A5034186790- Radio Astronomy Observations and Technology
- Astrophysics and Cosmic Phenomena
- Pulsars and Gravitational Waves Research
- Gamma-ray bursts and supernovae
- Astronomy and Astrophysical Research
- Stellar, planetary, and galactic studies
- Astro and Planetary Science
- Superconducting and THz Device Technology
- Antenna Design and Optimization
- Galaxies: Formation, Evolution, Phenomena
- Ionosphere and magnetosphere dynamics
- Geophysics and Gravity Measurements
- GNSS positioning and interference
- Astronomical Observations and Instrumentation
- Radio Wave Propagation Studies
- Solar and Space Plasma Dynamics
- Lightning and Electromagnetic Phenomena
- Astrophysical Phenomena and Observations
- Planetary Science and Exploration
- Astrophysics and Star Formation Studies
- Computational Physics and Python Applications
- Antenna Design and Analysis
- Scientific Research and Discoveries
- Advanced SAR Imaging Techniques
- Earthquake Detection and Analysis
University of New Mexico
2016-2025
Indiana University Bloomington
2008
We present results of the coordinated observing campaign that made first subarcsecond localization a Fast Radio Burst, FRB 121102. During this campaign, we simultaneous detection an burst by multiple telescopes: VLA at 3 GHz and Arecibo Observatory 1.4 GHz. Of nine bursts detected Very Large Array GHz, four had coverage other observatories. use multi-observatory constraints modeling seen only to confirm earlier showing spectra are not well modeled power law. find characterized ~500 MHz...
The first station of the Long Wavelength Array (LWA1) was completed in April 2011 and is currently performing observations resulting from its call for proposals addition to a continuing program commissioning characterization observations. instrument consists 258 dual-polarization dipoles, which are digitized combined into beams. Four independently-steerable beams available, each with two tunings 16 MHz bandwidth that can be independently tuned any frequency between 10 88 MHz. system...
The Large-aperture Experiment to Detect the Dark Age (LEDA) was designed detect predicted O(100) mK sky-averaged absorption of cosmic microwave background by hydrogen in neutral pre- and intergalactic medium just after cosmological Age. spectral signature would be associated with emergence a diffuse Lyα from starlight during 'Cosmic Dawn'. Recently, Bowman et al. have reported detection this feature, an unexpectedly large amplitude 530 mK, centred at 78 MHz. Verification result independent...
LWA1 is a new radio telescope operating in the frequency range 10-88 MHz, located central New Mexico. The consists of 258 pairs dipole-type antennas whose outputs are individually digitized and formed into beams. Simultaneously, signals from all dipoles can be recorded using one instrument's "all dipoles" modes, facilitating all-sky imaging. Notable features instrument include high intrinsic sensitivity (about 6 kJy zenith system equivalent flux density), large instantaneous bandwidth (up to...
The birth of the first luminous sources and ensuing epoch reionization are best studied via redshifted 21-cm emission line, signature two imprinting last. In this work we present a fully-Bayesian method, \textsc{hibayes}, for extracting faint, global (sky-averaged) signal from much brighter foreground emission. We show that simplified (but plausible), Gaussian model Cosmic Dawn ($15 \lesssim z 30$), parameterized by an amplitude $A_{\rm HI}$, frequency peak $\nu_{\rm HI}$ width $\sigma_{\rm...
The 21\,cm transition of neutral hydrogen is opening an observational window into the cosmic dawn universe---the epoch first star formation. We use 28\,hr data from Owens Valley Radio Observatory Long Wavelength Array (OVRO-LWA) to place upper limits on spatial power spectrum emission at $z \approx 18.4$ ($\Delta_{21} \lesssim 10^4\,\text{mK}$), and within absorption feature reported by EDGES experiment (Bowman et al. 2018). In process we demonstrate application double Karhunen-Lo\`{e}ve...
