Novel polarimetric technique to constrain the magnetic field strength and geometry of Gamma-ray burst jets

Manisha Shrestha (LJMU)
Friday, April 2, 2021 - 11:00am to 12:00pm

Optical polarimetry can play a key role in diagnostic of magnetic field strength/order/geometry in diverse time varying astrophysical sources such as active galactic nuclei (AGN), X-ray binaries(XRBs), and gamma-ray bursts(GRBs). For distant objects such as GRBs, polarization can probe the physical conditions at spatial scale that is not possible via other observational techniques. Generally polarization is measured via ratio of fluxes by taking consecutive exposures, however for rapidly varying objects such as GRBs, it is not an effective way to observe polarization. Liverpool Telescope (LT) has utilized rapidly rotating polaroid to overcome this problem and created a series of polarimeters RINGO, RINGO2, and RINGO3 which have successfully detected early-time optical polarimetry of various GRBs. MOPTOP is a next-generation dual beam polarimeter that replaced RINGO3 in LT. I will present photometric and polarimetric results of various GRBs observed by RINGO3. In addition, I will present the results of MOPTOP characterization, which shows an improvement in the sensitivity of MOPTOP compared to RINGO3.

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