The epoch of cosmic dawn, occurring in the first few hundred million years after the Big Bang, marks a critical period in the formation of the first galaxies and the reionization of the Universe. With the unprecedented capabilities of the James Webb Space Telescope (JWST), deep imaging surveys such as COSMOS-Web have opened a new window into this early era.
In this study, we employ the...
The measurement of galaxy-galaxy strong lens number density provides statistical constraints on foreground mass distributions. Dusty star-forming galaxies (DSFGs) uncovered in submillimeter surveys are particularly valuable for this purpose, given the large cosmological volumes they probe. Strongly lensed DSFGs have predominantly been identified as one of the brightest sources in previous...
Observations of the stellar medium have revealed many structures forming prior to the birth of stars. Filaments being omnipresent and highly correlated with prestellar cores, stellar cluster that contain massive stars are usually found to be embedded in a hub-filament system. Continuum observations could not reveal 3D information, while spectroscopic observations have suggested that...
The change in the relative importance of gravity, turbulence, and magnetic field affects the fragmentation of massive star-forming dark clouds. Using dust continuum and polarization data, as well as molecular transition lines from the JCMT, IRAM-30m and the SMA, we investigated the energetics of various star forming regions to understand the correlation between the three factors and...
Space weather events sourced from host stars, including stellar flares, coronal mass ejections, and stellar proton events, can substantially influence an exoplanet’s habitability and atmospheric evolution history. These time-dependent events may also affect our ability to measure and interpret its properties by modulating reservoirs of key chemical compounds and/or by changing the brightness...
The joint discovery of the binary neutron star (BNS) merger GW170817 and the associated short gamma-ray burst GRB170817A has shed new light on the study of such systems. In this work, assuming all BNS mergers produce GRBs, we aim to investigate the jet geometry of short gamma-ray bursts through a multimessenger approach. Our analysis incorporates observations from two BNS merger events,...
The production mechanism of fast radio bursts (FRBs) remains elusive, and potential correlations between burst occurrence times and various burst properties may offer important clues. Among them, the spectral peak frequency is particularly important because it may encode direct information about the physical conditions and environment at the emission site. Analyzing over 4,000 bursts from the...
Our ultimate goal is to enhance our understanding of planet formation by identifying the youngest exoplanets orbiting T Tauri Stars (TTSs), systems typically aged around or below 5 Myr. Detecting planets around TTSs poses significant challenges because of the strong stellar activity and interference from protoplanetary disks. Stellar spots, prominent on young stars, generate strong radial...
The presence of old open clusters but remaining rich in members challenges the conventional view that such systems dissociate within 1 Gyr in the typically inhospitable Galactic disk. We present a study of eight such clusters—Collinder 261, NGC 2158, NGC 2477, NGC 2506, NGC 6791, NGC 6819, NGC 7786, and Trumpler 5—each with an age comparable to those of globular clusters yet harbors thousands...
We investigate the magnetic field properties in the massive star-forming region Onsala 2 (ON2) in Cygnus using 850 µm polarization observations from the B-Fields in Star-Forming Region Observations (BISTRO) survey, which is a Large Program of the James Clerk Maxwell Telescope (JCMT). Our data cover the entire ON2 complex at a resolution of 0.12 pc, allowing us to spatially resolve polarized...
Fast Radio Bursts (FRBs) are enigmatic astrophysical phenomena that manifest as millisecond radio pulses. While the origin of FRBs is still unknown, observations confirm that some FRBs repeat and some do not apparently. In addition to the repetition nature, repeaters are known to show distinct physical properties from non-repeaters: broader pulses with narrower bandwidths for repeaters...
Millions of spectra have been collected by the Dark Energy Spectroscopic Instrument (DESI) survey. While the DESI survey is designed to observe specific types of sources, unexpected sources are often included and hidden within the dataset. In this talk, I will show that a fraction of the sources observed by DESI are galaxies producing strong Lyman-alpha emission lines, known as Lyman-alpha...
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 galaxy luminosity function, which describes a number density of a galaxy population as a function of their luminosities, provides key insights into galaxy formation and evolution. In this study, we investigate the optical luminosity functions of galaxies in clusters identified in the eROSITA Final Equatorial-Depth Survey (eFEDS), spanning redshifts from 0.1 to 1.3 and halo masses between...
