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Author: search.filters.author.Das, ArpanSubject: search.filters.subject.Gravitational waves

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    Pulsars as Weber gravitational wave detectors
    (Elsevier, 2019-04) Das, Arpan
    A gravitational wave (GW) passing through a pulsar will lead to a variation in the moment of inertia of the pulsar affecting its rotation. This will affect the extremely accurately measured spin rate of the pulsar as well as its pulse profile (due to induced wobbling depending on the source direction). The effect will be most pronounced at resonance and should be detectable by accurate observations of the pulsar signal. The pulsar, in this sense, acts as a remotely stationed Weber detector of gravitational waves whose signal can be monitored on earth. With possible GW sources spread around in the universe, pulsars in their neighborhoods can provide us a family of remote detectors all of which can be monitored on earth. Even if GW are detected directly by earth based conventional detectors, such pulsar detectors can provide additional information for accurate determination of the source location. This can be of crucial importance for sources which do not emit any other form of radiation such as black hole mergers. For the GW events already detected by LIGO (and Virgo), we propose that one should look for specific pulsars which would have been disturbed by these events, and will transmit this disturbance via their pulse signals in any foreseeable future. One should be able to predict these future pulsar events with some accuracy so that a focused effort can be made to detect any possible changes in the signals of those specific pulsars.
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    Probing dynamics of phase transitions occurring inside a pulsar
    (Springer, 2015-12) Layek, Biswanath; Das, Arpan
    During the evolution of a pulsar, various phase transitions may occur in its dense interior, such as superfluid transition, as well as transition to various exotic phases of quantum chromodynamics (QCD). We propose a technique which allows to probe these phases and associated transitions by detecting changes in rotation of the star arising from density changes and fluctuations during the transition affecting stars moment of inertia (MI). Our results suggest that these changes may be observable, and may possibly account for glitches and anti-glitches. Accurate measurements of pulsar timing and intensity modulations (from wobbling) may be used to pin down the particular phase transition occurring inside the pulsar core. We also discuss the possibility of observing gravitational waves from the changes in the quadrupole moment (QM) arising from these rapidly evolving density fluctuations.