A5051708983- Astrophysics and Cosmic Phenomena
- Neutrino Physics Research
- Dark Matter and Cosmic Phenomena
- Radio Astronomy Observations and Technology
- Gamma-ray bursts and supernovae
- Pulsars and Gravitational Waves Research
- Astrophysical Phenomena and Observations
- Particle physics theoretical and experimental studies
- Particle Detector Development and Performance
- Cosmology and Gravitation Theories
- Photocathodes and Microchannel Plates
- Radiation Detection and Scintillator Technologies
- Stellar, planetary, and galactic studies
- Medical Imaging Techniques and Applications
- Astro and Planetary Science
- Arctic and Antarctic ice dynamics
- Galaxies: Formation, Evolution, Phenomena
- Advanced Semiconductor Detectors and Materials
- Solar and Space Plasma Dynamics
- Superconducting Materials and Applications
- Earthquake Detection and Analysis
- Cryospheric studies and observations
- Particle Accelerators and Free-Electron Lasers
- Gyrotron and Vacuum Electronics Research
- Particle accelerators and beam dynamics
Queen's University
2021-2024
The University of Texas at Arlington
2024
Lawrence Berkeley National Laboratory
2024
Clark Atlanta University
2024
Southern University and Agricultural and Mechanical College
2024
Providence College
2024
University of Alaska Anchorage
2024
University of Wisconsin–Madison
2018-2022
Vrije Universiteit Brussel
2022
University of Geneva
2019-2020
This detection constrains the mechanism and emission region of gamma-ray radiation in pulsar’s magnetosphere.
High-energy gamma-ray emission from supernova remnants (SNRs) has provided a unique perspective for studies of Galactic cosmic-ray acceleration. Tycho's SNR is particularly good target because it young, type Ia that well-studied over wide range energies and located in relatively clean environment. Since the detection by VERITAS Fermi-LAT, there have been several theoretical models proposed to explain its broadband high-energy morphology. We report on an update measurements with 147 hours 84...
We report on observations of the pulsar / Be star binary system PSR J2032+4127 MT91 213 in energy range between 100 GeV and 20 TeV with VERITAS MAGIC imaging atmospheric Cherenkov telescope arrays. The orbit has a period approximately 50 years, most recent periastron occurring 2017 November 13. Our span from 18 months prior to one month after. A new, point-like, gamma-ray source is detected, coincident location 213. light curve spectrum are well-characterized over passage. flux variable at...
We present results from deep observations towards the Cygnus region using 300 hours of very-high-energy (VHE) $\gamma$-ray data taken with VERITAS Cherenkov telescope array and over seven years high-energy Fermi satellite at an energy above 1 GeV. As brightest diffuse emission in northern sky, provides a promising area to probe origins cosmic rays. report identification potential Fermi-LAT counterpart VER J2031+415 (TeV J2032+4130), resolve extended VHE source J2019+368 into two candidates...
We present a study of $\gamma$-ray emission from the core-collapse supernova remnant Cas~A in energy range 0.1GeV to 10TeV. used 65 hours VERITAS data cover 200 GeV - 10 TeV, and 10.8 years \textit{Fermi}-LAT 0.1-500 GeV. The spectral analysis shows significant curvature around $1.3 \pm 0.4_{stat}$ that is consistent with expected spectrum pion decay. Above this energy, joint deviates significantly simple power-law, best described by power-law index $2.17\pm 0.02_{stat}$ cut-off $2.3...
VERITAS has been monitoring the very-high-energy (VHE; >100GeV) gamma-ray activity of radio galaxy M87 since 2007. During 2008, flaring on a timescale few days was observed with peak flux (0.70 +- 0.16) X 10^{-11} cm^{-2} s^{-1} at energies above 350GeV. In 2010 April, detected flare from (2.71 0.68) for E>350GeV. The source six consecutive nights during flare, resulting in total 21 hr good quality data. most rapid variation occurred trailing edge an exponential decay time...
