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http://prints:80
2021-01-25T00:36:45Z
2021-01-25T00:36:45Z
Fock-space multireference coupled cluster calculations of Auger energies of noble gas elements using relativistic spinors
Chaudhuri, R. K
Chattopadhyay, S
http://prints.iiap.res.in/handle/2248/7510
2020-12-07T10:26:28Z
2019-08-01T00:00:00Z
Fock-space multireference coupled cluster calculations of Auger energies of noble gas elements using relativistic spinors
Chaudhuri, R. K; Chattopadhyay, S
We report the Auger and Coster-Kronig transition energies (related to double ionization potentials) of noble gas elements obtained using
the Fock-space multireference coupled cluster (FSMRCC) method with relativistic spinors. The resulting Auger and Coster-Kronig lines are
found to be in agreement with the experimental data and with other reference theoretical estimates. To the best of our knowledge, no prior
report of relativistic calculations is available for Auger transition energies at the FSMRCC level of theory. The ionization potentials resulted
from this method with no extra cost are also found to be in agreement with experiment, particularly the outer-valence ones. Interestingly, the
FSMRCC and the multiconfiguration Dirac-Fock calculations exhibit an inversion in the 3P energy levels of the xenon atom for N4,5–O23O23
Auger transitions, where the 3Pj state energies appear in the order J = 1, 0, 2, a feature which can be verified experimentally
Restricted Access © American Institute of Physics https://doi.org/10.1063/1.5094829
2019-08-01T00:00:00Z
Equation of motion approach for describing allowed transitions in Ne and Al3+ under classical and quantum plasmas
Chaudhuri, S. K
Mukherjee, P. K
Chaudhuri, R. K
Chattopadhyay, S
http://prints.iiap.res.in/handle/2248/7509
2020-12-07T10:26:29Z
2018-04-01T00:00:00Z
Equation of motion approach for describing allowed transitions in Ne and Al3+ under classical and quantum plasmas
Chaudhuri, S. K; Mukherjee, P. K; Chaudhuri, R. K; Chattopadhyay, S
The equation of motion coupled cluster methodology within relativistic framework has been applied
to analyze the electron correlation effects on the low lying dipole allowed excited states of Ne and
Al3þ under classical and quantum plasma environments. The effect of confinement due to classical
plasma has been incorporated through screened Coulomb potential, while that of quantum plasma has
been treated by exponential cosine screened Coulomb potential. The confined structural properties
investigated are the depression of ionization potential, low lying excitation energies (dipole allowed),
oscillator strengths, transition probabilities, and frequency dependent polarizabilities under systematic
variation of the plasma-atom coupling strength determined through the screening parameter. Specific
atomic systems are chosen for their astrophysical importance and availability of experimental data
related to laboratory plasma with special reference to Al3þ ion. Here, we consider 1s22s22p6ð1S0Þ !
1s22s22p5 ns=nd ð1P1Þ ðn ¼ 3; 4Þ dipole allowed transitions of Ne and Al3þ. Results for the free (isolated) atomic systems agree well with those available in the literature. Spectroscopic properties under
confinement show systematic and interesting pattern with respect to plasma screening parameter.
Restricted Access © American Institute of Physics https://doi.org/10.1063/1.5011791
2018-04-01T00:00:00Z
Consequences of high effective prandtl number on solar differential rotation and convective velocity
Karak, B. B
Miesch, Mark
Bekki, Y
http://prints.iiap.res.in/handle/2248/7508
2020-12-07T10:26:29Z
2018-04-01T00:00:00Z
Consequences of high effective prandtl number on solar differential rotation and convective velocity
Karak, B. B; Miesch, Mark; Bekki, Y
Observations suggest that the large-scale convective velocities obtained by solar convection simulations might be over-estimated (convective conundrum). One plausible solution to this could be the
small-scale dynamo which cannot be fully resolved by global simulations. The small-scale Lorentz
force suppresses the convective motions and also the turbulent mixing of entropy between upflows and
downflows, leading to a large effective Prandtl number (Pr). We explore this idea in three-dimensional
global rotating convection simulations at different thermal conductivity (κ), i.e., at different Pr. In
agreement with previous non-rotating simulations, the convective velocity is reduced with the increase
of Pr as long as the thermal conductive flux is negligible. A subadiabatic layer is formed near the
base of the convection zone due to continuous deposition of low entropy plumes in low-κ simulations.
The most interesting result of our low-κ simulations is that the convective motions are accompanied by a change in the convection structure that is increasingly influenced by small-scale plumes.
These plumes tend to transport angular momentum radially inward and thus establish an anti-solar
differential rotation, in striking contrast to the solar rotation profile. If such low diffusive plumes,
driven by the radiative-surface cooling, are present in the Sun, then our results cast doubt on the
idea that a high effective Pr may be a viable solution to the solar convective conundrum. Our study
also emphasizes that any resolution of the conundrum that relies on the downward plumes must
take into account the angular momentum transport and heat transport. Published by AIP Publishing.
Restricted Access © American Institute of Physics https://doi.org/10.1063/1.5022034
2018-04-01T00:00:00Z
Evolution of the M•-σ relation
Bhattacharyya, D
Mangalam, A
http://prints.iiap.res.in/handle/2248/7507
2020-12-07T10:26:28Z
2018-05-01T00:00:00Z
Evolution of the M•-σ relation
Bhattacharyya, D; Mangalam, A
Black holes at the centers of the galaxies grow mainly by the processes of accretion, mergers, and consumption of stars. In the case of gas accretion with cooling sources, the flow is momentum driven, after which the black hole reaches a saturated mass, and subsequently, it grows only by consumption of stars. In addition, we include the effect of mergers on the growth of black hole spin and mass and study its evolution as a function of redshift in a ΛCDM cosmology using an initial seed mass and spin distribution functions that we have derived. For the stellar ingestion, we have assumed a power-law density profile for the galaxy in our framework of a new relativistic loss cone theory that includes the effect of the black hole spin. We predict the impact of the evolution on the M•−σ relation and compare it with available observations.
Restricted Access © International Astronomical Union https://doi.org/10.1017/S1743921318007251
2018-05-01T00:00:00Z