Giant Lyman-alpha blobs with sizes of 50-100kpc represent dramatic episodes of on-going galaxy formation in the distant Universe. Research in the past decade has struggled to make progress on the question of what powers these huge Ly-alpha halos and whether the Ly-alpha-emitting gas is outflowing or infalling. In this talk, I will overview the recent progress in the Lya blob research, mainly based on my own works. First, I will present our deep and/or large area narrowband imaging surveys to identify tens of Lya blobs at redshifts ~2-5. These surveys have produced the first constraints on blobs' clustering and large-scale environment, showing that Lya blobs occupy massive halos likely to evolve into rich groups and clusters today. Second, we carried out large optical/NIR spectroscopic campaigns to investigate their gas kinematics. Our studies using non-resonant (optically-thin) emission lines show that there are only *weak* outflows within the blobs, therefore gas infall or extreme hyper/superwinds are not the source of the extended Ly-alpha emission. I will also present the first detection of molecular gas from a Ly-alpha blob and our on-going effort to characterize the physical conditions of its ISM. Lastly, I will discuss how the future facilities (GMT and ALMA) will play a role in revealing the nature of this mysterious sources.

천문학 분야 중 가장 빠르게 변화하는 분야가 있다면 그것은 태양계일 것입니다. 왜냐하면 우리는 이미 많은 탐사 장비를 태양계 곳곳으로 보냄으로써 과거에는 알 수 없었던 태양계의 많은 정보를 얻고 있는 시대에 살고 있기 때문입니다. 21세기 우주탐사시대를 맞아 태양계는 다다를 수 없는 곳이 아닌 개척의 영역으로 변하고 있습니다. 그리고 멀지 않은 미래에 우리나라도 태양계 탐사에 동참하게 될 예정입니다. 이번 강연은 인류가 살아가게 될 제2의 지구를 찾는다는 작은 주제를 가지고, 현재까지 인류가 찾아낸 태양계의 여러가지 모습들을 살펴보고자 합니다.

In the local universe, it is well known that various properties of galaxies show a clear environmental dependence. Still, it is an open question when and how this environmental dependence was developed and shaped. In this presentation, I will address this intriguing question, showing our recent results on the build-up of passive galaxies over a wide redshift range, from z~2 to z~0.5, focusing on its environmental dependence.

One of the main goals of physical cosmology is to find out the actual model of the Universe. Current standard model of cosmology, also known as concordance model, is a spatially flat FLRW Universe consist of weakly interacting cold dark matter, cosmological constant and baryons considering power-law form of the primordial perturbation. While we can use the data to model or reconstruct different characteristics of the Universe such as its expansion history or the form of the primordial spectrum, considering the data limitations and its uncertainties we have to deal with cosmographic degeneracies that makes it difficult to distinguish between different models. On the other hand one can use the power of the data to falsify different aspects of an assumed model using advanced statistical techniques. In my talk I review these two strategic approaches, 'reconstruction and falsification', highlighting the importance of each one and how they are connected; focusing on the concordance model of cosmology and how we can falsify this model.

Observations show that the Universe is fully ionized by z~6. The LyC photons from dwarf galaxies have been suggested as the most promising source of reionization, but little is yet known about how they escape from their host dark matter halos. In this talk, I will discuss two mechanisms (supernova feedback and runaway stars) that regulate the escape fraction at the epoch of reionization (z>7) by using high-resolution, cosmological radiation hydrodynamics simulations with adaptive mesh refinement. We find that a rapid build-up and subsequent destruction of star-forming clouds by SNe allows for the LyC photons to escape efficiently (~10%) through low-density channels. Inclusion of runaway OB stars further enhances the fraction (~14%), but the total number of escaping photons is found to be similar due to more effective suppression of star formation in this case. Both models (SN or SN+runaways) predict that a sufficient number of photons escapes from the halo at z~7 to keep the universe ionized, as observed. However, a still larger amount of ionizing photons appears necessary at z>9 to accommodate the electron optical depth inferred from the CMB measurements. I will finish the talk by discussing two possible solutions to this problem.

Coalescing compact binaries are the strongest gravitational wave emitters detectable by latest network of ground-based detectors that are ready to make detections beginning this year. However, in order to effectively localize the source of a gravitational wave signal as well as determine the parameters of the source and its environment, an electromagnetic counterpart is necessary. At present, there is convincing evidence that short gamma-ray bursts (sGRBs) are emitted by a compact binary merger, rendering it a promising electromagnetic counterpart for an impending gravitational signal. In this light, this work focuses on black hole-neutron star (BHNS) mergers as a viable site of sGRBs. More specifically, the work seeks to understand the role of the magnetic field of the neutron star companion in generating an sGRB. We use numerical relativity to study the magneto-rotational instability (MRI) as a viable magnetic field amplification mechanism in a BHNS merger and determine the possible outcomes that will render a BHNS merger as a promising sGRB site. We find that a large-scale poloidal field, which is necessary to collimate an sGRB jet, is likely generated via the MRI in the outer regions of the accretion disk of the black hole remnant.

