Sandip Kumar Chakrabarti

Sandip Kumar Chakrabarti
Indian Centre for Space Physics | CSP · Astronomy and Space Science

DSc (UGB), PhD (U Chicago)

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739
Publications
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9,423
Citations

Publications

Publications (739)
Preprint
Full-text available
We study the spectral properties and accretion flow behavior of an ultraluminous X-ray source M82\,X-1 using {\it NuSTAR} observations. We use the physical two component advective flow (TCAF) model to fit the data and to derive the accretion flow properties of the source. From the model fitted parameters, we found that M82\,X-1 is harboring an inte...
Article
Full-text available
We performed a diagnostic study of geomagnetic storm-induced disturbances that are coupled to the mid-latitude D region by quantifying the propagation characteristics of very low-frequency (VLF) radio signals from transmitters located in Cumbria, UK (call sign GQD), and Rhauderfehn, Germany (DHO), and received in southern France (A118). We characte...
Article
Full-text available
Electromagnetic emissions (EMEs) associated with earthquake (EQ) epicenters are found to be one of the most reliable phenomena for the short-term pre-seismic mechanism of earthquakes. The detection mechanism of such emissions can have both direct and indirect techniques. In this manuscript, we attempted to present the signature of such emissions be...
Preprint
Full-text available
The X-ray emission in BL Lac objects is believed to be dominated by synchrotron emission from their relativistic jets. However, when the jet emission is not strong, one could expect signatures of X-ray emission from inverse Compton scattering of accretion disc photons by the corona. Moreover, the observed X-ray variability can also originate in the...
Article
We perform a comparative spectro-temporal analysis on the variability classes of GRS 1915+105 and IGR J17091-3624 to draw inferences regarding the underlying accretion flow mechanism. The ν, as well as C2 class Rossi X-Ray Timing Explorer observation, have been considered for analysis. We investigate the intensity variation of the source in differe...
Preprint
Full-text available
Spectral and timing properties of accretion flows on a black hole depend on their density and temperature distributions, which in turn come from the underlying dynamics. Thus, an accurate description of the flow which includes hydrodynamics and radiative transfer is a must to interpret the observational results. In the case of non-rotating black ho...
Article
Full-text available
Atmospheric disturbances caused by seismic activity are a complex phenomenon. The Lithosphere–Atmosphere–Ionosphere Coupling (LAIC) (LAIC) mechanism gives a detailed idea to understand these processes to study the possible impacts of a forthcoming earthquake. The atmospheric gravity wave (AGW) is one of the most accurate parameters for explaining s...
Article
Full-text available
We focus on the possible thermal channel of the well-known Lithosphere–Atmosphere– Ionosphere Coupling (LAIC) mechanism to identify the behavior of thermal anomalies during and prior to strong seismic events. For this, we investigate the variation of Surface Latent Heat Flux (SLHF) as resulting from satellite observables. We demonstrate a spatio-te...
Article
It is speculated that there might be some linkage between interstellar aldehydes and their corresponding alcohols. Here an observational study and astrochemical modeling are coupled together to illustrate the connection between them. The ALMA cycle 4 data of a hot molecular core, G10.47+0.03, are utilized for this study. Various aldehydes (acetalde...
Article
Full-text available
Citation: Sasmal, S.; Chowdhury, S.; Kundu, S.; Politis, D.Z.; Potirakis, S.M.; Balasis, G.; Hayakawa, M.; Chakrabarti, S.K. Pre-Seismic Irregularities during the 2020 Samos (Greece) Earthquake (M = 6.9) as Investigated from Multi-Parameter Approach by Ground and Space-Based Techniques. Atmosphere 2021, 12, 1059. https://doi.
Preprint
It is speculated that there might be some linkage between interstellar aldehydes and their corresponding alcohols. Here, an observational study and astrochemical modeling are coupled together to illustrate the connection between them. The ALMA Cycle 4 data of a hot molecular core, G10.47+0.03 is utilized for this study. Various aldehydes (acetaldeh...
Preprint
Full-text available
We performed a diagnostic study of geomagnetic storm-induced disturbances that are coupled to the lower ionosphere in mid-latitude D-region using propagation characteristics of VLF radio signals. We characterised the diurnal VLF amplitude (from two propagation paths) into five metrics, namely the mean amplitude before sunrise (MBSR), midday amplitu...
Article
Full-text available
Lightning is a sudden release of electrostatic energy that plays a significant role in the ionospheric-magnetospheric coupling process. A short-term increase in the particle count rates (CR) in the Van Allen Radiation Belt (VAB) is known as the particle bursts. Due to lightning events, the increase in the number of high-energy particles in the inne...
