Ramakrishna Mission Residential College, Narendrapur

About: Ramakrishna Mission Residential College, Narendrapur is a based out in . It is known for research contribution in the topics: Ion & Electron. The organization has 61 authors who have published 92 publications receiving 456 citations.

A Search for Interstellar Monohydric Thiols

Abstract: It has been pointed out by various astronomers that very interesting relationship exists between interstellar alcohols and the corresponding thiols (sulfur analogue of alcohols) as far as the spectroscopic properties and chemical abundances are concerned. Monohydric alcohols such as methanol and ethanol are widely observed and 1-propanol is recently claimed to have been seen in Orion KL. Among the monohydric thiols, methanethiol (chemical analogue of methanol), has been firmly detected in Orion KL and Sgr B2(N2) and ethanethiol (chemical analogue of ethanol) has been claimed to be observed in Sgr B2(N2) though the confirmation of this detection is yet to come. It is very likely that higher order thiols could be observed in these regions. In this paper, we study the formation of monohydric alcohols and their thiol analogues. Based on our quantum chemical calculation and chemical modeling, we find that ‘Tg’ conformer of 1-propanethiol is a good candidate of astronomical interest. We present various spectroscopically relevant parameters of this molecule to assist its future detection in the Interstellar medium (ISM). Subject headings: Astrochemistry, spectra, ISM: molecules, ISM: abundances, ISM: evolution, methods: numerical

Passive‐Oxidation Kinetics of SiC Microparticles

Abstract: We investigated the oxidation kinetics of SiC materials in the form of powders (average dimension 4 μm) in the temperature range 1100°-1500°C in dry air The oxidation process was monitored through the relative mass gain in a thermobalance As the specific surface area of the particles was measured, the recorded mass gain could be converted into the corresponding oxide thickness The oxidation isotherms were fitted to a linear-parabolic equation, and the parabolic rate constant was evaluated Up to 1400°C, temperature dependence can be described by a single activation energy of 179 kJ/mol, which increases in the 1400°-1500°C temperature range These results are compared with the oxidation behavior of sintered polycrystalline and monocrystalline SiC materials

Neutrino floor in leptophilic U ( 1 ) models: Modification in U ( 1 ) L μ − L τ

Abstract: In this work, we investigate the beyond standard model (BSM) impact of leptophilic U(1) models, namely $U(1{)}_{{L}_{\ensuremath{\mu}}\ensuremath{-}{L}_{e}}$, $U(1{)}_{{L}_{e}\ensuremath{-}{L}_{\ensuremath{\tau}}}$ and $U(1{)}_{{L}_{\ensuremath{\mu}}\ensuremath{-}{L}_{\ensuremath{\tau}}}$ on coherent elastic neutrino-nucleus scattering ($\mathrm{CE}\ensuremath{ u}\mathrm{NS}$) and hence its effect on dark matter (DM) direct detection experiments. Imposing the latest relevant experimental constraints on these models, we obtain $\mathcal{O}(50%)$ enhancement for case of $U(1{)}_{{L}_{\ensuremath{\mu}}\ensuremath{-}{L}_{\ensuremath{\tau}}}$ in a region ${m}_{Z}^{\ensuremath{'}}\ensuremath{\approx}20\text{ }\text{ }\mathrm{MeV}$. Subsequently, we observe that the enhancement seen in $\mathrm{CE}\ensuremath{ u}\mathrm{NS}$ is roughly getting translated to enhancement by a factor of 2.7 (for germanium based detectors) and 1.8 (for xenon based detectors) in the neutrino scattering event rate which eventually enhances the neutrino floor by the same amount. This enhancement is more prominent in the region with DM masses less than 10 GeV. The model parameter space that leads to this enhancement, can simultaneously explain both anomalous magnetic moment of muon ($(g\ensuremath{-}2{)}_{\ensuremath{\mu}}$) and observed DM relic density, in a modified scenario. Enhancement of neutrino floor requires increased number of DM-nucleon scattering events in the future DM direct detection experiments, to establish themselves to be DM signal events. In absence of any DM signal, those experiments can directly be used to measure the neutrino rate, quantifying the BSM effects.

Studies of dissipative standing shock waves around black holes

Abstract: We investigate the dynamical structure of advective accretion flow around stationary as well as rotating black holes. For a suitable choice of input parameters, such as, accretion rate ( u M) and angular momentum (λ), global accretion solution may include a shock wave. The post shock flow is located at few tens of Schwarzchild radius and it is generally very hot and dense. This successfully mimics the so called Compton cloud which is believed to be responsible for emitting hard radiations. Due to the radiative loss, a significant energy from the accreting matter is removed and the shock moves forward towards the black hole in order to maintain the pressure balance across it. We identify the effective area of the parameter space ( u M λ) which allows accretion flows to have some energy dissipation at the shock (�E). As the dissipation is increased, the parameter space is reduced and finally disappears when the dissipation is reached its critical value. The dissipation has a profound effect on the dynamics of post-shock flow. By moving forward, an unstable shock whose oscillation causes Quasi-Periodic Oscillations (QPOs) in the emitted radiation, will produce oscillations of high frequency. Such an evolution of QPOs has been observed in several black hole candidates during their outbursts.