A5039871097- Astrophysical Phenomena and Observations
- Pulsars and Gravitational Waves Research
- Particle Detector Development and Performance
- Gamma-ray bursts and supernovae
- Astrophysics and Cosmic Phenomena
- Astronomical Observations and Instrumentation
- Nuclear Physics and Applications
- High-pressure geophysics and materials
- Mechanics and Biomechanics Studies
- Radiation Detection and Scintillator Technologies
- Advanced X-ray and CT Imaging
- Calibration and Measurement Techniques
- Statistical and numerical algorithms
- Planetary Science and Exploration
- Radiation Therapy and Dosimetry
- Infrared Target Detection Methodologies
- Scientific Measurement and Uncertainty Evaluation
- Scientific Computing and Data Management
- Cryospheric studies and observations
- Geophysics and Sensor Technology
- Advanced X-ray Imaging Techniques
- Particle Accelerators and Free-Electron Lasers
- Distributed and Parallel Computing Systems
- Adaptive optics and wavefront sensing
- Superconducting Materials and Applications
KTH Royal Institute of Technology
2018-2024
AlbaNova
2018-2024
Osaka University
2022-2023
Ehime University
2022-2023
Washington University in St. Louis
2023
Institute of Space and Astronautical Science
2020
Stony Brook University
2020
Goddard Space Flight Center
2020
Fraunhofer Chalmers Research Centre for Industrial Mathematics
2019
Inter-University Centre for Astronomy and Astrophysics
2019
The 2011 outburst of the black hole candidate IGR J17091-3624 followed canonical track state transitions along with evolution Quasi-Periodic Oscillation (QPO) frequencies before it began exhibiting various variability classes similar to GRS 1915+105. We use this spectral and temporal properties determine mass J17091-3624, using three different methods, viz : Photon Index ($\Gamma$) - QPO frequency ($\nu$) correlation, Time (day) broadband modelling based on Two Component Advective Flow....
We present the results of Target Opportunity (ToO) observations made with AstroSat newly discovered black hole binary MAXI J1535-571. detect prominent C-type Quasi-periodic Oscillations (QPOs) frequencies varying from 1.85 Hz to 2.88 Hz, along distinct harmonics in all observations. note that while fundamental QPO is seen 3 - 50 keV energy band, harmonic not significant above ~ 35 keV. The were hard intermediate state, as state transitions observed by and Swift. attempt spectral modelling...
Abstract The accretion-powered X-ray pulsar GX 301−2 was observed with the balloon-borne X-Calibur hard polarimeter during late 2018 December, contiguous observations by Neutron star Interior Composition Explorer Mission ( NICER ) telescope, Swift Telescope and Burst Alert Telescope, Fermi Gamma-ray Monitor spanning several months. detected in a rare apastron flaring state coinciding significant spin up of discovered Monitor. , reveal pulse profile strongly dominated one main peak, data show...
We study the variations in Cyclotron Resonant Scattering Feature (CRSF) during 2011 outburst of high mass X-ray binary 4U 0115+63 using observations performed with Suzaku, RXTE, Swift and INTEGRAL satellites. The wide-band spectral data low energy coverage allowed us to characterize broadband continuum detect CRSFs. find that is adequately described by a combination temperature (kT ~ 0.8 keV) blackbody power-law cutoff (Ecut 5.4 without need for broad Gaussian at 10 keV as used some earlier...
The Be X-ray Binary 4U 0115+63 was observed by Large Area Proportional Counter (LAXPC) instrument on AstroSat 2015 October 24 during the peak of a giant Type II outburst. Prominent intensity oscillations at ~ 1 and 2 mHz frequency were detected Nuclear Spectroscopic Telescope Array (NuSTAR) observations made same outburst also show quasi periodic (QPOs). Details their characteristics deduced from LAXPC/AstroSat NuSTAR are reported in this paper. Analysis archival Rossi Timing Explorer...
The XL-Calibur balloon-borne hard X-ray polarimetry mission comprises a Compton-scattering polarimeter placed at the focal point of an mirror. is housed within BGO anticoincidence shield, which needed to mitigate considerable background radiation present observation altitude ~40 km. This paper details design, construction and testing as well performance measured during week-long maiden flight from Esrange Space Centre Canadian Northwest Territories in July 2022. in-flight shield followed...
XL-Calibur is a balloon-borne Compton polarimeter for X-rays in the $\sim$15-80 keV range. Using an X-ray mirror with 12 m focal length collecting photons onto beryllium scattering rod surrounded by CZT detectors, minimum-detectable polarization as low $\sim$3% expected during 24-hour on-target observation of 1 Crab source at 45$^{\circ}$ elevation. Systematic effects alter reconstructed spot moves across scatterer, due to pointing offsets, mechanical misalignment or deformation carbon-fiber...
We report the results from a detailed timing and spectral study of transient X-ray pulsars, 4U 1901+03 during its 2019 outburst. performed broadband spectroscopy in 1-70 keV energy band using four observations made with Swift NuSTAR at different intensity levels. Our reveal presence highly variable pulse profiles dependent on both luminosity energy. showed cyclotron resonance scattering feature (CRSF) ~30 keV. This 30 is pulse-phase dependent. Phase-averaged spectra last two observations,...
IGR J16318-4848 is an X-ray binary with the highest known line of sight absorption column density among all systems in our galaxy. In order to investigate reason behind such a large column, we looked at variations intensity and spectral parameters as function tentatively discovered $\sim$ 80 day orbit this source. The orbital period firmly confirmed long term ($\sim$ 12 year) Swift BAT lightcurve. Two peaks about half apart, one narrow small, other broad are seen profile. We find that while...
XL-Calibur is a balloon-borne hard X-ray polarimetry mission, the first flight of which currently foreseen for 2021. carries an telescope consists 213 Wolter I grazing-incidence mirrors are nested in coaxial and cofocal configuration. The optics design nearly identical to Hard Telescope (HXT) on board ASTRO-H satellite. was originally fabricated Formation Flying Astronomical Survey (FFAST) project. However, can be used XL-Calibur, since FFAST project terminated before completion. mirror...
XL-Calibur is a balloon-borne mission for hard x-ray polarimetry. The first launch currently scheduled from Sweden in summer 2022. Japanese collaborators provide telescope to the mission. telescope's design identical Hard X-ray Telescope (HXT, conically-approximated Wolter-I optics) on board ASTROH with same focal length of 12 m and aperture 45 cm, which can focus x-rays up 80 keV. divided into three segments circumferential direction, confocal 213 grazing-incidence mirrors are precisely...
This paper introduces a second-generation balloon-borne hard X-ray polarimetry mission, XL-Calibur. promises to give qualitatively new information about high-energy astrophysical sources, such as pulsars and binary black hole systems. The XL-Calibur contains grazing incidence telescope with focal plane detector unit that is sensitive linear polarization. very similar in design the ASTRO-H HXT telescopes has world's largest effective area above ~10 keV. combines low atomic number Compton...