Morphology of galaxies at

z>1.4

Marseille June 10th, 2009

zCOSMOS deep v1.1

z>1.4&flag=2,3,4,9

317 galaxies

Ellipticals

Spirals

high-zhigh-z

low-zlow-z

Marseille Lidia Tasca June 10th, 2009

20 Ellipticals174 Spirals104 Irregulars

Need new classification scheme5 classes:class 1= compactclass 2= dominant single extended component, symmetricalclass 3= Irregularclass 4= Tadpoleclass 5= diffuse, low SB

&count number of distant componentsin 1 arcsec

Class 1Class 1 Class 2Class 2 Class 3Class 3

Class 5Class 5Class 4Class 4

Marseille Lidia Tasca June 10th, 2009

Class 3 -> dominant

Number of clumps increases with class

Link between CAS classification and visually defined classes

Class 1Class 1

Class 3Class 3 Class 4Class 4 Class 5Class 5

Class 2Class 2 “Typical” galaxy has a morphology comprising 1 or more distinct clumps, with some degree of diffuse nebulosity

Marseille Lidia Tasca June 10th, 2009

I vs K I vs K morphologymorphology

K-band morphology at z>1.4 not trivial (ground-based seeing-limited)

~50% of star-forming galaxies at z>1.4 are not detected in K

Interesting: blue compact galaxies at z>1.4

Class 1Class 1

Class 2Class 2

Class 3Class 3

Class 4Class 4

Class 5Class 5

HST-ACS F814WHST-ACS F814W IRCAM KsIRCAM Ks

High-z galaxies have irregular morphologies not only in the rest-UV but at rest-optical as well both regimes are dominated by emission from young starbursting components. Maybe fundamental differences between high and low z galaxies

Spectral vs. morphological Spectral vs. morphological propertiesproperties

Marseille Lidia Tasca June 10th, 2009

• Literature: galaxies at z~2-3 have irregular morphologies

• Is there a connection between rest-UV morphology and the content in star, dust, gas at these epochs?

• Can we connect these galaxies with lower z population?

• When did early and late type differentiate? • Do we see more mergers?

Spectral properties vs. Spectral properties vs. visual classvisual class

Marseille Lidia Tasca June 10th, 2009

ClassClass EW - EW - LyLy

11 -19.4-19.4

22 6.36.3

33 -18.7-18.7

44 -19.1-19.1

55 -13.0-13.0

Conclusions & Conclusions & PerspectivesPerspectives

Marseille Lidia Tasca June 10th, 2009

• Visual classification complementary from CAS classification

• Ly properties weakly linked to morphology classification

• UV morphology decoupled from physical observables, or physical processes too complex for a simple link ?

• Complete spectral classification based on Ly and UV continuum

• Continue exploration of parameter space, use morphological and spectral features to classify (ie. gini and Lylinear trend of increasing emission strength with increasing nucleation)