Saurabh Singh
A5049706043- Radio Astronomy Observations and Technology
- Astrophysics and Cosmic Phenomena
- Superconducting and THz Device Technology
- Antenna Design and Optimization
- Pulsars and Gravitational Waves Research
- Gamma-ray bursts and supernovae
- Galaxies: Formation, Evolution, Phenomena
- Radio Wave Propagation Studies
- Geophysics and Gravity Measurements
- Particle Accelerators and Free-Electron Lasers
- Neutrino Physics Research
- Astrophysical Phenomena and Observations
- Cosmology and Gravitation Theories
- Soil Moisture and Remote Sensing
- Particle physics theoretical and experimental studies
- Astronomy and Astrophysical Research
- Millimeter-Wave Propagation and Modeling
- earthquake and tectonic studies
- Solar and Space Plasma Dynamics
- Gyrotron and Vacuum Electronics Research
- Adsorption and biosorption for pollutant removal
- Digital Transformation in Industry
- History and Developments in Astronomy
- Ionosphere and magnetosphere dynamics
- Optical Wireless Communication Technologies
Raman Research Institute
2016-2025
McGill University
2019-2025
Dongguk University
2022
Manipur University
2022
The University of Texas at Arlington
2021
Indian Institute of Technology Roorkee
2008-2019
We report on the discovery of eight repeating fast radio burst (FRB) sources found using Canadian Hydrogen Intensity Mapping Experiment (CHIME) telescope. These span a dispersion measure (DM) range 103.5 to 1281 pc cm$^{-3}$. They display varying degrees activity: six were detected twice, another three times, and one ten times. FRBs likely represent bright and/or high-rate end distribution infrequently sources. For all sources, we determine sky coordinates with uncertainties...
We present a catalog of 536 fast radio bursts (FRBs) detected by the Canadian Hydrogen Intensity Mapping Experiment Fast Radio Burst (CHIME/FRB) Project between 400 and 800 MHz from 2018 July 25 to 2019 1, including 62 18 previously reported repeating sources. The represents first large sample, repeaters non-repeaters, observed in single survey with uniform selection effects. This facilitates comparative absolute studies FRB population. show that apparent non-repeaters have sky locations...
Abstract We report upper limits on the Epoch of Reionization 21 cm power spectrum at redshifts 7.9 and 10.4 with 18 nights data (∼36 hr integration) from Phase I Hydrogen Array (HERA). The show evidence for systematics that can be largely suppressed systematic models down to a dynamic range ∼10 9 respect peak foreground power. This yields 95% confidence limit <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msubsup> <mml:mrow> <mml:mi...
The Canadian Hydrogen Intensity Mapping Experiment (CHIME) is a drift scan radio telescope operating across the 400-800 MHz band. CHIME located at Dominion Radio Astrophysical Observatory near Penticton, BC Canada. instrument designed to map neutral hydrogen over redshift range 0.8 2.5 constrain expansion history of Universe. This goal drives design features instrument. consists four parallel cylindrical reflectors, oriented north-south, each 100 m $\times$ 20 and outfitted with 256 element...
Abstract We report the most sensitive upper limits to date on 21 cm epoch of reionization power spectrum using 94 nights observing with Phase I Hydrogen Epoch Reionization Array (HERA). Using similar analysis techniques as in previously reported limits, we find at 95% confidence that Δ 2 ( k = 0.34 h Mpc −1 ) ≤ 457 mK z 7.9 and 0.36 3496 10.4, an improvement by a factor 2.1 2.6, respectively. These are mostly consistent thermal noise over wide range after our data quality cuts, despite...
We present a detection of 21-cm emission from large-scale structure (LSS) between redshift 0.78 and 1.43 made with the Canadian Hydrogen Intensity Mapping Experiment (CHIME). Radio observations acquired over 102 nights are used to construct maps which foreground filtered stacked on angular spectral locations luminous red galaxies (LRG), line (ELG), quasars (QSO) eBOSS clustering catalogs. find decisive evidence for when stacking all three tracers LSS, logarithm Bayes Factor equal 18.9 10.8...
