Conveners
Compact objects and high-energy astrophysics
- Hsiang-Yi Karen Yang (National Tsing Hua University)
Compact objects and high-energy astrophysics
- YI CHOU (Graduate Institute of Astronomy, NCU)
Compact objects and high-energy astrophysics
- Chin-Ping Hu (National Changhua University of Education)
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Kai-I Cheng (NTU/ASIAA)5/16/26, 11:00 AMOral
30 Doradus is one of the most active star-forming regions. In its main body, confirming supernova remnants (SNRs) remains challenging due to the highly ionized environment, strong thermal emission, and diluted optical shock diagnostics.
In this work, we present compelling multiwavelength evidence for an SNR located in Shell 1 within the main body of 30 Dor A, based on archival observations...
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Mohammed Ramiz Aktar (Institute of Astronomy, National Tsing Hua University)5/16/26, 11:15 AMOral
We carry out three-dimensional radiation-relativistic magnetohydrodynamic (3D Rad-RMHD) simulations of accretion flows around spinning active galactic nuclei (AGNs). Our study focuses on the magnetically arrested disk (MAD) state, utilizing a single-temperature model that incorporates bremsstrahlung opacity as the sole radiation process while varying the black hole spin from non-spinning to...
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Dr Che-Jui Chang (National Taiwan University)5/16/26, 11:30 AMOral
Supermassive black holes (SMBHs) like M87∗ and Sgr A∗ have been observed with the Event Horizon Telescope (EHT), facilitating the investigation of null geodesics near a black hole. The null geodesic around black holes and relevant features such as photon ring, lensing ring and black hole shadow, have been modelled analytically. The emission and absorption of plasmas surrounding a black hole is...
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Chieh-Yu Kuo (NTNU)5/16/26, 11:45 AMOral
Polarized emission from the vicinity of black hole systems carries essential information about local magnetic field configurations in the strong gravity regime. In this work, we employ unsupervised learning to a library of model GRMHD Stokes images of M87*, cluster the images based on the polarized image features, and explore how the clustering depends on the model parameters such as black...
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Ishika Palit (National Tsing Hua University)5/16/26, 12:00 PMOral
We investigate the impact of equatorial asymmetry in the magnetic field geometry on accretion dynamics around a spinning black hole using axisymmetric general relativistic magnetohydrodynamic simulations. We consider a Fishbone--Moncrief torus orbiting a Kerr black hole with spin parameter $a = 0.9375$, threaded by large-scale magnetic fields that are asymmetric about the equatorial plane. The...
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Priyanka Jalan (Institute of Astronomy, National Tsing Hua University)5/16/26, 1:45 PMOral
We investigate the physical drivers of active galactic nucleus (AGN) luminosity and its connection to host galaxy evolution across cosmic time using a multi-wavelength dataset from the \textit{James Webb Space Telescope} (JWST) SMILES and JADES surveys. Our sample consists of 2,735 galaxies spanning lookback times from 0.8 to 13.6 Gyr ($z \gtrsim 0$--17), with robust spectral energy...
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Yi-Chi Chang (Institute of Astronomy, National Tsing Hua University, Hsinchu 30013, Taiwan)5/16/26, 2:00 PMOral
Identifying intermediate-mass black holes (IMBHs) is crucial for understanding the co-evolution of galaxies and the seeds of supermassive black holes. We present a comprehensive multi-wavelength analysis of IC 1633 X-4 (2CXO J010952.3-455526), a hyperluminous X-ray source projected at the outskirts of the galaxy IC 1633 (z $\approx$ 0.024). By combining optical photometry from HST/WFPC2 with...
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Dipak Debnath (National Tsing Hua University)5/16/26, 2:15 PMOral
GS 1354-64 is a dynamically confirmed Galactic transient black hole. Recently, it exhibited a bright outburst. We study the temporal, spectral, and polarimetric properties of the source using multi-satellite data. The outburst consists of two short-duration ($\sim 3$-$5$ days) bright X-ray flares, with peak fluxes of 1.4 and 0.8 Crab, respectively. The source exhibits strong signatures of...
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Ashwin Aravindaraj (Institute of Astronomy, National Tsing Hua University)5/16/26, 2:30 PMOral
Supernova remnants (SNRs) are widely regarded as the primary sources of Galactic cosmic rays, with particles accelerated at their shock fronts through the diffusive shock acceleration (DSA) mechanism, gaining energy via repeated shock crossings. Magnetic turbulence plays a crucial role in scattering these particles, making its characterization essential for understanding the acceleration...
