Gravitational Microlensing of Cosmological Gamma Ray Bursts with Spectrogram Analysis

In recent years, gravitational microlensing has become an important tool for probing astrophysical compact objects from galactic to cosmological scales. Several theoretical predictions of the effects of gravitational microlensing have been confirmed observationally, including the discovery of extrasolar planets and constraining the presence of dark matter in the galactic halo. An observable effect of gravitational microlensing on the cosmological Gamma-Ray Bursts (GRB) is expected to take place when the radiation from the bursts is lensed by compact objects in our line of sight. This project aims to investigate this effect. Gravitational microlensing will cause a path-dependent time delay of the Gamma-ray Burst radiation, leading to two signals with a small difference in their arrival times. The observed light curve is envisaged to be a degenerate outcome of the superposition of the two light curves with time differences in the order of magnitude of milliseconds. We will apply spectrogram and Fourier analysis to decompose the GRB light curves and calculate the time delay from available data archives of gamma-ray telescopes such as Fermi and Swift. This method was recently applied in analyzing gravitational wave data and it is shown to yield better sensitivity and more information than studying the time series alone. This approach allows using a dynamic window function along the time domain and to obtain Fourier power spectra inside these windows. This study will offer valuable insight on the instrumental sensitivity of current gamma-ray telescopes as well as planned ones to discern gravitational microlensing effects in Gamma-ray Bursts.

In recent years, gravitational microlensing has become an important tool for probing astrophysical compact objects from galactic to cosmological scales. Several theoretical predictions of the effects of gravitational microlensing have been confirmed observationally, including the discovery of extrasolar planets and constraining the presence of dark matter in the galactic halo. An observable effect of gravitational microlensing on the cosmological Gamma-Ray Bursts (GRB) is expected to take place when the radiation from the bursts is lensed by compact objects in our line of sight. This project aims to investigate this effect. Gravitational microlensing will cause a path-dependent time delay of the Gamma-ray Burst radiation, leading to two signals with a small difference in their arrival times. The observed light curve is envisaged to be a degenerate outcome of the superposition of the two light curves with time differences in the order of magnitude of milliseconds. We will apply spectrogram and Fourier analysis to decompose the GRB light curves and calculate the time delay from available data archives of gamma-ray telescopes such as Fermi and Swift. This method was recently applied in analyzing gravitational wave data and it is shown to yield better sensitivity and more information than studying the time series alone. This approach allows using a dynamic window function along the time domain and to obtain Fourier power spectra inside these windows. This study will offer valuable insight on the instrumental sensitivity of current gamma-ray telescopes as well as planned ones to discern gravitational microlensing effects in Gamma-ray Bursts.