W. Mitthumsiri
A5020228639- Astrophysics and Cosmic Phenomena
- Gamma-ray bursts and supernovae
- Dark Matter and Cosmic Phenomena
- Pulsars and Gravitational Waves Research
- Radio Astronomy Observations and Technology
- Astrophysical Phenomena and Observations
- Solar and Space Plasma Dynamics
- Particle Detector Development and Performance
- Neutrino Physics Research
- Particle physics theoretical and experimental studies
- Ionosphere and magnetosphere dynamics
- Astronomical Observations and Instrumentation
- Nuclear Physics and Applications
- Astronomy and Astrophysical Research
- Galaxies: Formation, Evolution, Phenomena
- Atomic and Molecular Physics
- Cosmology and Gravitation Theories
- Plasma Diagnostics and Applications
- Laser-induced spectroscopy and plasma
- Radiation Therapy and Dosimetry
- Radiation Detection and Scintillator Technologies
- Particle Accelerators and Free-Electron Lasers
- Stellar, planetary, and galactic studies
- Atomic and Subatomic Physics Research
- Astrophysics and Star Formation Studies
Mahidol University
2016-2025
Rajamangala University of Technology
2021-2023
National Astronomical Research Institute of Thailand
2021-2023
University of Delaware
2017-2023
High Altitude Observatory
2023
Ubon Ratchathani University
2017-2021
National Electronics and Computer Technology Center
2021
Chiang Mai University
2021
Kasetsart University
2021
Nanjing University
2021
The γ-ray sky can be decomposed into individually detected sources, diffuse emission attributed to the interactions of Galactic cosmic rays with gas and radiation fields, a residual all-sky component commonly called isotropic background (IGRB). IGRB comprises all extragalactic emissions too faint or resolved in given survey, as well any foregrounds that are approximately isotropic. first measurement Large Area Telescope (LAT) on board Fermi Gamma-ray Space (Fermi) used 10 months sky-survey...
The gamma-ray sky >100 MeV is dominated by the diffuse emissions from interactions of cosmic rays with interstellar gas and radiation fields Milky Way. Observations these provide a tool to study cosmic-ray origin propagation, medium. We present measurements first 21 months Fermi-LAT mission compare models emission generated using GALPROP code. are fitted data incorporate astrophysical input for distribution sources, fields. To assess uncertainties associated input, grid created varying...
We measured separate cosmic-ray electron and positron spectra with the Fermi Large Area Telescope. Because instrument does not have an onboard magnet, we distinguish two species by exploiting Earth's shadow, which is offset in opposite directions for charges due to magnetic field. estimate subtract proton background using different methods that produce consistent results. report electron-only spectrum, positron-only fraction between 20 GeV 200 GeV. confirm rises energy 20-100 range. The...
Satellite galaxies of the Milky Way are among most promising targets for dark matter searches in gamma rays. We present a search consisting weakly interacting massive particles, applying joint likelihood analysis to 10 satellite with 24 months data Fermi Large Area Telescope. No signal is detected. Including uncertainty distribution, robust upper limits placed on annihilation cross sections. The 95% confidence level range from about 10(-26) cm3 s(-1) at 5 GeV 5×10(-23) 1 TeV, depending final...
The dwarf spheroidal satellite galaxies of the Milky Way are some most dark-matter-dominated objects known. Due to their proximity, high dark matter content, and lack astrophysical backgrounds, widely considered be among promising targets for indirect detection via $\ensuremath{\gamma}$ rays. Here we report on $\ensuremath{\gamma}$-ray observations 25 based 4 years Fermi Large Area Telescope (LAT) data. None significantly detected in rays, present flux upper limits between 500 MeV GeV. We...
The Fermi Large Area Telescope (LAT) has provided the most detailed view to date of emission towards Galactic centre (GC) in high-energy gamma-rays. This paper describes analysis data taken during first 62 months mission energy range 1-100 GeV from a $15^\circ \times 15^\circ$ region about direction GC, and implications for interstellar emissions produced by cosmic ray (CR) particles interacting with gas radiation fields inner Galaxy point sources detected. Specialised models (IEMs) are...