HESS J0632+057 is the only gamma-ray binary known so far whose position in sky allows observations with ground-based observatories both northern and southern hemispheres. Here we report on long-term of conducted Very Energetic Radiation Imaging Telescope Array System High Energy Stereoscopic Cherenkov telescopes X-ray satellite Swift, spanning a time range from 2004 to 2012 covering most system's orbit. The very-high-energy (VHE) emission found be variable correlated that at energies. An...
We report on variability and correlation studies using multiwavelength observations of the blazar Mrk 421 during month February, 2010 when an extraordinary flare reaching a level $\sim$27~Crab Units above 1~TeV was measured in very-high-energy (VHE) $\gamma$-rays with VERITAS observatory. This is highest flux state for ever observed VHE $\gamma$-rays. Data are analyzed from coordinated campaign across multiple instruments including $\gamma$-ray (VERITAS, MAGIC), high-energy (HE) (Fermi-LAT),...
Abstract The ground-based gamma-ray observatory Very Energetic Radiation Imaging Telescope Array System (VERITAS, https://veritas.sao.arizona.edu/ ) is sensitive to photons of astrophysical origin with energies in the range between ≈85 GeV and ≈30 TeV. instrument consists four 12 m diameter imaging Cherenkov telescopes operating at Fred Lawrence Whipple Observatory southern Arizona. VERITAS started four-telescope operations 2007 collects about 1100 hr good-weather data per year....
Context. The response of imaging atmospheric Cherenkov telescopes to incident γ -ray-initiated showers in the atmosphere changes as age due exposure light and weather. These aging processes affect reconstructed energies events -ray fluxes. Aims. This work discusses implementation signal calibration methods for Very Energetic Radiation Imaging Telescope Array System (VERITAS) account optical throughput detector performance over time. Methods. total a telescope is product camera-dependent...
The results of gamma-ray observations the binary system HESS J0632+057 collected during 450 hours over 15 years, between 2004 and 2019, are presented. Data taken with atmospheric Cherenkov telescopes H.E.S.S., MAGIC, VERITAS at energies above 350 GeV were used together X-ray obtained Swift-XRT, Chandra, XMM-Newton, NuSTAR, Suzaku. Some these accompanied by measurements H{\alpha} emission line. A significant detection modulation VHE fluxes a period 316.7+-4.4 days is reported, consistent...
We report the discovery of TeV gamma-ray emission coincident with shell-type radio supernova remnant (SNR) CTA 1 using VERITAS observatory. The source, VER J0006+729, was detected as a 6.5 standard deviation excess over background and shows an extended morphology, approximated by two-dimensional Gaussian semimajor (semiminor) axis 030 (024) centroid 5' from Fermi pulsar PSR J0007+7303 its X-ray wind nebula (PWN). photon spectrum is well described power-law dN/dE = N0(E/3 TeV)−Γ, differential...
Blazars are variable emitters across all wavelengths over a wide range of timescales, from months down to minutes. It is therefore essential observe blazars simultaneously at different wavelengths, especially in the X-ray and gamma-ray bands, where broadband spectral energy distributions usually peak. In this work, we report on three "target-of-opportunity" (ToO) observations Mrk 421, one brightest TeV blazars, triggered by strong flaring event energies 2014. These feature long, continuous,...
We present the results of 71.6 hours observations Geminga pulsar (PSR J0633+1746) with VERITAS very-high-energy gamma-ray telescope array. Data taken between November 2007 and February 2013 were phase-folded using a timing solution derived from data recorded by XMM-\emph{Newton} \emph{Fermi}-LAT space telescopes. No significant pulsed emission above 100 GeV is observed, we report upper limits at 95% confidence level on integral flux 135 (spectral analysis threshold) 4.0$\times10^{-13}$...