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...
Based on arXiv: 2409.13022 (published in ApJ Letters). We update constraints on cosmological parameters in a 12-parameter model, which extends the standard 6-parameter ΛCDM to include dynamical dark energy and massive neutrinos, along with other new parameters. We use the latest Planck PR4 (2020) likelihoods, DESI DR1 BAO, and the latest uncalibrated type Ia Supernovae (SNe) datasets. In this...
The tidal disruptions of dwarf galaxies are thought to be the most important process in building diffuse stellar halos around galaxies. Multiple spectroscopic surveys seek to reconstruct major assembly events with chemical and dynamical information of stellar halo stars. In our recently published paper, we compute the number of progenitors that contribute to the accreted stellar halos of...
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 volume of astronomical data is growing at an unprecedented rate. Directly interacting with and interpreting vast amounts of high-dimensional data, such as galaxy spectra, has become increasingly challenging. To address this big-data challenge, dimensionality reduction techniques are essential for uncovering underlying patterns hidden within a dataset. In this talk, I will demonstrate how...
The outer solar system is theoretically predicted to harbor an undiscovered planet, often referred to as Planet Nine (P9). Simulations suggest that its gravitational influence could explain the unusual clustering of Kuiper Belt Objects (KBOs). However, there has been no observational evidence for the existence of P9 so far, since its predicted orbit is distantly beyond Neptune’s, where it...
We present Transit Timing Variations (TTVs) of HAT-P-12b, a low-density sub-Saturn mass planet orbiting a metal-poor K4 dwarf star. Using 14 years of observational data, we analyzed 46 lightcurves with various models, including linear, orbital decay, apsidal precession, and sinusoidal models, to investigate the presence of additional planets. Frequency analysis using the Generalized...
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...
It is generally believed that galaxies evolved from star-forming to quiescent over time, but the mechanism of how galaxies quench remains a question. Post-starburst galaxies (PSBs) are transitional galaxies that have rapid quenching recently, making them crucial for understanding galaxy quenching. In a theoretical model, it increased SFR during the early stage of galaxy merger. Then, massive...
Both Mercury and the Moon possess tenuous, collisionless "atmospheres", known as "exospheres". Mercury’s proximity to the Sun, coupled with the absence of a dense atmosphere, exposes its surface to intense solar wind, solar radiation, energetic particles, and interplanetary meteoroid impacts. These interactions contribute to the formation and variability of its surface-bound exosphere. The...
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...
The origin of dust and molecular gas observed outside of galaxies remains puzzling and poorly understood. Dust is expected to be rapidly destroyed via sputtering, suppressing the formation of molecular hydrogen. In addition, cool clouds should be dispersed via fluid instabilities within a few cloud-crushing times. To study this problem, we use a suite of cloud-crushing simulations featuring a...
How galaxies transition from star-forming to passive remains an open question. To shed light on this process, one can study the properties of the circumgalactic medium (CGM)—the site of gas inflow and outflow—around galaxies in transition, known as green valley galaxies. By doing so, we can better understand how gas flow processes drive galaxy transformation. In this talk, I will present our...
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...
A gravitational field flux conservation and redistribution picture is proposed with generalizing the Integral Gauss's law of gravity at non-relativistic limit. 1/r dependence along with a disk thickness dependence of gravitational field and the flat rotation curves are obtained by a Gaussian surface with cylindrical symmetry,
where most of the gravitational flux lines are assumed to be...
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...
I will briefly review HFGW physics and the current situation of HFGW detection.
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...
We investigate the effect of resistivity on the dynamics of accretion flow using a global simulation model. Our approach involves employing a resistive magnetohydrodynamic model (Res-MHD) around spinning active galactic nuclei (AGNs). We conduct a comparative study of 2D and 3D resistive models surrounding black holes. In our analysis, we examine the dynamics of accretion flow while...
We propose using likelihood ratio as a new ranking statistic for SPIIR to detect gravitational waves (GWs) from single detector data. We derived the forms of likelihood ratio for a candidate using its signal-to-noise ratio (SNR), chi-square, and auto-correlation length. For significance estimation, the background was constructed using one-week of data, and we used an exponential fit to...
