Ketan R. Sand
A5072981047- Pulsars and Gravitational Waves Research
- Gamma-ray bursts and supernovae
- GNSS positioning and interference
- Astrophysical Phenomena and Observations
- Geophysics and Gravity Measurements
- earthquake and tectonic studies
- Astrophysics and Cosmic Phenomena
- Statistical and numerical algorithms
- Radio Astronomy Observations and Technology
- Atomic and Subatomic Physics Research
- Astronomy and Astrophysical Research
- Astronomical Observations and Instrumentation
- Earthquake Detection and Analysis
- Seismology and Earthquake Studies
- Ionosphere and magnetosphere dynamics
- Galaxies: Formation, Evolution, Phenomena
- Geophysics and Sensor Technology
- Cosmology and Gravitation Theories
- Spacecraft and Cryogenic Technologies
- Spine and Intervertebral Disc Pathology
- Particle Accelerators and Free-Electron Lasers
- Seismic Imaging and Inversion Techniques
- Radiomics and Machine Learning in Medical Imaging
- Magnetic confinement fusion research
McGill University
2021-2025
We present the discovery of 25 new repeating fast radio burst (FRB) sources found among CHIME/FRB events detected between 2019 September 30 and 2021 May 1. The were using a clustering algorithm that looks for multiple co-located on sky having similar dispersion measures (DMs). repeaters have DMs ranging from $\sim$220 pc cm$^{-3}$ to $\sim$1700 cm$^{-3}$, include exhibited as few two bursts many twelve. report statistically significant difference in both DM extragalactic (eDM) distributions...
Abstract We present the host galaxies of four apparently nonrepeating fast radio bursts (FRBs), FRB 20181223C, 20190418A, 20191220A, and 20190425A, reported in first Canadian Hydrogen Intensity Mapping Experiment (CHIME/FRB) catalog. Our selection these FRBs is based on a planned hypothesis testing framework where we search all CHIME/FRB Catalog-1 events that have low extragalactic dispersion measure (<100 pc cm −3 ), with high Galactic latitude (∣ b ∣ > 10°) saved baseband data....
Abstract We present a search for host galaxy associations the third set of repeating fast radio burst (FRB) sources discovered by CHIME/FRB Collaboration. Using ∼1′ baseband localizations and probabilistic methods, we identify potential galaxies two FRBs, 20200223B 20190110C at redshifts 0.06024(2) 0.12244(6), respectively. also discuss properties marginal candidate association FRB 20191106C with redshift 0.10775(1). The three putative are all relatively massive, fall on standard...
Abstract We report the discovery of repeating fast radio burst (FRB) source FRB 20240209A using Canadian Hydrogen Intensity Mapping Experiment (CHIME)/FRB telescope. detected 22 bursts from this repeater between 2024 February and July, 6 which were also recorded at Outrigger station k’niʔatn k’l ⌣ stk’masqt (KKO). The multiple very long baseline interferometry localizations 66 km CHIME–KKO baseline, each with a different vector orientation due to repeater’s high decl. ∼86°, enabled combined...
Abstract The CHIME/FRB project has detected hundreds of fast radio bursts (FRBs), providing an unparalleled population to statistically probe the foreground media that they illuminate. One such medium is ionized halo Milky Way (MW). We estimate total Galactic electron column density from FRB dispersion measures (DMs) as a function latitude using four different estimators, including ones assume spherical symmetry MW and imply more latitudinal variation in density. Our observation-based...
Fast radio burst (FRB) source 20180916B exhibits a 16.33-day periodicity in its activity. It is as of yet unclear what proposed mechanism produces the activity, but polarization information key diagnostic. Here, we report on properties 44 bursts from FRB detected between 2018 December and 2021 by CHIME/FRB, project Canadian Hydrogen Intensity Mapping Experiment Experiment. In contrast to previous observations, find significant variations Faraday rotation measure (RM) 20180916B. Over nine...
Abstract Fast radio bursts (FRBs) display a confounding variety of burst properties and host-galaxy associations. Repeating FRBs offer insight into the FRB population by enabling spectral, temporal, polarimetric to be tracked over time. Here, we report on polarized observations 12 repeating sources using multiyear monitoring with Canadian Hydrogen Intensity Mapping Experiment (CHIME) 400–800 MHz. We observe significant rotation measure (RM) variations from many in our sample, including RM...
We report on improved sky localizations of thirteen repeating fast radio bursts (FRBs) discovered by CHIME/FRB via the use interferometric techniques channelized voltages from telescope. These so-called 'baseband localizations' improve localization uncertainty area presented in past studies more than three orders magnitude. The regions are provided for full sample FRBs to enable follow-up studies. uncertainties, together with limits source distances their dispersion measures (DMs), allow us...
Abstract In 2021, a catalog of 536 fast radio bursts (FRBs) detected with the Canadian Hydrogen Intensity Mapping Experiment (CHIME) telescope was released by CHIME/FRB Collaboration. This large collection bursts, observed single instrument and uniform selection effects, has advanced our understanding FRB population. Here we update results for 140 these FRBs which channelized raw voltage (“baseband”) data are available. With voltages measured telescope’s antennas, it is possible to maximize...
