How and when did the oldest galaxies
form?
history
CFHT/J.C.Cuillandre
building
blocks
Ron Marzke Karen Aiken
Vanessa Bell
JoEllen McBride Jon Brix
Shine Roshan
Measuring Galaxy Ages (1)
hot cool
10 Gyr
red
Galaxy
Color
blue
0.1 1 10
Age (Gyr)
Evolved Galaxies at High Redshift
Low-luminosity Quasars at High
Redshift
Karen Aiken
K. Cordes & S. Brown / STSCI
How old are the building blocks?
Ages of Evolved Dwarf Galaxies
MMT 6.5 m
Hectospec
Measuring Galaxy Ages (2)
Mg Fe
the age/abundance degeneracy
red
Galaxy
Color
blue
1 Age (Gyr) 10
Breaking the Age/Abundance
Degeneracy
H age
indicators
H
Hot star spectrum
(young populations) H
Cool star spectrum Mg
(old populations)
Fe
abundance
Ca indicators
Well maybe sort of almost breaking
the age/abundance degeneracy
Delbouille et al. 1981
Dwarf Galaxy Ages and Abundances
faint bright faint bright faint bright faint bright
Compact Galaxies Nearby:
Remnants of the Earliest Galaxies?
Jon Brix
Vanessa
Bell
The Soar Ultracompact Dwarf Survey
Shine Roshan