Article
Full-text available
Galactic transient black hole candidate (BHC) MAXI J1535-571 was discovered on 2017 September 02 simultaneously by MAXI/GSC and Swift/BAT instruments. It has also been observed by India’s first multi-wavelength astronomy-mission satellite AstroSat, during the rising phase of its 2017-18 outburst. We make both the spectral and the temporal analysis...
Preprint
Full-text available
An inverse P-Cygni profile of H13CO+ (1-0) in G31.41+0.31 was recently observed, which indicates the presence of an infalling gas envelope. Also, an outflow tracer, SiO, was observed. Here, exclusive radiative transfer modelings have been implemented to generate synthetic spectra of some key species (H13 CO+, HCN, SiO, NH3, CH3 CN, CH3OH, CH3SH, an...
Article
Full-text available
In 2016 − 17, the Galactic transient black hole candidate GRS 1716-249 exhibited an outburst event after a long qui-escence period of almost 23 years. The source remained in the outbursting phase for almost 9 months. We study the spectral and temporal properties of the source during this outburst using archival data from four astronomy satellites,...
Article
An inverse P-Cygni profile of H¹³CO⁺ (1 → 0) in G31.41+0.31 was recently observed, which indicates the presence of an infalling gas envelope. Also, an outflow tracer, SiO, was observed. Here, exclusive radiative transfer modelings have been implemented to generate synthetic spectra of some key species (H¹³CO⁺, HCN, SiO, NH3, CH3CN, CH3OH, CH3SH, an...
Article
Full-text available
We present the long-term X-ray spectral and temporal analysis of a ‘bare-type AGN’ Ark 120. We consider the observations from XMM-Newton, Suzaku, Swift, and NuSTAR from 2003 to 2018. The spectral properties of this source are studied using various phenomenological and physical models present in the literature. We report (a) the variations of severa...
Preprint
Full-text available
Phosphorus related species are not known to be as omnipresent in space as hydrogen, carbon, nitrogen, oxygen, and sulfur-bearing species. Astronomers spotted very few P-bearing molecules in the interstellar medium and circumstellar envelopes. Limited discovery of the P-bearing species imposes severe constraints in modeling the P-chemistry. In this...
Preprint
Full-text available
The abundance of interstellar ice constituents is usually expressed with respect to the water ice because, in denser regions, a significant portion of the interstellar grain surface would be covered by water ice. The binding energy (BE), or adsorption energy of the interstellar species regulates the chemical complexity of the interstellar grain man...
Article
Full-text available
The 2015 Outburst of V404 Cygni is an unusual one with several X-ray and radio flares and rapid variation in the spectral and timing properties. The outburst occurred after 26 years of inactivity of the black hole. We study the accretion flow properties of the source during its initial phase of the outburst using Swift/XRT and Swift/BAT data in the...
Article
Full-text available
In this work, we simulated the atmospheric drag effect on two model SmallSats (small satellites) in low Earth orbit (LEO) with different ballistic coefficients during 1-month intervals of solar–geomagnetic quiet and perturbed conditions. The goal of this effort was to quantify how solar–geomagnetic activity influences atmospheric drag and perturbs...
Article
We performed a detailed modelling of the background counts observed in a phoswich scintillator X-ray detector at balloon altitude, used for astronomical observations, on board small scientific balloon. We used Monte Carlo simulation technique in Geant4 simulation environment, to estimate the detector background from various plausible sources. High...
Article
Full-text available
The abundance of interstellar ice constituents is usually expressed with respect to the water ice because, in denser regions, a significant portion of the interstellar grain surface would be covered by water ice. The binding energy (BE) or adsorption energy of the interstellar species regulates the chemical complexity of the interstellar grain mant...
Article
We present the results obtained from a detailed timing and spectral studies of a black hole candidate MAXI J1813-095 using Swift, NICER, and NuSTAR observations during its 2018 outburst. The timing behaviour of the source is mainly studied by using NICER light curves in a 0.5 − 10 keV range. We did not find any signature of quasi-periodic oscillati...
Preprint
Full-text available
We present the results obtained from detailed timing and spectral studies of a black hole candidate MAXI~J1813-095 using {\it Swift}, {\it NICER}, and {\it NuSTAR} observations during its 2018 outburst. The timing behaviour of the source is mainly studied by using {\it NICER} light curves in a $0.5-10$ keV range. We did not find any signature of qu...
Article
Full-text available
Galactic short orbital period black hole candidate (BHC) XTE J1752-223 was discovered on 2009 Oct 21 by the Rossi X-ray Timing Explorer (RXTE). We study the spectral properties of this outburst using transonic flow solution based two component advective flow (TCAF) model. TCAF model fitted spectrum gives an estimation of the physical flow parameter...
