43 citations · 183 across the 24 of their papers we have counts for
25 papers
A NICER and AstroSat view of the neutron star low-mass X-ray binary 1A 1246-588
Vaidehi Poojyam, Vikas Mistry, Yash Bhargava +2
Neutron star (NS) low-mass X-ray binary (LMXB) systems depict a variety of X-ray spectral and timing features, which can be useful to probe the accretion-ejection mechanism in the…
A joint MeerKAT and Parkes view of Omega Centauri: New TRAPUM Searches and Pulsar Timing
Miquel Colom i Bernadich, Shi Dai, Federico Abbate +27
Millisecond pulsars (MSPs) are powerful probes of globular clusters (GCs), tracing stellar evolution, cluster dynamics, and the local gravitational potential. We investigate the MS…
Optical observations of the fast nova V1674 Herculis
Neeraj Singh Rawat, L. S. Sonith, U. S. Kamath +3
We present the evolution of optical spectra and lightcurves of the fast nova V1674 Herculis during 150 days past its eruption. Using the post-eruption AAVSO light curve, we have ca…
Infrared Synchrotron Emission in the Soft State of GX 339-4 and the Mid-Infrared/X-ray Luminosity Plane of Black Hole X-ray Binaries
P. Gandhi, D. M. Russell, M. C. Baglio +33
Progress in understanding the growth of accreting black holes remains hampered by a lack of sensitive coordinated multiwavelength observations. In particular, the mid-infrared (MIR…
Probing the accreting millisecond X-ray pulsar SAX J1808.4-3658 using the evolution of its spectral and aperiodic timing properties
Aman Kaushik, Yash Bhargava, Sudip Bhattacharyya +1
Understanding accretion components in neutron star (NS) low mass X-ray binary (LMXB) systems is important to probe fundamental aspects of accretion mechanism and evolution of the s…
Probing the origin of the extended flaring branch of Z-type X-ray binaries GX 340+0 and GX 5-1 using AstroSat
Tanmoy Dutta, Mayukh Pahari, Anish Sarkar +2
`Z' type neutron star low-mass X-ray binaries typically show a `Z'-like three-branched track in their hardness intensity diagram. However, a few such `Z' sources show an additional…
X-ray and Radio Campaign of the Z-source GX 340+0 II: the X-ray polarization in the normal branch
Yash Bhargava, Thomas D. Russell, Mason Ng +11
We present the first X-ray polarization measurement of the neutron star low-mass X-ray binary and Z-source, GX 3400, in the normal branch (NB) using a 200 ks observation with th…
Probing outbursts of the transient neutron star low mass X-ray binary Aql X-1 with NICER: a study of spectral evolution
Karthik Gananath Putha, Yash Bhargava, Sudip Bhattacharyya
X-ray observations of neutron star (NS) low mass X-ray binaries (LMXBs) are useful to probe physical processes close to the NS and to constrain source parameters. Aql X-1 is a tran…
Rapid Mid-Infrared Spectral-Timing with JWST. I. The prototypical black hole X-ray Binary GRS 1915+105 during a MIR-bright and X-ray-obscured state
P. Gandhi, E. S. Borowski, J. Byrom +44
We present mid-infrared (MIR) spectral-timing measurements of the prototypical Galactic microquasar GRS 1915+105. The source was observed with the Mid-Infrared Instrument (MIRI) on…
An IXPE-Led X-ray Spectro-Polarimetric Campaign on the Soft State of Cygnus X-1: X-ray Polarimetric Evidence for Strong Gravitational Lensing
James F. Steiner, Edward Nathan, Kun Hu +134
We present the first X-ray spectropolarimetric results for Cygnus X-1 in its soft state from a campaign of five IXPE observations conducted during 2023 May-June. Companion multiwav…
X-ray and Radio campaign of the Z-source GX 340+0: discovery of X-ray polarization and its implications
Yash Bhargava, Mason Ng, Liang Zhang +11
We present the discovery of X-ray polarization from the neutron star low-mass X-ray binary and Z-source, GX~3400, using an Imaging X-ray Polarimetry Explorer (IXPE) observation…
AstroSat and NICER timing view of the Z-type Neutron Star X-ray binary GX 340+0
Mayukh Pahari, Shree Suman, Yash Bhargava +5