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...
Compact binary coalescence (CBC) searches, which look for signals from binary black holes, binary neutron stars, and neutron star–black hole mergers, are a major part of contemporary gravitational wave (GW) astronomy. However, the sensitivity of these searches is often limited by local noise transients, or glitches, which can closely resemble real astrophysical signals in terms of...
We present a detailed analysis of molecular gas in jet-interacting regions of NGC 1068 using ALMA archival data of CO(1-0) and CO(2-1) transitions. We identified a distinct feature where CO(1–0) shows redshifted absorption while CO(2–1) exhibits emission at the same location and velocity, observed consistently across several regions along the jet. Spectral profiles of CO(2–1) reveal redshifted...
Now we are in the O4 run of the LIGO-Virgo-KAGRA (LVK) collaboration. Many machine learning techniques are being applied on the detection and data analysis on Gravitational Wave (GW) data. In this talk, I will introduce the current status of the noise subtraction method DeepClean in O4 run and how DeepClean and other machine learning techniques on the detection and parameter estimation of the...
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...
Recently, the ASKAP POSSUM and MeerKAT surveys revealed an apparent lack of radio source counts in the Fornax galaxy cluster field. The sources in this patch of sky also appeared to be less polarised. These observations are peculiar and could be important signatures of depolarisation on galaxy cluster scales. In this work, we quantified the effects on polarisation of radio point sources behind...
Diffuse interstellar bands (DIBs) are weak, mysterious absorption features that have been detected ubiquitously in the Milky Way and other galaxies. However, their existence outside of galaxies remains unknown.
In this talk, I will present our study of searching for a DIB (DIB$\lambda4430$) outside of galaxies in the circumgalactic medium (CGM) environments. To this end, we make use of...
We investigated the relationship between the GW denoiser’s signal recovery and the prediction of the ML-based CBC analysis by training BBH, NSBH, and BNS binary classifiers on denoised strain data. We found that the GW detector can make confident detections when the signal recovery, measured by overlap, is larger than 0.2 for BBH, NSBH, and 0.1 for BNS. The results are consistent with our...
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...
The search for gravitational waves (GWs) from astrophysical sources has become a central pursuit in modern astrophysics. Among the most compelling but elusive targets are GWs from core-collapse supernovae (CCSNe), which are expected to produce highly complex and stochastic waveforms. However, the presence of non-Gaussian, transient noise artifacts—commonly referred to as glitches—poses a...
This study explores a possible solution to the Fermi paradox, which questions why we have not observed alien civilizations despite the vastness of the universe. Previous simulations by Zackrisson et al. (2015) suggested that a Kardashev-III type civilization, capable of harnessing the energy of an entire galaxy, could expand across 50% of the Milky Way (MW) in just 25 Myr. Similarly, Wright et...
One of the most powerful tools in the study of galaxies is the thermal emission of interstellar dust, which dominates their spectral energy distribution (SED) at far-infrared wavelengths. Using a dust emission model such as a modified blackbody, fits to the SED reveal the dust (and interstellar medium) column density and its temperature, making the dust SED a key tracer in Galactic and...
Rapid localization plays an important role in multi-messenger astronomy. GW-SkyLocator_ARQS is a machine-learning method that realizes the low-latency search on compact binary coalescence. We provide the performance of GW-SkyLocator_ARQS on binary neutron star events with three detectors and four detectors.
Multi-band observation of deep fields provides a unique scope to study different aspects of galaxy evolution by effectively detecting fainter sources in the distant universe. We utilize the angular resolution (~1.2 arcsec), sensitivity, and field of view of the Ultra-Violet Imaging Telescope (UVIT) onboard AstroSat to image several HST deep fields in the FUV and NUV bands. Combining UVIT...
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,...
The scattered light is the diffused light recoupling to the main optical beam inside the interferometers. In the KAGRA interferometer, the scattered light noise sometimes contaminated the sensitivity in the band of 30 ~ 100 Hz. It appeared in the time-frequency map with the characteristic arch-shape with a period of 2.5 seconds. With more understanding of scattering light, we may mitigate the...