Preprint
Full-text available
Galactic short orbital period black hole candidate (BHC) XTE~J1752-223 was discovered on 2009 Oct 21 by the Rossi X-ray Timing Explorer (RXTE). We study the spectral properties of this outburst using transonic flow solution based two component advective flow (TCAF) model. TCAF model fitted spectrum gives an estimation of the physical flow parameter...
Article
Full-text available
We study the properties of the faint X-ray activity of Galactic transient black hole candidate XTE J1908+094 during its 2019 outburst. Here, we report the results of detailed spectral and temporal analysis during this outburst using observations from Nuclear Spectroscopic Telescope Array (NuSTAR). We have not observed any quasi-periodic-oscillation...
Preprint
Full-text available
We study the properties of the faint X-ray activity of Galactic transient black hole candidate XTE~J1908+094 during its 2019 outburst. Here, we report the results of detailed spectral and temporal analysis during this outburst using observations from {\it Nuclear Spectroscopic Telescope Array (NuSTAR)}. We have not observed any quasi-periodic-oscil...
Preprint
Full-text available
In $2016-17$, the Galactic transient black hole candidate GRS 1716-249 exhibited an outburst event after a long period of quiescence of almost 23 years. The source remained in the outbursting phase for $\sim 9$ months. We study the spectral and temporal properties of the source during this outburst using archival data from four astronomy satellites...
Preprint
We perform a comparative spectro-temporal analysis on the variability classes of GRS 1915+105 and IGR J17091-3624 to draw inferences regarding the underlying accretion flow mechanism. The $\nu$, as well as C2 class Rossi X-Ray Timing Explorer observation, have been considered for analysis. We investigate the intensity variation of the source in dif...
Preprint
Full-text available
We present the long-term X-ray spectral and temporal analysis of a 'bare-type AGN' Ark 120. We consider the observations from XMM-Newton, Suzaku, Swift, and NuSTAR from 2003 to 2018. The spectral properties of this source are studied using various phenomenological and physical models present in the literature. We report (a) the variations of severa...
Preprint
The fundamental difference between accretion around black holes and neutron stars is the inner boundary condition, which affects the behavior of matter very close to the compact objects. This leads to formation of additional shocks and boundary layers for neutron stars. Previous studies on the formation of such boundary layers focused on Keplerian...
Conference Paper
Full-text available
Very Low Frequency (VLF) remote sensing technique is used to probe the D-layer modeling for which we use a very conventional model known as Wait s 2-component iono-spheric model. This model is characterized by two iono-spheric parameters which are 'steepness parameter' (β) and 'effective reflection height' (h). International Reference Ionosphere (I...
Article
Full-text available
Sub-Ionospheric Very Low Frequency (VLF) radio wave propagation characteristics are the major tool to study the lower ionospheric heights mainly D-region. Wait’s 2-component exponential model is a well-known mechanism to understand the basic characteristics of this layer based on VLF remote sensing. This model deals with two major ionospheric param...
Preprint
Recent studies show that accretion flows around weakly magnetic Neutron Stars undergo multiple shocks, before reaching the surface of the star, which contribute to the spectral and timing variabilities observed in the X-Rays. Here, we report, for the first time, the spectral properties of a unified model of shocked accretion flows around Neutron St...
Preprint
Full-text available
We performed a detailed modelling of the background counts observed in a phoswich scintillator X-ray detector at balloon altitude, used for astronomical observations, on board small scientific balloon. We used Monte Carlo simulation technique in Geant4 simulation environment, to estimate the detector background from various plausible sources. High...
Article
The class variable source GRS 1915+105 exhibits a wide range of time variabilities on timescales of a few seconds to a few days. Depending on the count rates in different energy bands and the nature of the conventional color-color diagram, the variabilities were classified into sixteen classes that were later sequenced in ascending order of Compton...
Article
Full-text available
Study of seismo-ionospheric coupling mechanism demands the quiet geomagnetic condition to eliminate any kind of contamination in the lower atmospheric and ionospheric parameters. In this manuscript, we present the effect of back to back two geomagnetic storms before a strong earthquake happened in Imphal, India on January 4, 2016 (M = 6.7). We stud...
Preprint
G31.41+0.31 is a well known chemically rich hot molecular core (HMC). Using Band 3 observations of Atacama Large Millimeter Array (ALMA), we have analyzed the chemical and physical properties of the source. We have identified methyl isocyanate (CH3NCO), a precursor of prebiotic molecules, towards the source. In addition to this, we have reported co...
