Solar Energetic Particles (SEPs) are composed of protons, electrons, and heavy ions with energies ranging from hundreds of keV to MeV. They are accelerated in magnetic reconnection regions (impulsive events) and by Coronal Mass Ejection (CME)-driven shocks (gradual events). Large-scale SEP events are one of the most important phenomena in terms of space weather. They pose a risk of radiation exposure to humans and equipment in space. In this presentation, I will show the study of the large SEP sources using extreme-ultraviolet (EUV) images and Potential Field Source Surface (PFSS) extrapolations from the conventional magnetograms and AI-HMI magnetogram on a near real-time basis. The features of SEPs strongly depend on physical quantities of CMEs and flares at the connecting footpoints between the sources and the spacecraft. I will present the temporal and spatial variations of SEP fluxes observed by in-situ measurements and the relations between the fluxes and the quantities of the SEP sources.

Dwarf novae are a binary system with short orbital periods (a few minutes to hours). Being one of the cataclysmic variable stars, dwarf novae show quasi-periodic outbursts which are triggered in the accretion disk around the primary star via accreting materials from the secondary star. During outbursts, they show various peculiar shapes of the observed light curves. For the past ~70 years, over five thousand dwarf novae have been observed and outburst mechanisms became well known. Thermal-viscous instability makes accumulated mass in the accretion disk dumped onto the primary star during the outburst and the accretion disk become brightened. Despite the many previous studies, some parts of the evolution of dwarf novae are still unknown since, especially, dwarf novae with very short orbital periods of <60 minutes or low-metallicity secondary stars are rarely observed. KMTNet has the ability to discover these rare dwarf novae and in this talk, I will show the strength of the KMTNet in finding these invaluable pieces to get better understanding of their evolution.

There have been attempts to probe a wide range of dark matter candidates, whose mass ranges from 10^{-22} eV to the Planck scale (and beyond Planck scale if they are not particles). After presenting a brief history of dark matter search, I will discuss the dark matter parameter space allowed by the current observation data. I will then illustrate a few popular DM examples including axion-like particles (ALPs), Weakly Interacting Massive Particles (WIMPs), Primordial Black Holes (PBHs) along with the search efforts for those compelling dark matter candidates.

The evolution of the gravitational potentials on large scales due to the accelerated expansion of the Universe is an important and independent probe of dark energy, known as the integrated Sachs-Wolfe (ISW) effect. We measure this ISW effect through cross-correlating the cosmic microwave background maps from the Planck satellite with a radio continuum galaxy distribution map from the recent Rapid ASKAP Continuum Survey (RACS). We detect a positive cross-correlation at ~2.8σ relative to the null hypothesis of no correlation. We parameterise the strength of the ISW effect through an amplitude parameter and find the constraints to be A_ISW = 0.94^{+0.42}_{-0.41}, which is consistent with the prediction of an accelerating universe within the current concordance cosmological model, ΛCDM. The credible interval on this parameter is independent of the different bias models and redshift distributions that were considered when marginalising over the nuisance parameters. We also detect a power excess in the galaxy auto-correlation angular power spectrum on large scales (ℓ≤40), and investigate possible systematic causes.

Galaxies are known to change dramatically over cosmic time in terms of their star formation, masses, structure, and internal (chemical) properties. While single-wavelength studies in pencil-beam areas on sky provide some insights, multi-wavelength studies of the full galaxy population are crucial to understand galaxy evolution as a whole. In this talk, I present different aspects of galaxy evolution and the latest (and future) surveys that enable us to study them. The ALPINE survey with ALMA is one of the largest of such multi-wavelength surveys, combining UV to sub-mm observations of z=4-6 galaxies to study in detail the evolution of gas and dust during this early growth phase of galaxy evolution. ALPINE builds the basis sample and anchor for the comparison to surveys at lower and higher redshifts as well as to state-of-the-art simulations. Some of these galaxies may harbor accreting black holes and some may be on the verge of being quenched. With follow-up programs with existing (HST, JWST) and future (Euclid, Roman, SPHEREx) facilities, we will be able to study the beginning and fate of these galaxies.

