D. Kharbanda
A5055312004- Pulsars and Gravitational Waves Research
- Radio Astronomy Observations and Technology
- Geophysics and Gravity Measurements
- GNSS positioning and interference
- Advanced Frequency and Time Standards
- Cosmology and Gravitation Theories
- Gamma-ray bursts and supernovae
- Superconducting and THz Device Technology
- Astrophysics and Cosmic Phenomena
- Seismic Waves and Analysis
Indian Institute of Technology Hyderabad
2021-2024
We present the results of search for an isotropic stochastic gravitational wave background (GWB) at nanohertz frequencies using second data release European Pulsar Timing Array (EPTA) 25 millisecond pulsars and a combination with first Indian (InPTA). analysed (i) full 24.7-year EPTA set, (ii) its 10.3-year subset based on modern observing systems, (iii) set InPTA ten commonly timed pulsars, (iv) data. These combinations allowed us to probe contributions instrumental noise interstellar...
The European Pulsar Timing Array (EPTA) and Indian (InPTA) collaborations have measured a low-frequency common signal in the combination of their second first data releases, respectively, with correlation properties gravitational wave background (GWB). Such may its origin number physical processes including cosmic population inspiralling supermassive black hole binaries (SMBHBs); inflation, phase transitions, strings, tensor mode generation by non-linear evolution scalar perturbations early...
The European Pulsar Timing Array (EPTA) and Indian (InPTA) collaborations have measured a low-frequency common signal in the combination of their second first data releases respectively, with correlation properties gravitational wave background (GWB). Such may its origin number physical processes including cosmic population inspiralling supermassive black hole binaries (SMBHBs); inflation, phase transitions, strings tensor mode generation by non-linear evolution scalar perturbations early...
Aims. The nanohertz gravitational wave background (GWB) is expected to be an aggregate signal of ensemble waves emitted predominantly by a large population coalescing supermassive black hole binaries in the centres merging galaxies. Pulsar timing arrays (PTAs), which are ensembles extremely stable pulsars at approximately kiloparsec distances precisely monitored for decades, most precise experiments capable detecting this background. However, subtle imprints that GWB induces on pulsar data...
We present the results of a search for continuous gravitational wave signals (CGWs) in second data release (DR2) European Pulsar Timing Array (EPTA) Collaboration. The most significant candidate event from this has frequency 4–5 nHz. Such signal could be generated by supermassive black hole binary (SMBHB) local Universe. follow-up analysis using both Bayesian and frequentist methods. gives Bayes factor 4 favour presence CGW over common uncorrelated noise process. In contrast, estimates...
We present the pulse arrival times and high-precision dispersion measure estimates for 14 millisecond pulsars observed simultaneously in 300-500 MHz 1260-1460 frequency bands using upgraded Giant Metrewave Radio Telescope (uGMRT). The data spans over a baseline of 3.5 years (2018-2021), is first official release made available by Indian Pulsar Timing Array collaboration. This presents unique opportunity investigating interstellar medium effects at low radio frequencies their impact on timing...
We present the results of search for an isotropic stochastic gravitational wave background (GWB) at nanohertz frequencies using second data release European Pulsar Timing Array (EPTA) 25 millisecond pulsars and a combination with first Indian (InPTA). analysed (i) full 24.7-year EPTA set, (ii) its 10.3-year subset based on modern observing systems, (iii) set InPTA ten commonly timed pulsars, (iv) data. These combinations allowed us to probe contributions instrumental noise interstellar...
We present the results of a search for continuous gravitational wave signals (CGWs) in second data release (DR2) European Pulsar Timing Array (EPTA) collaboration. The most significant candidate event from this has frequency 4-5 nHz. Such signal could be generated by supermassive black hole binary (SMBHB) local Universe. follow-up analysis using both Bayesian and frequentist methods. gives Bayes factor 4 favor presence CGW over common uncorrelated noise process, while estimates p-value to...
