Credit: Danielle Futselaar
The other area of my active research includes the investigation of progenitors of fast radio bursts by studying radio emissions and the surroundings of these events. Fast radio bursts are transient intense radio pulses of unknown origin. The detection rate of fast radio bursts indicates that these events are overabundant in the universe (more than 1000 events per sky every day), however, we still lack an understanding of the progenitors and emission mechanisms of these objects.
Left video credit: NASA's GSFC
Theoretical Study: Analyzing the evolution of the dispersion measure and rotation measure through the merged material of a white dwarf binary, we showed that, at least for some of the fast radio bursts, the merger of two white dwarfs was a potential channel that formed the fast radio burst sources (Kundu & Ferrario 2020, MNRAS, 492, 3753 ). Recently, the source of a non-repeating fast radio burst, FRB 191001, has been localized to the spiral arm of a starburst galaxy. Applying the model developed in my previous paper and performing a statistical analysis on the location of supernovae in the spiral arm of their host galaxies, I established that FRB 191001 was most likely the outcome of a core-collapse supernova (Kundu 2022, MNRAS Letters, 512, L1-L5 ).
Among fast radio bursts, a substantial number of bursts, mainly those from repeating sources, have shown a drift in frequency and time in their spectra. We found that the free-free absorption in relativistic shocks could produce the observed drifts in the spectra of some of the fast radio bursts (Kundu and Zhang 2021, MNRAS Letters, 508, L48-L52 ).
FRB in a Globular cluster: Recently FRB 20200120E was discovered in a globular cluster (GC) in galaxy M81 at a distance of 3.63 Mpc. It is usually thought that FRBs are produced by highly magnetized young neutron stars (NS) or magnetars. On the other hand, GCs contain old populations of stars. This discovery, therefore, challenges the current understanding of both FRBs and the dynamical evolution of GCs.
My summer student, Emma Dugan at Michigan State University started examining if there exists a substantial population of likely-to-produce FRB X-ray binaries in GCs and the local universe. In this work, we found that there can be a significant fraction of FRB sources in the local globular clusters which Emma presented as a poster in the Mid-Sure Symposium on 26th July 2023 at Michigan State University.
Since this is a large project, it will be pursued in the future as a Ph.D. project.