Spherical symmetry breaking in the transition from Red Giant to Planetary Nebula, and the mechanism that governs it, have been a topic of intense interest for decades. Recent observations with high sensitivity and angular resolution have shown that spherical symmetry breaking was already present, in many cases, in the early AGB phase. At large distances from the star the circumstellar envelopes of AGB stars have been shown very complex with many fragments in the form of bipolar outflows, blobs, arcs and spirals. At smaller distance, the nascent winds share some features which need to pay attention including the presence of line broadening in the inner layer, the strong absorption of SiO emission over and beyond the stellar disc and the rotation within 30 au or so from the star. In this presentation, I will review the properties of their circumstellar envelopes (CSE) and their nascent winds with the aim of revealing significant similarities or differences in the hope of improving our understanding of the mechanisms at stake.

The general picture of planet formation is well agreed: planets are formed within a few million years after the collapse phase in a protoplanetary disk surrounding the protostar. However, the detailed formation conditions and mechanisms are still debated, requiring more sophisticated studies both in theoretical, modeling, and observations. A substantial portion of observed exoplanets is found in binary or higher hierarchical systems. Therefore, studying the physical properties and chemical contents of the protoplanetary disk in binary/multiple systems is essential to understand the formation and variety of planetary systems. I will present a study of GG Tauri A using sub-millimeter observations carried out with ALMA and NOEMA interferometers. GG Tauri A is the prototype of a young triple T Tauri star that is surrounded by a massive and extended Keplerian outer disk. The central cavity is not devoid of gas and dust and at least GG Tauri Aa exhibits its own disk of gas and dust emitting at millimeter wavelengths. Its observed properties make this source an ideal laboratory for investigating planet formation in young multiple solar-type stars. A general picture of gas properties and dynamics from the cavity to outer disk as well as its chemical content and the hint of planet(s) in formation in the circumbinary disk of GG Tau A will be presented.

박성현 서울대학교 명예교수(자연과학대학 통계학과)님께서  다음의 네가지 주제로 1시간 정도 발표해주실 예정입니다.

1. 에너지 사용 현황과 전망

2. 기후변화

3. 재생에너지와 원자력

4. 탄소중립 2050과 과학기술정책

In order to answer the fundamental open question of ``Where do nuclei and elements come from'', studies of nuclear properties with powerful rare isotope beam (RIB) facilities are critical. Moreover, with the recent astonishing observation of the first neutron star merger by astronomers, understanding nuclear spectroscopic properties of short-lived nuclei has become very important to demonstrate outcomes of the event such as gamma-ray, optical and X-ray emissions. However, because most of the key nuclei constraining the nucleosynthesis models including the rapid proton capture process (rp-process) and the rapid neutron capture process (r-process) are far from stability, our understanding of astronomical observables is still very limited due to large uncertainties in calculated properties of the nuclei and a lack of measurements with radioactive ion beams for the spectroscopic information. While there are a few RIB facilities in the world, which provide short-lived radioactive beams to perform studies of nuclear properties of exotic nuclei, new generation RIB accelerator facilities around the world including FRIB in the U.S., RIBF in Japan and RAON in Korea will be available soon. Recent experimental studies of key nuclei performed at the existing facilities will be presented as well as new active research activities at the Center for Exotic Nuclear Studies (CENS), Institute for Basic Science (IBS). Future plans on how to take advantage of the new facilities including RAON will also be addressed.

Digital humanities, as the intersection of computing and the disciplines of the humanities, have offered new opportunities for teaching and research innovation that complement the traditional approach in the humanities. While surveying the past, present, and future studies in the humanities, this lecture explores how the digital transformation will influence science classics.

This year marks the 30 years to launch the first Korean satellite KitSat-1. South Korea is now on the verge of entering the space economy era based on technological capability in the space sector and increased private capacity. The talk will illustrate the process of Korea's space development system from a historical point of view, first, and will touch on the policy issue related the limitations of the current national space innovation system, including governance, government R&D, space industrialization, space security/defense, international cooperation for exploration and diplomacy, and so on.

