Research Information System
BOSTANCI GÜVER Z. F. (Executive), Göğüs E., Haneko Y.
TUBITAK Project, 1001 - Program for Supporting Scientific and Technological Research Projects, 2020 - 2022
Gamma Ray Bursts (GRBs) are short duration events that emit very large energy (1050) and they can show themselves in gamma ray emission from the depth of the Universe. GRBs are categorized as short GRBs and long GRBs based on their observed durations. Although this classification is very general, the physical mechanism that produces short (less than 2 seconds) and long (more than 2 seconds) bursts differs markedly. Long bursts can occur with core-collapse supernovae by the giant star at the end of its life. Short bursts are likely to occur as coalescence of binary systems of two neutron stars (NSNS) or neutron star and black hole (NSBH) mergers.
A new group of GRBs has been identified especially in the last ten years. These events are characterized with an initial short burst phase, followed by a much longer emission episode (extended emission, EE). Considering duration of total emission, these are categorized as long bursts. These properties may therefore place GRBs with EE at an important junction between short- and long GRB classes.
On August 17, 2017, the observation of gravitational waves emitted by the binary neutron star merger by the Advanced LIGO and Virgo detectors and the independent observation of the short GRB associated with this event by the Fermi GBM satellite telescope formed another important course of this area. Subsequent to this event, the neutron-rich ejecta from the binary neuron star merger gave rise to low-energy supernova radiation called as a kilonova explosion. The probability of some EE radiation being observable is increased before the compact binary coalescence collapsed into a black hole.
Within the scope of this project, events exhibiting EE episode will be studied using the data of GRB events observed with Fermi/GBM and Swift/BAT satellite telescopes. Both an initial short burst phase and EE episode of the identified GRBs with EE will be subjected to detailed investigations such as spectral lag and spectral modelling. In addition, the data of EE episodes will be examined with timing analysis in detail and they will be investigated for the first time whether they contain any periodic or quasi-periodic oscillations expected from neutron stars, which are able to radiate before they collapse into a black hole. In the light of the obtained results, the characteristic spectral and temporal properties of GRBs with EE will be revealed in the most comprehensive way. Similar investigations will be applied to short GRBs without EE and the processes that consist of the EE phase will be examined to obtain clues about the prompt emission that still preserves its mystery.
Assoc. Prof. Dr. Funda Bostancı, Assoc. Prof. Dr. Yuki Kaneko and Prof. Ersin Göğüş have deep knowledge and experience on GRB. Two graduate and two undergraduate-level scholarship students will participate in the project research studies and they will gain experience in the analysis and interpretation of high-energy astrophysical data. The results of the project have the potential to be published in scientific journals with high impact factor.