Development of ASIAA and the Future of EAO

Chile is widely recognized as the leading site for ground-based observational astronomy in the world, with many first-class facilities and a growing local research community. In an effort to promote bilateral collaborations in astronomy, the Chinese Academy of Sciences (CAS) has recently established an office in Chile to coordinate its programs. I will introduce the operations of this office and its recent activities, then discuss its long-term mission and the prospect of international cooperation in the Southern Hemisphere.

I will present the star formation work we have done at Universidad de Chile. Starting with the establishment of the Maipu radio observatory in the 1960s, radio-astronomy was the first modern astrophysical expertise developed in Chile, before the advent of modern telescopes in the north of Chile. The 1980s brought the establishment of the 1.2m Columbia telescope at CTIO for the Milky Way CO 1-0 survey, and later the SEST 15m telescope. Thus, we began the study of dense gas in star forming regions. The 2000s brought the high frequency regime with the advent of the ASTE and APEX telescopes and now high angular resolution with ALMA. I will explain some of the survey work we have carried with the above instruments and how it led to the discovery of landmark sources that we are studying now with ALMA. Finally, I will mention what we hope to accomplish with ALMA in the forthcoming decade, in particular with the establishment of the Chilean Virtual Observatory.

In this talk I will present numerical simulations of dynamically relaxed rotating dense stellar systems (e.g. Globular, Nuclear Star Clusters). Targeted are systems characterized by their long-term evolution (Gyr) and particularly, by the presence of initial axi-symmetry due to rotation. A central massive Black Hole is alternatively included, which grows due to consumption of stellar matter. Our models are compared to available observations of galactic rotating globular clusters, and is concluded that initial rotation significantly modifies the shape and lifetime of these systems. Recent simulations of clumped Dark Matter particles can reproduce the Galactic rotation curve over a Hubble time. The advantages of up-to-date high performance computing is discussed in this context.

Recent observations of sunspot's umbra suggested that it may be finely structured at a sub-arcsecond scale representing a mix of hot and cool plasma elements. In this study we will report the first detailed observations of the umbral spikes, which are cool jet-like structures seen in the chromosphere of an umbra. The preliminary analysis indicates that the spikes are not associated with photospheric umbral dots and they rather tend to occur above darkest parts of the umbra, where magnetic fields are strongest. The spikes exhibit up and down oscillatory motions and their spectral evolution suggests that they might be driven by upward propagating shocks generated by photospheric oscillations. We analyze sunspot oscillations using Interface Region Imaging Spectrograph (IRIS) slit-jaw and spectral data and narrow-band chromospheric images from the New Solar Telescope (NST). The intensity of chromospheric shocks displays a long term (about 20~min) variations. Data allowed us to conclude that sunspot umbral flashes (UFs) may appear in the form of narrow bright lanes running along the light bridges and surrounding clusters of umbral bright points. Time series also suggested that UFs preferred to appear on the sunspot-center side of light bridges, which may indicate the existence of a compact sub-photospheric driver of sunspot oscillations. The sunspot's umbra as seen in the IRIS chromospheric and transition region data appears bright above the locations of light bridges and the areas where the dark umbra is dotted with clusters of umbral dots. Co-spatial and co-temporal SDO/AIA data showed that the same locations were associated with bright footpoints of coronal loops suggesting that the light bridges may play an important role in heating the coronal sunspot loops. Finally, the power spectra analysis showed that the intensity of chromospheric and transition region oscillations significantly vary across the umbra and with height, suggesting that umbral non-uniformities and the structure of sunspot magnetic fields may play a role in wave propagation and heating of umbral loops.

