A5035768431- Pulsars and Gravitational Waves Research
- Gamma-ray bursts and supernovae
- Astrophysical Phenomena and Observations
- earthquake and tectonic studies
- Astrophysics and Cosmic Phenomena
- Radio Astronomy Observations and Technology
- Galaxies: Formation, Evolution, Phenomena
- High-pressure geophysics and materials
- Cosmology and Gravitation Theories
- Astro and Planetary Science
- Seismology and Earthquake Studies
- Geological and Geophysical Studies
- Atomic and Subatomic Physics Research
- Astronomy and Astrophysical Research
- Geophysics and Sensor Technology
- Astrophysics and Star Formation Studies
- Stellar, planetary, and galactic studies
- Geophysics and Gravity Measurements
- Statistical and numerical algorithms
National Chung Hsing University
2022-2024
Hebrew University of Jerusalem
2020-2022
The University of Tokyo
2016-2020
Tel Aviv University
2020
Abstract A new model of the Milky Way (MW) halo component dispersion measure (DM) for extragalactic sources, such as fast radio bursts, is presented in light recent diffuse X-ray observations. In addition to spherical isothermal gas ( kT ∼ 0.3 keV) hydrostatic equilibrium with Galactic gravitational potential, our includes a disk-like nonspherical hot reproduce directional dependence observed emission (EM). The total mass (1.2 × 10 11 M ⊙ ) dominated by component, and consistent baryon MW...
ABSTRACT Fast radio bursts (FRBs) are mysterious millisecond pulses in radio, most of which originate from distant galaxies. Revealing the origin FRBs is becoming central astronomy. The redshift evolution FRB energy function, i.e. number density sources as a function energy, provides important implications for progenitors. Here, we show functions selected recently released Canadian Hydrogen Intensity Mapping Experiment (CHIME) catalogue using Vmax method. method allows us to measure it...
Most of fast radio bursts (FRB) do not show evidence for repetition, and such non-repeating FRBs may be produced at the time a merger binary neutron stars (BNS), provided that BNS rate is close to high end currently possible range. However, environment polluted by dynamical ejecta, which prohibit signal propagate. We examine this using general-relativistic simulation merger, ejecta appears about 1 ms after rotation speed merged star becomes maximum. Therefore there window in an FRB can reach...
Abstract Fast Radio Bursts (FRBs) are bright millisecond-duration radio transients that appear about 1000 times per day, all-sky, for a fluence threshold 5 Jy ms at 600 MHz. The FRB radio-emission physics and the compact objects involved in these events subjects of intense active debate. To better constrain source models, Bustling Universe Survey Telescope Taiwan (BURSTT) is optimized to discover localize large sample rare, high-fluence, nearby FRBs. This population most amenable...
ABSTRACT Recently, a new population of circular radio (∼GHz) objects has been discovered at high Galactic latitudes, called the odd circles (ORCs). A fraction ORCs encircles massive galaxies in sky with stellar mass ∼1011 M⊙ situated z = 0.2–0.6, suggesting possible physical connection. In this paper, we explore possibility that these originate from accretion shocks/virial shocks around (${\gtrsim} 10^{13}\, \ {\rm M}_\odot$) dark matter halo ∼ 0.5. We found flux density emitting shell is...
Abstract The production mechanism of fast radio bursts (FRBs)—mysterious, bright, millisecond-duration flashes from cosmological distances—remains unknown. Understanding potential correlations between burst occurrence times and various properties may offer important clues about their origins. Among these properties, the spectral peak frequency an individual (the at which its emission is strongest) particularly because it encode direct information physical conditions environment site....
Fast Radio Bursts (FRBs) are a mysterious flash phenomenon detected in radio wavelengths with duration of only few milliseconds, and they may also have prompt gamma-ray flashes. Here we carry out blind search for msec-duration flashes using the 7-year Fermi Large Area Telescope (Fermi-LAT) all-sky data. About 100 candidates detected, but after removing those associated bright steady point sources, find no events at high Galactic latitude region (|b|>20 deg). Events lower regions consistent...
Observations of TeV emission from early gamma-ray burst (GRB) afterglows revealed the long sought for inverse Compton (IC) upscattering lower energy synchrotron. However, it turned out that hoped ability to easily interpret synchrotron-self-Compton (SSC) spectra didn't materialize. The is in Klein-Nishina (KN) regime and simple Thomson SSC spectrum modified, complicating scene. We describe here a methodology obtain an analytic approximation observed infer conditions at emitting region....
ABSTRACT Fast Radio Bursts (FRBs) are classified into repeaters and non-repeaters, with only a few per cent of the observed FRB population from Canadian Hydrogen Intensity Mapping Experiment (CHIME) confirmed as repeaters. However, this figure represents lower limit due to observational biases, true fraction remains unknown. Correcting for these biases uncovers notable decline in apparently non-repeating detection rate CHIME operational time increases. This finding suggests that significant...
