Astroparticle Physics

404 D Important Constants for Astroparticle Physicsrelativeuncertaintystandard atmosphere, atm 101 325 Pa exactacceleration due to gravity g 9.806 65 m s −2 exactHubble constant H 0 71 km s −1 Mpc −1 5%age of the universe t 0 13.7 × 10 9 a 1.5%Hubble distance c/H 0 4 225 Mpc 5%critical density ϱ c = 3H0 2/8πG 9.469 × 10−30 g/cm 3 ≈ 10%density of galaxies≈ 0.02 Mpc −3temperature of the blackbody radiation 2.725 K 4 × 10 −4number density of blackbody photons 410.4cm −3 1.2 × 10 −3astronomical unit, AU 1.495 978 706 60 × 10 11 m 1.3 × 10 −10parsec, pc (1 AE/1arcsec) 3.085 677 5807 × 10 16 m 1.3 × 10 −10light-year, LY0.3066 pc = 0.9461 × 10 16 mSchwarzschild radiusof the Sun: 2GM⊙/c 2 2.953 250 08 km 3.6 × 10 −4mass of the Sun M⊙ 1.988 44 × 10 30 kg 1.5 × 10 −4solar constant 1 360 W/m 2 0.2%solar luminosity L⊙ 3.846 × 10 26 W 0.2%mass of the Earth M ♁ 5.9723 × 10 24 kg 1.5 × 10 −4radius of the Earth R ♁6.378 140 × 10 6 mSchwarzschild radiusof the Earth: 2GM ♁ /c 2 0.887 056 22 cm 1.5 × 10 −4velocity of the solar systemabout the galactic center 220 km/s 9%distance of the Sunfrom the galactic center 8.0 kpc 6%matter density of the universe Ω m 0.27 18%baryon density of the universe Ω b 0.044 9%dark-matter density of the universe Ω dm 0.22 18%radiation density of the universe Ω γ 4.9 × 10 −5 10%neutrino density of the universe Ω ν ≤ 0.015 95% C.L.dark-energy density of the universe Λ 0.73 5%total energy density of the universe Ω tot 1.02 2%(Ω tot ≡ Ω)number density of baryons n b 2.5 × 10 −7 /cm 3 4%baryon-to-photon ratio η 6.1 × 10 −10 3%0 ◦ C 273.15 K