南瀛天文館具有全國唯一球幕3D星象劇場，每場次除了播映球幕影片之外，還包含了簡短的星象解說節目，從星座介紹、在太陽系內遨遊、特殊天象、各種主題式節目等，透過身歷其境的模擬效果，讓觀影民眾獲取天文新知。本主題將分享近年來在星象節目製作的經驗以及探討星象軟體發展的潛力。
Circumstellar interaction of supernova (SN) ejecta is an essential process in the evolution and observations of SNe have found the signature of circumstellar interaction both in the early and late evolutionary phase of SNe. Here we show that if the SN forward shock plunges into tenuous stellar wind from dense circumstellar medium (CSM) residing in the vicinity of the progenitor, the subsequent...
In this paper, we present a comprehensive catalog of magnetar bursts detected with NICER, aimed at characterizing their temporal and spectral properties. This study includes all available NICER observations of known magnetars and two magnetar-like rotation-powered pulsars, covering 7.5 years of data. Using the Bayesian blocks method, we systematically search for rapid flux variations in the...
隨著AI輔助的程式撰寫工具興起，軟體開發的技術門檻大幅降低，即便沒有程式設計經驗的人，也能透過與AI的協作，快速實踐自己的創意構想。天文教育領域也受益於此趨勢，現在人人都能成為星艦工程師，建造出專屬的「天文探索方舟」。我將以Replit、Windsurf、Cursor等工具為例，示範大眾如何與AI協作，結合開放資料，打造出專屬個人學習需求與興趣的天文探索App。
X-ray polarization is a powerful tool for studying particle acceleration in high-energy astrophysical phenomena such as supernova remnants (SNRs) and pulsar wind nebulae (PWNe). Measurements of X-ray polarization provide valuable insights into the geometry and physical processes within these objects, revealing details about their magnetic field structures, particle acceleration mechanisms, and...
‘Estuary Planetarium’ has been funded since June 2024. We have a strong passion for teaching and outreach in astronomy. The image of "estuary" represents the connection between the stream of human history to the vast, and boundless ocean of the universe. Our team hopes to play such a role, guiding everyone into the world of astronomy. We used interactive astronomical teaching tools and escape...
Complex organic molecules (COMs) in solar-like young stellar objects (YSOs) are of great interest due to their potential link to the origin of life. Under the ALMA Survey of Orion PGCCs (ALMASOP) project, we have identified 11 out of 56 protostellar cores that are rich in warm COMs. Our modeling suggests that the observed COMs are primarily located in the warm, innermost regions of the...
Orion KL is a chemically rich high-mass star-forming region, characterized by strong molecular line emission and complex thermal structures. Using ALMA Band 1 data, we present rotational temperature (Trot) and column density (Ntot) maps of CH3OH and NH3, two key tracers of dense gas and warm chemistry. CH3OH, often considered a cornerstone...
Prestellar cores represent the initial conditions of star formation. The Orion B prestellar core G205.46 M3 has been reported to exhibit two substructures, B1 and B2, which have been proposed as the stellar embryos of a future protobinary system. At this stage, heavy molecules such as CO are significantly depleted in these cold, dense environments, limiting our ability to probe core centers....
Discussions are made on an alternative interpretation for the Hubble constant of red-shift. The expansion of the space is relaxed to a relative scaling between the space and the matter with gravity. The possible mechanism and results including the energy difference between space and matterd are discussed.
With the rapid development of sky survey projects and observational technology, over 20,000 transient celestial objects have been discovered annually in recent years. However, due to limited telescope time and observational resources, only about 10% of these transients have been classified through spectroscopic analysis, leaving the physical nature of most objects is unknown. Recently, the...
This study aims to investigate the characteristics of X-ray sources in elliptical (E), lenticular (S0), spiral (S), and active/interacting galaxies, and analyze their relationship with star formation activity. We use X-ray data from the Chandra X-ray Observatory, combined with infrared observations from Spitzer and Herschel, to estimate the star formation rate (SFR) using the X-ray luminosity...