The timing properties of the Z-type low-mass X-ray binaries provide insights into the emission components involved in producing the unique Z-shaped track in the hardness-intensity…
Soft X-ray and FUV observations of Nova Her 2021 (V1674~Her) with AstroSat
Yash Bhargava, Gulab Chand Dewangan, G. C. Anupama +8
Nova Her 2021 or V1674 Her was one of the fastest novae to be observed so far. We report here the results from our timing and spectral studies of the source observed at multiple ep…
Probing the soft state evolution of 4U 1543-47 during its 2021 outburst using AstroSat
Nazma Husain, Yash Bhargava, Akash Garg +3
4U 1543-47 underwent its brightest outburst in 2021 after two decades of inactivity. During its decay phase, AstroSat conducted nine observations of the source spanning from July $…
AstroSat view of the neutron star low-mass X-ray binary GX 340+0
Yash Bhargava, Sudip Bhattacharyya, Jeroen Homan +1
Understanding the spectral evolution along the `Z'-shaped track in the hardness-intensity diagram of Z-sources, which are a class of luminous neutron star low-mass X-ray binaries,…
High hard X-ray polarization in Cygnus X-1 confined to the intermediate hard state: evidence for a variable jet component
Tanmoy Chattopadhyay, Abhay Kumar, A. R. Rao +7
Cygnus X-1, the well-known accreting black hole system, exhibits several observational features hinting at an intricate interplay between the accretion disk, its atmosphere known a…
Flux-resolved Spectropolarimetric Evolution of the X-Ray Pulsar Hercules X-1 Using IXPE
Akash Garg, Divya Rawat, Yash Bhargava +2
We conduct a spectro-polarimetric study of the accreting X-ray pulsar Hercules X-1 using observations with the Imaging X-ray Polarimetry Explorer (IXPE). IXPE monitored the source…
Probing the shot behaviour in Cygnus X-1 using simultaneous AstroSat-NICER observation
Yash Bhargava, Nandini Hazra, A. R. Rao +4
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.…
Accreting on the edge: a luminosity-dependent cyclotron line in the Be/X-ray Binary 2S 1553-542 accompanied by accretion regimes transition
Christian Malacaria, Yash Bhargava, Joel B. Coley +15
Accreting X-ray pulsars (XRPs) undergo luminous X-ray outbursts during which the luminosity-dependent spectral and timing features of the neutron star's emission can be analyzed in…
The Remarkable Spin-down and Ultra-fast Outflows of the Highly-Pulsed Supersoft Source of Nova Hercules 2021
Jeremy J. Drake, Jan-Uwe Ness, Kim L. Page +12
Nova Her 2021 (V1674 Her), which erupted on 2021 June 12, reached naked-eye brightness and has been detected from radio to -rays. An extremely fast optical decline of 2 magnitud…
A timing-based estimate of the spin of the black hole in MAXI J1820+070
Yash Bhargava, Tomaso Belloni, Dipankar Bhattacharya +2
MAXI J1820+070 (ASSASN-18ey) is a Black hole X-ray binary discovered in 2018. The brightness of the source triggered multi-wavelength campaigns of this source from different observ…
Spectro-timing analysis of MAXI J1535-571 using AstroSat
Yash Bhargava, Tomaso Belloni, Dipankar Bhattacharya +1
We report the results of the analysis of an AstroSat observation of the Black Hole candidate MAXI J1535-571 during its Hard Intermediate state. We studied the evolution of the spec…
Explaining the asymmetric line profile in Cepheus X-4 with spectral variation across pulse phase
Yash Bhargava, Varun Bhalerao, Ralf Ballhausen +4
The high mass X-ray binary Cep X-4, during its 2014 outburst, showed evidence for an asymmetric cyclotron line in its hard X-ray spectrum. The 2014 spectrum provides one of the cle…
A precise measurement of the orbital period parameters of Cygnus X-3
Yash Bhargava, A. R. Rao, K. P. Singh +9
We present X-ray light curves of Cygnus X-3 as measured by the recently launched AstroSat satellite. The light curve folded over the binary period of 4.8 hours shows a remarkable s…