PUNE A group of scientists working at the National Centre for Radio Astrophysics (NCRA), Pune have for the first time unravelled the eclipse mechanisms for the millisecond pulsars in compact binary systems using the upgraded Giant Metrewave Radio Telescope (uGMRT). Devojyoti Kansabanik a Ph.D. student at NCRA is the lead author of the paper, done under the guidance of Dr. Bhaswati Bhattacharyya.
Millisecond pulsars (MSPs) are ultra-dense dead stars that act like celestial lighthouses sending periodic flashes of radio light as fast as a few hundred times in a second. Being extremely stable rotators, MSPs act as laboratories for the study of matter in extreme conditions. MSPs often have orbital companions.
Devojyoti Kansabanik and team observed a spider MSP, J1544+4937, (which had been discovered earlier at the GMRT in 2013), using the upgraded uGMRT. The unique wide bandwidth sensitive observations allowed the authors to clearly measure how the eclipse depends on the radio frequency, particularly during the transitions as the pulsar went into and came out of eclipse.
Talking about the discovery Dr Bhattchayya said, “We could study the eclipsing seamlessly and determine the starting frequency of the dependent eclipse with 20 times better accuracy than the previous estimations. This allowed us to study the cause of frequency dependent eclipsing for the first time by studying broadband radio spectrum, a crucial discriminator between different eclipse mechanisms.”
Devojyoti Kansabanik said, “We could determine the mechanism of the eclipses for a spider MSP unambiguously for the first time. There are several possible mechanisms like refraction, scattering and different types of absorptions of radio emission from the pulsar by the materials ejected from the companion star. Our study could distinctively spot that the eclipse is caused due to absorption by the magnetised materials ejected from the companion star and ruled out other possible mechanisms.”
{{/usCountry}}Devojyoti Kansabanik said, “We could determine the mechanism of the eclipses for a spider MSP unambiguously for the first time. There are several possible mechanisms like refraction, scattering and different types of absorptions of radio emission from the pulsar by the materials ejected from the companion star. Our study could distinctively spot that the eclipse is caused due to absorption by the magnetised materials ejected from the companion star and ruled out other possible mechanisms.”
{{/usCountry}}“Interestingly, the eclipse properties depend on the frequency of the radio pulse, with low radio frequencies being eclipsed, while high radio frequencies are not. The exact mechanism by which this occurs has not been established earlier. Understanding the eclipse mechanism and physical properties of these spider MSPs will provide more insight about the evolutionary processes and the ultimate fate of these exotic systems,” he added.