Dark energy, the name given to the cause of the accelerating expansion of the Universe, is one of the most profound mysteries in modern science. Current cosmological models hold that dark energy is currently the dominant component of the Universe, but the exact nature of dark energy remains poorly understood. There are ambitious ground-based surveys underway that seek to understand dark energy and NASA is participating in the development of significantly more ambitious space-based surveys planned for the next decade. NASA is providing mission-enabling technology to the European Space Agency‘s (ESA) Euclid mission in exchange for US scientists to participate in the Euclid mission. NASA is also developing the Wide Field Infrared Survey Telescope-Astrophysics Focused Telescope Asset (WFIRST-AFTA) mission for possible launch in ?2023. WFIRST was the highest ranked space mission in the Astro2010 Decadal Survey and the AFTA incarnation of the WFIRST design uses a 2.4m space telescope to go beyond what the Decadal Survey envisioned for WFIRST. Understanding dark energy is one of the primary science goals of WFIRST-AFTA. I’ll discuss the status of Euclid and WFIRST and comment on the complementarity of the two missions. I’ll also briefly discuss other, exciting science goals for WFIRST, including a search for exoplanets using both microlensing and a dedicated coronagraph for exoplanet imaging.

Most stars in our Galaxy form in clusters which often contain the massive stars which, with their prodigious energy output, dominate the evolution of the interstellar medium. Understanding how these clusters and the massive stars within them form and evolve is one key questions for astrophysics. A major challenge is identifying the clumps of dense gas in molecular clouds which give rise to these clusters before star formation significantly modifies their properties. Infrared dark clouds (IRDCs), dense regions seen in absorption against the diffuse infrared emission in the Galactic Plane, are amongst the best candidates for identifying such objects. In this talk I will draw on IRDCs identified in a recent new catalogue, plus other recent data, to explore how the gas in molecular clouds gathers to form massive dense clumps and how these subsequently evolve as star formation takes place within them.

Galaxy clusters are the largest well defined objects in the Universe which form from density fluctuations originating from the early Universe. They are interesting large-scale astrophysical laboratories for the study of a wealth of phenomena on one hand, and their evolution and abundance represent an excellent probe to test cosmological models that can describe our Universe on the other hand. In the talk I will illustrate this potential of galaxy cluster research with three examples. X-ray observations of the intracluster medium allow us to probe the chemical composition of the intracluster medium, which contains more than half of the products of stellar nucleosynthesis. A comparison of the abundances of the most important heavy elements leads very roughly to a consistent picture with our theoretical understanding of supernova yields. The second example concerns the interaction of AGN jets at the center of clusters with the intracluster medium. This "AGN feedback mechanism" prevents the gas in the centers of clusters from catastrophic cooling. This well observed scenario in galaxy clusters has shaped the modelling of feedback effects in theoretical studies of galaxy evolution. Based on the largest X-ray galaxy cluster sample with a well defined selection function from the ROSAT All-Sky Survey we obtain measures of the large-scale structure of the Universe which allow us to test cosmological models. The parameters which are best determined by our survey are the cosmic matter density and the amplitude of the matter density fluctuations today. We discuss these results in context with other observational constraints of cosmological parameters. We also use the clusters to map the large-scale matter distribution in the local Universe.

Through KASI, Korean astronomers will have access to the Gemini Observatory starting in 2015. Gemini operates two optical/infrared 8m-class telescopes: one on the northern hemisphere in Hawaii, one on the southern hemisphere in Chile. Both are equipped with state of the art instruments and adaptive optics systems that will be presented. Gemini also offers the opportunity for instrument development, and welcomes visiting instruments. In Operations, Gemini offers to its partners three ways of applying for time: through semesterly calls for standard programs, through yearly calls for Large and Long Programs, and through monthly calls for fast turnaround programs. Gemini operates in queue mode (observing for the principal investigators and allowing flexibility in the time domain), as well as in the classical visitor mode (where principal investigators come to the telescope). The requirements and advantages of all these modes will be explained. The talk will review these topics and more to provide a full update on the Gemini Observatory.

Due to increasing size of astronomical data and expected boom of survey projects, it becomes important to detect interesting objects reliably in the large amount of data. I explain the importance of applying machine learning algorithms in future astronomical research. Focusing on application of clustering algorithms to detect groups in data, I introduce a non-parametric Bayesian clustering method and a consensus clustering method which improve reliability of detecting genuine variable sources in time-series astronomical data. I also present a new strategy of time-series data analysis to identify variable sources quickly by using ensemble of clustering methods as the data size grows. Possible applications of the non-parametric Bayesian method are presented for theoretical and observational astronomical research, emphasising the role of data-driven models.

The feedback from massive young stars has a profound impact on the interstellar medium (ISM), driving turbulence and regulating star formation. Among many feedback processes, supernovae provide predominant amount of momentum to the ISM in scales larger than individual star forming regions. In this talk, I will review our recent hydrodynamic numerical simulations in local galactic disks, including momentum feedback from supernovae. Our models demonstrate that the star formation rates are regulated to establish all thermal, turbulent, and vertical dynamical equilibria. In addition, synthetic HI 21cm emission and absorption lines constructed from our simulations successfully reproduce and explain the observed distribution of the brightness temperature, optical depth, and spin temperature. Finally, I will introduce our current attempt to quantify a necessary condition for the correct treatment of supernova feedback.