The protostellar phase, an early phase of star formation, has recently gained the spotlight as a phase for planet formation. On the other hand, the place of planet formation, “disk”, is difficult to identify in the protostellar phase because disks are embedded in envelopes in this phase. Identifying a disk also tells us the most important parameter of the protostar, central stellar mass M*. Previous works reported observational identification of disks in protostellar systems. The method is, however, different from work to work. To verify the consistency among different methods, I applied representative methods to synthetic observations using a magnetohydrodynamic simulation of protostellar evolution. This test demonstrates that a method using position-velocity diagrams can estimate the disk size and the central stellar mass accurately, particularly when M* >~ 0.2 Msun. Our group has been using this method with SMA and ALMA observations almost for a decade and are continuing to develop it. Even after a disk is identified in a protostar, the system provides questions related to the disk and planet formation: e.g., how the disk obtains mass or how dust grains grow in the disk. I introduce a case study of the protostar TMC-1A to investigate these questions, based on dust continuum, spectral line, and dust polarization observations using the SMA and ALMA. In addition to these studies I accomplished in KASI, I would also like to review my activities in KASI during the ~3-yr term.

Coronal mass ejections (CMEs) are among the most energetic and powerful solar phenomena. The CMEs transfer solar energetic particles to the Earth and cause geomagnetic storms, which can produce severe space weather conditions. Previous studies have found that the CME plasmas are strongly heated in the low solar corona. Also, ion charge compositions from in situ measurements have shown that ionization state models require strong and rapid heating around 2 R⊙. In addition, solar coronal plasma is often interpreted assuming equilibrium ionization and Maxwellian electron velocity distributions. But, if the thermodynamical timescale in a rapidly evolving system is shorter than the ionization and recombination timescale, then the plasma can be far from the equilibrium ionization state because of rapid heating or cooling. Non-Maxwellian electron distributions can be caused by particle acceleration, turbulence, or shocks. High-energy observations show that their particle velocity distributions reveal suprathermal tails, which Kappa (κ) distribution functions can represent. In this talk, I introduce previous studies of the heating of CME plasmas using the observations by UV coronagraph spectrometer and EUV and X-ray imaging observations. And I present how we study the heating of the nonequilibrium state coronal plasmas by comparing in situ observations such as interplanetary coronal mass ejection and solar wind. 

SI Analytics는 쎄트렉아이의 자회사이자 인공지능 기반 위성 항공 영상 분석 전문기업으로 지구 관측을 통해 현명한 결정을 하기 위한 가치를 제공한다. SI Analytics 인공지능 연구소는 객체 탐지, 변화 탐지, 초해상화 등의 다양한 인공지능 모델을 개발하고, 위성 데이터로부터 국방, 기상, 기후 변화 등 지구 관측과 관련된 다양한 주제에 대해 분석하여 정보를 제공하고 있다. 최근 연구소는 사회적으로 이슈인 ESG (Environment Social Governance) 의 주요 키워드인 탄소 중립의 중요성과 탄소 배출량 측정 방법의 한계를 인지하고, 정부의 2050년 탄소 중립을 실현 하기 위해 배출량 산정 근거가 될 수 있는 위성 관측을 활용한 인공지능 기반 탄소 배출량 측정 기술 연구를 시작하였다. 현재 탄소 배출량은 위성 또는 현장 관측을 통해 다양한 방법으로 측정되고 있지만, 관측 방법의 다양성과 관측으로부터 탄소 농도를 산출하는 모델의 다양성으로 인해 일관성 있는 분석에 어려움이 있다. 따라서 탄소 분포와 농도를 같은 기준으로 감시, 관리하기 위해서는 표준화된 측정 데이터 제공이 필수적이다. 위성은 전 지구를 같은 센서로 관측하고 있으며, 점차 고해상도 관측이 가능해 지고 있기 때문에, 탄소 측정에 매우 중요한 수단이 되고 있다. 따라서 본 연구자는 이러한 사회적 필요성에 발맞추어 탄소 관측  OCO-2 위성 데이터를 활용하여 Level 1b 자료를 Level 2 로 변환하는 물리기반 역변환 모델을 인공지능 모델이 대치할 수 있는지에 대한 가능성을 확인하고, 그 결과에 대해 소개하고자 한다. 

