Observing the epoch of reionization and dark ages with redshifted 21-cm hydrogen line

The billion years subsequent to the Big Bang pose the next challenging frontier for precision cosmology. The concordant cosmological model, ΔCDM, propounds that during this period, the dark matter gravitationally shepherds the baryonic matter to form the primordial large-scale structures. This era is termed the Dark Ages (DA). The following era, the Epoch of Reionization (EoR), leads to the formation of the first stars and galaxies that reionize the permeating neutral hydrogen. The linear polarization of the cosmic background radiation and the Gunn-Peterson troughs in quasar absorption spectra provide indirect evidence for the EoR. Currently, there is no observational evidence for the DA. While state-of-the-art radio telescope arrays, Low Frequency Array (LOFAR) and Square Kilometre Array (SKA), propose various strategies to observe the early phases of the Universe, the advanced simulations employing high-performance computing (HPC) methodologies continue to play significant role in constraining various models based upon limited observational data. Despite a wide range of research, there is no end-to-end simulation solution available to quantifiably address the observational challenges due to statistical and systematic errors including foregrounds, ionosphere, polarization, RFI, instrument stability, and directional dependent gains. This research consolidates the cutting-edge simulation solutions, Cube-P3M, C2-Ray, and MeqTrees, to build an HPC prototype pipeline entitled, Simulating Interferometry Measurements (SIM). To establish and validate the efficacy of the SIM pipeline, the research builds a theoretical framework of two science drivers, viz., the presence of Lymanlimit absorbers and measuring non-Gaussianity from the 21-cm data. Thereafter, using the LOFAR and SKA telescope configurations, the SIM generates data visibility cubes with direction dependent and independent propagation effects. Finally, SIM extracts the original signal through standard techniques exploring the parametric phase-space. Results are presented herein

GPU Acceleration of Image Convolution using Spatially-varying Kernel

Image subtraction in astronomy is a tool for transient object discovery such as asteroids, extra-solar planets and supernovae. To match point spread functions (PSFs) between images of the same field taken at different times a convolution technique is used. Particularly suitable for large-scale images is a computationally intensive spatially-varying kernel. The underlying algorithm is inherently massively parallel due to unique kernel generation at every pixel location. The spatially-varying kernel cannot be efficiently computed through the Convolution Theorem, and thus does not lend itself to acceleration by Fast Fourier Transform (FFT). This work presents results of accelerated implementation of the spatially-varying kernel image convolution in multi-cores with OpenMP and graphic processing units (GPUs). Typical speedups over ANSI-C were a factor of 50 and a factor of 1000 over the initial IDL implementation, demonstrating that the techniques are a practical and high impact path to terabyte-per-night image pipelines and petascale processing.Comment: 4 pages. Accepted to IEEE-ICIP 201

Violation of Entropic Leggett-Garg Inequality in Nuclear Spins

We report an experimental study of recently formulated entropic Leggett-Garg inequality (ELGI) by Usha Devi et al. (arXiv: 1208.4491v2 (2012)). This inequality places a bound on the statistical measurement outcomes of dynamical observables describing a macrorealistic system. Such a bound is not necessarily obeyed by quantum systems, and therefore provides an important way to distinguish quantumness from classical behavior. Here we study ELGI using a two-qubit nuclear magnetic resonance system. To perform the noninvasive measurements required for the ELGI study, we prepare the system qubit in a maximally mixed state as well as use the `ideal negative result measurement' procedure with the help of an ancilla qubit. The experimental results show a clear violation of ELGI by over four standard deviations. These results agree with the predictions of quantum theory. The violation of ELGI is attributed to the fact that certain joint probabilities are not legitimate in the quantum scenario, in the sense they do not reproduce all the marginal probabilities. Using a three-qubit system, we experimentally demonstrate that three-time joint probabilities do not reproduce certain two-time marginal probabilities.Comment: 5 pages, 5 figures, 1 page supplementar

