A5046707876- Astrophysical Phenomena and Observations
- Pulsars and Gravitational Waves Research
- Gamma-ray bursts and supernovae
- Astrophysics and Cosmic Phenomena
- High-pressure geophysics and materials
- Geophysics and Gravity Measurements
- Astronomical Observations and Instrumentation
- Stellar, planetary, and galactic studies
- Cosmology and Gravitation Theories
- Particle Detector Development and Performance
- Geophysics and Sensor Technology
- Advanced X-ray Imaging Techniques
- X-ray Spectroscopy and Fluorescence Analysis
- Dark Matter and Cosmic Phenomena
- Seismic Waves and Analysis
- Astrophysics and Star Formation Studies
- Particle Accelerators and Free-Electron Lasers
- Mechanics and Biomechanics Studies
- Geomagnetism and Paleomagnetism Studies
- Nuclear Physics and Applications
- Solar and Space Plasma Dynamics
- Atomic and Subatomic Physics Research
- Radiology practices and education
- Advanced Semiconductor Detectors and Materials
- Seismic Imaging and Inversion Techniques
National Cheng Kung University
2020-2024
National Tsing Hua University
2012-2022
Ulsan National Institute of Science and Technology
2019-2020
Chungnam National University
2020
Michigan State University
2016-2018
The intermediate Palomar Transient Factory reports our discovery of a young supernova, iPTF13bvn, in the nearby galaxy, NGC 5806 (22.5 Mpc). Our spectral sequence optical and infrared suggests Type Ib classification. We identify blue progenitor candidate deep pre-explosion imaging within 2σ error circle 80 mas (8.7 pc). has an MB luminosity −5.52 ± 0.39 mag B − I color 0.25 mag. If confirmed by future observations, this would be first direct detection for Ib. Fitting power law to early light...
Recent observations strongly suggest that the millisecond pulsar binary PSR J1023+0038 has developed an accretion disk since 2013 June. We present a multi-wavelength analysis of J1023+0038, which reveals 1) its gamma-rays suddenly brightened within few days in June/July and remained at high gamma-ray state for several months; 2) both UV X-ray fluxes have increased by roughly order magnitude, 3) spectral energy distribution changed significantly after sudden flux change. Time variabilities...
We present optical and near-infrared photometric spectroscopic observations of SN 2013ej, in galaxy M74, from 1 to 450 d after the explosion. 2013ej is a hydrogen-rich supernova, classified as Type IIL due its relatively fast decline following initial peak. It has high peak luminosity (absolute magnitude MV = −17.6) but small 56Ni production ∼0.023 M⊙. Its photospheric evolution similar other II SNe, with shallow absorption Hα profile typical for IIL. During transition radioactive decay tail...
KAGRA is a gravitational-wave (GW) detector constructed in Japan with two unique key features: It was underground, and the test-mass mirrors are cooled to cryogenic temperatures. These features not included other kilometer-scale detectors but will be adopted future such as Einstein Telescope. performed its first joint observation run GEO600 2020. In this observation, sensitivity of GWs inferior that LIGO Virgo. However, further upgrades ongoing reach for detecting next run, which scheduled...
The iPTF detection of the most recent outburst recurrent nova system RX J0045.4+4154 in Andromeda Galaxy has enabled unprecedented study a massive ($M>1.3\ M_\odot$) accreting white dwarf (WD). We detected this as part near daily monitoring M31 to depth $R\approx 21$\,mag and triggered optical photometry, spectroscopy soft X-ray outburst. Peaking at an absolute magnitude $M_R=-6.6$ mag, with decay time 1 mag per day, it is faint very fast nova. It shows emission lines He/N expansion...
