr < -19

log

MB

H (

Mʘ )

z=0.5z=2 z=1.2

z=4.2

z=3

Data from Hartwick & Shade 1990, Boyle et al 2000, Fan et al 2001

The normalization of the QSO LFs - increases from z=0 to z=2- decreases for z>2

The shape of the QSO LFsprogressively flattens for z>2.5

The rise with z of the normalization is due to the increasing fraction of destabilized cold gas feeding the BH

The encounter rate and the hence the accretion rate increases with z

BECAUSE

The flattening is due to the rapid exaustion of galactic cold gas in larger galaxies, whose star formation is peaked at higher z

Data from Hartwick & Shade 1990, Warren, Hewitt, Osmer 1994, Goldschmidt & Miller 1998, Boyle et al 2000, Fan et al 2001

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 SAMstreated the accreted fraction fas a free parameter constant with z(missed process #3)

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

Data from Steidel et al. 99

The effect of Starbursts on the Galaxy Lum. Function.

NM et al. 2004

The effect of Starbursts induced by fly-by events in the K-band observables

K-band Lumin. Functions

K-band z-counts

NM et al 2004

Data from Fontana et al. 03

The stellar Mass Function (Fontana et al. 04)

M=1013 M⊙

M=1012 M⊙

M=2.5 1011 M⊙

M=5 1010 M⊙

Evolutinary Tracks Galaxies with DM mass of:

At z > 2.5 - 3rapid 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

declineii) decline of accreted fraction f ≈ j / j iii) exaustion of cold gas particulary 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

The Global Picture