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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)