Conveners
High-energy astrophysics
- Ching-Ping Hu (National Changhua University of Education)
High-energy astrophysics
- Hung-Yi Pu (National Taiwan Normal University)
High-energy astrophysics
- Hsiang-Yi Karen Yang (National Tsing Hua University)
We investigate the ultraviolet (UV) spectral properties of Type Ia supernovae (SNe Ia) at early times and near peak brightness using observations from the Swift UVOT grism. Our goal is to identify potential differences in UV features between these two phases. We examine how UV flux ratios correlate with key parameters such as the supernova decline rate, host-galaxy stellar mass, metallicity,...
The coalescence of binary neutron star (BNS) in the event GW170817, leading to the generation of gravitational waves (GW) and accompanied by kilonova (KNe), the electromagnetic (EM) counterpart, has been a prime topic of interest for the Astronomy community in recent times as it provided much insight into multi-messenger astronomy. Since its discovery in 2017, several research teams have put...
The Rubin and Roman telescopes will come online soon and are expected to detect over 1000 “orphan afterglows” per year: broad-band long lasting emission from a gamma-ray burst (GRB), but without the GRB. Having a method to extract the physical parameters of these orphan afterglows will give us a better understanding of the progenitor systems. We start with a model that takes physical...
Fast radio bursts (FRBs) are short-duration, bright radio emission pulses with energies. The exact origin of FRBs remains a mystery. However, FRBs are classified into two types depending on their repetition: repeaters and non-repeaters. Different progenitor types, such as magnetars for repeaters and cataclysmic events for non-repeaters, might explain their distinct behaviors. Therefore,...
Using Swift Burst Alert Telescope event-mode data during Gamma Ray Burst occurrences, we conducted spectral analysis for the Crab system. From 38 good observations, which spans over a period of 18 years from 2006 to 2023, we found that the Crab's X-ray flux does not only flicker, but also significantly anti-correlates to its spectral power-law photon index. Since emission contribution of the...
The Galactic transient black hole candidate exhibited 'faint' outbursting activity for approximately 10 months following its discovery on February 05, 2023. We study the evolution of both the temporal and spectral properties of the source using archival data from the NICER and NuSTAR satellites. The outburst profiles and the nature of QPOs suggest that the source underwent a mini-outburst...
Using 18 X-ray/B-band simultaneous XMM-Newton observations (717 ks in total) of PSR J1023+0038 taken during the low-mass X-ray binary (LMXB) state, we find a general trend that the amplitude of the B-band orbital modulation was lower when the observed X-ray flux was higher. Depending on the analysis method adopted, the statistical significance of the anti-correlation can be from 1.3$\sigma$ to...
The radiation mechanism of fast radio bursts (FRBs) remains unknown. Because currently-survived theoretical models can basically explain the common features of FRBs in radio, including their short timescales and extremely high brightness temperatures, solely using radio data is not effective in distinguishing FRB models. Simultaneously detected optical counterparts of FRBs are the final piece...
4U 1820-30 is a ultra-compact low mass X-ray binary located near the center of globular cluster NGC 6624. In addition to its 685s orbital variation, it also exhibits a superorbital orbital modulation with a period of ~171 days. From the stability of this period, the superorbital modulation was considered being induced by a hierarchical third star orbiting around the binary system. To further...
Theories of the formation of massive galaxies suggest that active galactic nuclei (AGN) play an important role in their evolution by shutting down star formation, which slows down stellar mass growth. However, the size and shape of galaxies during the AGN phase are not well established. Such information may shed light on the formation pathways in which galaxies evolve. Thanks to the...
Core-collapse supernovae (CCSNe) are among the most energetic astrophysical events and key sites for nucleosynthesis of heavy elements, and also thought be the multimessenger signal site, especially gravitational waves (GW). They are driven mainly by the neutrino explosion, but also complicate interplay of equation of state, gravity, and magnetohydrodynamics. We present results from numerical...
The detection of the neutron star merger event GW170817 through gravitational wave detectors and electromagnetic observations has provided critical insights into the properties of merger ejecta. In these mergers, the observed light curve, powered by radioactive decay, indicates that rapid neutron capture (r-process) nucleosynthesis generates heavy elements. The final abundances of these...
Magnetars, highly magnetized neutron stars, exhibit transient bursting activities and might accelerate ultrahigh-energy cosmic rays (CRs). Due to their strong magnetic fields, a magnetar can be deformed into a triaxial shape, leading to unstable free precession where one of the principal axes flips, a phenomenon known as the Dzhanibekov effect.
This phenomenon induces a sudden increase in the...
Active galactic nuclei (AGN) feedback’s role in suppressing cooling flows in cool-core clusters is acknowledged, but the primary heating mechanism of AGN jets is debated. One potential heating mechanism is heating caused by turbulence within the intracluster medium (ICM). However, there has been disagreement between simulation and observational studies. Therefore, the goal of our study is to...
Radio galaxies are a subtype of active galactic nuclei (AGN) generated by supermassive black hole jets. Polarization measurements of the radio lobes could potentially probe the magnetic field geometry and initial magnetization of the jets. Previous polarization observations have found magnetic field aligned with the jet axis; however, the connection between the magnetization of the jets and...
Modeling the multiwavelength spectra of hot accretion flows around black holes requires incorporating key radiative processes, including synchrotron emission, bremsstrahlung, and inverse Compton scattering, along with general relativistic effects. We present Iliad, a GPU-accelerated Monte Carlo ray tracing code for radiative transfer in Kerr spacetime. Covering frequencies from radio to X-ray,...