Abstract The region around the Galactic Center (GC) is now well established to be brighter at energies of a few GeV than what expected from conventional models diffuse gamma-ray emission and catalogs known sources. We study excess using 6.5 yr data Fermi Large Area Telescope. characterize uncertainty GC spectrum morphology due uncertainties in cosmic-ray source distributions propagation, distribution interstellar gas Milky Way, potential contribution bubbles. also evaluate properties...
We present an incremental version (4FGL-DR3, for Data Release 3) of the fourth Fermi-LAT catalog gamma-ray sources. Based on first twelve years science data in energy range from 50 MeV to 1 TeV, it contains 6658 The analysis improves that used 4FGL over eight data: more sources are fit with curved spectra, we introduce a robust spectral parameterization pulsars, and extend points TeV. parameters, distributions, associations updated all Light curves rebuilt yr intervals (not 2 month...
We present a catalog of sources detected above 10 GeV by the Fermi Large Area Telescope (LAT) in first 7 years data using Pass 8 event-level analysis. This is Third Catalog Hard Fermi-LAT Sources (3FHL), containing 1556 objects characterized - 2 TeV energy range. The sensitivity and angular resolution are improved factors 3 relative to previous LAT at same energies (1FHL). vast majority (79%) associated with extragalactic counterparts other wavelengths, including 16 located very high...
The Fermi bubbles are two large structures in the gamma-ray sky extending to 55° above and below Galactic center. We analyze 50 months of Large Area Telescope data between 100 MeV 500 GeV 10° latitude derive spectrum morphology bubbles. thoroughly explore systematic uncertainties that arise when modeling diffuse emission through separate approaches. is well described by either a log parabola or power law with an exponential cutoff. exclude simple more than 7σ significance. cutoff has index...
We report the discovery with Fermi/LAT of gamma-ray emission from three radio-loud narrow-line Seyfert 1 galaxies: PKS 1502+036 (z=0.409), 1H 0323+342 (z=0.061) and 2004-447 (z=0.24). In addition to PMN J0948+0022 (z=0.585), first source this type be detected in gamma rays, they may form an emerging new class active galactic nuclei (AGN). These findings can have strong implications on our knowledge about relativistic jets unified model AGN.
The origin of Galactic cosmic rays is a century-long puzzle. Indirect evidence points to their acceleration by supernova shockwaves, but we know little escape from the shock and evolution through turbulent medium surrounding massive stars. Gamma can probe spreading ambient gas radiation fields. Fermi Large Area Telescope (LAT) has observed star-forming region Cygnus X. 1- 100-gigaelectronvolt images reveal 50-parsec-wide cocoon freshly accelerated that flood cavities carved stellar winds...
Dark matter particle annihilation or decay can produce monochromatic gamma-ray lines and contribute to the diffuse background. Flux upper limits are presented for spectral from 7 200 GeV background 4.8 264 obtained two years of Fermi Large Area Telescope data integrated over most sky. We give cross-section lifetime lower dark models that spectrum, including proposed as explanations PAMELA cosmic-ray data.
Weakly interacting massive particles (WIMPs) are a theoretical class of that excellent dark matter candidates. WIMP annihilation or decay may produce essentially monochromatic γ rays detectable by the Fermi Large Area Telescope (LAT) against astrophysical γ-ray emission Galaxy. We have searched for spectral lines in energy range 5–300 GeV using 3.7 years data, reprocessed with updated instrument calibrations and an improved dispersion model compared to previous Fermi-LAT Collaboration line...
We present observations of the young supernova remnant (SNR) RX J1713.7−3946 with Fermi Large Area Telescope (LAT). clearly detect a source positionally coincident SNR. The is extended best-fit extension 055 ± 004 matching size non-thermal X-ray and TeV gamma-ray emission from remnant. positional coincidence allow us to identify LAT SNR J1713.7−3946. spectrum can be described by very hard power law photon index Γ = 1.5 0.1 that coincides in normalization steeper H.E.S.S.-detected at higher...
Abstract The Large Area Telescope (LAT) aboard the Fermi spacecraft routinely observes high-energy emission from gamma-ray bursts (GRBs). Here we present second catalog of LAT-detected GRBs, covering first 10 yr operations, 2008 to 2018 August 4. A total 186 GRBs are found; these, 91 show in range 30–100 MeV (17 which seen only this band) and 169 detected above 100 MeV. Most these sources were discovered by other instruments ( /GBM, Swift /BAT, AGILE, INTEGRAL ) or reported Interplanetary...
