A5100420649- Gamma-ray bursts and supernovae
- Astrophysics and Cosmic Phenomena
- Pulsars and Gravitational Waves Research
- Astrophysical Phenomena and Observations
- Astro and Planetary Science
- Astronomy and Astrophysical Research
- Stellar, planetary, and galactic studies
- Dark Matter and Cosmic Phenomena
- Radio Astronomy Observations and Technology
- Astronomical Observations and Instrumentation
- Galaxies: Formation, Evolution, Phenomena
- Particle Detector Development and Performance
- Nuclear Physics and Applications
- Magnetic properties of thin films
- Neutrino Physics Research
- Physics of Superconductivity and Magnetism
- SAS software applications and methods
- Particle physics theoretical and experimental studies
- Solar and Space Plasma Dynamics
- Advanced Condensed Matter Physics
- Radio Frequency Integrated Circuit Design
- Mobile Ad Hoc Networks
- Advancements in Semiconductor Devices and Circuit Design
- Ionosphere and magnetosphere dynamics
- Superconductivity in MgB2 and Alloys
International Center for Relativistic Astrophysics
2018-2024
Guangxi University
2011-2024
Collurania Teramo Observatory
2020-2023
Sapienza University of Rome
1990-2023
AlbaNova
2014-2021
KTH Royal Institute of Technology
1991-2021
Stockholm University
2014-2021
National Institute for Astrophysics
2016-2021
Chinese Academy of Sciences
1991-2019
Purple Mountain Observatory
2018-2019
We present the third Fermi Large Area Telescope (LAT) source catalog (3FGL) of sources in 100 MeV–300 GeV range. Based on first 4 yr science data from Gamma-ray Space mission, it is deepest yet this energy Relative to Second LAT catalog, 3FGL incorporates twice as much data, well a number analysis improvements, including improved calibrations at event reconstruction level, an updated model for Galactic diffuse γ-ray emission, refined procedure detection, and methods associating with...
The dwarf spheroidal satellite galaxies (dSphs) of the Milky Way are some most dark matter (DM) dominated objects known. We report on gamma-ray observations dSphs based 6 years Fermi Large Area Telescope data processed with new Pass 8 event-level analysis. None significantly detected in gamma rays, and we present upper limits DM annihilation cross section from a combined analysis 15 dSphs. These constraints among strongest robust to date lie below canonical thermal relic for mass $\lesssim$...
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 third catalog of active galactic nuclei (AGNs) detected by the Fermi-LAT (3LAC) is presented. It based on (3FGL) sources between 100 MeV and 300 GeV with a Test Statistic (TS) greater than 25, 2008 August 4 2012 July 31. 3LAC includes 1591 AGNs located at high Galactic latitudes (|b|>10{\deg}), 71% increase over second 2 years data. There are 28 duplicate associations, thus 1563 2192 high-latitude gamma-ray 3FGL AGNs. Most them (98%) blazars. About half newly blazars unknown type, i.e.,...
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...
Dark matter in the Milky Way may annihilate directly into gamma rays, producing a monoenergetic spectral line. Therefore, detecting such signature would be strong evidence for dark annihilation or decay. We search lines Fermi Large Area Telescope observations of halo energy range 200 MeV to 500 GeV using analysis methods from our most recent line searches. The main improvements relative previous works are use 5.8 years data reprocessed with Pass 8 event-level and additional resulting...
We present a catalog of sources detected above 50 GeV by the {\it Fermi}-Large Area Telescope (LAT) in 80 months data. The newly delivered Pass 8 event-level analysis allows detection and characterization GeV--2 TeV energy range. In this band, Fermi}-LAT has 360 sources, which constitute second hard (2FHL). improved angular resolution enables precise localization point ($\sim$1.7$'$ radius at 68 % C.~L.) spatially extended sources. find that 86 can be associated with counterparts other...
