Quasi-Periodic Eruption (QPE) is a phenomenon in which the X-ray luminosity curve shows quasi-periodic bursts near the center of a galaxy. The burst interval is a few hours to a few days, the duration is 10% of the burst interval, the peak luminosity is about $10^{41-43}\,{\rm erg}\,{\rm s}^{-1}$, and the...
Relativistic jets are widely observed in astronomical objects including active galactic nuclei and gamma-ray bursts. However, the acceleration mechanisms that drive these jets are not yet fully understood. Recent studies have shown that when a jet possesses an initial velocity corresponding to approximately 90% of the speed of light, it...
The Square Kilometre Array (SKA) Low and Mid, the world's largest radio telescopes, are currently under construction in Australia and South Africa. Covering frequency ranges of 50–350 MHz for SKA Low and 350 MHz–15.4 GHz for SKA Mid, the SKA will enable a wide range of scientific studies, leveraging its...
Recent JWST observations have revealed a wealth of detail about high-redshift galaxies, including strong [OIII] emission and clumpy structures. To interpret these observations, we utilize FirstLight zoom-in simulations with pc-scale resolution. This talk will discuss: (1) the physical properties of [OIII] emitters and the use of line diagnostics, (2) the...
This talk is about modelling the X-ray emission from black hole accretion discs. We discuss the standard model for these discs, and how this model needs to be modified in order to explain the observational data, in particular from super-Eddington discs and X-ray binaries. The standard model is a simple...
We present simulations of the formation of young massive clusters (YMCs) through high-velocity collisions of HI gas in the Large Magellanic Cloud. The simulation models the magnetized interstellar gas dynamics, including the effects of self-gravity, heating/cooling, and stellar feedback. The results show that fast collisions of HI gas can form...
We study the thermal evolution of star-forming clouds in the primordial halos at $z>100$, considering the effect of the cosmic microwave background (CMB). The CMB inhibits the formation of H2 via the photodissociation of H-, resulting in a higher temperature than in the standard evolution of the first stars at...
The first wave of observations with JWST has revealed a striking overabundance of luminous galaxies at early times ($z > 10$) compared to models of galaxies calibrated to pre-JWST data. Early observations have also uncovered a large population of supermassive black holes (SMBHs) at $z > 6$. Because many of...
We investigate the innermost structure of black hole-disk-jet systems through polarization images. First, we focus on linear and circular polarization (LP and CP) separation along the jet, based on our general relativistic radiation transfer code. We find that the LP and CP components are separated by the Faraday effects. Next,...
We study the metallicity dependence of the disk fragmentation using 2D hydrodynamics simulations. We perform long-term simulations up to 0.1 Myr with a wide metallicity range of $10^{-5}Z_{\odot}
Quasi-Periodic Eruption (QPE) is a phenomenon in which the X-ray luminosity curve shows quasi-periodic bursts near the center of a galaxy. The burst interval is a few hours to a few days, the duration is 10% of the burst interval, the peak luminosity is about $10^{41-43}\,{\rm erg}\,{\rm s}^{-1}$, and the...
March 2025 13 : 30 SMBH, X-rays, and accretion discs
Relativistic jets are widely observed in astronomical objects including active galactic nuclei and gamma-ray bursts. However, the acceleration mechanisms that drive these jets are not yet fully understood. Recent studies have shown that when a jet possesses an initial velocity corresponding to approximately 90% of the speed of light, it...
March 2025 13 : 00 relativistic jets, SPH, and Godunov scheme
The Square Kilometre Array (SKA) Low and Mid, the world's largest radio telescopes, are currently under construction in Australia and South Africa. Covering frequency ranges of 50–350 MHz for SKA Low and 350 MHz–15.4 GHz for SKA Mid, the SKA will enable a wide range of scientific studies, leveraging its...
February 2025 13 : 30 21cm line, SKA, and MWA
Recent JWST observations have revealed a wealth of detail about high-redshift galaxies, including strong [OIII] emission and clumpy structures. To interpret these observations, we utilize FirstLight zoom-in simulations with pc-scale resolution. This talk will discuss: (1) the physical properties of [OIII] emitters and the use of line diagnostics, (2) the...
February 2025 13 : 00 first galaxies, early universe, and cosmological simulations
This talk is about modelling the X-ray emission from black hole accretion discs. We discuss the standard model for these discs, and how this model needs to be modified in order to explain the observational data, in particular from super-Eddington discs and X-ray binaries. The standard model is a simple...
January 2025 13 : 30 accretion discs
We present simulations of the formation of young massive clusters (YMCs) through high-velocity collisions of HI gas in the Large Magellanic Cloud. The simulation models the magnetized interstellar gas dynamics, including the effects of self-gravity, heating/cooling, and stellar feedback. The results show that fast collisions of HI gas can form...
November 2024 13 : 30 star formation and clouds
We study the thermal evolution of star-forming clouds in the primordial halos at $z>100$, considering the effect of the cosmic microwave background (CMB). The CMB inhibits the formation of H2 via the photodissociation of H-, resulting in a higher temperature than in the standard evolution of the first stars at...
October 2024 13 : 00 first stars, IMF, and SPH
The first wave of observations with JWST has revealed a striking overabundance of luminous galaxies at early times ($z > 10$) compared to models of galaxies calibrated to pre-JWST data. Early observations have also uncovered a large population of supermassive black holes (SMBHs) at $z > 6$. Because many of...
October 2024 13 : 00 reionization and JWST
We investigate the innermost structure of black hole-disk-jet systems through polarization images. First, we focus on linear and circular polarization (LP and CP) separation along the jet, based on our general relativistic radiation transfer code. We find that the LP and CP components are separated by the Faraday effects. Next,...
June 2024 13 : 00 black holes, accretion discs, and relativistic jets
We study the metallicity dependence of the disk fragmentation using 2D hydrodynamics simulations. We perform long-term simulations up to 0.1 Myr with a wide metallicity range of $10^{-5}Z_{\odot}
和 英