We report the discovery of an eclipsing low-mass X-ray binary at center 3FGL error ellipse unassociated Fermi/Large Area Telescope gamma-ray source J0427.9-6704. Photometry from OGLE and SMARTS 1.3-m telescope spectroscopy SOAR have allowed us to classify system as (P = 8.8 hr) with a main sequence donor neutron star accretor. Broad double-peaked H He emission lines suggest ongoing presence accretion disk. Remarkably, shows separate sets absorption associated disk secondary, we use their...
Abstract The detection of GeV γ -ray emission from Galactic novae by the Fermi-Large Area Telescope has become routine since 2010, and is generally associated with shocks internal to nova ejecta. These are also expected heat plasma ∼10 7 K, resulting in detectable X-ray emission. In this paper, we investigate 13 emitting observed Neil Gehrels Swift Observatory, searching for 1–10 keV concurrent detections. We analyze observations V407 Lup (2016) V357 Mus (2018). find that most do eventually...
Abstract KAGRA, the kilometer-scale underground gravitational-wave detector, is located at Kamioka, Japan. In April 2020, an astrophysics observation was performed KAGRA detector in combination with GEO 600 detector; this operation called O3GK. The optical configuration O3GK based on a power-recycled Fabry–Pérot–Michelson interferometer; all mirrors were set room temperature. duty factor of approximately 53%, and displacement sensitivity 1 × 10−18 ${\rm m}/\sqrt{\rm {Hz}}$ 250 Hz....
PSR J2032+4127 is a radio-loud gamma-ray-emitting pulsar; it orbiting around high-mass Be type star with very long orbital period of 25-50years, and approaching periastron, which will occur in late 2017/early 2018. This system comprises young pulsar star, similar to the so-called gamma-ray binary PSR~B1259-63/LS2883. It expected therefore that shows an enhancement high-energy emission caused by interaction between wind wind/disk periastron. Ho et al. recently reported rapid increase X-ray...
We report the first hard X-ray (3-79 keV) observations of millisecond pulsar (MSP) binary PSR J1023+0038 using NuSTAR. This system has been shown transiting between a low-mass (LMXB) state and rotation-powered MSP state. The NuSTAR were taken in both LMXB source is clearly seen states up to ~79 keV. During state, 3-79 keV flux about factor 10 higher that X-rays show clear orbital modulation during faint but period not detected bright In addition, spectrum changes from flat power-law steeper...
ABSTRACT We have investigated a number of factors that can significant impacts on the classification performance gamma-ray sources detected by Fermi Large Area Telescope (LAT) with machine learning techniques. show framework automatic feature selection construct simple model small set features yields better over previous results. Secondly, because sample size training/test sets certain classes in gamma-ray, nested re-sampling and cross-validations are suggested for quantifying statistical...
ABSTRACT Peaking at 3.7 mag on 2020 July 11, YZ Ret was the second-brightest nova of decade. The nova’s moderate proximity (2.7 kpc, from Gaia) provided an opportunity to explore its multiwavelength properties in great detail. Here, we report as part a long-term project identify physical mechanisms responsible for high-energy emission classical novae. We use simultaneous Fermi/LAT and NuSTAR observations complemented by XMM–Newton X-ray grating spectroscopy probe parameters shocked ejecta...
Abstract We present the study of multiwavelength observations an unidentified Fermi Large Area Telescope (LAT) source, 4FGL J1910.7−5320, a new candidate redback millisecond pulsar binary. In 95% error region we find possible binary with 8.36 hr orbital period from Catalina Real-Time Transient Survey, confirmed by optical spectroscopy using SOAR telescope. This source was recently independently discovered as TRAPUM project, confirming our prediction. fit spectral energy distributions...
Abstract We have performed a systematic study of the rotational, orbital, and X-ray properties millisecond pulsars (MSPs) in globular clusters (GCs) compared their nature with those MSPs Galactic field (GF). found that GC generally rotate slower than counterparts GF. Different from expectation simple recycling scenario, no evidence for correlation between orbital period rotation can be MSP binaries GCs. There is also an indication surface magnetic stronger All these suggest dynamical...
