J. P. Harding
A5075900855- Astrophysics and Cosmic Phenomena
- Dark Matter and Cosmic Phenomena
- Gamma-ray bursts and supernovae
- Particle Detector Development and Performance
- Particle physics theoretical and experimental studies
- Neutrino Physics Research
- Pulsars and Gravitational Waves Research
- Radio Astronomy Observations and Technology
- Radiation Detection and Scintillator Technologies
- Cosmology and Gravitation Theories
- Astrophysical Phenomena and Observations
- Particle Accelerators and Free-Electron Lasers
- Atomic and Subatomic Physics Research
- Solar and Space Plasma Dynamics
- Computational Physics and Python Applications
- Galaxies: Formation, Evolution, Phenomena
- Ionosphere and magnetosphere dynamics
- Radiation Therapy and Dosimetry
- Particle accelerators and beam dynamics
- Geological and Geochemical Analysis
- Black Holes and Theoretical Physics
- Protist diversity and phylogeny
- CCD and CMOS Imaging Sensors
- Scientific Research and Discoveries
- Glaucoma and retinal disorders
Los Alamos National Laboratory
2016-2025
Friedrich-Alexander-Universität Erlangen-Nürnberg
2023
Tecnológico de Monterrey
2023
University of Padua
2022
Istituto Nazionale di Fisica Nucleare, Sezione di Padova
2022
Michigan State University
2021
Universidade de São Paulo
2021
Universidade Federal de São Carlos
2021
George Mason University
2021
Georgia Institute of Technology
2021
Exotic origin for cosmic positrons Several cosmic-ray detectors have found more arriving at Earth than expected. Some researchers interpret this as a signature of exotic physics, such the annihilation dark matter particles. Others prefer mundane explanation that involves positron generation pulsars followed by diffusion to Earth. Abeysekara et al. detected extended emission gamma rays around two nearby pulsars, generated high-energy electrons and positrons. The size was used calculate how...
The Crab Nebula is the brightest TeV gamma-ray source in sky and has been used for past 25 years as a reference astronomy, calibration verification of new instruments. High Altitude Water Cherenkov Observatory (HAWC), completed early 2015, to observe at high significance across nearly full spectrum energies which HAWC sensitive. unique its wide field-of-view, 2 sr any instant, high-energy reach, up 100 TeV. HAWC's sensitivity improves with energy. Above $\sim$1 driven by best background...
We present the first catalog of TeV gamma-ray sources realized with recently completed High Altitude Water Cherenkov Observatory (HAWC). It is most sensitive wide field-of-view telescope currently in operation, a 1-year survey sensitivity ~5-10% flux Crab Nebula. With an instantaneous field view >1.5 sr and >90% duty cycle, it continuously surveys monitors sky for gamma ray energies between hundreds GeV tens TeV. HAWC located Mexico at latitude 19 degree North was March 2015. Here, we 2HWC...
Abstract We present TeV gamma-ray observations of the Crab Nebula, standard reference source in ground-based astronomy, using data from High Altitude Water Cherenkov (HAWC) Gamma-Ray Observatory. In this analysis we use two independent energy estimation methods that utilize extensive air shower variables such as core position, angle, and lateral distribution. contrast, previously published HAWC spectrum roughly estimated with only number photomultipliers triggered. This new methodology...
Abstract The High Altitude Water Cherenkov (HAWC) gamma-ray observatory is a wide field of view sensitive to 500 GeV–100 TeV gamma-rays and cosmic rays. It can also perform diverse indirect searches for dark matter annihilation decay. Among the most promising targets detection are dwarf spheroidal galaxies. These objects expected have few astrophysical sources but high content, making them ideal candidates an with gamma-rays. Here we present individual limits on cross section decay lifetime...
The High-Altitude Water Cherenkov (HAWC) Observatory is sensitive to gamma rays and charged cosmic at TeV energies.The detector still under construction, but data acquisition with the partially deployed started in 2013.An analysis of cosmic-ray arrival direction distribution based on 4.9 × 10 events recorded between June 2013 February 2014 shows anisotropy -4 level angular scales about • .The HAWC sky map exhibits three regions significantly enhanced flux; two these were first reported by...
those from other present and future gamma-ray observatories, will likely probe the thermal relic annihilation cross section of Weakly Interacting Massive Particles for all masses ~80 TeV down to GeV range in most channels.
Abstract We present the detection of very-high-energy gamma-ray emission above 100 TeV from HAWC J2227+610 with High-Altitude Water Cherenov Gamma-Ray Observatory (HAWC) observatory. Combining our observations previously published results by Very Energetic Radiation Imaging Telescope Array System (VERTIAS), we interpret as protons a lower limit in their cutoff energy 800 TeV. The most likely source is associated supernova remnant G106.3+2.7, making it good candidate for Galactic PeVatron....
The HAWC experiment reports the first ground-based measurement of all-particle cosmic-ray spectrum in 10-500 TeV energy range. This data overlaps with direct measurements made by balloon-borne detectors as well those other higher air-shower detectors. closes an important gap between these different experiments.
Abstract We present the first full-sky analysis of cosmic ray arrival direction distribution with data collected by High-Altitude Water Cherenkov and IceCube observatories in northern southern hemispheres at same median primary particle energy 10 TeV. The combined sky map angular power spectrum largely eliminate biases that result from partial coverage a key to probe into propagation properties TeV rays through our local interstellar medium interaction between heliospheric magnetic fields....
