L12

Question 1

metallicity meaning
formula?

Answer 1

measure of elements (not H, He)

Question 2

methods to find metalliicty?

Answer 2

x

Question 3

mass meta relation MZR for gal

Answer 3

massive galsxies: more metal

Question 4

simple model for gal chem evo? basic conditions?

Answer 4

closed sys
change in mass of gas = - change in stellar mass

aim: metallicity relation w time

Question 5

metal time relation by simple model

Answer 5

Z = ypt
(linear relation, Z indicator of t)

R= mass frac returned

y = mass fraction of metals returned to ISM (‘stellar yields’)

p= const

Question 6

prob w simple model?

Answer 6

take Z of present time only

most SF in earlier uni (when Z was lower)

Question 7

sol for prob of simple model?

Answer 7

1, cosmo redshift as lookback indicator and

2, decompose integrated spectra

3, predict Z dist of stars and compare w obs

Question 8

why age relation doesnt work for MZR?

Answer 8

high mass galaxies: old stars (low metal)—— gal: high metal

low mass galaxies: young stars (high metal)—— gal: low metal

gal metal doesnt match stellar pop metal by simple age effect
LMGal should then be older then high mass galaxies