| Name: | Pranjal Chaturvedi |
| Affiliation: | Indian Institute of Technology, Indore |
| Conference ID : | ASI2024_170 |
| Title : | Quasi-Periodic Oscillations in the Gamma-Ray Emissions of a few Flat Spectrum Radio Quasars |
| Authors : | P. Chaturvedi1, K.K. Singh2,3, A. Datta1 |
| Authors Affiliation: | 1 Department of Astronomy, Astrophysics and Space Engineering, Indian Institute of
Technology, Indore, 453552, India
2 Astrophysical Sciences Division, Bhabha Atomic Research Centre, Mumbai, 400085, India
3 Homi Bhabha National Institute, Anushakti Nagar, Mumbai, 400094, India |
| Mode of Presentation: | Poster |
| Abstract Category : | Galaxies and Cosmology |
| Abstract : | Flat Spectrum Radio Quasars (FSRQs) are a subclass of blazars with strong and broad spectral lines in their UV/optical continuum. They represent a dominant population of distant gamma-ray sources in the Universe compared to the other class of blazars. The gamma-ray emission from blazars is observed to be highly variable at different timescales with a possibility of periodic behaviour at a period of the order of days to years. The Large Area Telescope on board the Fermi satellite (Fermi-LAT) provides continuous monitoring of the entire gamma-ray sky in the energy range above 100 MeV. In this contribution, we investigate the quasi-periodic features in the gamma-ray emission of a sample of FSRQs using long-term light curves publicly available from the Fermi-LAT repository with a time binning of 3-days,7-days and 30-days. We apply various statistical tests to quantify the level of flux variability in these light curves. The light curves with significant variability are treated as a time series to identify the periodicity by employing Fourier methods. The Lomb-Scargle Periodogram (LSP) and Weighted Wavelet Z-Transform (WWZT) methods are used in tandem to quantify the quasi-periodic oscillations (QPOs). It is found that the gamma-ray light curves of the FSRQs, considered in this study exhibit QPOs with periods ranging from 3 years to 9.5 years at a confidence level of 95%. Further investigation indicates no correlation between the identified QPOs and the mass of the super-massive black hole situated at the centre of the host galaxies and their redshifts. |