가장 오랜 역사를 갖고 있는 학문 중 하나인 천문학은 관측과 함께 시작했다. 이러한 관측은 데이터를 만들고 이러한 데이터를 분석하는 다양한 기법들이 함께 발전했다. 빅데이터라는 용어가 나오기 전부터 천문학자들은 대용량의 데이터를 분석하고 이를 이용해 물리 법칙을 증명해왔다. 이러한 경험을 바탕으로 최근 천문학 전공자들이 데이터과학 분야로 뛰어들고 있으며 다양한 도메인에서 데이터과학자로서 역할을 해내고 있다. 본 발표에서는 천문학 전공자로서 겪은 데이터과학과 인공지능 기술에 대해 공유하고, 이러한 최신 기술들이 어떻게 의료 분야에서 적용되고 상용화까지 이르고 있는지 소개하고자 한다. 

In this talk, we would like to discuss how large-scale filaments affect the evolution of galaxies. By analyzing the HORIZON-AGN simulation data at a fixed redshift of z~2, we found that the dependency of galaxy properties on large-scale environment is mostly inherited from the (large-scale) environmental dependency of their host halo mass. When adopting a residual analysis that removes the host halo mass effect, we detected a direct and non-negligible influence of cosmic filaments. Proximity to filaments enhances the build-up of stellar mass. However, our multi-scale analysis also reveals that, at the edge of filaments, star formation is suppressed. We suggest that gas transfer from the outside to the inside of the haloes (where galaxies reside) becomes less efficient closer to filaments, due to high angular momentum supply at the vorticity-rich edge of filaments. To understand the underlying causality of such impacts of filaments on galaxy properties more directly, it is needed to track individual galaxies in time. Along that direction, we first tracked galaxy-hosting halos using a dark matter-only simulation. We examined the settling process of halos into the filament potential well in a phase space and their mass evolution along with it. Halos’ orbital trajectories and mass evolution are determined quite much by the initial condition of halos (i.e., initial position and formation time), which are also affected by the density of filaments. We found the mass segregation around filaments as with observations, which can be explained with massive halos being those that arrived filaments earlier. 

Since physical processes in the magnetopause can be observed in the high-latitude ionosphere via field lines and current systems, ground magnetic field responses to solar wind and IMF changes can provide valuable information on dayside transient phenomena involved in solar wind-magnetosphere-ionosphere coupling process.

The basic processes at the magnetopause boundary are magnetic reconnection, and viscous-like interaction, such as Kelvin-Helmholtz instability (KHI) and pressure-pulse drive. The magnetic reconnection occurs preferentially at the region where magnetosheath largest when the IMF is southward. On the other hand, the KHI is generally known to be driven by the velocity shear with a rapid magnetosheath plasma at the boundary for northward IMF condition. The magnetosphere boundary can also fluctuate in response to solar wind dynamic pressure pulse. However, it still need to be understood what kind of factors of magnetopause boundary are more important depending on the solar wind and IMF conditions.

We have studied magnetospheric dynamics and ionospheric phenomena by using a high-resolution 3-D global MHD simulation of the solar wind and planetary magnetosphere interaction as a function of IMF condition. The results of these studies will be presented.

The isotope ratio of molecules is a powerful tool for investigating the origin of solar system materials and for revealing the possible chemical link between the solar system and the interstellar medium. More and precise isotope ratios have been quantified through spacecraft missions to various solar system bodies and the high sensitivity ALMA observations of molecular isotopologues in star and planet forming regions.  Furthermore, the development of numerical modeling considering detailed gas-phase chemical networks with grain surface reactions, has improved our understanding of isotope chemistry. In this talk, I will present observational and theoretical progress of isotope ratios, especially the nitrogen and carbon isotope ratios, in the protoplanetary disks. 