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Dr Swadesh Chand (Postdoc, Institute of Astronomy, National Tsing Hua University)5/16/26, 2:45 PMOral
We present a comprehensive broadband spectral and timing study of the bright atoll neutron star low-mass X-ray binary GX~9+9 using two simultaneous NICER, NuSTAR, and MAXI observations obtained in 2019 and 2022. During both epochs, the source resides in the lower banana branch of the color–color diagram, consistent with a soft spectral state. The broadband spectra in the $0.7-40$ keV band are...
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Che-Yen Chu (National Changhua University of Education)5/16/26, 3:00 PMOral
Radio emission from magnetars is closely linked to their X-ray activity, yet the connection remains complex. Radio emission is typically observed during and after X-ray outbursts, exhibiting highly variable flux evolution, in contrast to the more monotonic decay seen in X-rays. In this paper, we present a phase-resolved X-ray spectroscopic analysis of the 2018 outburst of XTE J1810−197. Pulse...
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Koothodil Abhijith Augustine (Institute of Astronomy, National Tsing Hua University, Hsinchu)5/16/26, 3:15 PMOral
Pulsars are critical laboratories for studying extreme particle acceleration, with the Crab pulsar serving as a benchmark across the electromagnetic spectrum. Observations in the MeV gamma-ray band ($0.2–5$ MeV) are essential for probing the spectral turnover where emission mechanisms transition. The upcoming Compton Spectrometer and Imager (COSI) will provide sensitive measurements in this...
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JR-YUE HSIANG5/16/26, 4:15 PMOral
We present the assessment of scientific capabilities of the Gamma-ray Transient Monitor (GTM) for observing the Crab pulsar. GTM is the science payload on board FORMOSAT-8B (FS-8B), a remote sensing satellite of Taiwan Space Agency (TASA) to launch in late 2026. Two modules of GTM detectors are mounted on opposite (+y and -y) sides of FS-8B, and each consists of four sensor units comprising...
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Kaustubha Sen (IoA, NTHU)5/16/26, 4:30 PMOral
This study reports the localization performance and detection efficiency analysis of a compact GRB monitor to fly on a future CubeSat. Our current study involves four model concepts of the instrument. Among them, two consist of four hexagonal CsI(Tl) scintillator detectors of geometric area 12.5 cm$^2$, read out by silicon photomultipliers (SiPM), encased in aluminum of 2-mm thickness on the...
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Yu-Chiung Lin (National Tsing Hua University)5/16/26, 4:45 PMOral
Estimating the background noise power is essential for gravitational wave (GW) analysis. Typically, people compute the power spectral density (PSD) of the noise background using the Welch method, which is a sliding average over a long period of data, usually spanning tens to thousands of seconds. However, the detector strain data is non-stationary and sometimes glitchy due to the detector's...
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Nim Ki Wong (National Yang Ming Chiao Tung University)5/16/26, 5:00 PMOral
We present an automated noise subtraction pipeline combining Coherence Monitor (CohMon) and DeepClean for KAGRA’s O4a data. CohMon evaluates PEM sensors via frequency-domain coherence to select optimal witness channels. These feed into DeepClean, a 1D CNN, to model and subtract non-linear noise. Applied to O4a strain, it removes artifacts without altering astrophysical signals. Evaluated by...
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Dr Peter Lott (Phenikaa University)5/16/26, 5:15 PMOral
ravitational-wave astronomy has provided a unique probe into the dynamics of globular clusters, active galactic nuclei, and few-body gravitationally interacting systems. While binary black hole systems are a prevalent source of gravitational waves in ground-based interferometers, such systems could also be perturbed by the presence of a distant, third body, i.e. a supermassive black hole. Over...
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Tetsuya Hashimoto (National Chung Hsing University)5/16/26, 5:30 PMOral
Fast Radio Bursts (FRBs) are luminous, coherent radio pulses primarily of extragalactic origin. While a Galactic magnetar has been linked to a few FRB-like events, the progenitors for the vast majority of FRBs remain elusive, largely due to the poor localization capabilities of current FRB instruments. To circumvent this limitation, we employ a statistical approach by investigating the...
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Mr Chakrapani Reddy (National Chung Hsing University)5/16/26, 5:45 PMOral
Fast radio bursts (FRBs) are bright millisecond-duration radio transients from distant galaxies, whose physical origin remains uncertain. Studying relations between burst properties, such as energy and intrinsic duration, may enable the use of FRBs as cosmological probes by providing luminosity distance estimates when combined with spectroscopic redshifts, without relying on the $H_0$--$f_{\rm...
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