The binary system PSR B1259-63/LS 2883 is well sampled in radio, X-rays, and TeV gamma-rays, shows orbital phase-dependent variability these frequencies. first detection of GeV gamma-rays from the was made around 2010 periastron passage. In this Letter, we present an analysis X-ray gamma-ray data obtained by Swift/XRT, NuSTAR/FPM, Fermi/LAT, through recent passage which occurred on 2014 May 4. While not detected LAT before during passage, show that flares at a similar phase as early 2011,...
We present a multi-wavelength analysis of the very fast X-ray transient MAXI J0158-744, which was detected by MAXI/GSC on 2011 November 11. The subsequent exponential decline flux followed with Swift observations, all revealed spectra low temperatures (~100eV) indicating that J0158-744 is new Supersoft Source (SSS). near maximum show features around 0.8 keV we interpret as possible absorption from OVIII, and emission O, Fe, Ne lines. obtained SAAO ESO optical counterpart early in outburst...
ABSTRACT We present a multiwavelength study of the unidentified Fermi object, 3FGL J0212.1+5320. Within 95% error ellipse, Chandra detects bright X-ray source (i.e., <?CDATA ${F}_{0.5\mbox{--}7\mathrm{keV}}=1.4\times {10}^{-12}$?> erg cm −2 s −1 ) that has low-mass optical counterpart ( $M\lesssim 0.4\,{M}_{\odot }$?> and $T\sim 6000$?> K). A clear ellipsoidal modulation is shown in optical/infrared at 20.87 hr. The gamma-ray properties J0212.1+5320 are all consistent with millisecond pulsar...
We present a systematic search for optical counterparts to 13 gravitational wave (GW) triggers involving at least one neutron star during LIGO/Virgo's third observing run. searched binary (BNS) and black hole (NSBH) merger localizations with the Zwicky Transient Facility (ZTF) undertook follow-up Global Relay of Observatories Watching Transients Happen (GROWTH) collaboration. The GW had median localization 4480 deg^2, distance 267 Mpc false alarm rates ranging from 1.5 1e-25 per yr. ZTF...
We present optical observations of the redback millisecond pulsar PSR J1048+2339, which is a 4.66 ms radio in compact binary with an orbital period six hours. obtained high-quality light curves J1048+2339 Lulin 1 m Telescope. The system shows two distinct six-hour modulations, ellipsoidal modulation changes into sinusoidal-like profile less than 14 days. In addition to change, brightness companion increased by one magnitude, suggesting that latter type caused wind heating and became dominant...
Abstract PSR J2021+4026 is a radio-quiet gamma-ray pulsar and the first that shows state change of emission spindown rate. The was observed at 2011 October, which changes from high flux/low rate to low flux/high state. In 2014 December, recovered before over timescale few months. We report long-term evolution flux timing behavior suggests changed near 2018 February 1 entered new At change, averaged dropped (1.29 ± 0.01) × 10 −6 cts cm −2 s −1 (1.12 , similar event. has increased by ∼3% in...
Shocks in gamma-ray emitting classical novae are expected to produce bright thermal and non-thermal X-rays. We test this prediction with simultaneous NuSTAR Fermi/LAT observations of nova V906 Car, which exhibited the brightest GeV emission date. The is detected hard X-rays while it still bright, but contrary simple theoretical expectations, 3.5-78 keV Car much weaker than simultaneously observed >100 MeV emission. No X-ray detected, our deep limits imply that gamma-rays likely hadronic....
We have investigated the intrabinary shock emission from redback millisecond pulsar PSR J2129-0429 with XMM-Newton and Fermi. Orbital modulation in X-ray UV can be clearly seen. Its has a double-peak structure dip between. The observed X-rays are non-thermal dominant which modeled by power-law photon index of ~1.2. Intrabinary origin X-rays. light curve is resulted ellipsoidal companion. Modeling prefers large viewing angle. heating effect found to negligible suggests high energy radiation...