Abstract We present a 400–800 MHz polarimetric analysis of 128 nonrepeating fast radio bursts (FRBs) from the first CHIME/FRB baseband catalog, increasing total number FRB sources with polarization properties by factor ∼3. A 89 FRBs have >6 σ linearly polarized detections, 29 fall below this significance threshold and are deemed unpolarized, for 10 FRBs, data contaminated instrumental polarization. For we find Faraday rotation measure (RM) amplitudes, after subtracting approximate Milky...
Abstract We present a spectro-temporal analysis of 137 fast radio bursts (FRBs) from the first CHIME/FRB baseband catalog, including 125 one-off and 12 repeat bursts, down to microsecond resolution using least-squares optimization fitting routine fitburst . measure subburst components within burst envelopes as narrow ~23 μ s (FWHM), with 20% sample displaying substructures narrower than 100 s, offering constraints on emission mechanisms. Scattering timescales in range 30 13 ms at 600 MHz....
The precise origins of fast radio bursts (FRBs) remain unknown. Multiwavelength observations nearby FRB sources can provide important insights into the enigmatic phenomenon. Here we present results from a sensitive, broadband X-ray and observational campaign 20200120E, closest known extragalactic repeating source (located 3.63 Mpc away in an ~10-Gyr-old globular cluster). We place deep limits on persistent prompt emission which use to constrain possible for source. compare our with various...
Abstract We present a framework for modeling astrophysical pulses from radio pulsars and fast bursts (FRBs). This framework, called fitburst , generates synthetic representations of dynamic spectra that are functions several physical heuristic parameters; the parameters can nonetheless accommodate vast range distributions in spectral energy. is designed to optimize features induced by effects intrinsic extrinsic emission mechanism, including magnitude frequency dependence pulse dispersion...
Abstract Dedicated surveys searching for fast radio bursts (FRBs) are subject to selection effects that bias the observed population of events. Software injection systems one method correcting these biases by injecting a mock synthetic FRBs directly into real-time search pipeline. The injected may then be used map intrinsic burst properties onto an expected signal-to-noise ratio (S/N), so long as telescope characteristics such beam model and calibration factors properly accounted for. This...
Abstract FRB 20180916B is a repeating fast radio burst (FRB) with 16.3 day periodicity in its activity. In this study, we present morphological properties of 60 bursts detected by CHIME/FRB between 2018 August and 2021 December. We recorded raw voltage data for 45 these bursts, enabling microseconds time resolution some cases. studied variation spectro-temporal activity phase. find that the dispersion measure (DM) ≲1 pc cm −3 there burst-to-burst scattering estimates ranging from ∼0.16 to...
Abstract We present a multiband study of FRB 20180916B, repeating source with 16.3 day periodicity. report the detection four, one, and seven bursts from observations spanning 3 days using upgraded Giant Metrewave Radio Telescope (300–500 MHz), Canadian Hydrogen Intensity Mapping Experiment (400–800 MHz) Green Bank (600–1000 respectively. first ever in 800–1000 MHz range along one widest instantaneous bandwidth detections (200 at lower frequencies. identify 30 μ s wide structures 800 MHz,...
Abstract We present the discovery of 12 apparently nonrepeating fast radio burst (FRB) sources, detected by Canadian Hydrogen Intensity Mapping Experiment (CHIME) telescope. These only one which has been presented previously in first CHIME/FRB catalog, were selected from a database comprising <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mi class="MJX-tex-calligraphic" mathvariant="script">O</mml:mi> <mml:mo stretchy="false">(</mml:mo> <mml:msup> <mml:mrow>...
We present the first catalog of fast radio burst (FRB) host galaxies from CHIME/FRB Outriggers, selected uniformly in and optical by localizing 81 new bursts to 2'' x ~60'' accuracy using CHIME KKO Outrigger, located 66 km CHIME. Of localized bursts, we use Probabilistic Association Transients their Hosts (PATH) algorithm securely identify 21 FRB galaxies, compile spectroscopic redshifts for 19 systems, 15 which are newly obtained via observations. The most nearby source is 20231229A, at a...
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...
Abstract We report 10 fast radio bursts (FRBs) detected in the far sidelobe region (i.e., ≥5° off-meridian) of Canadian Hydrogen Intensity Mapping Experiment (CHIME) from August 28 2018 to 31 2021. localize by fitting their spectra with a model CHIME/FRB synthesized beam response. find that events have on average ∼500 times greater fluxes than CHIME’s main lobe. show sample is therefore statistically ∼20 closer lobe sample. promising host galaxy candidates ( P cc < 1%) for two FRBs,...
Abstract In this work, we present follow-up observations of two known repeating fast radio bursts (FRBs) and seven nonrepeating FRBs with complex morphology discovered the CHIME/FRB project. These were conducted Arecibo Observatory 327 MHz receiver. We detected no additional from these sources, nor did detect any sources during our program. Based on nondetections, provide constraints repetition rate for all nine sources. calculate rates above 1 Jy using both a Poisson distribution Weibull...
Fast radio bursts (FRBs) last for milliseconds and arrive at Earth from cosmological distances. While their origin(s) emission mechanism(s) are presently unknown, signals bear similarities with the much less luminous generated by pulsars within our Galaxy several lines of evidence point toward neutron star origins. For pulsars, linear polarisation position angle (PA) often exhibits evolution over pulse phase that is interpreted a geometric framework known as rotating vector model (RVM)....