Abstract
In the past research of 433 Eros [1] mentioned that there would probably become the Earth-crossing asteroid within many numerical simulation tests. In this research, we deeply investigated the orbital evolution of 433 Eros. In addition to simulate 433 Eros' orbital evolution, we checked when Eros encounters the Earth, and even hits the Earth. Then, since with long-time simulations...
Over the past decades, photometric methods have led to the discoveries of thousands of exoplanets. While similar techniques have been used to search for exomoons, none have been confirmed. We aim to survey potential exomoons using Transiting Exoplanet Survey Satellite (TESS) data and present a case study to illustrate our methodology. Based on previously proposed systems with exomoon...
We present a study of flare properties on the highly active M dwarf Wolf 359 using simultaneous multiband ground-based optical observations. High-cadence data were obtained with the instrument TRIPOL on the Lulin 1-m telescope, supplemented by the Lulin 41-cm telescope, over five nights between February 17–22 in 2023. In total, we detected twelve flares. Three flares observed on the first...
Non-thermal escape via hot oxygen production, primarily from the dissociative recombination of O₂⁺, significantly influences atmospheric loss on Mars. These hot oxygen atoms can collide with other atmospheric species, such as helium and minor gases, affecting their energy distributions and contributing to escape processes. Previous studies have indicated that solar wind helium contributes...
Gravitational microlensing is an essential technique for detecting small exoplanets, including Earth-like planets. Interestingly, from an alternative perspective, the Earth Microlensing Zone (EMZ) can be defined as the region where extraterrestrial civilizations could observe gravitational microlensing events caused by Earth. Updating the EMZ map is crucial for improving microlensing...
The ultra-compact low mass X-ray binary 4U 1820-30 exhibits a ~3% orbital modulation in its X-ray light curve with a period of 685 seconds, along with a superorbital modulation where the flux varies by a factor of 2 over a period of ~170 days. Zdziarski et al.(2007), using early RXTE data, discovered a correlation between the amplitude of the orbital modulation and the accretion rate,...
The Chamaeleon cloud complex is active in star formation hosting hundreds of newly born stars. Yet the adjacent Musca cloud, filamentary in shape, seem to be barren, with only a few dense cores detected, signifying the cloud being prestellar. While a far-infrared source, IRAS 12322-7023, on the basis of its IRAS colors, was reported in the literature as a T Tauri candidate, i.e., a newly...
The enigma of the missing baryons poses a prominent and unresolved problem in astronomy. Dispersion measures (DM), serving as a distinctive observable of fast radio bursts (FRBs), quantify the electron column density along each line-of-sight, revealing the missing baryons described in the Macquart (DM-z) relation. The scatter of this relation is anticipated to be caused by the variation of...
We present the discovery and characterization of debris stellar groups around
the Double Cluster h (NGC 869) and chi (NGC 884) Persei to diagnose the formation
and dynamical evolution of binary star clusters. Stars are formed in groups, and
those surviving the emergence out of the molecular clouds become a star cluster.
Open star clusters, primarily located in the Galactic disk, are...
Multi-dimensional instabilities coupled with magnetic fields, such as the magnetorotational instability (MRI), are considered important contributors to the explosion mechanism of core-collapse supernovae in extreme scenarios. In this work, we present three-dimensional simulations of a 40-solar-mass progenitor using the GPU-accelerated magnetohydrodynamics code GAMER. We investigate the effects...
This study aims to investigate the properties of host galaxies of Fast Radio Burst (FRB). We begin by extracting FRB event data from the Transient Name Server (TNS), using their sky positions (Right Ascension and Declination) and observed Dispersion Measures (DMs) to identify potential host galaxy candidates. By cross-matching with astronomical catalogs such as SDSS and Gaia, we filter out...
We use 3D special relativistic hydrodynamic (SRHD) simulations to study AGN-driven winds in a disk galaxy. Our results reveal an early-stage (t ~ 0.1 Myr) asymmetry in bubble formation, with one bubble reaching velocities up to 2000 km/s while the other remains underdeveloped due to interactions with the clumpy disk. This aligns with JWST observations of NGC 7469, which show a circumnuclear...
Binary asteroids provide crucial information of the solar system evolution. This study presents a machine learning (ML) approach, using Random Forest classifiers, to identify binary asteroids from lightcurves. We aim to study the population of binary asteroids in the main asteroid belt. To achieve this, we develop the asteroids model to simulate the lightcurves as the training set, which...