We present a survey of the radio sky accessible from first station Long Wavelength Array. Images are presented at nine frequencies between 35 and 80 MHz with spatial resolutions ranging 4|$_{.}^{\circ}$|7 to 2|$_{.}^{\circ}$|0, respectively. The maps cover north declination −40° represent most modern systematic diffuse Galactic emission within this frequency range. also combine our other low-frequency create an updated model sky. Due low probed by survey, better accounts for effects...
Abstract A host of new low-frequency radio telescopes seek to measure the 21 cm transition neutral hydrogen from early universe. These have potential directly probe star and galaxy formation at redshifts 20 ≳ z 7 but are limited by dynamic range they can achieve against foreground sources emission. Consequently, there is a growing demand for modern, high-fidelity maps sky frequencies below 200 MHz use in modeling removal. We describe wide-field imaging technique drift-scanning...
We present initial pulsar results from the first station of Long Wavelength Array (LWA1) obtained during commissioning period LWA1 and early science results.We detections periodic emission 44 previously known pulsars, including 3 millisecond pulsars (MSPs).The effects interstellar medium on are significantly enhanced at low frequencies band (10-88 MHz), making a very sensitive instrument for characterizing changes in dispersion measures (DM) other medium.Pulsars also often have significant...
ABSTRACT The Large-aperture Experiment to detect the Dark Age (LEDA) was designed measure 21-cm signal from neutral hydrogen at Cosmic Dawn, z ≈ 15–30. Using observations made with 200 m diameter core of Owens Valley Radio Observatory Long Wavelength Array (OVRO–LWA), we present a 2D cylindrical spatial power spectrum for data 43.1–53.5 MHz (zmedian 28) incoherently integrated 4 h, and an analysis array sensitivity. Power foregrounds is localized ‘wedge’ within k⊥, $k_\parallel$ space. After...
A “large-N” correlator that makes use of Field Programmable Gate Arrays and Graphics Processing Units has been deployed as the digital signal processing system for Long Wavelength Array station at Owens Valley Radio Observatory (LWA-OV), to enable Large Aperture Experiment Detect Dark Ages (LEDA). The samples a [Formula: see text][Formula: text]MHz baseband processes signals from 512 antennas (256 dual polarization) over instantaneous sub-band, achieving 16.8[Formula: text]Tops[Formula:...
Abstract The recent detection of the “cosmic dawn” redshifted 21 cm signal at 78 MHz by Experiment to Detect Global EoR Signatures (EDGES) differs significantly from theoretical predictions. In particular, absorption trough is roughly a factor two stronger than most optimistic models. early interpretations origin this discrepancy fall into categories. first that there increased cooling gas due interactions with dark matter, while second background radiation field includes contribution...
We present a census of 100 pulsars, the largest below MHz, including 94 normal pulsars and six millisecond with Long Wavelength Array (LWA). Pulse profiles are detected across range frequencies from 26 to 88 new narrow-band facilitating profile evolution studies breaks in pulsar spectra at low frequencies. report mean flux density, spectral index, curvature, low-frequency turnover frequency measurements for 97 61 sources. Multi-frequency widths presented all component spacing 27 two...
Abstract We present a census of 100 pulsars, the largest below MHz, including 94 normal pulsars and six millisecond with Long Wavelength Array (LWA). Pulse profiles are detected across range frequencies from 26–88 new narrowband facilitating profile evolution studies, breaks in pulsar spectra at low frequencies. report mean flux density, spectral index, curvature, low-frequency turnover-frequency measurements for 97 61 sources. Multifrequency widths presented all component spacing 27 two...
Multi-instrument studies have recently shed new light on the morphology of sporadic E, especially intense E. Here we present simultaneous observations dense E ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="m1"><mml:mrow><mml:msub><mml:mrow><mml:mtext>E</mml:mtext></mml:mrow><mml:mrow><mml:mi>s</mml:mi></mml:mrow></mml:msub></mml:mrow></mml:math> ) structures using Long Wavelength Array (LWA) radio telescopes and a Digisonde Portable Sounder 4D (DPS4D). Our coordinated show...
