M. K. Daniel
A5024168359- Astrophysics and Cosmic Phenomena
- Gamma-ray bursts and supernovae
- Dark Matter and Cosmic Phenomena
- Particle Detector Development and Performance
- Astrophysical Phenomena and Observations
- Radio Astronomy Observations and Technology
- Neutrino Physics Research
- Particle physics theoretical and experimental studies
- Pulsars and Gravitational Waves Research
- Cosmology and Gravitation Theories
- Radiation Detection and Scintillator Technologies
- Particle Accelerators and Free-Electron Lasers
- Black Holes and Theoretical Physics
- Astronomical Observations and Instrumentation
- Quantum Chromodynamics and Particle Interactions
- Astronomy and Astrophysical Research
- Stellar, planetary, and galactic studies
- Noncommutative and Quantum Gravity Theories
- Geophysics and Gravity Measurements
- Astrophysics and Star Formation Studies
- Galaxies: Formation, Evolution, Phenomena
- Atomic and Subatomic Physics Research
- Atmospheric Ozone and Climate
- Radiation Therapy and Dosimetry
- Photocathodes and Microchannel Plates
University of Houston
2023-2024
Center for Astrophysics Harvard & Smithsonian
2017-2023
Pacific University Oregon
2023
Universidade Federal de Mato Grosso do Sul
2023
Lone Star College Kingwood
2023
Nova Southeastern University
2022
HCA Healthcare
2022
Centro de Investigaciones Energéticas, Medioambientales y Tecnológicas
2009-2021
Mount Washington Observatory
2018-2020
Universidad Veritas
2019
The measurement of an excess in the cosmic-ray electron spectrum between 300 and 800 GeV by ATIC experiment has - together with PAMELA detection a rise positron fraction up to 100 motivated many interpretations terms dark matter scenarios; alternative explanations assume nearby source like pulsar or supernova remnant. Here we present H.E.S.S. starting at 340 GeV. While overall flux measured is consistent data within statistical systematic errors, exclude pronounced peak as suggested for...
A search for a very-high-energy (VHE; ≥100 GeV) γ-ray signal from self-annihilating particle dark matter (DM) is performed towards region of projected distance r∼45-150 pc the Galactic center. The background-subtracted spectrum measured with High Energy Stereoscopic System (H.E.S.S.) instrument in energy range between 300 GeV and 30 TeV shows no hint residual flux. Assuming conventional Navarro-Frenk-White Einasto density profiles, limits are derived on velocity-weighted annihilation cross...
Gamma-ray line signatures can be expected in the very-high-energy (${E}_{\ensuremath{\gamma}}>100\text{ }\text{ }\mathrm{GeV}$) domain due to self-annihilation or decay of dark matter (DM) particles space. Such a signal would readily distinguishable from astrophysical $\ensuremath{\gamma}$-ray sources that most cases produce continuous spectra span over several orders magnitude energy. Using data collected with H.E.S.S. instrument, upper limits on linelike emission are obtained energy range...
The long gamma-ray burst (GRB) 100621A, at the time brightest X-ray transient ever detected by Swift-XRT in $0.3\textrm{--}10$ keV range, has been observed with H.E.S.S. imaging air Cherenkov telescope array, sensitive to gamma radiation very-high-energy (VHE, $>100$ GeV) regime. Due its relatively small redshift of $z\sim0.5$, favourable position southern sky and short follow-up ($<700 \rm{s}$ after satellite trigger) observations, this GRB could be within sensitivity reach instrument....
We provide an updated assessment of the power Cherenkov Telescope Array (CTA) to search for thermally produced dark matter at TeV scale, via associated gamma-ray signal from pair-annihilating particles in region around Galactic centre. find that CTA will open a new window discovery potential, significantly extending range robustly testable models given standard cuspy profile density distribution. Importantly, even cored profile, projected sensitivity be sufficient probe various...
The appropriate language for describing the pure Yang-Mills theories is introduced. An elementary but precise presentation of mathematical tools which are necessary a geometrical description gauge fields given. After recalling basic notions differential geometry, it shown in what sense potential connection some fiber bundle, and corresponding field associated curvature. It also how global aspects theory (e.g., boundary conditions) coded into structure bundle. Gauge transformations equations...
We report the discovery of faint very high energy (VHE; E > 100 GeV) γ-ray emission from radio galaxy Centaurus A in observations performed with High Energy Stereoscopic System (H.E.S.S.) experiment, an imaging atmospheric Cherenkov telescope array consisting four telescopes located Namibia. has been observed for more than 120 hr. signal a statistical significance 5.0σ is detected region including core and inner kpc jets. The integral flux above threshold ∼250 GeV measured to be 0.8% Crab...
