Abstract

We investigate nucleosynthesis inside the gamma-ray burst (GRB) accretion disks and in the outflows launched fromthese disksmainly in the context of Type II collapsars. We report the synthesis of several unusual nuclei like ³¹P, ³⁹K, ⁴³Sc, ³⁵Cl and various isotopes of titanium, vanadium, chromium, manganese and copper in the disk. We also confirm the presence of iron-group and α−elements in the disk, as shown by previous authors. Much of these heavy elements thus synthesized are ejected from the disk and survive in the outflows. While emission lines of several of these elements have been observed in the X-ray afterglows of GRBs by BeppoSAX, Chandra, XMM-Newton etc., Swift seems to have not found these lines yet.