Radio astronomy observatories with high throughput back end instruments require real-time data processing. While computing hardware continues to advance rapidly, development of processing pipelines remains difficult and time-consuming, which can limit scientific productivity. Motivated by this, we have developed Bifrost: an open-source software framework for rapid pipeline development. (a) Bifrost combines a high-level Python interface highly efficient reconfigurable transport library blocks...
ABSTRACT The utility of Faraday rotation to measure the magnetic field solar corona and large-scale transients within is a small, yet growing in physics. This largely because it has been recognized as potentially valuable frontier space weather studies, ability intrinsic coronal mass ejections (CMEs) when they are close Sun great interest for understanding key element weather. Such measurements have attempted over last few decades using radio signals from artificial sources (i.e., spacecraft...
As a backend to the first station of Long Wavelength Array (LWA1) Prototype All Sky Imager (PASI) has been imaging sky $>$ -26$^{\circ}$ declination during 34 Gamma Ray Bursts (GRBs) between January 2012 and May 2013. Using this data we were able put most stringent limits date on prompt low frequency emission from GRBs. While our depend zenith angle observed GRB, estimate 1$\sigma$ RMS sensitivity 68, 65 70 Jy for 5 second integrations at 37.9, 52.0, 74.0 MHz zenith. These are relevant...
We present a description of the Prototype All-Sky Imager (PASI), backend correlator and imager first station Long Wavelength Array (LWA1). PASI cross-correlates live stream 260 dual-polarization dipole antennas LWA1, creates all-sky images, uploads them to LWA-TV website in near real time. has recorded over 13,000[Formula: see text]hr images at frequencies between 10 88[Formula: text]MHz creating opportunities for new research discoveries. also report rate density pulse energy limits on...
We present the findings from Prototype All-Sky Imager, a back end correlator of first station Long Wavelength Array, which has recorded over 11,000 hr all-sky images at frequencies between 25 and 75 MHz. In search this data for radio transients, we have found 49 long-duration (10 s seconds) transients. Ten these transients correlate both spatially temporally with large meteors (fireballs), their signatures suggest that fireballs emit previously undiscovered low frequency, non-thermal pulse....
The Long Wavelength Array Software Library (LSL) is a Python module that provides collection of utilities to analyze and export data collected at the first station Array, LWA1. Due nature format large-N (≳100 inputs) challenges faced by LWA, currently available software packages are not suited process data. Using tools provided LSL, observers can read in raw LWA1 data, synthesize filter bank, apply incoherent de-dispersion extensible LSL also makes it an ideal tool for building analysis...
LWA1 is a new large radio telescope array operating in the frequency range 10-88 MHz, located central New Mexico. The consists of about 260 pairs dipole-type antennas whose outputs are individually digitized and formed into beams. Simultaneously, signals from all dipoles can be recorded using one telescope's "all dipoles" modes, facilitating all-sky imaging. Notable features instrument include four independently-steerable beams utilizing digital true time delay beamforming, high intrinsic...
Total-power radiometry with individual meter-wave antennas is a potentially effective way to study the Cosmic Dawn ($z\sim20$) through measurement of sky brightness arising from $21$~cm transition neutral hydrogen, provided this can be disentangled much stronger Galactic and extra-galactic foregrounds. In process, measured spectra integrated temperature used quantify foreground emission properties. work, we analyze subset data Large-aperture Experiment Detect Dark Age (LEDA) in range...
Neutral hydrogen clouds are found in the Milky Way and Andromeda halo both as large complexes smaller isolated clouds. Here we present a search for Hi of M33, third spiral galaxy Local Group. We have used two complementary data sets: 3^o x map area provided by Arecibo Legacy Fast ALFA (ALFALFA) survey deeper pointed observations carried out with telescope fields that permit sampling north eastern south-western edges HI disc. The total amount around M33 detected our is $\sim 10^7$...