Article
Full-text available
We study spectral and temporal properties of Galactic short orbital period transient black hole XTE J1118+480 during its 2005 outburst using archival data of RXTE PCA and HEXTE instruments in the combined energy range of 3 – 100 keV. Spectral analysis with the physical two component advective flow (TCAF) model allows us to understand the accretion...
Preprint
Full-text available
The first identification of the argonium ion (ArH+) towards the Crab Nebula supernova remnant was proclaimed by the Herschel in the sub-millimeter and far-infrared domain. Very recently the discovery of the hydro-helium cation (HeH+) in the planetary nebula (NGC 7027) has been reported by using the SOFIA. The elemental abundance of neon is much hig...
Article
Full-text available
Evolution of variability properties of Galactic transient sources is a diagnostic tool to under stand various regimes of the accretion flow and its dynamics close to the central black hole. In this paper, we concentrate on the variability properties of the X-ray transient XTE J1650-500 and investigate the evolution of viscous delay, time lag, QPO f...
Preprint
Full-text available
The Galactic microquasar GRS 1915+105 shows rich variability which is categorized into different classes. In this paper, we report temporal and spectral analysis of GRS 1915+105 to study the properties of the accretion flow when the light curve is showing $\theta$ class variability. For this purpose, we use the LAXPC data from the Target of Opportu...
Preprint
Full-text available
In this work we simulated the effects of atmospheric drag on two model SmallSats in Low Earth Orbit (LEO) with different ballistic coefficients during 1-month intervals of solar-geomagnetic quiet and perturbed conditions. The goal of this effort was to quantify how solar-geomagnetic activity influences atmospheric drag and perturbs satellite orbits...
Preprint
Full-text available
Evolution of variability properties of Galactic transient sources is a diagnostic tool to understand various regimes of the accretion flow and its dynamics close to the central black hole. In this paper, we concentrate on the variability properties of the X-ray transient XTE J1650-500 and investigate the evolution of viscous delay, time lag, QPO fr...
Article
Galactic black hole candidate MAXI J1348-630 was recently discovered by MAXI and Swift/BAT satellites during its first outburst in 2019 January which continued for ∼ 4 months. We study the spectral and timing properties of the source in detail. The combined 1−150 keV Swift/XRT, Swift/BAT and MAXI/GSC spectra are investigated with the two component...
Preprint
Full-text available
Galactic transient black hole candidate (BHC) MAXI~J1535-571 was discovered on 2017 September 02 simultaneously by {\it MAXI}/GSC and {\it Swift}/BAT instruments. It has also been observed by India's first multi-wavelength astronomy-mission satellite {\it AstroSat}, during the rising phase of its 2017-18 outburst. We make both the spectral and the...
Preprint
The 2015 Outburst of V404 Cygni is an unusual one with several X-ray and radio flares and rapid variation in the spectral and timing properties. The outburst occurred after $26$ years of inactivity of the black hole. We study the accretion flow properties of the source during its initial phase of the outburst using {\it Swift}/XRT and {\it Swift}/B...
Preprint
Full-text available
Spectroscopic studies play a key role in the identification and analysis of interstellar ices and their structure. Some molecules have been identified within the interstellar ices either as pure, mixed, or even as layered structures. Absorption band features of water ice can significantly change with the presence of different types of impurities (C...
Article
Spectroscopic studies play a key role in the identification and analysis of interstellar ices and their structure. Some molecules have been identified within the interstellar ices either as pure, mixed, or even as layered structures. Absorption band features of water ice can significantly change with the presence of different types of impurities (C...
Preprint
Full-text available
Galactic black hole candidate MAXI~J1348-630 was recently discovered by MAXI and Swift/BAT satellites during its first outburst in 2019 January which continued for ~4 months. We study the spectral and timing properties of the source in detail. The combined 1-150 keV Swift/XRT, Swift/BAT and MAXI/GSC spectra are investigated with the two component a...
Preprint
Full-text available
We study spectral and temporal properties of Galactic short orbital period transient black hole XTE J1118+480 during its 2005 outburst using archival data of RXTE PCA and HEXTE instruments in the combined energy range of $3-100$ keV. Spectral analysis with the physical two-component advective flow (TCAF) model allows us to understand the accretion...
Article
Full-text available
Spectral and timing properties of the stellar-mass black hole candidate XTE J1752-223 during its 2009-10 outburst are studied using RXTE PCA data in the 2.5–25 keV energy range. Low frequency quasi-periodic oscillations are seen during outburst. The spectral analysis is done using two types of models: one is the combined disc blackbody plus power-l...