A5077292694- Astrophysics and Cosmic Phenomena
- Gamma-ray bursts and supernovae
- Dark Matter and Cosmic Phenomena
- Radio Astronomy Observations and Technology
- Astrophysical Phenomena and Observations
- Particle Detector Development and Performance
- Neutrino Physics Research
- Pulsars and Gravitational Waves Research
- Particle Accelerators and Free-Electron Lasers
- Particle physics theoretical and experimental studies
- Astro and Planetary Science
- Stellar, planetary, and galactic studies
- Quantum Chromodynamics and Particle Interactions
- Solar and Space Plasma Dynamics
- Space Science and Extraterrestrial Life
- High-Energy Particle Collisions Research
- Astrophysics and Star Formation Studies
- Astronomical Observations and Instrumentation
- Computational Physics and Python Applications
- Black Holes and Theoretical Physics
- Spacecraft Design and Technology
- Advanced Optical Sensing Technologies
- Gyrotron and Vacuum Electronics Research
- Adaptive optics and wavefront sensing
- Nuclear Physics and Applications
McGill University
2015-2024
Universidad Veritas
2020-2023
DePauw University
2019
Smithsonian Astrophysical Observatory
2004
Istituto Nazionale di Fisica Nucleare
2000
University of Bologna
2000
Instituto de Física de Cantabria
2000
Universidad de Cantabria
2000
Children's Defense Fund
2000
Rockefeller University
2000
The accretion of matter onto a massive black hole is believed to feed the relativistic plasma jets found in many active galactic nuclei (AGN). Although some AGN accelerate particles energies exceeding 10^12 electron Volts (eV) and are bright sources very-high-energy (VHE) gamma-ray emission, it not yet known where VHE emission originates. Here we report on radio observations galaxy M87, revealing period extremely strong flares accompanied by increase flux from its nucleus. These results...
This detection constrains the mechanism and emission region of gamma-ray radiation in pulsar’s magnetosphere.
We report the discovery of TeV gamma-ray emission from Type Ia supernova remnant (SNR) G120.1+1.4, known as Tycho's remnant. Observations performed in period 2008-2010 with VERITAS ground-based observatory reveal weak coming direction remnant, compatible a point source located at $00^{\rm h} \ 25^{\rm m} 27.0^{\rm s},\ +64^{\circ} 10^{\prime} 50^{\prime\prime}$ (J2000). The photon spectrum measured by can be described power-law $dN/dE = C(E/3.42\;\textrm{TeV})^{-\Gamma}$ $\Gamma 1.95 \pm...
LS I +61 303 is one of only a few high-mass X-ray binaries currently detected at high significance in very energy gamma-rays. The system was observed over several orbital cycles (between September 2006 and February 2007) with the VERITAS array imaging air-Cherenkov telescopes. A signal gamma-rays energies above 300 GeV found statistical 8.4 standard deviations. flux measured to be strongly variable; maximum during most apastron. spectrum for period emission can characterized by power law...
We report a possible detection of TeV gamma-rays from the Galactic Center by Whipple 10m gamma-ray telescope. Twenty-six hours data were taken over an extended period 1995 through 2003 resulting in total significance 3.7 standard deviations. The measured excess corresponds to integral flux \Flux above energy $2.8 \mathrm{TeV}$, roughly 40% Crab Nebula at this energy. 95% confidence region has angular extent about 15 arcmin and includes position Sgr A*. is consistent with point source shows...
Observations of radio halos and relics in galaxy clusters indicate efficient electron acceleration. Protons should likewise be accelerated and, on account weak energy losses, can accumulate, suggesting that may also sources very high (VHE; E > 100 GeV) gamma-ray emission. We report here VHE observations the Coma cluster with VERITAS array imaging Cerenkov telescopes, complementing Fermi Large Area Telescope at GeV energies. No significant emission from Cluster was detected. Integral flux...
The VERITAS array of Cherenkov telescopes has carried out a deep observational program on the nearby dwarf spheroidal galaxy Segue 1. We report results nearly 48 hours good quality selected data, taken between January 2010 and May 2011. No significant $\ensuremath{\gamma}$-ray emission is detected at nominal position 1, upper limits integrated flux are derived. According to recent studies, 1 most dark matter-dominated currently known. derive stringent bounds various annihilating decaying...
We report on the detection of a very rapid TeV gamma-ray flare from BL Lacertae 2011 June 28 with Very Energetic Radiation Imaging Telescope Array System (VERITAS). The flaring activity was observed during 34.6-minute exposure, when integral flux above 200 GeV reached $(3.4\pm0.6) \times 10^{-6} \;\text{photons}\;\text{m}^{-2}\text{s}^{-1}$, roughly 125% Crab Nebula measured by VERITAS. light curve indicates that observations missed rising phase but covered significant portion decaying...
Outbursts from gamma-ray quasars provide insights on the relativistic jets of active galactic nuclei and constraints diffuse radiation fields that fill universe. The detection significant emission above 100 GeV a distant quasar would show some radiated gamma-rays escape pair-production interactions with low-energy photons, be it extragalactic background light (EBL), or near supermassive black hole lying at jet's base. VERITAS detected up to ∼200 PKS 1441+25 (z = 0.939) during 2015 April,...