We report results from an intensive multiwavelength monitoring campaign on the TeV blazar Mrk 421 over period of 2003-2004. The source was observed simultaneously at energies with Whipple 10 m telescope and X-ray Rossi X-Ray Timing Explorer (RXTE) during each clear night within observing windows. Supporting observations were also frequently carried out optical radio wavelengths to provide simultaneous or contemporaneous coverages. large amount data has allowed us examine variability in...
Starburst galaxies exhibit in their central regions a highly increased rate of supernovae, the remnants which are thought to accelerate energetic cosmic rays up energies ~ 10^15 eV. We report detection gamma -- tracers such from starburst galaxy NGC 253 using H.E.S.S. array imaging atmospheric Cherenkov telescopes. The gamma-ray flux above 220 GeV is F = (5.5 +/- 1.0stat 2.8sys) x 10^-13 ph. s-1 cm-2, implying cosmic-ray density about three orders magnitude larger than that center Milky Way....
The extragalactic background light (EBL) is the diffuse radiation with second highest energy density in Universe after cosmic microwave background. aim of this study measurement imprint EBL opacity to γ-rays on spectra brightest sources detected High Energy Stereoscopic System (H.E.S.S.). originality method lies joint fit optical depth and intrinsic sources, assuming smoothness. Analysis a total ~105γ-ray events enables detection an signature at 8.8σ level constitutes first using very-high...
Dwarf spheroidal (dSph) galaxies are prime targets for present and future γ-ray telescopes hunting indirect signals of particle dark matter. The interpretation the data requires careful assessment their matter content in order to derive robust constraints on candidate relic particles. Here, we use an optimized spherical Jeans analysis reconstruct 'astrophysical factor' both annihilating decaying 21 known dSphs. Improvements with respect previous works are: (i) more flexible luminosity...
The giant radio galaxy M 87 with its proximity (16 Mpc), famous jet, and very massive black hole ((3 − 6) × 109 M☉) provides a unique opportunity to investigate the origin of high energy (VHE; E > 100 GeV) γ-ray emission generated in relativistic outflows surroundings supermassive holes. has been established as VHE emitter since 2006. displays strong variability on timescales short day. In this paper, results from joint monitoring campaign by MAGIC VERITAS instruments 2010 are reported....
We report on the first simultaneous observations that cover optical, X-ray, and high-energy gamma-ray bands of BL Lac object PKS 2155−304. The were observed for 11 days, between 2008 August 25 September 6 (MJD 54704−54715), jointly with Fermi Gamma-ray Space Telescope HESS atmospheric Cherenkov array, providing MeV–TeV spectral energy distribution (SED) new generation γ-ray telescopes. ATOM telescope RXTE Swift observatories provided optical X-ray coverage low-energy component over same time...
Axionlike particles (ALPs) are hypothetical light (sub-eV) bosons predicted in some extensions of the Standard Model particle physics. In astrophysical environments comprising high-energy gamma rays and turbulent magnetic fields, existence ALPs can modify energy spectrum for a sufficiently large coupling between photons. This modification would take form an irregular behavior limited range. Data from H.E.S.S. observations distant BL Lac object PKS 2155-304 (z = 0.116) used to derive upper...
The Cherenkov Telescope Array (CTA) is a project for next-generation observatory very high energy (GeV-TeV) ground-based gamma-ray astronomy, currently in its design phase, and foreseen to be operative few years from now. Several tens of telescopes 2-3 different sizes, distributed over large area, will allow sensitivity about factor 10 better than current instruments such as H.E.S.S, MAGIC VERITAS, an coverage GeV several TeV, field view up deg. In the following study, we investigate...
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 present evidence that the very high energy (VHE, E > 100 GeV) gamma-ray emission coincident with supernova remnant IC 443 is extended. contains one of best studied sites remnant/molecular cloud interaction and pulsar wind nebula CXOU J061705.3+222127, both which are important targets for VHE observations. VERITAS observed 37.9 hr during 2007 detected above 300 GeV an excess 247 events, resulting in a significance 8.3 standard deviations (σ) before trials 7.5σ after point-source search....
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...
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...
<i>Aims. <i/>A detailed study of the spectrum and variability source HESS J1745-290 in Galactic Center (GC) region using new data from H.E.S.S. array Cherenkov telescopes is presented. Flaring activity quasi periodic oscillations (QPO) are investigated.<i>Methods. <i/>The image analysis performed with a combination semi-analytical shower model statistical moment-based Hillas technique. The lightcurves derived likelihood method based on spectral shape hypothesis. Rayleigh tests Fourier GC...
<i>Aims. <i/>Recent theoretical predictions of the lowest very high energy (VHE) luminosity SN 1006 are only a factor 5 below previously published HESS upper limit, thus motivating further in-depth observations this source.<i>Methods. <i/>Deep at VHE energies (above 100 GeV) were carried out with stereoscopic system (HESS) Cherenkov Telescopes from 2003 to 2008. More than h data have been collected and subjected an improved analysis procedure.<i>Results. <i/>Observations resulted in...