Jayashree Roy
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View article: Spectral Evolution of GX 17+2 Using AstroSat and NICER Observations
Spectral Evolution of GX 17+2 Using AstroSat and NICER Observations Open
We study the spectral evolution of the Z-track source GX 17+2 using AstroSat and NICER observations taken between 2016 and 2020. The AstroSat observations cover the period when the source is in the normal branch (NB) and the flaring branch…
View article: Dust Collisions in the Protoplanetary Disk: Atomic Simulations to Better Understand the Surface Free Energy
Dust Collisions in the Protoplanetary Disk: Atomic Simulations to Better Understand the Surface Free Energy Open
Introduction: The formation of planetesimals within a protoplanetary disk is strongly influenced by the collision and eventual aggregation of nano- and micro-scale dust particles (1). This granular collision process is most often modelled …
View article: A 350 MHz Green Bank Telescope Survey of Unassociated Fermi LAT Sources: Discovery and Timing of 10 Millisecond Pulsars
A 350 MHz Green Bank Telescope Survey of Unassociated Fermi LAT Sources: Discovery and Timing of 10 Millisecond Pulsars Open
We have searched for radio pulsations toward 49 Fermi Large Area Telescope (LAT) 1FGL Catalog γ -ray sources using the Green Bank Telescope at 350 MHz. We detected 18 millisecond pulsars (MSPs) in blind searches of the data; 10 of these we…
View article: AstroSat Observations of the Be/X-Ray Binary XTE J1946+274 During 2018 and 2021 Outbursts
AstroSat Observations of the Be/X-Ray Binary XTE J1946+274 During 2018 and 2021 Outbursts Open
We present the timing and spectral studies of the Be/X-ray binary XTE J1946+274 during its 2018 and 2021 giant outbursts using observations with the SXT and LAXPC instruments on the AstroSat satellite. Unlike the 1998 and 2010 outbursts, w…
View article: AstroSat observations of the Be/X-ray binary XTE J1946+274 during 2018 and 2021 outbursts
AstroSat observations of the Be/X-ray binary XTE J1946+274 during 2018 and 2021 outbursts Open
We present the timing and spectral studies of the Be/X-ray binary XTE J1946+274 during its 2018 and 2021 giant outbursts using observations with the SXT and the LAXPC instruments on the AstroSat satellite. Unlike the 1998 and 2010 outburst…
View article: AstroSat observation of rapid Type-I thermonuclear burst from the low mass X-ray binary GX 3+1
AstroSat observation of rapid Type-I thermonuclear burst from the low mass X-ray binary GX 3+1 Open
We report the results of an observation of low mass X-ray binary GX 3+1 with {\it AstroSat}'s Large Area X-ray Proportional Counter (LAXPC) and Soft X-ray Telescope (SXT) instruments on-board for the first time. We have detected one Type-1…
View article: Probing the shot behaviour in Cygnus X-1 using simultaneous <i>AstroSat</i>-<i>NICER</i> observation
Probing the shot behaviour in Cygnus X-1 using simultaneous <i>AstroSat</i>-<i>NICER</i> observation Open
We analyse the aperiodic flaring features, also known as shots, observed in Cyg X-1 in the 0.1–80 keV energy band using a 6.39 ks simultaneous observation with AstroSat and Neutron star Interior Composition ExploreR (NICER). We detect 49 s…
View article: Probing the shot behaviour in Cygnus X-1 using simultaneous AstroSat-NICER observation
Probing the shot behaviour in Cygnus X-1 using simultaneous AstroSat-NICER observation Open
We analyse the aperiodic flaring features, also known as shots, observed in Cyg X-1 in the 0.1-80 keV energy band using a 6.39 ks simultaneous observation with AstroSat and NICER. We detect 49 simultaneous shots in the soft and hard X-ray …
View article: AstroSat detection of a quasi-periodic oscillation at ∼42 Hz in Cygnus X-2
AstroSat detection of a quasi-periodic oscillation at ∼42 Hz in Cygnus X-2 Open
We report the results of AstroSat observations of Cygnus X-2 during 2016 February. The source’s power density spectrum generated using Large Area X-ray Proportional Counter (LAXPC) data revealed the presence of a prominent quasi-periodic o…
View article: Detection of nearly periodic spin period reversals in Vela X-1 on long time-scales: inkling of solar-like cycle in the donor star?