The elemental abundance in the solar corona is different from the photosphere. The fractionation between photospheric and coronal abundances is related to the “First Ionization Potential (FIP) effect.” In the corona, the low FIP (FIP < 10 eV) elements are enhanced by factors of 3–4 relative to the photospheric abundances. In contrast, the high FIP elemental abundance ratio to photospheric is approximately equal. Still, it is not revealed how the solar abundance is fractionated. Recently, the most probable model is “Abundance fractionation by the Pondermotive force”. The pondermotive force induced by the Alfvén wave preferentially affects the ionized elements (low FIP element), not the neutral in the chromospheric plasma, which is partially ionized. Then, the force drags up (or down) the low FIP elements depending on the Alfvén wave existence and their energy density in the chromosphere. For investigating the relations between the abundance fractionation and wave energy density in the chromosphere, we analyze the H alpha and Ca II data from GST/FISS for the Alfvén wave detection and Si X (low FIP element) and S X (high FIP element) spectra from Hinode/EIS for determining the relative abundance in an active region. We present the result of detecting Alfvén waves in the chromosphere compared to the spatial distribution of the abundance fractionation.

OB associations are large stellar systems composed of groups of young stars spread over several tens of parsecs. They are the prime sites of star formation in galaxies. More than one stellar cluster and distributed stellar populations are found in such stellar systems. This is a general structural feature. It has been believed that such structural features may contain a clue to the formation process of OB associations because OB associations are young. Before the Gaia undertook its own mission, it was very difficult to obtain homogeneous observational data for various associations distributed over wide sky areas. Furthermore, the selection of members was even more limited. The Gaia mission has now opened a new window to study OB associations in detail as it measures the precise parallaxes and proper-motions of stars in the Galaxy. In this talk, I will present the observational results of several galactic OB associations and discuss their formation process. 

The distribution of galaxies in the low redshift Universe provides information on the initial conditions, energy content and evolution of the Universe from its almost Gaussian primordial state to the highly non-linear cosmic web that we observe today. In this talk I will introduce a class of statistics that are capable of extracting both Gaussian and non-Gaussian information from the matter distribution. The so-called Minkowski Functionals and their rank-2 tensorial generalisation are a class of topological descriptors of a field which can be used to measure cosmological parameters, test the degree of non-Gaussianity as a function of scale and also provide a mechanism to test statistical isotropy. I will describe these statistics, explain how we extract them from galaxy catalogs and elucidate what they can tell us about the properties of the Universe. 

Cosmic rays go hand-in-hand with violent and energetic astrophysical conditions, and can produce observable signatures across the electromagnetic spectrum. They also play a role as an active agent in shaping the evolution of their local environment, and their effects in modifying astrophysical processes over a broad range of length-scales can be substantial. In this talk, I will present an overview of some of my recent work on modeling the effects and signatures of cosmic rays in different environments - from star-forming cores in our cosmic backyard, to circum-galactic structures and populations in the furthest reaches of the observable Universe. I will outline the impacts that cosmic rays can have on the evolution and dynamics their host system, how their astrophysical effects can manifest themselves on sub-galactic, galactic, and super-galactic scales, and how the microphysics of cosmic ray feedback may operate within interstellar and circum-galactic settings.

Magnetic field is believed to play an important role in modern Astrophysics. Dust polarization induced by aligned dust grains is widely used to study magnetic fields in various condition from diffuse medium to star-forming regions. A popular  theory of grain alignment is based on RAdiative Torques (RATs). Recently, suprathermal rotation of dust by RATs is found to induce rotational disruption of large grains into small fragments, which modifies the grain size distribution and affects the dust extinction, emission, and polarization properties. Thus, thermal dust polarization also allows us to study fundamental dust physics (alignment and disruption) and dust properties. In this talk, I will (1) present the recent development of the theory of the grain alignment and disruption by RATs to interpret the polarimetric observations toward molecular cloud w/o embedded sources and PDR regions and applications; (2) introduce the recent works on studying the role of magnetic fields in star-forming regions; (3) discuss the new effect of grain alignment and disruption on surface chemistry; and (4) discuss the future perspectives.

