Astrophysics, Cosmology & Relativity
4 terms
Dark Energy
Astrophysics, Cosmology & Relativity
Cosmological Constant Λ (J/m³)
An unknown form of energy with negative pressure that permeates all space and drives the accelerated expansion of the universe.
Ω_Λ ≈ 0.68, w = P / ρ ≈ -1
Dark Matter
Astrophysics, Cosmology & Relativity
M_☉ or kg (Cosmological Density)
A non-baryonic form of matter that does not absorb, reflect, or emit electromagnetic radiation, detectable solely through its gravitational effects.
Ω_dm ≈ 0.27 (27% of total cosmic mass-energy)
Dark Matter Halo
Astrophysics, Cosmology & Relativity
kpc (Halo Radius) & M_☉ (Halo Mass)
An extended, nearly spherical region of dark matter enveloping a galaxy or galaxy cluster that extends far beyond the visible stellar disk.
NFW Density Profile: ρ(r) = ρ₀ / ((r/r_s) (1 + r/r_s)²)
Drake Equation
Astrophysics, Cosmology & Relativity
Number of Civilizations N
A probabilistic equation formulated by Frank Drake in 1961 to estimate the number N of active, communicative extraterrestrial civilizations in the Milky Way.
N = R* · f_p · n_e · f_l · f_i · f_c · L