The high-frequency-peaked BL Lacertae object 1ES 0229+200 is a relatively distant (z = 0.1396), hard-spectrum (Gamma ~ 2.5), very-high-energy-emitting (E > 100 GeV) gamma-ray blazar. Very-high-energy measurements of this active galactic nucleus have been used to place constraints on the intensity extragalactic background light and intergalactic magnetic field. A multi-wavelength study centered around very-high-energy observations by VERITAS presented. This obtained, over period three years,...
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...
The Galactic Center (GC) region hosts a variety of powerful astronomical sources and rare astrophysical processes that emit large flux non-thermal radiation. inner 375 pc x 600 region, called the Central Molecular Zone, is home to supermassive black hole Sagittarius A*, massive cloud complexes, particle accelerators such as supernova remnants. We present results our improved analysis very-high-energy (VHE) gamma-ray emission above 2 TeV from GC using 125 hours data taken with VERITAS...
The multiwavelength observation of the nearby radio galaxy M87 provides a unique opportunity to study in detail processes occurring active galactic nuclei from waves TeV γ-rays. Here we report detection γ-ray emission above 250 GeV spring 2007 with VERITAS atmospheric Cerenkov telescope array and discuss its correlation X-ray emission. is measured be pointlike an intrinsic source radius less than 4.5'. differential energy spectrum fitted well by power-law function: dΦ/dE = (7.4 ± 1.3stat...
The intermediate-frequency peaked BL Lacertae (IBL) object 3C 66A is detected during 2007 - 2008 in VHE (very high energy: E > 100 GeV) gamma-rays with the VERITAS stereoscopic array of imaging atmospheric Cherenkov telescopes. An excess 1791 events detected, corresponding to a significance 21.2 standard deviations (sigma), these observations (32.8 hours live time). observed integral flux above 200 GeV 6% Crab Nebula's and shows evidence for variability on time-scale days. measured energy...
We report on observations of very high energy γ rays from the shell-type supernova remnant (SNR) Cassiopeia A with Very Energetic Radiation Imaging Telescope Array System stereoscopic array four imaging atmospheric Cherenkov telescopes in Arizona. The total exposure time for these is 22 hr, accumulated between September and November 2007. γ-ray source associated SNR was detected above 200 GeV a statistical significance 8.3σ. estimated integral flux this about 3% Crab-Nebula flux. photon...
We report the detection of very-high-energy (VHE) gamma-ray emission from supernova remnant (SNR) G106.3+2.7. Observations performed in 2008 with VERITAS atmospheric Cherenkov telescope resolve extended overlapping elongated radio SNR. The 7.3 sigma (pre-trials) has a full angular extent roughly 0.6deg by 0.4deg. Most notably, centroid VHE is centered near peak coincident 12CO (J = 1-0) emission, 0.4deg away pulsar PSR J2229+6114, situated at northern end Evidently current-epoch particles...
TeV J2032+4130 was the first unidentified source discovered at very high energies (VHE; E $>$ 100 GeV), with no obvious counterpart in any other wavelength. It is also extended to be observed VHE gamma rays. Following its discovery, intensive observational campaigns have been carried out all wavelengths order understand nature of object, which met limited success. We report here on a deep observation J2032+4130, based 48.2 hours data taken from 2009 2012 by VERITAS (Very Energetic Radiation...
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 very high energy (VHE) imaging of MGRO J2019+37 obtained with the VERITAS observatory. The bright extended ($\sim2^{\circ}$) unidentified Milagro source is located towards rich star formation region Cygnus-X. resolved into two sources. faint point-like VER J2016+371 overlaps CTB 87, a filled-center remnant (SNR) no evidence supernova shell at time. Its spectrum well fit in $0.65 - 10$ TeV range by power-law model photon index $2.3\pm0.4$. J2019+368 ($\sim1^{\circ}$) source, that...
We present a search for magnetically broadened gamma-ray emission around active galactic nuclei (AGNs), using VERITAS observations of seven hard-spectrum blazars. A cascade process occurs when multi-TeV gamma-rays from an AGN interact with extragalactic background light (EBL) photons to produce electron–positron pairs, which then cosmic microwave via inverse-Compton scattering gamma-rays. Due the deflection non-zero intergalactic magnetic field (IGMF) would potentially detectable effects on...
Cosmic-ray electrons and positrons (CREs) at GeV-TeV energies are a unique probe of our local Galactic neighborhood. CREs lose energy rapidly via synchrotron radiation inverse-Compton scattering processes while propagating within the Galaxy, these losses limit their propagation distance. For with TeV energies, is on order kiloparsec. Within that distance, there only few known astrophysical objects capable accelerating to such high energies. It also possible products annihilation or decay...
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...
Abstract Dark matter is a key piece of the current cosmological scenario, with weakly interacting massive particles (WIMPs) leading dark candidate. WIMPs have not been detected in their conventional parameter space (100 GeV ≲ M χ 100 TeV), mass range accessible Imaging Atmospheric Cherenkov Telescopes. As ultraheavy (UHDM; ≳ TeV) has suggested as an underexplored alternative to WIMP paradigm, we search for indirect annihilation signal higher (up 30 PeV) VERITAS γ -ray observatory. With 216...