Abstract The Earth is bombarded by ultrarelativistic particles, known as cosmic rays (CRs). CRs with energies up to a few PeV (=10 15 eV), the knee in particle spectrum, are believed have Galactic origin. One or more factories of CRs, PeVatrons, must thus be active within our Galaxy. direct detection protons from their sources not possible since they deflected magnetic fields. Hundred TeV γ -rays decaying π 0 , produced when collide ambient gas, can provide decisive evidence proton...
We report the first detection of a TeV γ-ray flux from solar disk (6.3σ), based on 6.1 years data High Altitude Water Cherenkov (HAWC) observatory. The 0.5–2.6 spectrum is well fit by power law, dN/dE=A(E/1 TeV)−γ, with A=(1.6±0.3)×10−12 TeV−1 cm−2 s−1 and γ=3.62±0.14. shows strong indication anticorrelation activity. These results extend bright, hard GeV emission observed Fermi-LAT, seemingly due to hadronic Galactic cosmic rays showering nuclei in atmosphere. However, current theoretical...
We examine the constraints on models of weakly interacting massive particle (WIMP) dark matter from recent observations Galactic center by High Energy Spectroscopic System (HESS) telescope. analyze canonical WIMP annihilation into Standard Model final states, including b/b-bar, t/t-bar and W^+ W^-. The b/b-bar is within an order magnitude thermal cross section at ~3 TeV, while tau^+/tau^- channel a factor ~2 thermal. also study Sommerfeld-enhanced models, find that gamma-ray observational...
We present results from daily monitoring of gamma rays in the energy range $\sim0.5$ to $\sim100$ TeV with first 17 months data High Altitude Water Cherenkov (HAWC) Observatory. Its wide field view 2 steradians and duty cycle $>95$% are unique features compared other observatories that allow us observe every source transits over HAWC for up $\sim6$ hours each sidereal day. This regular sampling yields unprecedented light curves unbiased measurements independent seasons or weather conditions....
Abstract The highest-energy known gamma-ray sources are all located within 0.°5 of extremely powerful pulsars. This raises the question whether ultra-high-energy (UHE; >56 TeV) emission is a universal feature expected near pulsars with high spin-down power. Using four years data from High Altitude Water Cherenkov Gamma-Ray Observatory, we present joint-likelihood analysis 10 to search for subthreshold UHE correlated these locations. We report significant detection (>3 σ ), indicating...
ABSTRACT Glaucoma was cultured in various concentrations of bacteria which were kept as constant possible. The rate disappearance the a function concentration Glaucoma. In low feeding bacteria. high able to find almost much food they could take in; so that tended become independent Counts vacuoles showed never became quite For every increase concentration, up at least 8,000,000 per cu. mm., there an formation vacuoles. High did not inhibit growth or reproduction When less than 600,000 mm....
A measurement with high statistics of the differential energy spectrum light elements in cosmic rays, particular, primary H plus He nuclei, is reported. The presented range from $6$ to $158$ TeV per nucleus. Data was collected High Altitude Water Cherenkov (HAWC) Observatory between June 2015 and 2019. analysis based on a Bayesian unfolding procedure, which applied subsample vertical HAWC data that enriched $82\%$ events induced by nuclei. To achieve mass separation, cut lateral age air...
Abstract Extended very-high-energy (VHE; 0.1–100 TeV) γ -ray emission has been observed around several middle-aged pulsars and referred to as “TeV halos.” Their formation mechanism remains under debate. It is also unknown whether they are ubiquitous or related a certain subgroup of pulsars. With 2321 days observation, the High Altitude Water Cherenkov (HAWC) Gamma-Ray Observatory detected VHE at location radio-quiet pulsar PSR J0359+5414 with >6 σ significance. By performing likelihood...
We examine the constraints on luminosity-dependent density evolution model for of blazars given observed spectrum diffuse gamma-ray background (DGRB), blazar source-count distribution, and spectral energy distribution sequence model, which relates to its luminosity. show that DGRB by Large Area Telescope (LAT) aboard Fermi Gamma Ray Space can be produced entirely emission from nonblazar active galactic nuclei, our is consistent with constrained flux function Fermi-LAT. Our results are...
We study the relation between measured anisotropies in extragalactic diffuse gamma-ray background (DGRB) and DGRB spectral intensity, their potential origin from unresolved blazar population. Using a physical-evolution model for blazars with luminosity dependent evolution (LDDE) an observationally-determined luminosity-dependent energy distribution (SED), we find that can account observed anisotropy of consistent source-count distribution, but are turn constrained contributing significantly...
We perform a detailed examination of current constraints on annihilating and decaying dark matter models from both prompt inverse-Compton emission photons, including model-dependent model-independent bounds. also show that the observed isotropic diffuse gamma-ray background (DGRB), which provides one most conservative weak-scale particles, may enhance its sensitivity by factor ~2 to 3 (95% C.L.) as Fermi-LAT experiment resolves DGRB contributing blazar sources with five years observation....
Abstract We present a new catalog of TeV gamma-ray sources using 1523 days data from the High-Altitude Water Cherenkov (HAWC) Observatory. The represents most sensitive survey northern sky at energies above several TeV, with three times exposure compared to previous HAWC catalog, 2HWC. report 65 detected ≥5 σ significance, along positions and spectral fits for each source. contains eight that have no counterpart in 2HWC but are within 1° previously emitters, 20 more than away any Of these...