The accretion of hot , dense matter which consists of heavy nuclei , free nucleons , degenerated electrons , photons and neutrinos is studied .
The composition of free nucleons and their chemical potentials are provided through the equation of state for hot , dense matter proposed by Lattimer & Swesty ( 21 ) .
The numbers of leptons are calculated through the reactions of neutrinos and through the simplified transfers of neutrinos in the accreting matter .
The thermally equilibrium fluid structure of the accretion is solved .
The angular momentum transfer in the disk is analyzed with the shear stress which is driven in the frame of the general relativity .
When the mass of a central black hole and the accretion rate are selected as M _ { BH } \approx 3 { M } _ { \odot } and \dot { M } \approx 0.1 { M } _ { \odot } sec ^ { -1 } , which provide the typical luminosity of gamma ray bursts ( GRBs ) , the fraction of free protons in the accreting matter becomes very small , Y _ { p } \approx 10 ^ { -4 } , while that of free neutrons is closer to unity , Y _ { n } \approx 0.7 .
Then the antielectron neutrinos \bar { \nu } _ { e } can freely escape through the disk but the electron neutrinos \nu _ { e } are almost absorbed in the disk .
Thus the frequent collisions of \bar { \nu } _ { e } with \nu _ { e } over the disk couldn ’ t be occurred .
The accretion disk is cooled mainly by \bar { \nu } _ { e } , which suppresses the increase of temperature and increases the density in the accreting matter such as T \approx 3 \times 10 ^ { 10 } K and \rho \approx 3 \times 10 ^ { 13 } g/cm ^ { 3 } at the inner side of the disk .
The scattering optical depths of \bar { \nu } _ { e } and \nu _ { e } then reach to be very large , \tau _ { s } ( \bar { \nu } _ { e } ) \approx \tau _ { s } ( { \nu } _ { e } ) \approx 10 ^ { 2 } .
Thus the accretion disk could be thermally unstable within the duration of diffusion time of neutrinos , t _ { diff } \approx 10 ( ms ) .
The ram pressure produced by many scattering of \bar { \nu } _ { e } are very strong , which might produce the neutrino driven wind or jets .
The luminosity and mean energy of neutrinos , L _ { \nu } , \bar { E } _ { \nu } , ejected from the disk increases with the specific angular momentum of a black hole .
The mean energy is inversely proportional to the central mass , \bar { E } _ { \nu } \propto M _ { BH } ^ { -1 } , while the luminosity L _ { \nu } is independent of its mass , M _ { BH } .
The diagram determining the physical properties of a central black hole from the observation of each flavor of neutrino is proposed .