We present a measurement of the cosmic-ray electron+positron spectrum between 7 GeV and 2 TeV performed with almost seven years data collected Fermi Large Area Telescope. find that is well fit by broken power law break energy at about 50 GeV. Above GeV, described single spectral index $3.07 \pm 0.02 \; (\text{stat+syst}) 0.04 (\text{energy measurement})$. An exponential cutoff lower than 1.8 excluded 95\% CL.
We report on the gamma-ray activity of blazar Mrk 501 during first 480 days Fermi operation. find that average LAT spectrum can be well described by a single power-law function with photon index 1.78 +/- 0.03. While we observe relatively mild flux variations Fermi-LAT (within less than factor 2), detect remarkable spectral variability where hardest observed within energy range is 1.52 0.14, and softest one 2.51 0.20. These unexpected changes do not correlate measured above 0.3GeV. In this...
The first published Fermi large area telescope (Fermi-LAT) measurement of the isotropic diffuse gamma-ray emission is in good agreement with a single power law, and not showing any signature dominant contribution from dark matter sources energy range 20 to 100 GeV. We use absolute size spectral shape this measured flux derive cross section limits on three types generic candidates: annihilating into quarks, charged leptons monochromatic photons. Predicted fluxes are strongly affected by...
We report on the observations of 14 dwarf spheroidal galaxies with Fermi Gamma-Ray Space Telescope taken during first 11 months survey mode operations. The telescope provides a new opportunity to test particle dark matter models through expected gamma-ray emission produced by pair annihilation weakly interacting massive particles (WIMPs). Local Group galaxies, largest galactic substructures predicted cold scenario, are attractive targets for such indirect searches because they nearby and...
We report the detection of high-energy gamma-ray emission from two starburst galaxies using data obtained with Large Area Telescope on board Fermi Gamma-ray Space Telescope. Steady point-like above 200 MeV has been detected at significance levels 6.8 sigma and 4.8 respectively, sources positionally coincident locations M82 NGC 253. The total fluxes are consistent originating interaction cosmic rays local interstellar gas radiation fields constitute evidence for a link between massive star...
The flat-spectrum radio quasar 3C 454.3 underwent an extraordinary 5-day gamma-ray outburst in November 2010 where the daily flux measured with Fermi Large Area Telescope (LAT) at photon energies E>100 MeV reached (66+/-2) x 10^-6 ph cm^-2 s^-1. This is a factor of 3 higher than its previous maximum recorded December 2009 and ~5 times brighter Vela pulsar, which normally brightest source sky. 3-hr peak was (85+/-5) s^-1, corresponding to apparent isotropic luminosity 2.1+/-0.2 10^50 erg...
Dark matter (DM) particle annihilation or decay can produce monochromatic γ rays readily distinguishable from astrophysical sources. γ-ray line limits 30 to 200 GeV obtained 11 months of Fermi Large Area Space Telescope data 20–300 are presented using a selection based on requirements for analysis, and integrated over most the sky. We obtain flux upper in range 0.6–4.5×10−9 cm−2 s−1, give corresponding DM cross-section lifetime limits. Theoretical implications briefly discussed.Received 19...
We present detailed analysis of two gamma-ray sources, 1FGL J1801.3−2322c and J1800.5−2359c, that have been found toward the supernova remnant (SNR) W28 with Large Area Telescope (LAT) on board Fermi Gamma-ray Space Telescope. is to be an extended source within boundary SNR W28, extensively overlap TeV HESS J1801−233, which associated a dense molecular cloud interacting SNR. The spectrum measured LAT from 0.2 100 GeV can described by broken power-law function break at ∼1 photon indices 2.09...
Nearby clusters and groups of galaxies are potentially bright sources high-energy gamma-ray emission resulting from the pair-annihilation dark matter particles. However, no significant has been detected so far in first 11 months observations with Fermi Large Area Telescope. We interpret this non-detection terms constraints on particle properties. In particular for leptonic annihilation final states masses greater than ~200 GeV, inverse Compton scattering CMB photons is expected to dominate...