Nucleosynthesis in Advective Accretion Disks around Galactic and Extra-galactic Black Holes

Many of the observational evidences for black hole rely on the fact that the incoming gas has the potential to become as hot as its virial temperature Tvirial ∼ 10 13 K (Rees, 1984). This flow is usually cooled down through bremsstrahlung and Comptonization effects and hard and soft states are produced depending on the degree by which this cooling takes place (Chakrabarti & Titarchuk, 1995). The generally sub-Keplerian, advective flow after deviating from a Keplerian disk, especially in the hard states, remains sufficiently hot to cause a significant amount of nuclear reactions around a black hole before plunging in it. The energy generated could be high enough to destabilize the flow and the modified composition may be dispersed through winds to change the metalicity of the galaxy (Chakrabarti, Jin & Arnett, 1987 [CJA]; Jin, Arnett & Chakrabarti, 1988; Chakrabarti, 1988; Mukhopadhyay & Chakrabarti, 1998). Earlier works have been done in cooler thick accretion disks only. Below, we present a few examples of nuclear reactions in advective flows and discuss the implications. Results of more detailed study could be seen in Mukhopadhyay & Chakrabarti (1998) [MC98].