ABSTRACT Extremely bright coherent radio bursts with millisecond duration, reminiscent of cosmological fast bursts, were codetected anomalously-hard X-ray from a Galactic magnetar SGR 1935 + 2154. We investigate the possibility that event was triggered by magnetic energy injection inside magnetosphere, thereby producing magnetically-trapped fireball (FB) and relativistic outflows simultaneously. The thermal component burst is consistent trapped FB an average temperature ∼200–300 keV size...
There is growing evidence that a clear distinction between magnetars and radio pulsars may not exist, implying the population of neutron stars exhibit both pulsations bursting activities could be potentially large. In this situation, new insights into burst mechanism gained by combining temporal behavior pulsations. We present general model for suppression relativistic $e^{\pm}$ plasma outflows at onset magnetar flares. A sudden ejection magnetic energy magnetosphere would generate fireball...
Spectral modification of energetic magnetar flares by resonant cyclotron scattering (RCS) is considered. During flares, photons emitted from the magnetically-trapped fireball near stellar surface should resonantly interact with magnetospheric electrons or positrons. We show a simple thought experiment that such particles are expected to move at mildly relativistic speeds along closed magnetic field lines, which would slightly shift incident photon energy due Doppler effect. develop toy model...
A correlation between the intrinsic energy and burst duration of non-repeating fast radio bursts (FRBs) has been reported. If it exists, can be used to estimate from duration, thus provide us with a new distance measure for cosmology. However, suffered small number statistics (68 FRBs) was not free contamination by latent repeating populations, which might have such correlation. How separate/exclude mixture all different types FRBs is essential see this property. Using much larger sample FRB...
ABSTRACT In this study, we explore the dynamical stability of magnetar bursts within context chaos-randomness phase space for first time, aiming to uncover unique behaviours compared various astrophysical transients, including fast radio (FRBs). We analyse burst energy time series data from active sources SGR J1550−5418 and J1935+2154, focusing on arrival differences between consecutive events. find a distinct separation in domain, where exhibit significantly lower randomness FRBs, solar...
The light curve of the fast radio burst (FRB) 181112 is resolved into four successive pulses, and time interval ($\sim0.8$ ms) between first third pulses coincides with that second fourth which can be interpreted as a neutron star (NS) spinning at period about $0.8$ ms. Although this shorter than most rapidly rotating pulsar currently known ($1.4$ ms), it typical for simulated massive NS formed immediately after coalescence binary stars (BNS). Therefore, BNS merger good candidate origin FRB...
We have searched for optical variability in the host galaxy of radio variable source which is possibly associated with fast burst (FRB) 150418. compare images taken 1 day after using Subaru/Suprime-Cam $\sim$ year Gemini-South/GMOS. No found between two epochs a limiting absolute magnitude $\gtrsim -19$ (AB). This limit applies to putative active galactic nucleus on timescale year, and also luminosity an counterpart FRB~150418 one should it occurred this galaxy.
SGR J1935+2154 has truly been the most prolific magnetar over last decade: It entering into burst active episodes once every 1-2 years since its discovery in 2014, it emitted first Galactic fast radio associated with an X-ray 2020, and hundreds of energetic short bursts. Here, we present time-resolved spectral analysis 51 bright bursts from J1935+2154. Unlike conventional spectroscopic studies literature, follow a two-step approach to probe true evolution. For each burst, extract information...
Abstract SGR J1935+2154 has truly been the most prolific magnetar over last decade: it entering into burst active episodes once every 1–2 yr since its discovery in 2014, emitted first Galactic fast radio associated with an X-ray 2020, and hundreds of energetic short bursts. Here, we present time-resolved spectral analysis 51 bright bursts from J1935+2154. Unlike conventional spectroscopic studies literature, follow a two-step approach to probe true evolution. For each burst, extract...
The production mechanism of fast radio bursts (FRBs) remains elusive, and potential correlations between burst occurrence times various properties may offer important clues. Among them, the spectral peak frequency is particularly because it encode direct information about physical conditions environment at emission site. Analyzing over 4,000 from three most active sources -- FRB 20121102A, 20201124A, 20220912A we measure two-point correlation function $\xi(\Delta t, \Delta\nu_{\:\rm...
The recent detection of a Fast Radio Burst (FRB) from Galactic magnetar secured the fact that neutron stars (NSs) with super-strong magnetic fields are capable producing these extremely bright coherent radio bursts. One leading mechanisms to explain origin such emission is curvature radiation process within dipolar field structure. It has, however, already been demonstrated magnetars likely have more complex topology. Here we critically investigate in presence inclined and quadrupolar...
Fast Radio Bursts (FRBs) are classified into repeaters and non-repeaters, with only a few percent of the observed FRB population from Canadian Hydrogen Intensity Mapping Experiment (CHIME) confirmed as repeaters. However, this figure represents lower limit due to observational biases, true fraction remains unknown. Correcting for these biases uncovers notable decline in apparently non-repeating detection rate CHIME operational time increases. This finding suggests that significant portion...