Physics
https://repository.iitgn.ac.in/handle/123456789/607
Sun, 09 Aug 2020 09:18:34 GMT2020-08-09T09:18:34ZGW190814: gravitational waves from the coalescence of a 23 solar mass black hole with a 2.6 solar mass compact object
https://repository.iitgn.ac.in/handle/123456789/5611
GW190814: gravitational waves from the coalescence of a 23 solar mass black hole with a 2.6 solar mass compact object
Sengupta, Anand S. et al.
We report the observation of a compact binary coalescence involving a 22.2�24.3 M ? black hole and a compact object with a mass of 2.50�2.67 M ? (all measurements quoted at the 90% credible level). The gravitational-wave signal, GW190814, was observed during LIGO's and Virgo's third observing run on 2019 August 14 at 21:10:39 UTC and has a signal-to-noise ratio of 25 in the three-detector network. The source was localized to 18.5 deg2 at a distance of ${241}_{-45}^{+41}$ Mpc; no electromagnetic counterpart has been confirmed to date. The source has the most unequal mass ratio yet measured with gravitational waves, ${0.112}_{-0.009}^{+0.008}$, and its secondary component is either the lightest black hole or the heaviest neutron star ever discovered in a double compact-object system. The dimensionless spin of the primary black hole is tightly constrained to ?0.07. Tests of general relativity reveal no measurable deviations from the theory, and its prediction of higher-multipole emission is confirmed at high confidence. We estimate a merger rate density of 1�23 Gpc?3 yr?1 for the new class of binary coalescence sources that GW190814 represents. Astrophysical models predict that binaries with mass ratios similar to this event can form through several channels, but are unlikely to have formed in globular clusters. However, the combination of mass ratio, component masses, and the inferred merger rate for this event challenges all current models of the formation and mass distribution of compact-object binaries.
Mon, 01 Jun 2020 00:00:00 GMThttps://repository.iitgn.ac.in/handle/123456789/56112020-06-01T00:00:00ZThermoelectric transport coefficients of quark matter
https://repository.iitgn.ac.in/handle/123456789/5613
Thermoelectric transport coefficients of quark matter
Abhisek, Aman; Das, Arpan; Kumar, Deepak; Mishra, Hiranmaya
A thermal gradient and/or a chemical potential gradient in a conducting medium can lead to an electric field, an effect known as thermoelectric effect or Seebeck effect. In the context of heavy-ion collisions, we estimate the thermoelectric transport coefficients for quark matter within the ambit of the Nambu-Jona Lasinio (NJL) model. We estimate the thermal conductivity, electrical conductivity, and the Seebeck coefficient of hot and dense quark matter. These coefficients are calculated using the relativistic Boltzmann transport equation within relaxation time approximation. The relaxation times for the quarks are estimated from the quark-quark and quark-antiquark scattering through in-medium meson exchange within the NJL model.
Wed, 01 Jul 2020 00:00:00 GMThttps://repository.iitgn.ac.in/handle/123456789/56132020-07-01T00:00:00ZRecent progresses in the dynamics of QCD matter
https://repository.iitgn.ac.in/handle/123456789/5614
Recent progresses in the dynamics of QCD matter
Chandra, Vinod
Wed, 01 Jul 2020 00:00:00 GMThttps://repository.iitgn.ac.in/handle/123456789/56142020-07-01T00:00:00ZScattering cross-section under external magnetic field using the optical theorem
https://repository.iitgn.ac.in/handle/123456789/5596
Scattering cross-section under external magnetic field using the optical theorem
Ghosh, Snigdha; Chandra, Vinod
The cross-section for the lowest order 2\rightarrow 2 elastic scattering between two charged scalars under external magnetic field mediated via a neutral scalar, has been computed in strong as well as weak magnetic field limits. This has been done by applying the optical theorem where the cross-section is expressed in terms of the imaginary parts of different one-loop graphs contributing to the forward scattering amplitudes. The modification in the amplitudes due to the external magnetic field has been done by means of replacing the charged scalar propagators with the Schwinger proper-time ones. Significant modifications of the cross-sections with respect to the vacuum cross-section are observed due to the external magnetic field.
Wed, 01 Jul 2020 00:00:00 GMThttps://repository.iitgn.ac.in/handle/123456789/55962020-07-01T00:00:00Z