Multi-tracer surveys have revealed the hierarchical nature of molecular clouds, showing how high-density, small-scale features are always nested within more rarefied, larger envelopes. This structural hierarchy is, however, a non-trivial one: over-densities can always be found when smaller scales are resolved. The highest density in the hierarchy of cloud structure correspond to the site of...
Chiral effects induced by quantum anomalies, such as the chiral magnetic effect, are expected to influence the dynamics of core-collapse supernovae (CCSN). These effects arise in strong magnetic fields and rapid flows, which are common in supernova cores. In this project, we investigate the potential impact of chiral neutrino radiation transport in CCSN, focusing on contributions from...
The observation of the M87* black hole shadow has opened new avenues for exploring horizon-scale phenomena around astrophysical black holes.
Current interpretations of black hole images often rely on state-of-the-art general relativistic magnetohydrodynamics (GRMHD) simulations to model ion
temperatures, combined with post-processed radiative modeling of electron radiation. However, these...
Aims. Cold gas ( $T \sim 10^4$ K) filamentary structures with H$\alpha$ emissions were found around central regions of some
cool-core galaxy clusters. We wish to compare the results
between the observation of the Perseus cluster and our simulation
in order to interpret velocity structures of observed filaments.
Methods. We perform hydrodynamic simulations to trace gas
motions in...
Fast Radio Bursts (FRBs) are high-energy, transient phenomena with extremely short durations, and their origin remains uncertain. Various theories have been proposed to explain their mechanism. Among these, FRB 200428 has been confirmed to originate from the magnetar SGR 1935+2154, providing a potential model for understanding other FRBs. In this study, I use the physical parameters of FRB...
Supernova remnants (SNRs) are considered the primary sources of Galactic cosmic ray acceleration. Particles are energized at the shock front of SNR through the diffusive shock acceleration mechanism, gaining energy by repeatedly crossing the shock. Magnetic turbulence plays a crucial role in scattering these particles back and forth; therefore, investigating this turbulence is essential for...
Galaxy clusters are the most massive gravitationally bound systems and represent the most recently formed structures in the Universe under the hierarchical formation model. In this work, we reconstruct the dynamical mass profiles of galaxy clusters from the TNG300 and TNG-Cluster simulations by numerically solving the Jeans equation based on the kinematics of member galaxies. By comparing our...
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We present an analysis of observations pointing on the trailing L5 cloud using the Zwicky Transient Facility in early Oct and Nov of 2024. The obtained images with the g' and r' filter allowed for the measurement of g − r color. We detected 579 Trojans in the observed fields, and the median value of g'-r' color is $0.633\pm0.094$. Because each target had at least five g-r data sets and...
With the growing population of gravitational-wave (GW) events, electromagnetic (EM) follow-up observations have become important for multi-messenger astronomy. Since the EM afterglows of the compact binary coalescences (CBCs) decay rapidly, prompt and reliable GW localizations are essential for the EM counterpart identification. This poster presents the results of the Auto-regressive Rational...
One of the most fascinating and difficult tasks in contemporary astronomy is the finding of exomoons, the moons orbiting exoplanets. In order to find possible exomoons, this study investigates the use of transit timing variations (TTV) and transit duration variations (TDV) as indirect methods. Our goal is to find the dynamical signatures that indicate to the gravitational impact of an orbiting...
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...
We present an in-depth analysis of the timing and spectral properties of NGC 7314, a Seyfert 1.9 galaxy, using data from XMM-Newton, NuSTAR, and RXTE/PCA. Our timing analysis reveals significant variability across multiple energy bands, with fractional variability (Fvar). We observe that soft X-ray photons exhibit greater variability compared to harder photons, suggesting distinct emission...
SMC X-1 is a high-mass X-ray binary exhibiting an X-ray pulsar with a ~0.7 s spin period and a non-stationary superorbital modulation ranging from ~40 to ~65 days. Its luminosity of 5E38 erg/s makes it a local analogue of ultraluminous X-ray pulsars, powered by supercritical accretion. To investigate whether SMC X-1's superorbital modulation originates from a change in the mass accretion rate...