The International Astronomical Union (IAU) Office for Astronomy Outreach (OAO) is an IAU new office hosted at National Astronomical Observatory of Japan (NAOJ) at Tokyo. After the International Year of Astronomy 2009, IAU decided to establish the OAO to coordinate the international astronomical outreach efforts. Two major campaigns that OAO are running are the International Year of Light 2015 and the Public Naming of Exoplanets. IAU is one of the supporting organisation of the International Year of Light 2015 (IYL2015), and one of the IYL2015 cornerstone project is “Cosmic Light”, which connect astronomy to light. On the other hand, IAU has launched the NameExoWorlds campaign, to name exoplanets, however, using a different approach than the naming of solar system bodies like asteroids or comets, the naming of exoplanet will involve public voting and proposal nominations from public organizations.

In the first part of my talk, I will briefly introduce my research interests. I will talk about my works on the observations toward high-mass star forming regions. In the second part of my talk, I will focus on the follow-up observations toward Planck cold clumps with ground-based radio telescopes, which is becoming a large internationally collaborating project. Below is the brief introduction of this project. Stars form in dense regions within molecular clouds, called pre-stellar cores (PSCs), which provide information on the initial conditions in the process of star formation. The low dust temperature (<14 K) of Planck cold clumps/cores makes them likely to be pre-stellar objects or at the very initial stage of protostellar collapse. We have proposed follow-up observations towards these sources with ground-based telescopes (IRAM 30-m, PMO 14m, APEX, Mopra, Effelsberg 100 m, CSO, NRO 45-m and SMA). We will identify and characterize starless cores, prestellar cores and preclusters, and determine the evolutionary sequence for these cores and study their physical and chemical properties. We will also study the fragmentation of these starless Planck cold clumps to see whether the fragmentation in the earliest phase of star formation is determined by turbulence or not. This study will greatly improve our understanding of the initial conditions for star formation and core evolution. I will discuss the progress and the plans (e.g. ALMA) of this internationally collaborating project.

The first part of this talk will be the research highlights of my galaxy cluster studies. While I keep deep optical imaging campaigns on galaxy clusters, my research interests also have expanded into the environmental effect on galaxy evolution and the high-z galaxy clusters. Recent results and ongoing observational projects in which I am closely involved will be introduced. The second part will be a brief introduction to Astronomy in Chile. I would like to share my experiences of the research environment in Chile as a Chilean astronomer.

Beyond the local universe, neutral hydrogen (HI) gas, a tentative star formation reservoir, is poorly constrained by observation, compared to star formation. It is because existing observing facilities in radio frequency to detect HI 21-cm emission lines are not sensitive to directly measure weak HI signals from individual galaxies at z > 0.2. To overcome the sensitivity limitation, two new techniques have been proposed and recently proved their viability. One is HI spectral stacking technique, and the other is HI intensity mapping. These are the most promising techniques to push the sensitivity limit of even future radio facilities such as SKA pathfinders and SKA still further. In this talk, I will present how HI gas content of galaxies in the intermediate redshift 0.1 < z < 0.4 has been measured using the HI spectral stacking that I used in my previous works and briefly introduce an HI intensity mapping experiment which I am heavily working on at the moment.

The standard model of physics does not require the fundamental constants of nature (the FCs) to be constant in space and time. In the past, quests to measure possible variations have mostly been performed with atomic and also molecular hydrogen as well as metal absorption lines at (observer frame) optical wavelengths. At (sub)millimeter and radio wavelengths, in various cases dramatically different dependences of certain spectral lines on FCs allow for extremely sensitive constancy tests. Farthest back in time, to 12.8 Gyr, reach our recent sensitive limits on a combination of the fine structure constant and the proton-to-electron mass ratio, that we determined from sensitive measurements of emission from rotational CO and fine structure lines from atomic or ionized carbon toward high redshift (up to z = 6.4) quasar host galaxies. We shall briefly summarize these but shall concentrate on absorption line measurements, which are much more sensitive. At present, 5 (sub)mm- and/or radio-wavelength molecular line absorbers are known at cosmological distances, all at z < 0.9 and thus probing look back times up to about 7 Gyr. Three of these are the lensing galaxies of graviations lens systems. Observations of numerous different molecules toward on of these systems not only delivers the tighest cosmological limits on the proton-to-electron mass to date but also reveal a fasciating astrochemistry that is quite different from that of the Milky Way’s interstellar medium. We shall also provide an outlook on opportunities with the ALMA, the JVLA and the SKA.

