Wideband Monitoring of FRB 20180916B Across a Half-Decade Bandwidth Using the Upgraded GMRT

TL;DR

This study used the upgraded GMRT to monitor FRB 20180916B across a broad frequency range, detecting numerous bursts, analyzing their properties, and revealing insights into their emission processes and energy distribution.

Contribution

First wideband monitoring of FRB 20180916B with the upgraded GMRT over four months, providing new insights into burst rates, energy distribution, and scattering properties.

Findings

Detected 74 bursts at 250-500 MHz and 4 at 550-750 MHz.

Found maximum energy emission near the middle of the activity window.

Observed a strong correlation between excess dispersion measure and scattering width.

Abstract

With the uGMRT having unprecedented sensitivity and unique capability of providing instantaneous frequency coverage of 250$-$1460 MHz, we studied ${\rm FRB}\,20180916$B over four months sampling during its active phase. We report the detection of $74$ bursts at Band-3 (i.e. 250$-$500 MHz) and $4$ bursts at Band-4 (i.e. 550$-$750 MHz) of uGMRT providing a burst rate of $\sim 4$ bursts/hour above a fluence of 0.05 Jy ms. We find that the source emits maximum energy and luminosity up to a fractional bandwidth of 70 MHz near the middle of its activity window consistent with earlier studies. We see a strong correlation between the excess dispersion measure and excess scattering width. We find that the normalized cumulative distribution of the waiting time can be well-fitted by an exponential function, indicating a stochastic emission process. We also notice that the cumulative burst rate changes rapidly with the intrinsic energy of the bursts near the middle of the activity window considering the full observed window of 0.4-0.6 of this FRB, where this change is much steeper for the high-energy bursts and shallower for the low-energy bursts.