We present weak lensing shear measurements of two ICM-selected galaxy cluster samples. The cluster samples, RASS-MCMF and ACT-DR5 MCMF, are selected by applying the Multi-Component Matched Filter (MCMF) algorithm to the second ROSAT All-Sky-Survey (RASS) source catalog (2RXS) and the ACT-DR5 dataset, respectively. For the RASS-MCMF catalog, 171 out of 8449 clusters within the redshift range...
Physics-inspired neural networks (PINNs) have gained considerable importance in recent years in the domain of Astronomy & Astrophysics, particularly, being a potential tool to solve differential equations within the given boundary conditions, not limiting to accurate predictions but also providing efficient approach for large computations. In this work, we have focused on solving the kilonova...
Previous studies have investigated the quenching mechanisms of quiescent galaxies at high redshift. However, due to limitations in angular resolution and sample size, the underlying processes remain poorly understood. In this study, as an initial step, we aim to explore the quenching process by analyzing the spatially resolved color profiles of quiescent galaxies at $z > 3$ using data from...
The magnetic field structure within protoplanetary disks is thought to influence key processes in star and planet formation.
In this study, we aim to infer the magnetic field structure within the protoplanetary disk surrounding HD 163296, a young Class II Herbig Ae star, by analyzing archival ALMA polarization data at a wavelength of 870 µm.
Traditionally, magnetic field morphology is...
The interstellar medium (ISM) is inherently non-uniform. The inhomogeneous structures on both large and small scales influence the propagation of EM waves. Theoretical studies and simulations of the ISM are typically performed on parsec-scale resolution, yet, structures on AU or sub-AU scales are not well explored. Pulsar scintillation is a powerful probe of the small scale structures...
Supernovae explosion (SNe) are among the most energetic astrophysical phenomena, where the ejecta from a stellar explosion collides with a dense circumstellar medium (CSM), leading to intense shock interactions and enhanced radiation output. We employ two-dimensional radiation hydrodynamics (RHD) simulations using the CASTRO code, incorporating adaptive mesh refinement (AMR) to model the...
Multiple systems are common in field stars and the frequency is found to be higher in early evolutionary stages. Thus, it is crucial to study young multiple systems during the embedded stages. In particular, the way material accretes from the large-scale envelope into the inner region and how this flow interacts with the system physically and chemically has not been well characterized to date....
We have developed a Python tool for simulating the optical observations of tidally-locked companions in compact binary systems based on the Roche potential and the PHOENIX spectral library. The tool generates phase-resolved spectra and light curves observed from a given viewing angle. With the simulations, we aim to investigate the impact of the irradiation effect on the observed radial...
We present our time-series spectroscopic observation of comet 12P/Pons-Brooks using the LISA spectrograph mounted on the Lulin One-meter Telescope. The data were obtained between 25 November, 2023 and 24 March 2024, with heliocentric distances from 2.463 to 0.941 au at the pre-perihelion epoch. We clearly detected the emission features of CN, C₂, C₃, NH₂, and OI, and estimated the production...
The Atacama Large Millimeter/submillimeter Array (ALMA) has been providing continuous observations since 2011. To date, ALMA has carried out nearly 5,000 observing projects, contributing to more than 4,000 journal papers. This report presents an update on the current status of ALMA, with a particular focus on Taiwan's participation in the project and the role of the ALMA Regional Center (ARC)...
Io, Jupiter's most volcanically active moon, has a dynamic atmosphere primarily composed of sulfur dioxide (SO₂). Minor atmospheric components, such as sulfur monoxide (SO), sodium chloride (NaCl), and potassium chloride (KCl), are likely produced by volcanic outgassing. Some SO also originates from the photodissociation of SO₂. These components serve as indicators of atmospheric processes and...
The interstellar medium (ISM) is fundamental to star formation and galaxy evolution, with dust serving as a pivotal regulator of various astrophysical processes. Yet, the mechanisms driving dust evolution in stellar feedback–dominated environments remain elusive. While photoionization feedback from massive stars—responsible for generating HII regions and reshaping the ISM’s structure and...
