Physicshttps://repository.iitgn.ac.in/handle/123456789/6072019-11-18T15:15:39Z2019-11-18T15:15:39ZSearch for intermediate mass black hole binaries in the first and second observing runs of the advanced LIGO and virgo networkSengupta, Anand S.https://repository.iitgn.ac.in/handle/123456789/49272019-11-01T12:49:19Z2019-07-01T00:00:00ZSearch for intermediate mass black hole binaries in the first and second observing runs of the advanced LIGO and virgo network
Sengupta, Anand S.
Gravitational wave astronomy has been firmly established with the detection of gravitational waves from the merger of ten stellar mass binary black holes and a neutron star binary. This paper reports on the all-sky search for gravitational waves from intermediate mass black hole binaries in the first and second observing runs of the Advanced LIGO and Virgo network. The search uses three independent algorithms: two based on matched filtering of the data with waveform templates of gravitational wave signals from compact binaries, and a third, model-independent algorithm that employs no signal model for the incoming signal. No intermediate mass black hole binary event was detected in this search. Consequently, we place upper limits on the merger rate density for a family of intermediate mass black hole binaries. In particular, we choose sources with total masses M=m1+m2?[120,800]M? and mass ratios q=m2/m1?[0.1,1.0]. For the first time, this calculation is done using numerical relativity waveforms (which include higher modes) as models of the real emitted signal. We place a most stringent upper limit of 0.20~Gpc?3yr?1 (in co-moving units at the 90% confidence level) for equal-mass binaries with individual masses m1,2=100M? and dimensionless spins ?1,2=0.8 aligned with the orbital angular momentum of the binary. This improves by a factor of ?5 that reported after Advanced LIGO's first observing run.
2019-07-01T00:00:00ZSearch for intermediate mass black hole binaries in the first and second observing runs of the advanced LIGO and virgo networkSengupta, Anand S.https://repository.iitgn.ac.in/handle/123456789/49262019-11-01T12:49:19Z2019-09-01T00:00:00ZSearch for intermediate mass black hole binaries in the first and second observing runs of the advanced LIGO and virgo network
Sengupta, Anand S.
2019-09-01T00:00:00ZHeavy quark dynamics in a hot magnetized QCD mediumKurian, ManuDas, Santosh K.Chandra, Vinodhttps://repository.iitgn.ac.in/handle/123456789/49052019-11-01T12:49:18Z2019-10-01T00:00:00ZHeavy quark dynamics in a hot magnetized QCD medium
Kurian, Manu; Das, Santosh K.; Chandra, Vinod
The heavy quark drag and momentum diffusion have been investigated in a hot magnetized quark-gluon plasma, along the directions parallel and perpendicular to the magnetic field. The analysis is done within the framework of Fokker-Planck dynamics by considering the heavy quark scattering with thermal quarks and gluons at the leading order in the coupling constant. An extended quasiparticle model is adopted to encode the thermal QCD medium interactions in the presence of a magnetic field. Further, the higher Landau level effects on the temperature behavior of the parallel and perpendicular components of the drag force and diffusion coefficients have studied. It has been observed that both the equation of state and the magnetic field play key roles in the temperature dependence of the heavy quark dynamics.
2019-10-01T00:00:00ZA comparative analysis of non-relativistic and relativistic calculations of electric: dipole moments and polarizabilities of heteronuclear Alkali dimersMitra, R.Prasannaa, V. S.Sahoo , B. K.,https://repository.iitgn.ac.in/handle/123456789/49132019-11-01T12:49:18Z2019-10-01T00:00:00ZA comparative analysis of non-relativistic and relativistic calculations of electric: dipole moments and polarizabilities of heteronuclear Alkali dimers
Mitra, R.; Prasannaa, V. S.; Sahoo , B. K.,
We analyze the molecular electric dipole moments (PDMs) and static electric dipole polarizabilities of heteronuclear alkali dimers in their ground states by employing coupled-cluster theory, both in the non-relativistic and four-component relativistic frameworks. The roles of electron correlations as well as relativistic effects are demonstrated by studying them at different levels of theory, followed by a comprehensive treatment of error estimates. We compare our obtained values with the previous non-relativistic calculations, some of which include lower-order relativistic corrections, as well as with the experimental values, wherever available. We find that the PDMs are very sensitive to relativistic effects, as compared to polarizabilities; this aspect can explain the long-standing question on the difference between experimental values and theoretical results for LiNa. We show that consideration of relativistic values of PDMs improves significantly the isotropic Van der Waals C6 coefficients of the investigated alkali dimers over the previously reported non-relativistic calculations. The dependence of dipole polarizabilities on molecular volume is also illustrate
2019-10-01T00:00:00Z