Strong gravitational lenses with variable sources, like supernovae (SNe), quasars (QSO), can be the next frontier in cosmic probes. Since the path differences between multiple images contain cosmological information, one can obtain crucial constraints on cosmological parameters, such as the value of Hubble constant, evolution of dark energy etc, independent of other probes by measuring the time delays (between the images). Lensed SNe and QSOs have their own advantages, e.g. lensed SNe are extremely rare as compared to lensed QSOs but the former have much better understood light curves with the time scale of a few months only. The ongoing and the upcoming time-domain surveys like ZTF, LSST, Roman will observe a lot of lenses of both kinds of sources. However, many will have the images spatially unresolved, with the observed lightcurve a superposition of time-delayed image fluxes. We investigate whether the unresolved sources can be recognized as lensed given only the lightcurve information and whether time delays can be extracted robustly.

In this talk, I will discuss a few such interesting techniques that can identify the unresolved lensed systems of both source kinds (SN and QSO). Most importantly, these techniques are very much generic and, hence, do not assume any particular property of the sub-classes of the sources, such as the type of SNe, the flux variability of QSOs etc. These techniques can be very useful in detecting the lensed systems in  wide-field surveys and in measuring the time delays simultaneously to improve our understanding of the cosmos.

The feedback of massive stars and clusters, such as radiation, wind, and supernovae, accounts for most of the energy budget in galaxies. However, our understanding of massive stars and cluster formation is still poor. Statistics studies of various evolutionary stages of massive star formation are crucial to reach a comprehensive understanding of massive star and cluster formation. In order to investigate the formation of massive stars and their associated cluster, we carried out a systematic program with the interferometers (e.g., ALMA, SMA, JVLA) and single dish telescopes (e.g., IRAM-30m, SMT, CSO) toward different evolutionary stages of massive star-forming regions. Our studies yield promising clues to the formation of massive stars and protoclusters. For instance, we find that the nonthermal motions are predominantly subsonic and transonic, and gas filament widths are narrower than the previously proposed ‘quasi-universal’ 0.1 pc filament width. In this talk, I will present a detailed of our recent results using different observations from 10 pc scales to a few 0.01 pc scales, including turbulence, filament, prestellar/protostelar core,  molecular outflows, accretion, fragmentation, etc.

Solar Coronal Mass Ejections (CMEs) are large-scale eruptive events in which large amounts of plasma (up to 1013-1016 g) and magnetic field are expelled into interplanetary space at very high velocities (typ. 450 km/s, but up to 3000 km/s). When sampled in situ by a spacecraft in the interplanetary medium, they are termed Interplanetary CMEs (ICMEs). They are nowadays considered to be the major drivers of “space weather” and the associated geomagnetic activity. The detectable space weather effects on Earth appear in a broad spectrum of time and length scales and have various harmful effects for human health and for our technologies on which we are ever more dependent. Severe conditions in space can hinder or damage satellite operations as well as communication and navigation systems and can even cause power grid outages leading to a variety of socio-economic losses. 

We aim at developing an advanced space weather forecasting tool, combining the MHD solar wind and CME evolution model EUHFORIA[1] with the Solar Energetic Particle (SEP) transport and acceleration model PARADISE[2]. We will first introduce EUHFORIA and PARADISE and then elaborate on our plans of to model the geo-effectiveness of impacts and mitigation to avoid (part of the) damage, including that of extreme events, related to solar eruptions, solar wind streams, and SEPs, with particular emphasis on its application to forecast Geomagnetically Induced Currents (GICs) and radiation on geospace. The novel tool will be accessible by the whole space weather community via the ESA Space Weather Service Network as it will be integrated in the Virtual Space Weather Modelling Centre (VSWMC)[3].

