A generic relation between baryonic and radiative energy densities of stars

Abstract

By using elementary astrophysical concepts, we show that for any self-luminous astrophysical object, the ratio of radiation energy density inside the body (rho_r) and the baryonic energy density (rho_0) may be crudely approximated, in the Newtonian limit, as rho_r/rho_0 ~ GM/Rc^2, where G is constant of gravitation, c is the speed of light, M is gravitational mass, and R is the radius of the body. The key idea is that radiation quanta must move out in a diffusive manner rather than free stream inside the body of the star. When one would move to the extreme General Realtivistic case i.e., if the surface gravitational redshift, z >> 1, it is found that, rho_r/rho_0 ~ (1+z). Previous works on gravitational collapse, however, generally assumed rho_r/rho_0 << 1. On the other hand, actually, during continued general relativistic gravitational collapse to the Black Hole state (z --> infty), the collapsing matter may essentially become an extremely hot fireball a la the very early universe even though the observed luminosity of the body as seen by a faraway observer, L^\infty ~ (1+z)^{-1} --> 0 as z --> infty, and the collapse might appear as ``adiabatic''.

Small changes at proof stage, shows zero radiation density for collapse implies zero restmass density, MNRAS Letters (in press)

Cited by in corpus (6)

• Why Gravitational Contraction Must be Accompanied by Emission of Radiation Both in Newtonian and Einstein Gravity
• Likely formation of general relativistic radiation pressure supported stars or "eternally collapsing objects"
• Radiation Pressure Supported Stars in Einstein Gravity: Eternally Collapsing Objects
• The fallacy of Oppenheimer Snyder Collapse: no general relativistic Collapse at all, no black hole, no physical singularity
• Thermal Radiation from Compact Objects in Curved Space-Time
• Masses of radiation pressure supported stars in extreme relativistic realm