Majority of galaxies reside in groups and clusters where they are understood to evolve also through galaxy-galaxy interactions. Multiple mergers at the core of galaxy groups can develop a luminosity deficiency or gap, which is quantified as the difference between the luminosity of the two brightest galaxies in groups and clusters. This observable carries important information about the evolution of galaxy groups, for instance, there are indications that collapsed groups with a large luminosity gap, known as fossil groups, are associated with the halos that are relatively old. In a series of recent studies, employing X-ray, optical and radio observations complemented by cosmological simulations, we have utilized the luminosity gap to probe the formation scenarios for galaxies and specially the most luminous galaxies in groups and clusters, introduce a powerful age-date routine for galaxy groups, and also obtain clues about the AGN activity and the IGM heating.

According to the modern theory of galaxy formation, galaxies form because of cooling of baryons and star formation at the centers of gigantic halos of dark matter.The cold neutral hydrogen (HI) layer of the galactic disk serves as an effective tracer of the underlying gravitational potential of the dark matter halo in nearby, edge-on spiral galaxies. In the first part of the talk, I will discuss how the density profile of the dark matter halo can be constrained by using the observed HI rotation curve and the HI layer thickness, as applied to the superthin low surface brightness galaxy UGC 7321, the Andromeda (M31) and our the Galaxy. In the second part, I will show how the superthin nature of the disk of the stars in the low surface brightness galaxy UGC7321 can be traced back to the presence of a dense and compact dark matter halo in this galaxy.

Even after more than 45 years of their discovery in late 1960s, the radiation mechanism of gamma-ray bursts (GRBs) remains unclear. Since the main component of GRB prompt emission in sub-MeV energy range exhibits a non-thermal nature with a smoothly-joined broken power-law spectral shape ("Band function"), the synchrotron radiation of relativistic electrons in the emitting region has been put forward as the leading mechanism that powers GRBs. However, it was soon realized that the standard synchrotron spectrum in the fast-cooling regime is not consistent with the observed low-energy spectral index of prompt emission spectra, and as a result, the synchrotron mechanism has been disfavored and other photospheric models were invoked for the prompt emission. Under these circumstances, a theoretical breakthrough in understanding the GRB radiation mechanism is recently made on the synchrotron side. It is shown that, when the magnetic field strength in the emitting region decreases in time, the fast-cooling synchrotron spectrum is in fact in a non-steady state and becomes significantly harder than the "standard" one, becoming well consistent with the observed low-energy index. This new physics of synchrotron cooling of relativistic electrons also applies to the GRB afterglow phase where the magnetic field strength in the shocked region naturally decreases as the blast wave propagates through the surrounding ambient medium. Recent theoretical developments made on the blast wave dynamics and afterglow modeling will also be presented for generic models with various density structures in the ejecta and ambient medium.

We describe two recent developments regarding the diffuse interstellar medium. One involves the 'Leo Cloud', a nearby, very cold and very high-pressure sheetlike cloud that resides in the 'Local Bubble'. The Local Bubble was originally discovered from X-ray emission from its hot gas, but it is now thought that it does not, in fact, emit X-rays, nor does it contain hot gas. So what keeps the highly overpressured Leo cloud confined? The other derives from the recent availability of Faraday Rotation measurements with angular resolution about 1 degree. These reveal spectacular magnetic structures in the high-latitude ISM, and also show surprising magneto turbulent behavior in the edge of the Eridanus/Orion superbubble.

Recently, Hershel observation has revealed that filaments are fundamental structure forming interstellar molecular clouds. In addition, magnetic field, which is believed to be important in supporting the cloud, is observed perpendicular to the filament. We studied the magnetohydrostatic equilibrium structure of the filament with prependicular magnetic field. Two types of magnetohydrostatic structure are found. Critical mass (maximum supported mass against gravity) is obtained as a function of the magnetic flux. It is shown that the critical line-mass lambda is proportional to the magnetic flux per unit length Phi as lambda ~ 0.24 Phi / G^1/2. Polarization pattern expected for the magnetized filaments is also studied. The interstellar polarization shows both perpendicular and parallel pattern to the filament depending on the line-of-sight. We discuss the configuration of the magnetic field expected from the interstellar polarization.

HETDEX (Hobby-Eberly Telescope Dark Energy eXperiment) is a galaxy survey targeting Lyman-alpha emitters (LAEs) at high redshifts (1.9