References

[1] J. Pomoell and S. Poedts: "EUHFORIA: EUropean Heliospheric FORecasting Information Asset", J. of Space Weather and Space Climate, 8, A35 (2018). DOI: https://doi.org/10.1051/swsc/2018020

[2]N. Wijsen, “PARADISE: a model for energetic particle transport in the solar wind”. Dissertation presented in partial fulfilment of the requirements for the degree of Doctor of Science (PhD): Mathematics (KU Leuven) and the degree of Doctor of Physics (Universitat de Barcelona). April 2020.

[3] S. Poedts, A. Kochanov, A. Lani, C. Scolini, C. Verbeke, S. Hosteaux, E. Chané, H. Deconinck, N. Mihalache, F. Diet, D. Heynderickx, J. De Keyser, E. De Donder, N.B. Crosby, M. Echim, L. Rodriguez, R. Vansintjan, F. Verstringe, B. Mampaey, R. Horne, S. Glauert, P. Jiggens, R. Keil, A. Glover, G. Deprez, J.-P. Luntama: "The Virtual Space Weather Modelling Centre", J. of Space Weather and Space Climate, 10, Art. 14 (2020). Open Access DOI: 10.1051/swsc/2020012

Active galactic nuclei (AGNs) activity is expected to be closely related to the gas fuel availability and mechanism of the gas-inflow into the nuclear region. External processes such as galaxy interactions, major/minor mergers, and high-local-density environments affect not only physical quantities of their host galaxy (e.g., gas fuel) but also bar presence itself that is one of the possible gas-inflow mechanisms, and seem even to control the central gas supply to the galactic center. The entanglement between the three primary factors (environment, host properties, and bar presence) may have provoked conflicting observational results on the observed galaxy–AGN coevolution. In this talk, I would like to present the results of our work which relatively quantify the role of galactic environment and bar presence in blackhole feeding of spiral galaxies. The large volume-limited galaxy sample obtained from the Sloan Digital Sky Survey (SDSS) makes it possible to minimize the possible entangled effects and to isolate the effect of each of the three factors. We conclude that from the perspective of AGN–galaxy coevolution, a massive black hole is one of the key drivers of spiral galaxy evolution. If it is not met, a bar instability helps the evolution, and in the absence of bars, galaxy interactions/ mergers become important. In other words, in the presence of a massive central engine, the role of the two gas inflow mechanisms is reduced or almost disappears. We also find that bars in massive galaxies are very decisive in increasing AGN fractions when the host galaxies are inside clusters.

Active galactic nuclei (AGNs) activity is expected to be closely related to the gas fuel availability and mechanism of the gas-inflow into the nuclear region. External processes such as galaxy interactions, major/minor mergers, and high-local-density environments affect not only physical quantities of their host galaxy (e.g., gas fuel) but also bar presence itself that is one of the possible gas-inflow mechanisms, and seem even to control the central gas supply to the galactic center. The entanglement between the three primary factors (environment, host properties, and bar presence) may have provoked conflicting observational results on the observed galaxy–AGN coevolution. In this talk, I would like to present the results of our work which relatively quantify the role of galactic environment and bar presence in blackhole feeding of spiral galaxies. The large volume-limited galaxy sample obtained from the Sloan Digital Sky Survey (SDSS) makes it possible to minimize the possible entangled effects and to isolate the effect of each of the three factors. We conclude that from the perspective of AGN–galaxy coevolution, a massive black hole is one of the key drivers of spiral galaxy evolution. If it is not met, a bar instability helps the evolution, and in the absence of bars, galaxy interactions/ mergers become important. In other words, in the presence of a massive central engine, the role of the two gas inflow mechanisms is reduced or almost disappears. We also find that bars in massive galaxies are very decisive in increasing AGN fractions when the host galaxies are inside clusters.