Cosmological tests using gamma-ray bursts, the star formation rate and possible abundance evolution

摘要: The principal goal of this paper is to use attempts at reconciling the Swift long gamma-ray bursts (LGRBs) with star formation history (SFH) compare predictions Lambda cold dark matter (Lambda CDM) those in R-h = ct Universe. In context former, we confirm that latest sample GRBs reveals an increasing evolution GRB rate relative (SFR) high redshifts. observed discrepancy between and SFR may be eliminated by assuming a modest parametrized as (1 + z)(0.8) - perhaps indicating cosmic metallicity. However, find higher metallicity cut Z 0.52 Z(circle dot) than was seen previous studies, which suggested LGRBs occur preferentially metal-poor environments, i.e. similar 0.1-0.3 dot). We simple power-law approximation high-z ( greater or 3.8) SFH, R-SF proportional [(1 z)/4.8](alpha), examine how impacted possible abundance sample. For expansion consistent CDM, redshift luminosity distributions can reproduced reasonable accuracy if alpha -2.41(-2.09)(+1.87). Universe, slightly different from but also requires extra evolutionary effect, 0.44 Assuming are related via evolving metallicity, data constrain slope -3.60(-2.45)(+2.45). Both cosmologies fit GRB/SFR rather well. one-on-one comparison using Akaike information criterion, best-fitting model statistically preferred over CDM probability 70 per cent versus 30 cent.