Cyclic-Prešić–Ćirić operators in metric-like spaces and fixed point theorems

In this paper, we define the cyclic-Prešić–Ćirić operators in metric-like spaces and prove some fixed point results for such operators. Our results generalize that of S.B. Prešić [Sur une classe d'inéquations aux différences finite et sur la convergence de certaines suites, Publications de l'Institut Mathématique (N.S.), 5(19):75–78, 1965] and several later results. An example is given which shows that the results proved herein are the proper generalizations of existing ones

HI tomographic imaging of the Cosmic Dawn and Epoch of Reionization with SKA

We provide an overview of 21cm tomography of the Cosmic Dawn and Epoch of Reionization as possible with SKA-Low. We show why tomography is essential for studying CD/EoR and present the scales which can be imaged at different frequencies for the different phases of SKA- Low. Next we discuss the different ways in which tomographic data can be analyzed. We end with an overview of science questions which can only be answered by tomography, ranging from the characterization of individual objects to understanding the global processes shaping the Universe during the CD/EoRComment: 14 pages, 3 figures. Accepted for publication in the SKA Science Book 'Advancing Astrophysics with the Square Kilometre Array', to appear in 2015. PoS(AASKA14)01

Neutral Hydrogen in the Ringed Barred Galaxies NGC 1433 and NGC 6300

We have made observations of the \ion{H}{1} in the southern ringed barred spiral galaxies NGC~1433 and NGC~6300 with the Australia Telescope Compact Array (ATCA), the main goal being to test the resonance theory for the origin of these rings. NGC~1433 is the prototypical ringed barred spiral, and displays distinct \ion{H}{1}~counterparts to its nuclear ring, inner ring, outer pseudoring, and plume-like features. The $L_{4}$ and $L_{5}$ regions at corotation, as well as the bar itself, are relatively devoid of neutral atomic hydrogen. By associating the inner ring of NGC~1433 with the inner second harmonic resonance, and its outer pseudoring with the outer Lindblad resonance, we are able to infer a bar pattern speed for NGC~1433 of $26\pm5$~km~s$^{-1}$~kpc$^{-1}$. By way of contrast, NGC~6300 possesses a much more extended \ion{H}{1}~disk than NGC~1433. There is a gas ring underlying the inner pseudoring, but it is both broader and slightly larger in diameter than the optical feature. By again linking this inner ring feature to the inner second harmonic resonance, we derive a bar pattern speed for NGC~6300 of $27\pm8$~km~s$^{-1}$~kpc$^{-1}$, but in this case, neither the outer pseudoring nor the nuclear ring predicted by the resonance-ring theory can be identified in NGC~6300. Although it may be the case that the ring in NGC~6300 is not related to a resonance with the bar at all, we postulate instead that NGC~6300 is merely a less well-developed example of a resonance-ring galaxy than is NGC~1433.Comment: 21 pages, aas2pp4 LaTeX, no figures included. Accepted for April 1 1996 ApJ. Full paper (with figures) available from http://www.phys.unsw.edu.au/~sdr/prep.htm

Inversion of moments to retrieve joint probabilities in quantum sequential measurements

A sequence of moments encode the corresponding probability distribution. Probing if quantum joint probability distribution can be retrieved from the associated set of moments -- realized in the sequential measurement of a dichotomic observable at different time intervals -- reveals a negative answer i.e., the joint probabilities of sequential measurements do not agree with the ones obtained by inverting the moments. This is indeed a reflection of the non-existence of a bonafide grand joint probability distribution, consistent with all the physical marginal probability distributions. Here we explicitly demonstrate that given the set of moments, it is not possible to retrieve the three-time quantum joint probability distribution resulting from quantum sequential measurement of a single qubit dichotomic observable at three different times. Experimental results using a nuclear magnetic resonance (NMR) system are reported here to corroborate these theoretical observations viz., the incompatibility of the three-time joint probabilties with those extracted from the moment sequence.Comment: 7 pages, 5 figures, RevTe

