Lecture 30 Flashcards
what causes the cosmic web
gravitational instability
ellipsoidal collapse forms sheets which form filaments which form nodes leaving voids
denser regions have larger fluctuations so collapse quicker
all stages present at any given time
why is distance approximate in redshift surveys
peculiar velocities
how is redshift actually measured
from emission lines or absorption lines from galaxies
cosmic webs effect on cosmological parameters
cosmic web pattern constrains cosmological parameters
what does the correlation function do
measures how clustered galaxies are
what is the endpoint of collapse in dark matter halos
triaxial halo supported by velocity dispersion
why do dark matter halos rotate
due to uneven pull of nearby mass
what are dark matter halos defined by
mass, velocity dispersion, spin, concentration
how are other galaxies formed from spirals
spirals merge, orbits random, elliptical galaxy is formed
Hubble sequence
ellipticals - red and dead , spirals - blue and star forming , irregulars - mergers and starbursts
what are the 4 galaxy environments
clusters, groups, field, voids
what is gas in clusters and groups heated to
virial temperature
explain massive stars (>8M)
live fast (<30mil yr) , burn bright, emit energetic bluer light, die explosively in supernova
they are rare but one massive star can outshine hundreds of low mass stars
explain galaxy colours based on stars and galaxy mass to light
if it is blue, has formed stars recently, most mass is in the lower mass stars but most of the light comes form higher mass stars
what do we see galaxies to be at earlier times
younger, smaller, more star forming, bluer, more irregular
from lambda CDM model and cooling, what do we expect the %mass of any halo to be in stars
10%
what happens with supernova feedback when a massive star goes supernovae
releases a significant amount of energy 10^51J, that can boil gas out of galaxies
what is supernova feedback particularly effective for
starburst galaxies, smaller galaxies, higher redshift galaxies
what does supernovae feedback explain about low mass halos converting baryons to stars
explains why they are so inefficient
how is supernovae feedback detected
high vel emission or absorption
how do supernovae effect elements
create and disperse heavy elements
where are most of the cosmic baryons contained
IGM - intergalactic medium that is outside halos
where can gas reside in space
inside galaxies (ISM), within the galaxies halo (CGM) or outside of halos (IGM)
what is baryon cycling
gas inflows and outflows going through the cgm
