Tez özetleri Astronomi ve Uzay Bilimleri Anabilim Dalı

Correlation Between Optical and Gamma-Ray Properties of Gamma-Ray Bursts Associated with Supernovae

Even relationship between gamma-ray bursts (GRBs) and catastropic deaths (a supernova explosion; SN) of very massive stars are proven by observations and predicted by some theoretical models, their physical processes are still unknown. So, studies of finding possible relations between observed intrinsic parameters must be encouraged. GRBs are observed as prompt emissions and SNe are emerged in the afterglow emission in those selected candidates. To observe possible SN emerge, there are several factors interfered. These are brightness of GRB component, luminosity of SN component, distance of the star (these objects are extra-galactic), properties of the host galaxy and technical capability of observations. Due to these reasonings, possible relations between optical and gamma-ray properties of GRB/SNe are taken under intense examination.

In this study possible underlying physical relations between long-duration gamma-ray bursts (GRBs) and broad lined supernovae (SNe) Type Ic is examined. As a result of literature search 10 compatible objects are found. This study can be divided into two parts. In the first part, existing prompt emission relations are combined with the only existing optical and gamma-ray relation presented by Li (2006). After combining relations several purely mathematical optic and gamma-ray relations are obtained. The resultant equations are tested by two ways. In one way candidates with known optical property (peak bolometric luminosity) are used to calculate possible gamma-ray properties. In the other way, candidates with known gamma-ray properties are used to calculate their possible optical property (peak bolometric luminosity). Then, the results obtained by two sided calculations are compared with real values and thus, qualities of relations are tested.

In the second part, parametric relations between optical and gamma-ray properties of 10 GRB/SN that are found from literature are examined. Every optical and gamma-ray parameter couple are moved into the parameter spaces and possible biases are analyzed. Strong biases are fitted by a linear functions and equations of the fits are obtained. Quality of the fit is tested by calculationg the Spearman correlation coefficient.

In the last part of the study, results are evaluated under the considerations like nature of GRB/SN candidates, their small number and existing literature and discuss how this study might evolve in the future.

General result is MNi, MSN,peak and Eγ,peak parameters have critical importance for relations between gamma-ray and optical properties. This result first suggested by Li (2006) with lesser GIP/SN candidates