The EDGES collaboration reported an unexpectedly deep absorption in the radio background at 78 MHz and interpreted dip as first detection of a redshifted 21 cm signal from cosmic dawn (CD). We attempt alternate analysis by adopting maximally smooth function approach to model foreground. A joint fit spectrum using such together with flattened profile yields best-fit amplitude 921 ± 35 mK. depth inferred required invoking nonstandard cosmology, or new physics, sources CD, this tension accepted...
Spectral distortions in the cosmic microwave background over 40--200~MHz band are imprinted by neutral hydrogen intergalactic medium prior to end of reionization. This signal, produced redshift range $z = 6-34$ at rest frame wavelength 21 cm, has not been detected yet; and poor understanding high astrophysics results a large uncertainty expected spectrum. The SARAS~2 radiometer was purposely designed detect sky-averaged 21-cm signal. instrument, deployed Timbaktu Collective (Southern India)...
Abstract This paper presents the design and deployment of Hydrogen Epoch Reionization Array (HERA) phase II system. HERA is designed as a staged experiment targeting 21 cm emission measurements Reionization. First results from I array are published early 2022, system nearing completion. We describe discuss progress on commissioning future upgrades. As designated Square Kilometre pathfinder instrument, we also show number “case studies” that investigate systematics seen while system, which...
Long wavelength spectral distortions in the Cosmic Microwave Background arising from 21-cm transition neutral Hydrogen are a key probe of Dawn and Epoch Reionization. These features may reveal nature first stars ultra-faint galaxies that transformed spin temperature ionization state primordial gas. SARAS~2 is radiometer purposely designed for precision measurement these monopole or all-sky global distortions. We use 63~hr night time observing radio background frequency band 110-200~MHz with...
We describe the validation of HERA Phase I software pipeline by a series modular tests, building up to an end-to-end simulation. The philosophy this approach is validate and algorithms used in upper limit analysis on wholly synthetic data satisfying assumptions that analysis, not addressing whether actual meet these assumptions. discuss organization approach, specific tests performed, construction simulations. explicitly limitations scope current simulation effort. With mock visibility...
Abstract The precise characterization and mitigation of systematic effects is one the biggest roadblocks impeding detection fluctuations cosmological 21 cm signals. Missing data in radio experiments, often due to frequency interference (RFI), pose a particular challenge power spectrum analysis as this could lead ringing bright foreground modes Fourier space, heavily contaminating Here we show that problem missing becomes even more arduous presence effects. Using realistic numerical...
ABSTRACT Detection of the faint 21 cm line emission from Cosmic Dawn and Epoch Reionization will require not only exquisite control over instrumental calibration systematics to achieve necessary dynamic range observations but also validation analysis techniques demonstrate their statistical properties signal loss characteristics. A key ingredient in achieving this is ability perform high-fidelity simulations kinds data that are produced by large, many-element, radio interferometric arrays...
We introduce DAYENU, a linear, spectral filter for HI intensity mapping that achieves the desirable foreground mitigation and error minimization properties of inverse co-variance weighting with minimal modeling underlying data. Beyond 21 cm power-spectrum estimation, our is suitable any analysis where high dynamic-range removal spectrally smooth foregrounds in irregularly (or regularly) sampled data required, something required by many other techniques. Our filtering matrix diagonalized...
ABSTRACT The first billion years of cosmic history remains largely unobserved. We demonstrate, using a novel machine learning technique, how combining upper limits on the spatial fluctuations in 21-cm signal with observations sky-averaged from neutral hydrogen can improve our understanding this epoch. By jointly analysing data Shaped Antenna measurement background RAdio Spectrum (SARAS3, redshift z ≈ 15−25) and Hydrogen Epoch Reionization Array (HERA, 8 10), we show that such synergetic...
Abstract Fast radio bursts (FRBs) are bright transients of microsecond to millisecond duration and unknown extragalactic origin. Central the mystery FRBs their extremely high characteristic energies, which surpass typical energies other similar duration, like Galactic pulsar magnetar bursts, by orders magnitude. Calibration FRB-detecting telescopes for burst flux fluence determination is crucial FRB science, as these measurements enable studies energy brightness distribution in comparison...