ABSTRACT Most of the celestial γ rays detected by Large Area Telescope (LAT) on board Fermi Gamma-ray Space originate from interstellar medium when energetic cosmic interact with nucleons and photons. Conventional point-source extended-source studies rely modeling this diffuse emission for accurate characterization. Here, we describe development Galactic Interstellar Emission Model (GIEM), which is standard adopted LAT Collaboration publicly available. This model based a linear combination...
We report on the search for spectral irregularities induced by oscillations between photons and axionlike-particles (ALPs) in γ-ray spectrum of NGC 1275, central galaxy Perseus cluster. Using 6 years Fermi Large Area Telescope data, we find no evidence ALPs exclude couplings above 5×10^{-12} GeV^{-1} ALP masses 0.5≲m_{a}≲5 neV at 95% confidence. The limits are competitive with sensitivity planned laboratory experiments, and, together other bounds, strongly constrain possibility that can...
We report for the first time a gamma-ray and multi-wavelength nearly-periodic oscillation in an active galactic nucleus. Using Fermi Large Area Telescope (LAT) we have discovered apparent quasi-periodicity flux (E >100 MeV) from GeV/TeV BL Lac object PG 1553+113. The marginal significance of 2.18 +/-0.08 year-period cycle is strengthened by correlated oscillations observed radio optical fluxes, through data collected OVRO, Tuorla, KAIT, CSS monitoring programs Swift UVOT. appearing ~10 years...
The Fermi Large Area Telescope (LAT) Collaboration has recently released a catalog of 360 sources detected above 50 GeV (2FHL). This was obtained using 80 months data re-processed with Pass 8, the newest event-level analysis, which significantly improves acceptance and angular resolution instrument. Most 2FHL at high Galactic latitude are blazars. Using detailed Monte Carlo simulations, we measure, for first time, source count distribution, dN/dS, extragalactic γ-ray E>50 find that it is...
ABSTRACT To uniformly determine the properties of supernova remnants (SNRs) at high energies, we have developed first systematic survey energies from 1 to 100 GeV using data Fermi Large Area Telescope (LAT). Based on spatial overlap sources detected with SNRs known radio surveys, classify 30 as likely SNRs. We also report 14 marginal associations and 245 flux upper limits. A mock catalog in which positions are scrambled Galactic longitude allows us an limit 22% number candidates falsely...
The external forward shock (EFS) models have been the standard paradigm to interpret broad-band afterglow data of gamma-ray bursts (GRBs). One prediction is that some temporal breaks at different energy bands should be achromatic. Observations in Swift era revealed chromatic behaviors least GRBs, casting doubts on EFS origin GRB afterglows. In this paper, we perform a systematic study address question: how bad/good are models? Our sample includes 85 GRBs well-monitored X-ray and optical...
Well-sampled optical lightcurves of 146 gamma-ray bursts (GRBs) are compiled from the literature. By empirical fitting we identify eight possible emission components and summarize results in a "synthetic" lightcurve. Both flare early shallow-decay likely related to long-term central engine activities. We focus on their statistical properties this paper. Twenty-four flares obtained 19 GRBs. The isotropic R-band energy is smaller than 1% $E_{\gamma, \rm iso}$. relation between luminosities...
We continue our systematic statistical study of various components gamma-ray burst (GRB) optical light curves. decompose the early onset bump and late re-brightening with empirical fits analyze their properties. Among 146 GRBs that have well-sampled curves, bumps are observed in 38 26 GRBs, respectively. It is found typical rising decaying slopes for both ∼1.5 ∼ − 1.15, No X-ray band detected to be associated bumps, while an half bumps. The peak luminosity anti-correlated time Both Lp...
ABSTRACT We present results from γ -ray observations of the Coma cluster incorporating six years Fermi -LAT data and newly released “Pass 8” event-level analysis. Our analysis region reveals low-significance residual structures within virial radius that are too faint for a detailed investigation with current data. Using likelihood approach is free assumptions on spectral shape we derive upper limits flux expected energetic particle interactions in cluster. also consider benchmark spatial...
