A5026039471- Gamma-ray bursts and supernovae
- Astrophysics and Cosmic Phenomena
- Astronomical Observations and Instrumentation
- Radio Astronomy Observations and Technology
- Astrophysical Phenomena and Observations
- Pulsars and Gravitational Waves Research
- Particle Detector Development and Performance
- SAS software applications and methods
- Dark Matter and Cosmic Phenomena
- Astronomy and Astrophysical Research
- Stellar, planetary, and galactic studies
- Neutrino Physics Research
- Astro and Planetary Science
- Geophysics and Gravity Measurements
- Solar and Space Plasma Dynamics
- Galaxies: Formation, Evolution, Phenomena
- Astrophysics and Star Formation Studies
- Calibration and Measurement Techniques
- Adaptive optics and wavefront sensing
- Particle Accelerators and Free-Electron Lasers
- Spectroscopy and Chemometric Analyses
- Planetary Science and Exploration
- Isotope Analysis in Ecology
- Historical Astronomy and Related Studies
- Particle physics theoretical and experimental studies
Bisei Astronomical Observatory
2019-2022
Hiroshima University
2011-2020
Tokyo Institute of Technology
2016-2020
University of Crete
2018
Goddard Space Flight Center
2018
University of Maryland, College Park
2018
Max Planck Institute for Radio Astronomy
2018
California Institute of Technology
2018
Institute for Space Astrophysics and Planetology
2018
High Energy Accelerator Research Organization
2001-2016
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.,...
We report on the first Fermi Large Area Telescope (LAT) measurements of so-called "extragalactic" diffuse gamma-ray emission (EGB). This component is generally considered to have an isotropic or nearly distribution sky with diverse contributions discussed in literature. The derivation EGB based detailed modeling bright foreground Galactic emission, detected LAT sources, and solar emission. find spectrum consistent a power law differential spectral index gamma = 2.41 +/- 0.05 intensity I(>100...
We present the first catalog of active galactic nuclei (AGNs) detected by Large Area Telescope (LAT), corresponding to 11 months data collected in scientific operation mode. The First LAT AGN Catalog (1LAC) includes 671 γ-ray sources located at high Galactic latitudes (|b|>10°) that are with a test statistic greater than 25 and associated statistically AGNs. Some multiple AGNs, consequently, 709 comprising 300 BL Lacertae objects, 296 flat-spectrum radio quasars, 41 AGNs other types, 72...
Merging neutron stars offer an exquisite laboratory for simultaneously studying strong-field gravity and matter in extreme environments. We establish the physical association of electromagnetic counterpart EM170817 to gravitational waves (GW170817) detected from merging stars. By synthesizing a panchromatic dataset, we demonstrate that are long-sought production site forging heavy elements by r-process nucleosynthesis. The weak gamma-rays seen dissimilar classical short gamma-ray bursts with...
A young and energetic pulsar powers the well-known Crab Nebula. Here, we describe two separate gamma-ray (photon energy greater than 100 mega-electron volts) flares from this source detected by Large Area Telescope on board Fermi Gamma-ray Space Telescope. The first flare occurred in February 2009 lasted approximately 16 days. second was September 2010 4 During these outbursts, flux nebula increased factors of four six, respectively. brevity implies that gamma rays were emitted via...
This paper presents light curves as well the first systematic characterization of variability 106 objects in high-confidence Fermi Large Area Telescope Bright AGN Sample (LBAS). Weekly this sample, obtained during 11 months survey (2008 August 4–2009 July 4), are tested for and their properties quantified through autocorrelation function structure analysis. For brightest sources, 3 or 4 day binned extracted order to determine power density spectra (PDSs) fit temporal major flares. More than...
The fourth catalog of active galactic nuclei (AGNs) detected by the Fermi Gamma-ray Space Telescope Large Area (4LAC) between 2008 August 4 and 2016 2 contains 2863 objects located at high Galactic latitudes (|b|>10{\deg}). It includes 85% more sources than previous 3LAC based on years data. AGNs represent least 79% high-latitude in Fermi-Large Source Catalog (4FGL), which covers energy range from 50 MeV to 1 TeV. In addition, 344 gamma-ray are found low latitudes. Most 4LAC blazars (98%),...
The first detected gravitational wave from a neutron star merger was GW170817. In this study, we present J-GEM follow-up observations of SSS17a, an electromagnetic counterpart SSS17a shows 2.5-mag decline in the $z$-band 1.7 days to 7.7 after merger. Such rapid is not comparable with supernovae light curves at any epoch. color also evolves rapidly and becomes redder for later epochs; $z-H$ changed by approximately 2.5 mag period 0.7 days. evolution both optical brightness are consistent...
Wide-field optical surveys have begun to uncover large samples of fast (trise ≲ 5 d), luminous (Mpeak < −18), blue transients. While commonly attributed the breakout a supernova shock into dense wind, great distances transients this class found so far hampered detailed investigation their properties. We present photometry and spectroscopy from comprehensive worldwide campaign observe AT 2018cow (ATLAS 18qqn), first fast-luminous transient be in real time at low redshift. Our spectra (<2 days...
We report on the observation of bright, long gamma-ray burst, GRB 090926A, by Gamma-ray Burst Monitor (GBM) and Large Area Telescope (LAT) instruments board \Fermi\ Space Telescope. 090926A shares several features with other bright LAT bursts. In particular, it clearly shows a short spike in light curve that is present all detectors see this turn suggests there common region emission across entire energy range. addition, while separate high-energy power-law component has already been...