Role of cartridge-based nucleic acid amplification test to diagnose tuberculosis at tertiary care teaching hospital in Rajasthan, India

Background: Tuberculosis is one of the top 10 causes of death worldwide as per the Global TB report 2017, the estimated incidence of TB in India was approximately 28,00,000 cases accounting for about a quarter of the world’s TB cases (10 million). It is of utmost important to diagnose early and treat it to reduce disease transmission. GeneXpert MTB/RIF, an automated cartridge-based molecular technique detects Mycobacterium Tuberculosis and rifampicin resistance within two hours, has been recommended by WHO for rapid diagnosis of TB.Methods: Author conducted a retrospective study in the Department of TB and Chest, of tertiary care center at Jhalawar Medical College (JMC), Jhalawar to evaluate and analyze the role of CBNAAT to diagnose tuberculosis from 1st January 2018 to 31st December 2018. Author included all patients who came to department of TB and Chest of JMC, Jhalawar either new/ relapsed/ defaulters/ referred cases from ART/ ICTC center, Pediatric Department; Gynaecology and Obstetrics Department, peripheral Government Health Care Facilities and Private Hospitals of Jhalawar District catering about 15.5 lac population were subjected to both ZN staining/ Fluorescent microscopy and CBNAAT in the study period.Results: A total of 3078 samples (pulmonary 2739+EP 339) were tested for ZN staining / Fluorescent microscopy and CBNAAT during the study period. Mean age of the study population was 36.5±10.3 years. 1873 tested were negative and 1205 samples were positive for CBNAAT. Of these 1205 positive samples, 1174 were sputum/ BAL samples and 31 were extra pulmonary samples. Authors found rifampicin resistance rate of 6.98% (82/1174) in pulmonary tuberculosis cases, 3 rifampicin resistance cases were detected in extra pulmonary samples. CBNAAT could identify 255 cases (14.01%) that were smear negative. Author found TB-HIV coinfection rate of 18.75%.Conclusions: Author found CBNAAT to be an important diagnostic modality especially in smear negative patients for early diagnosis and treatment. Author could detect Mycobacterium Tuberculosis in 14.01% of patients with negative smear microscopy for AFB. In PLHIV, CBNAAT detected Mycobacterium Tuberculosis in 18.75% (12/64) of patients. Author found rifampicin resistance rate of 6.98% (82/1174) in pulmonary tuberculosis cases

The effects of Lyman-limit systems on the evolution and observability of the epoch of reionization

We present the first large-scale, full radiative transfer simulations of the reionization of the intergalactic medium in the presence of Lyman-limit systems (LLSs). To illustrate the impact of LLS opacity, possibly missed by previous simulations, we add either a uniform or spatially varying hydrogen bound–free opacity. This opacity, implemented as the mean free path (MFP) of the ionizing photons, extrapolates the observed, post-reionization redshift dependence into the epoch of reionization. In qualitative agreement with previous studies, we find that at late times the presence of LLSs slows down the ionization fronts, and alters the size distribution of H II regions. We quantitatively characterize the size distribution and morphological evolution of H II regions and examine the effects of the LLSs on the redshifted 21-cm signal from the patchy reionization. The presence of LLSs extends the ionization history by Δz ∼ 0.8. The LLS absorbers significantly impede the late-time growth of the H II regions. The position-dependent LLS distribution slows reionization further and additionally limits the late growth of the ionized regions. However, there is no ‘freeze out’ of the H II regions and the largest regions grow to the size of the simulation volume. The 21-cm power spectra show that at large scales the power drops by a factor of 2 for 50 per cent and 75 per cent ionization stages (at k = 0.1 h Mpc−1) reflecting the limiting effect of the LLSs on the growth of ionized patches. The statistical observables such as the rms of the brightness temperature fluctuations and the peak amplitudes of the 21-cm power spectra at large scales (k = 0.05–0.1 h  Mpc−1) are diminished by the presence of LLS