PSR J1713+0747 is one of the most precisely timed pulsars in international pulsar timing array experiment. This showed an abrupt profile shape change between April 16, 2021 (MJD 59320) and 17, 59321). In this paper, we report results from multi-frequency observations carried out with upgraded Giant Metrewave Radio Telescope (uGMRT) before after event. We demonstrate seen Band 5 (1260 MHz - 1460 MHz) 3 (300 500 MHz). The analysis shows a disturbance accompanying followed by recovery timescale...
High-precision measurements of the pulsar dispersion measure (DM) are possible using telescopes with low-frequency wideband receivers. We present an initial study application timing technique, which can simultaneously times arrival (ToAs) and DMs, for a set five pulsars observed upgraded Giant Metrewave Radio Telescope (uGMRT) as part Indian Pulsar Timing Array (InPTA) campaign. have used observations 300-500 MHz band uGMRT this purpose. obtain high precision in DM precisions order...
The nanohertz gravitational wave background (GWB) is expected to be an aggregate signal of ensemble waves emitted predominantly by a large population coalescing supermassive black hole binaries in the centres merging galaxies. Pulsar timing arrays, ensembles extremely stable pulsars, are most precise experiments capable detecting this background. However, subtle imprints that GWB induces on pulsar data obscured many sources noise. These must carefully characterized increase sensitivity GWB....
The Indian Pulsar Timing Array (InPTA) collaboration has recently made its first official data release (DR1) for a sample of 14 pulsars using 3.5 years uGMRT observations. We present the results single-pulsar noise analysis each these InPTA DR1. For this purpose, we consider white noise, achromatic red dispersion measure (DM) variations, and scattering variations in our analysis. apply Bayesian model selection to obtain preferred models among pulsar. PSR J1600$-$3053, find no evidence DM...
ABSTRACT The wideband timing technique enables the high-precision simultaneous estimation of pulsar times arrival (ToAs) and dispersion measures (DMs) while effectively modelling frequency-dependent profile evolution. We present two novel independent methods that extend standard to handle multiband data incorporating evolution over a larger frequency span estimate DMs ToAs with enhanced precision. implement likelihood using libstempo python interface perform in tempo2 framework. application...
The Indian Pulsar Timing Array (InPTA) collaboration has recently made its first official data release (DR1) for a sample of 14 pulsars using 3.5 years uGMRT observations. We present the results single-pulsar noise analysis each these InPTA DR1. For this purpose, we consider white noise, achromatic red dispersion measure (DM) variations, and scattering variations in our analysis. apply Bayesian model selection to obtain preferred models among pulsar. PSR J1600$-$3053, find no evidence DM...
We present the pulse arrival times and high-precision dispersion measure estimates for 14 millisecond pulsars observed simultaneously in 300-500 MHz 1260-1460 frequency bands using upgraded Giant Metrewave Radio Telescope (uGMRT). The data spans over a baseline of 3.5 years (2018-2021), is first official release made available by Indian Pulsar Timing Array collaboration. This presents unique opportunity investigating interstellar medium effects at low radio frequencies their impact on timing...
Decades long monitoring of millisecond pulsars, which exhibit highly stable rotational periods, in pulsar timing array experiments is on the threshold discovering nanohertz stochastic gravitational wave background. This paper describes Indian Pulsar (InPTA) experiment, employs upgraded Giant Metrewave Radio Telescope (uGMRT) for an ensemble pulsars this purpose. We highlight InPTA's observation strategies and analysis methods, are relevant a future PTA experiment with more sensitive Square...
The wideband timing technique enables the high-precision simultaneous estimation of pulsar Times Arrival (ToAs) and Dispersion Measures (DMs) while effectively modeling frequency-dependent profile evolution. We present two novel independent methods that extend standard to handle multi-band data incorporating evolution over a larger frequency span estimate DMs ToAs with enhanced precision. implement likelihood using libstempo python interface perform in tempo2 framework. application these...