The Trans-Pacific Two-Meter Telescope (TP2m) is a collaborative project between NCU, ASIAA, UNAM, SHAO, UNAM, and HNAS. The telescope is expected to be deployed in San Pedro Mártir, Mexico, around 2025. The TP2m's will collaborate with the nearby COLIBRI 1.3m telescope, and its primary scientific focus is on transient targets.
We aim to develope the telescope control system for the TP2m...
In this project, our goal is to measure the stellar mass function of galaxy clusters selected in X-rays in the eROSITA Final Equatorial Depth Survey (eFEDS), which is the deepest X-ray survey over a contiguous footprint.
The sample consists of galaxy clusters spanning a mass range of $10^{13}\,h^{-1}M_\odot \leq M \leq 10^{15}\,h^{-1}M_\odot$, and a redshift range of $0.1 < z_{\mathrm{cl}} <...
Galaxy interactions play a crucial role in the evolution of galaxies in the local universe, often triggering enhanced star formation. Simulations consistently suggest that such interactions significantly reshape the distribution of molecular gas within galactic disks, thereby altering the spatial distribution of star formation. In this study, we aim to observationally investigate the...
The cosmic infrared background (CIB) originated from reprocessed dust emission after dust in galaxies absorbs the UV light from young massive stars and accreting supermassive blackholes. Resolving the diffuse CIB into individual galaxies provides insights into the cosmic star-forming activities that are obscured at the optical wavelength. Previous studies have constructed number counts of...
Fast Radio Bursts (FRBs) are millisecond-duration radio wave transients that emit enormous energy with unknown origins. In this project, we aim to constrain the environment of galaxies hosting FRBs by measuring their cross correlations with other populations of galaxies. To explore the methodology, we construct realistic mock catalogs of FRBs and galaxies using a semi-analytical method.
To...
We compared several empirical period-luminosity-metallicity (PLZ) and period-Wesenheit-metallicity (PWZ) relations of RR Lyrae stars to evaluate their validity and precision in distance estimation. Our analysis used data from various observations and surveys of the Large Magellanic Cloud as benchmarks. We further investigated intrinsic factors contributing to discrepancies among the empirical...
Low-latency searches are crucial for Multi-Messenger Astronomy (MMA), where gravitational waves help us to quickly locate where events happened and promptly inform other telescopes to conduct follow-up observations. Gravitational waves, like ripples in space and time, are generated by the mergers of massive compact binaries such as binary black holes, binary neutron stars, and neutron...
We present a follow-up X-ray study of the redback millisecond pulsar PSR J2215+5135. PSR J2215+5135 was discovered as a radio pulsar with an orbital period of 0.17 day. It is in a compact binary system with a low-mass companion of 0.33 $\text{M}_\odot$ (Linares, et al., 2018).
Observationally, redback systems occasionally exhibit a double-peaked structure in their X-ray light curves. This...
即使在資訊爆炸的時代，天文學仍常被誤解、浪漫化，甚至神秘化。為了拉近研究者與大眾之間幾億光年的距離，我們開始製作 Podcast 節目《不是那種天文學 Astronomy, But Not What You Think》。
我們是一群天文研究的見習生，也曾是清華天文社的正副社長。我們曾經兩度參加國科會創意科普影片競賽，分別獲得金獎與創意獎，並持續探索用創意說天文的可能。Podcast 是我們延續熱忱的新形式，也是目前中文世界中相對稀少、專注於研究議題的天文科普聲音。節目從大眾對天文的疑問出發，延伸至介紹實際研究的知識、觀測與理論背後的故事，以閒聊、訪談或是新聞討論等節目形式，破除常人對天文的浪漫誤解。我們希望這個節目不只推廣天文，更是一種邀請：歡迎更多天文人參與科普、打開對話，用自己的方式，讓科學被更多人看見與聽見。
Astronomy is often...
南瀛天文館為天文教育帶來嶄新的面貌。透過展示館更新工程，我們將展示的焦點從傳統的物件展示解說，轉移至以「學習者」為中心的生活之中，不再停留在課本知識的重現，而是著重讓參觀者體驗到天文和生活元素的連結。從食衣住行等面項，使天文的學習更貼近生活。