Detection of nearly periodic spin period reversals in Vela X-1 on long time-scales: inkling of solar-like cycle in the donor star? Open
We explore the long-term evolution of the spin period of the high-mass X-ray binary pulsar Vela X-1 over a period of 46 yr. Our analysis indicates nearly periodic variations in the spin period of the pulsar on time-scales of about 5.9 yr. …
View article: Multifrequency study of the peculiar pulsars PSR B0919+06 and PSR B1859+07
Multifrequency study of the peculiar pulsars PSR B0919+06 and PSR B1859+07 Open
Since their discovery more than 50 years ago, broad-band radio studies of pulsars have generated a wealth of information about the underlying physics of radio emission. In order to gain some further insights into this elusive emission mech…
View article: X-ray and Gamma-ray Variability of NGC 1275
X-ray and Gamma-ray Variability of NGC 1275 Open
Gamma-ray emission from the bright radio source 3C 84, associated with the Perseus cluster, is ascribed to the radio galaxy NGC 1275 residing at the centre of the cluster. Study of the correlated X-ray/gamma-ray emission from this active g…
View article: Possible detection of a new cyclotron feature in 4U 1700–37
Possible detection of a new cyclotron feature in 4U 1700–37 Open
We present a spectral and timing study of the high-mass X-ray binary transient source 4U 1700–37 using NuSTAR and ASTROSAT/LAXPC. The source is observed in two different flux states. A combined spectral analysis of NuSTAR’s focal plane mod…
View article: Study of recent outburst in the Be/X-ray binary RX J0209.6−7427 with AstroSat: a new ultraluminous X-ray pulsar in the Magellanic Bridge?
Study of recent outburst in the Be/X-ray binary RX J0209.6−7427 with AstroSat: a new ultraluminous X-ray pulsar in the Magellanic Bridge? Open
We present the timing and spectral studies of RX J0209.6–7427 during its rare 2019 outburst using observations with the Soft X-ray Telescope (SXT) and Large Area X-ray Proportional Counter (LAXPC) instruments on the AstroSat satellite. Pul…
View article: Five new real-time detections of fast radio bursts with UTMOST
Five new real-time detections of fast radio bursts with UTMOST Open
We detail a new fast radio burst (FRB) survey with the Molonglo Radio Telescope, in which six FRBs were detected between 2017 June and 2018 December. By using a real-time FRB detection system, we captured raw voltages for five of the six e…
View article: Re-awakening of GRS 1716–249 after 23 yr, observed by Swift/XRT and NuSTAR
Re-awakening of GRS 1716–249 after 23 yr, observed by Swift/XRT and NuSTAR Open
In this work, we present a spectral and temporal analysis of Swift/XRT and NuSTAR
\nobservations of GRS 1716–249 during its recent 2016–2017 outburst. This low-mass X-ray
\nbinary underwent an extraordinary outburst after a long quiescence…
View article: Simulations and Tests of Prototype Antenna System for Low Frequency Radio Experiment (LORE) Space Payload for Space Weather Observations
Simulations and Tests of Prototype Antenna System for Low Frequency Radio Experiment (LORE) Space Payload for Space Weather Observations Open
Low frequency Radio Experiment (LORE) is a proposed space payload for space weather observations from space, operating between few kHz to 30 MHz. This paper presents preliminary design and practical implementation of LORE antenna systems, …
View article: Low Frequency Radio Experiment (LORE)
Low Frequency Radio Experiment (LORE) Open
In this paper, we present a case study of Low Frequency Radio Experiment (LORE) payload to probe the corona and the solar disturbances at solar offsets greater than 2 solar radii, i.e., at frequencies below 30 MHz. The LORE can be complime…