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Description
We report the detection of a transient quasi-periodic flux modulation in the 6-hour binned $\gamma$-ray light curve of blazar PKS 0903-57 observed by Fermi-LAT. Several independent periodicity search analyses revealed a periodicity of $\sim$6 days that lasted for 5 full cycles during its outburst in March-April 2020. Using Monte-Carlo light curve simulation technique, we found the QPO detection significance to be 4.7$\sigma$. We explored a few physical models responsible for the observed transient QPO, such as a binary black hole system, precession of the jet, a hotspot rotating around the central black hole near the innermost stable circular orbit etc. The flaring episode can be explained as the emergence of a bright plasma blob close to the central engine. The periodic flux variation with a trend of decreasing peak flux can probably be attributed to the helical motion of the blob inside a curved jet.
| Track | AGN |
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