A5089358809- Astrophysics and Cosmic Phenomena
- Gamma-ray bursts and supernovae
- Radio Astronomy Observations and Technology
- Dark Matter and Cosmic Phenomena
- Particle Detector Development and Performance
- Neutrino Physics Research
- Astrophysical Phenomena and Observations
- Radiation Detection and Scintillator Technologies
- Pulsars and Gravitational Waves Research
- Stellar, planetary, and galactic studies
- Particle Accelerators and Free-Electron Lasers
- COVID-19 diagnosis using AI
- Particle physics theoretical and experimental studies
- Micro and Nano Robotics
- Photocathodes and Microchannel Plates
- Modular Robots and Swarm Intelligence
- Superconducting Materials and Applications
- Solar and Space Plasma Dynamics
- Astrophysics and Star Formation Studies
- Cosmology and Gravitation Theories
- Adaptive optics and wavefront sensing
- Soft Robotics and Applications
- Astro and Planetary Science
- Astronomical Observations and Instrumentation
- Advanced Optical Sensing Technologies
Cornell University
2022
University of Minnesota
2020-2021
University of Minnesota System
2021
The Open University
2021
Deutsches Elektronen-Synchrotron DESY
2021
Istituto Nazionale di Fisica Nucleare, Sezione di Bari
2019-2020
Universidad Veritas
2020
University of Iowa
2016-2020
Istituto Nazionale di Fisica Nucleare, Sezione di Perugia
2020
University of Utah
2019
We present constraints on the annihilation cross section of weakly interacting massive particles dark matter based joint statistical analysis four dwarf galaxies with VERITAS. These results are derived from an optimized photon weighting technique that improves standard imaging atmospheric Cherenkov telescope (IACT) analyses by utilizing spectral and spatial properties individual events. report $\ensuremath{\sim}230$ hours observations five galaxies. find no evidence gamma-ray emission any...
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 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 On 2017 September 22, the IceCube Neutrino Observatory reported detection of high-energy neutrino event IC 170922A, potential astrophysical origin. It was soon determined that direction consistent with location gamma-ray blazar TXS 0506+056 (3FGL J0509.4+0541), which in an elevated emission state as measured by Fermi satellite. Very Energetic Radiation Imaging Telescope Array System (VERITAS) observations neutrino/blazar region started on 23 response to alert and continued through...
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 radio source 3C 264, hosted by the giant elliptical galaxy NGC 3862, was observed with Very Energetic Radiation Imaging Telescope Array System (VERITAS) between 2017 February and 2019 May. These deep observations resulted in discovery of very high energy (VHE; E > 100 GeV) γ -ray emission from this active galaxy. An analysis ∼57 hr quality-selected live time yields a detection at position source, corresponding to statistical significance 7.8 standard deviations above...
Combined with very-long-baseline interferometry measurements, the observations of fast TeV gamma-ray flares probe structure and emission mechanism blazar jets. However, only a handful such have been detected to date, within last few years these observed from lower-frequency-peaked BL~Lac objects flat-spectrum radio quasars. We report on flare BL~Lacertae by VERITAS, rise time $\sim$2.3~hr decay $\sim$36~min. The peak flux above 200 GeV is $(4.2 \pm 0.6) \times 10^{-6} \;\text{photon}...
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...
We present a new measurement of the energy spectrum iron nuclei in cosmic rays from 20 to 500 TeV. The makes use template-based analysis method, which, for first time, is applied reconstruction iron-induced air showers recorded by VERITAS array imaging atmospheric Cherenkov telescopes. event selection direct light which emitted charged particles before interaction, as well other parameters related shape shower images. measured described power law $\frac{\mathrm{d} F}{\mathrm{d} E}=f_0\cdot...
Abstract The extragalactic background light (EBL), a diffuse photon field in the optical and infrared range, is record of radiative processes over universe’s history. Spectral measurements blazars at very high energies (>100 GeV) enable reconstruction spectral energy distribution (SED) EBL, as blazar spectra are modified by redshift- energy-dependent interactions gamma-ray photons with EBL. 14 VERITAS-detected included new measurement EBL SED that independent models. resulting covers an...
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 We conduct a search for periodic emission in the very high-energy (VHE) gamma-ray band ( E > 100 GeV) from total of 13 pulsars an archival VERITAS data set with exposure over 450 hr. The includes many brightest young visible Northern Hemisphere. analysis resulted nondetections pulsed VHE gamma-rays each pulsar. Upper limits on potential flux are derived at 95% confidence level above three energy thresholds using two methods. These first such searches pulsars, and obtained...
We report on the search for very-high-energy gamma-ray emission from regions around three nearby supersonic pulsars (PSR B0355+54, PSR J0357+3205 and J1740+1000) that exhibit long X-ray tails. To date there is no clear detection of TeV any pulsar tail prominent in or radio. provide upper limits flux, luminosity, also compare these with other wind nebulae detected X-rays model predictions. find at least one tails likely to be observations are a factor 2-3 more sensitive. The analysis...
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 Transient X-ray binaries produce major outbursts in which the flux can increase over quiescent level by factors as large 10 7 . The low-mass binary V 404 Cyg and high-mass system 4U 0115+634 underwent such 2015 June October, respectively. We present here observations at energies above hundreds of GeV with VERITAS observatory taken during some brightest activity ever observed from these systems. No gamma-ray emission has been detected 2.5 hr microquasar 2015, 20–21. upper limits...
Very-high-energy (VHE; $>$ 100 GeV) gamma-ray emission from the blazar RGB J2243+203 was discovered with VERITAS Cherenkov telescope array, during period between 21 and 24 December 2014. The energy spectrum this source can be fit by a power law photon index of $4.6 \pm 0.5$, flux normalization at 0.15 TeV $(6.3 1.1) \times 10^{-10} ~ \textrm{cm}^{-2} \textrm{s}^{-1} \textrm{TeV}^{-1}$. integrated \textit{Fermi}-LAT 1 GeV to detection is $(4.1 0.8) 10^{\textrm{-8}}...
On 2015 March 23, VERITAS responded to a $Swift$-BAT detection of gamma-ray burst, with observations beginning 270 seconds after the onset BAT emission, and only 135 main emission peak. No statistically significant signal is detected above 140 GeV. The upper limit on fluence in 40 minute integration corresponds about 1% prompt fluence. Our particularly since very-high-energy (VHE) observation started $\sim$2 minutes peaked, $Fermi$-LAT numerous other bursts have revealed that high-energy...