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Different red disclike galaxies at intermediate/high redshifts
Daniele Pierini (MPE) in collaboration with: M. Pannella (MPE), M. Salvato (Caltech), K.D. Gordon (Un. of Arizona), C. Maraston (Un. of Oxford), A.N. Witt (Un. of Toledo)


Outline


Distant Red Galaxies JK selected disclike galaxies from GOODS How to obtain JK>2.3 with models Results Conclusions










Distant Red Galaxies


JSKS>2.3 to select galaxies among the oldest ones at z>2
(Franx et al. 2003)



V~26.6: specz hard
(van Dokkum et al. 2003)



the contamination by objects at z<2 can be as high as 50%
(Daddi et al. 2004)


DRGs @ z>2 I.

(van Dokkum 2003)


DRGs @ z>2 II. (

FЖrsterSchreiber et al. 2004)


DRGs @ z<2 (

Conselice et al. 2007)


GOODS JK selected "disc" galaxies


JK>2.3 @ > 1 sigma ACS imaging 0.6nSer1.6 12 objects (4 @ z<2) 18.8












Models for normal starforming discs


composite stellar populations including the TPAGB phase of intermediatemass stars
(Maraston 2005)



exponentially declining SFRs with efolding times of 37Gyr solar metallicity zf=10 (LCDM cosmology) or fixed age (0.6 Gyr) dust attenuation for a disc geometry
(Ferrara et al. 1999; Pierini et al. 2004)








How to make a DRdG?


To make a DRdG... (


Pierini et al. 2005)

@ 2











DRdGs @ z<2 as...


ULIRGs: exp. decl. SFR (efolding time: 5 Gyr), ages from 0.1 to 1.5 Gyr, homogeneous SHELL models with SMC dust (Witt & Gordon 2000) postULIRGs: constant SFR for only 0.5 Gyr, ages from 0.6 to 1.5 Gyr, homogeneous SHELL models with SMC dust starbursts: as ULIRGs but with a two/phase, clumpy ISM poststarbursts: as postULIRGs but with a two/phase clumpy ISM









A truncated starformation history?


truncation after 4 Gyr at constant SFR
(Maraston 2005)



6 Gyrold @ z=0.83 DIRTY disc models
(Pierini et al. 2004)




Conclusions


Need of more complex starformation histories and dust/stars configurations Use of Nbody/semianalytic simulations
(Jonsson et al. 2006; Rocha et al. 2007)