ASTRO 142 Chapter Notes - Chapter 13: Virial Theorem, Accelerating Expansion Of The Universe, Energy Density
Document Summary
Hubble constant: describes the rate of expansion of the universe: similar to velocity, sets the basic time and length scales for the universe. Curvature of the universe: describes the geometry of space (hyperbolic, spherical, flat: determined by the matter-energy content of the universe. Mass density parameter: overall matter density of the universe. Ca(cid:374) use the para(cid:373)eter to a(cid:272)(cid:272)ou(cid:374)t for e(cid:448)erythi(cid:374)g that (cid:272)a(cid:374) (cid:272)o(cid:374)tri(cid:271)ute to the gravitational forces in the universe: radiation, ordinary matter (baryons, dark matter. Deceleration parameter: tells us whether the rate of expansion is decelerating or accelerating. Determine redshift of galaxy: measuring the lookback time, when light from the galaxy first started on its way to us. Emission distance: when the galaxy emitted the light, it was the (emission distance) away. Reception distance: distance to the galaxy once we receive the light, increased by (1+z) due to the hubble expansion. High density universe decelerates more rapidly than a low-density universe.
