9 research outputs found
Classification of pulsar glitch amplitudes using extreme deconvolution
We carry out a classification of the glitch amplitudes of radio pulsars using Extreme Deconvolution technique based on the Gaussian Mixture Model, where the observed uncertainties in the glitch amplitudes [Formula presented] are taken into account. Our dataset consists of 699 glitches from 238 pulsars. We then use information theory criteria such as AIC and BIC to determine the optimum number of glitch classes. We find that both AIC and BIC show that the pulsar glitch amplitudes can be optimally described using a bimodal distribution. The mean values of [Formula presented] for the two components are equal to 4.79×10−9 and 1.28×10−6, respectively with standard deviation given by 1.01 and 0.55 dex. We also applied this method to classify the pulsar inter-glitch time intervals, and we find that AIC prefers two components, whereas BIC prefers a single component. The unified data set and analyses codes used in this work have been made publicly available
Noise analysis of the Indian Pulsar Timing Array data release I
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 of
uGMRT observations. We present the results of single-pulsar noise analysis for
each of these 14 pulsars using the InPTA DR1. For this purpose, we consider
white noise, achromatic red noise, dispersion measure (DM) variations, and
scattering variations in our analysis. We apply Bayesian model selection to
obtain the preferred noise models among these for each pulsar. For PSR
J16003053, we find no evidence of DM and scattering variations, while for
PSR J19093744, we find no significant scattering variations. Properties vary
dramatically among pulsars. For example, we find a strong chromatic noise with
chromatic index 2.9 for PSR J1939+2134, indicating the possibility of a
scattering index that doesn't agree with that expected for a Kolmogorov
scattering medium consistent with similar results for millisecond pulsars in
past studies. Despite the relatively short time baseline, the noise models
broadly agree with the other PTAs and provide, at the same time,
well-constrained DM and scattering variations.Comment: Accepted for publication in PRD, 30 pages, 17 figures, 4 table
Multi-band Extension of the Wideband Timing Technique
The wideband timing technique enables the high-precision simultaneous
estimation of Times of Arrival (ToAs) and Dispersion Measures (DMs) while
effectively modeling frequency-dependent profile evolution. We present two
novel independent methods that extend the standard wideband technique to handle
simultaneous multi-band pulsar data incorporating profile evolution over a
larger frequency span to estimate DMs and ToAs with enhanced precision. We
implement the wideband likelihood using the libstempo python interface to
perform wideband timing in the tempo2 framework. We present the application of
these techniques to the dataset of fourteen millisecond pulsars observed
simultaneously in Band 3 (300 - 500 MHz) and Band 5 (1260 - 1460 MHz) of the
upgraded Giant Metrewave Radio Telescope (uGMRT) as a part of the Indian Pulsar
Timing Array (InPTA) campaign. We achieve increased ToA and DM precision and
sub-microsecond root mean square post-fit timing residuals by combining
simultaneous multi-band pulsar observations done in non-contiguous bands for
the first time using our novel techniques.Comment: Submitted to MNRA
Structure-Property-Performance Relationships of Dielectric Nanostructures for Mie Resonance-Enhanced Dye-Sensitization
Dye-sensitized photocatalytic (DSP) approach is considered as one of the promising approaches for developing visible light- and near-infrared light-responsive photocatalysts. DSP systems are still affected by significant drawbacks, such as low light absorption efficiency. Recently, it has been demonstrated that the plasmonic metal nanostructures can be used to enhance the light absorption efficiency and the overall dye-sensitization rate of DSP systems through the plasmonic Mie resonance-enhanced dye-sensitization approach. In this contribution, we report an alternate and novel approach, dielectric Mie resonance-enhanced dye sensitization. Specifically, we demonstrate that the dielectric Mie resonances in cuprous oxide (Cu2O) spherical and cubical nanostructures can be used to enhance the dye-sensitization rate of methylene blue dye. The Cu2O nanostructures exhibiting dielectric Mie resonances exhibit up to an order of magnitude higher dye-sensitization rate as compared to Cu2O nanostructures not exhibiting dielectric Mie resonances. Our model system developed from finite-difference time-domain simulation predicts a volcano-type relationship between the dye sensitization rate and the size of Cu2O nanostructures. The predicted structure-property-performance relationship is experimentally verified and the optimal size ranges of Cu2O nanospheres and nanocubes are identified. Although we demonstrate the dielectric Mie resonance-enhanced dye-sensitization approach using Cu2O nanostructures, the proposed approach can be used to design a wide range of DSP systems, including CeO2, {\alpha}-Fe2O3, and TiO2 nanostructures-based DSP systems