A new synthesis route has been applied to obtain . Instead of the conventional high‐temperature technique leading crystalline form, a solution producing amorphous form used. This material, after dehydration, shows an electrochemical performance exceeding that one. The rationale for this behavior mainly lies in microscopic factors, i.e., possibility unit cell insert up 9 Li+, instead six Furthermore, absence long‐range crystallographic order reduces length pathways through which Li+ ions...
The nearby Large Magellanic Cloud (LMC) provides a rare opportunity of spatially resolved view an external star-forming galaxy in gamma-rays. LMC was detected at 0.1-100GeV as extended source with CGRO/EGRET and using early observations the Fermi-LAT. emission found to correlate massive regions be particularly bright towards 30 Doradus. Studies origin transport cosmic rays (CRs) Milky Way are frequently hampered by line-of-sight confusion poor distance determination. offers complementary way...
ABSTRACT The Fermi Large Area Telescope (LAT) has an instantaneous field of view (FoV) covering <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mo>∼</mml:mo> <mml:mn>1</mml:mn> <mml:mrow> <mml:mo stretchy="true">/</mml:mo> </mml:mrow> <mml:mn>5</mml:mn> </mml:math> the sky and it completes a survey entire in high-energy gamma-rays every 3 hr. It enables searches for transient phenomena over timescales from milliseconds to years. Among these could be...
ABSTRACT We report the Fermi Large Area Telescope detection of extended γ -ray emission from lobes radio galaxy Fornax A using 6.1 years Pass 8 data. After Centaurus A, this is now second example an source attributed to a galaxy. Both flat disk morphology and following were preferred over point-source description, core contribution was constrained be <?CDATA $\lt 14$?> % total flux. alignment elongation with demonstrated by rotating template. found no significant evidence for variability on...
Galaxy clusters are one of the prime sites to search for dark matter (DM) annihilation signals. Depending on substructure DM halo a galaxy cluster and cross sections channels, these signals might be detectable by latest generation $\gamma$-ray telescopes. Here we use three years Fermi Large Area Telescope (LAT) data, which most suitable searching very extended emission in vicinity nearby Virgo cluster. Our analysis reveals statistically significant can well characterized uniformly emitting...
Abstract Gamma-ray bursts (GRBs) are fascinating events due to their panchromatic nature. We study optical plateaus in GRB afterglows via an extended search into archival data. comprehensively analyze all published GRBs with known redshifts and observed by many ground-based telescopes (e.g., Subaru Telescope, RATIR) around the world several space-based observatories such as Neil Gehrels Swift Observatory. fit 500 light curves, showing existence of plateau 179 cases. This sample is 75% larger...
The central engine of gamma-ray bursts (GRBs) is poorly constrained. There exist two main candidates: a fast-rotating black hole and rapidly spinning magnetar. Furthermore, the X-ray plateaus are widely accepted by energy injection into external shock. In this paper, we systematically analyze \emph{Swift}/XRT light curves 101 GRBs having plateau phases known redshifts (before May 2017). Since maximum budget ($\sim2\times10^{52}$ erg) exists for magnetars but not hole, provides good clue to...
ABSTRACT We present the largest optical photometry compilation of gamma-ray bursts (GRBs) with redshifts (z). include 64813 observations 535 events (including upper limits) from 28 February 1997 to 18 August 2023. also a user-friendly web tool grbLC which allows users visualize photometry, coordinates, redshift, host galaxy extinction, and spectral indices for each event in our database. Furthermore, we have added Gamma-ray Coordinate Network (GCN) scraper that can be used collect data by...
Pulsars are rapidly spinning, highly magnetized neutron stars, created in the gravitational collapse of massive stars. We report detection pulsed giga-electron volt gamma rays from young pulsar PSR J0540-6919 Large Magellanic Cloud, a satellite galaxy Milky Way. This is first gamma-ray detected another galaxy. It has most luminous emission yet observed, exceeding Crab pulsar's by factor 20. presents an extreme test case for understanding structure and evolution star magnetospheres.