Novae are thermonuclear explosions on a white dwarf surface fueled by mass accreted from companion star. Current physical models posit that shocked expanding gas the nova shell can produce X-ray emission but at higher energies has not been widely expected. Here, we report Fermi Large Area Telescope detection of variable gamma-ray (0.1-10 GeV) recently-detected optical symbiotic star V407 Cygni. We propose material interacts with dense ambient medium red giant primary, and particles be...
This is the first of a series papers aimed at characterizing populations detected in high-latitude sky Fermi-LAT survey. In this work, we focus on intrinsic spectral and flux properties source sample. We show that when selection effects are properly taken into account, Fermi sources average steeper than previously found (e.g., bright list) with an photon index 2.40 ± 0.02 over entire 0.1–100 GeV energy band. confirm flat spectrum radio quasars have spectra BL Lacertae objects 2.48 versus...
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...
We report the results of a multi-band observing campaign on famous blazar 3C 279 conducted during phase increased activity from 2013 December to 2014 April, including first observations it with NuSTAR. The $\gamma$-ray emission source measured by Fermi-LAT showed multiple distinct flares reaching highest flux level in this object since beginning Fermi mission, $F(E > 100\,{\rm MeV})$ $10^{-5}$ photons cm$^{-2}$ s$^{-1}$, and doubling time scale as short 2 hours. spectrum one was very hard,...
We present time-resolved broad-band observations of the quasar 3C 279 obtained from multi-wavelength campaigns conducted during first two years Fermi Gamma-ray Space Telescope mission. While investigating previously reported gamma-ray/optical flare accompanied by a change in optical polarization, we found that emission appears delayed with respect to gamma-ray about 10 days. X-ray reveal pair `isolated' flares separated ~90 days, only weak counterparts. The spectral structure measured...
We present γ-ray observations with the Large Area Telescope (LAT) on board Fermi Gamma-Ray Space of nearby radio galaxy Centaurus A (Cen A). The previous EGRET detection is confirmed, and localization improved using data from first 10 months science operation. In work, we presented lobes by LAT; in this concentrate core Cen A. Flux levels as seen LAT are not significantly different that found EGRET, nor extremely soft spectrum (Γ = 2.67 ± 0.10stat 0.08sys where photon flux Φ ∝ E−Γ)....
We present early phase observations in optical and near-infrared wavelengths for the extremely luminous Type Ia supernova (SN Ia) 2009dc. The decline rate of light curve is $\Delta m_{15}(B)=0.65\pm 0.03$, which one slowest among SNe Ia. peak $V$-band absolute magnitude $M_{V}=-19.90\pm 0.15$ mag even if host extinction $A_{V}=0$ mag. It reaches $M_{V}=-20.19\pm 0.19$ $A_{V}=0.29$ as inferred from observed Na {\sc i} D line absorption host. Our $JHK_{s}$-band photometry shows that SN most...
We present a new analysis of double charmonium production in e^+ e^- annihilation. The observation the processes -> J/psi eta_c, chi_c0, and eta_c(2S) is confirmed using dataset more than three times larger that Belle's previous report, no evidence for process found. perform an angular eta_c set upper limit on J/psi. Processes type psi(2S) (cc)_res have been observed first time; their rates are found to be comparable those processes.
We report an analysis of the interstellar $\gamma$-ray emission in third Galactic quadrant measured by {Fermi} Large Area Telescope. The window encompassing plane from longitude $210\arcdeg$ to $250\arcdeg$ has kinematically well-defined segments Local and Perseus arms, suitable study cosmic-ray densities across outer Galaxy. measure no large gradient with Galactocentric distance emissivities per H atom over regions sampled this study. depends, however, on optical depth correction applied...
Context. Over the past few years, on several occasions, large, continuous rotations of electric vector position angle (EVPA) linearly polarized optical emission from blazars have been reported. These events are often coincident with high energy γ-ray flares and they attracted considerable attention, since could allow us to probe magnetic field structure in emitting region jet. The flat-spectrum radio quasar 3C 279 is one most prominent examples showing this behaviour.
We present the results of a series radio, optical, X-ray and gamma-ray observations BL Lac object S50716+714 carried out between April 2007 January 2011. The multi-frequency were obtained using several ground space based facilities. intense optical monitoring source reveals faster repetitive variations superimposed on long-term variability trend at time scale ~350 days. Episodes fast recur scales ~ 60-70 simultaneous activity frequencies favors SSC mechanism for production high-energy...
We describe a dynamic science portal called the GROWTH Marshal that allows time-domain astronomers to define programs; program filters save sources from different discovery streams; coordinate follow-up with various robotic or classical telescopes; analyze panchromatic data; and generate summary tables for publication. The marshal currently serves 137 scientists, 38 programs, 67 telescopes. Every night, in real time, several programs apply customized 105 nightly alerts Zwicky Transient...
The BL Lacertae object 3C 66A was detected in a flaring state by the Fermi Large Area Telescope (LAT) and VERITAS 2008 October. In addition to these gamma-ray observations, F-GAMMA, GASP-WEBT, PAIRITEL, MDM, ATOM, Swift, Chandra provided radio X-ray coverage. available light curves show variability and, particular, correlated flares are observed optical Fermi-LAT band. resulting spectral energy distribution can be well fitted using standard leptonic models with without an external radiation...
The Large Area Telescope (LAT) on board the Fermi Gamma-ray Space detected a γ-ray source that is spatially consistent with location of Eta Carinae. This has been persistently bright since beginning LAT survey observations (from 2008 August to 2009 July, time interval considered here). signal significantly throughout energy band (i.e., up ∼100 GeV). 0.1–100 GeV spectrum well represented by combination cutoff power-law model (<10 GeV) and hard component (>10 total flux (>100 MeV) 3.7+0.3−0.1...