Abstract HESS J1943+213 is a very high energy (VHE; >100 GeV) γ -ray source in the direction of Galactic plane. Studies exploring classification are converging toward its identification as an extreme synchrotron BL Lac object. Here we present 38 hr VERITAS observations taken over 2 yr. The detected with significance ∼20 standard deviations, showing remarkably stable flux and spectrum VHE -rays. Multifrequency Very Long Baseline Array (VLBA) confirm extended, jet-like structure previously...
Abstract The High Altitude Water Cherenkov (HAWC) collaboration recently published their 2HWC catalog, listing 39 very high energy (VHE; >100 GeV) gamma-ray sources based on 507 days of observation. Among these, 19 are not associated with previously known teraelectronvolt (TeV) sources. We have studied 14 these without counterparts VERITAS and Fermi -LAT. detected weak emission in the 1 TeV–30 TeV band region DA 495, a pulsar wind nebula coinciding J1953+294, confirming discovery source...
Abstract G106.3+2.7, commonly considered to be a composite supernova remnant (SNR), is characterized by boomerang-shaped pulsar wind nebula (PWN) and two distinct (“head” “tail”) regions in the radio band. A discovery of very-high-energy gamma-ray emission ( E γ > 100 GeV) followed recent detection ultrahigh-energy TeV) from tail region suggests that G106.3+2.7 PeVatron candidate. We present comprehensive multiwavelength study Boomerang PWN (100″ around PSR J2229+6114) using archival...
Abstract HELIX is a new NASA-sponsored instrument aimed at measuring the spectra and composition of light cosmic-ray isotopes from hydrogen to neon nuclei, in particular clock 10 Be (radioactive, with 1.4 Myr lifetime) 9 (stable). The latter are unique markers production Galactic propagation secondary needed resolve such important mysteries as proportion positrons excess antimatter observed by AMS-02 experiment. By using combination 1 T superconducting magnet spectrometer (with drift-chamber...
Abstract Pulsar wind nebula DA 495 (G65.7+1.2) was detected in TeV gamma-rays by the High Altitude Water Cerenkov Observatory 2017 (2HWC J1953+294). Follow-up observations Very Energetic Radiation Imaging Telescope Array System confirmed association between 2HWC J1953+294 and found emission to be spatially coincident with radio first reported 1968. The detection of from 495, along past X-ray up 10 keV, prompted high-energy as part NuSTAR Galactic Legacy Survey. We present results these...
Abstract Blazars are known for their variability on a wide range of timescales at all wavelengths. Most studies TeV gamma-ray blazars focus short timescales, especially during flares. With decade observations from the Fermi -LAT and VERITAS, we present an extensive study long-term multiwavelength radio-to-gamma-ray flux-density variability, with addition couple short-time radio-structure optical polarization blazar 1ES 1215+303 ( z = 0.130), its emission 100 MeV to 30 TeV. Multiple strong...
Abstract HESS J0632+057 belongs to a rare subclass of binary systems that emit gamma rays above 100 GeV. It stands out for its distinctive high-energy light curve, which features sharp “primary” peak and broader “secondary” peak. We present the results contemporaneous observations by NuSTAR VERITAS during secondary between 2019 December 2020 February, when orbital phase ( ϕ ) is 0.55 0.75. detected X-ray spectral evolution, while TeV emission. fit leptonic wind-collision model...
The HELIX cosmic-ray detector is a balloon-borne instrument designed to measure the flux of light isotopes in energy range from 0.2 GeV/n beyond 3 GeV/n. It will rely on ring-imaging Cherenkov (RICH) for particle identification at energies greater than 1 and use aerogel tiles with refractive index near 1.15 as radiator. To achieve performance goals experiment it necessary know its position dependence over lateral extent precision O(10−4). In this paper we describe apparatus methods developed...
Compilation of papers presented by the VERITAS Collaboration at 34th International Cosmic Ray Conference (ICRC), held July 30 through August 6, 2015 in The Hague, Netherlands.