Week 3 Contents of the Milky Way Galaxy

Question 1

what is the matter/energy composition of the Universe

Answer 1

75% Dark Energy

25% Matter

Question 2

how do Dark energy and matter affect the universe

Answer 2

Dark energy accelerates the expansion of the universe, matter tends to slow down this acceleration

Question 3

what is the matter composition of the universe

Answer 3

18% Baryonic matter

82% Dark matter

Question 4

how does the matter composition of galaxies compare to the rest of the universe

Answer 4

generally galaxies are over-baryonic in comparison

Question 5

what are the 3 methods for detecting Dark Matter

Answer 5

1 Rotation curves of spiral galaxies
2 Velocity dispersion in clusters of galaxies
3 Gravitational micro-lensing

Question 6

what does the proportion of dark matter in a galaxy depend on

Answer 6

galaxy type

Question 7

what are the two methods for predicting the shape of dark matter halo

Answer 7

1 Study kinematics of debris

2 Scale height of H1 in disc

Question 8

what are 3 features of the initial mass function of stars

Answer 8

only applies @ birth
is a decaying power law
evidence it flattens leading to fewer brown dwarfs

Question 9

what is the general luminosity relation for most stars

Answer 9

L ∝ M^(3.5)

Question 10

what are the two corrections for the luminosity function

Answer 10

Malmquist bias - prevent missing low L stars at long distance
K-correction - corrects the distortion from the spectral output at high redshift

Question 11

what are the 5 main Interstellar Material (ISM) phases

Answer 11

1 Hot
2 Warm Neutral Medium
3 Cool Neutral Medium
4 Molecular Clouds
5 Photoionised Gas