Colloquiums and Seminars

Gaia is an ESA satellite project launched at Dec. 2013. It will map our Galaxy in 3D by measuring six astrometric parameters (i.e. two positions, two proper motions, parallax, and radial velocity) of one billion stars over the whole sky. Astrometric accuracy of Gaia for G type star is 5-16 μas for bright stars, 24 μas at V = 15 mag and 540 μas at V = 20 mag, which is the highest accuracy that has ever been achieved. Gaia simultaneously obtains low-resolution spectrum of each star using Blue and Red Photometer (BP and RP: 330-680nm and 640-1000nm, respectively). By the nature of Gaia, it will produce enormous amount of complex data. Analyzing Gaia data is thus a challenging and huge task requiring Big Data experts and dedicated computing powers as well. In this talk, I will give an overview of the Gaia mission and efforts for Gaia data analysis in DPAC (Data Processing and Analysis Consortium).

In the past decade, weak gravitational lensing has become one of the best ways of measuring galaxy halo masses for galaxy samples at low to intermediate redshifts. Measurements of the average halo density profiles for galaxies with a given luminosity or stellar mass (observable mass proxies) have revealed a great deal about the connection between halo masses and these mass proxies. After a broad overview of what such measurements have shown us in several datasets, I will describe some recent measurements in the SDSS that illustrate a bimodality in halo mass at fixed stellar mass, with red galaxies that reside at the centers of dark matter halos having host halo masses that are a factor of 2-3 larger than those that host blue central galaxies. I will discuss the implications of these results for models of galaxy formation and evolution, and also propose future measurements with upcoming datasets such as HSC that will shed further light on the relevant galaxy formation and evolution processes.

In this talk I will give an overview of the state of the art in two widely used techniques for modelling the cosmological galaxy population: hydrodynamical simulations and semi-analytic models. Over the last 25 years, these techniques have acted as focal points, drawing together theories for many different phenomena interacting over a wide range of scales. The result is something approaching a 'standard model' for galaxy formation, which provides a remarkably straightforward and consistent framework for interpreting a host of observations in the nearby Universe. Ambitious galaxy surveys planned for the next decade and new instruments such as ALMA will greatly improve this model by constraining the specific evolutionary paths that galaxies take from their first formation to the present day. This in turn will require a new era of interaction between `macroscopic' simulations and detailed modelling of astrophysics at 'sub-galactic' scales. I'll describe my work on two exciting but relatively under-exploited constraints on galaxy evolution: metal enrichment (including the case for an varying stellar initial mass function based on sub-mm number counts) and diffuse light in the outskirts of galaxies. Finally, I'll briefly advertise the Milky Way and Bright Galaxy surveys that will be carried out with the Dark Energy Spectroscopic Instrument.

I will present recent results on the connection between galaxies and dark matter haloes up to z=1, measured from a combined lensing and clustering analysis in the CFHTLS/VIPERS field. We obtained 30 deg2 of deep NIR data over the entire VIPERS area: whereas this program was initially designed to get robust stellar masses for the spectroscopic targets, we have shown that when properly calibrating photo-z's with spectro-z's and accounting for photo-z error in the modelling, one is able to get accurate constraints from projected clustering and galaxy-galaxy lensing from a photometric sample. This significant increase in survey area for such depths and good lensing data allowed us to consistently probe the Mstar-Mh relation from the peak of the stellar-to-halo mass ratio (SHMR) up to the most massive clusters, a key asset to bring new insights on galaxy evolution.

The supply and lifetime of gas and dust in circumstellar disks are among the primary determinants of the properties of young planetary systems. Most of the information on disk evolution has so far come from infrared surveys, which have established that hot dust in primordial disks dissipates in approximately 5-10 Myr. ALMA is now playing a central role in these studies by probing colder gas and dust in disks. In this talk, I present recent results from an ALMA survey of 106 disks in the Upper Sco OB association. At an age of 5 Myr, Upper Sco is a benchmark region to establish the properties of disks at the end state of their evolution. By comparing Upper Sco with disk properties in young regions, we can assess how the gas and dust in disks evolve on timescales of 5 Myr. [This is a joint special seminar and planetary science group talk.]

I will examine two aspects of the growth of galaxy clusters from z~1.8 to the present time: the evolution of the shape of galaxy clusters and the growth of the brightest cluster galaxies (BGCs). Using two large samples of galaxy clusters from the Second Red-sequence Cluster Survey (RCS2) and the Spitzer Adaptation of RCS (SpARCS) survey, we measure the ellipticities of galaxy clusters from z~0.2 to 2.0. Using the 418 most massive clusters in the samples, we find the average ellipticity of the projected spatial distributions of galaxies in the clusters increases with redshift. This evolution in cluster shape is consistent with that measured from N-body simulations. I will also present recent results on the evolution of the star-formation rate and the growth of the stellar mass of BCGs using clusters from the SpARCS survey. I will briefly discuss possible connections between the BCG and the cluster shape.

In this colloquium I will talk about our SMA / ALMA observations of protostellar binaries L1551 IRS 5, L1551 NE, and XZ Tau, including our latest ALMA cycle 2 results of L1551 NE. We found that the structures of the disks surrounding the binaries, circumbinary disks, are different among these protostellar binaries in the L1551 region. While in L1551 NE the circumbinary disk consists of two spiral arms stemming from the individual stars, in L1551 IRS 5 such arm features are not seen, and in XZ Tau no circumbinary disk is present. In L1551 IRS 5 and NE the gas motions in the circumbinary disks exhibit Keplerian rotation, but in the innermost part of the circumbinary disk in L1551 NE infalling motion toward the protostellar binary is also seen. I will discuss these results in the context of mass accretion onto the protostellar binaries and physical mechanism to set the final binary mass and mass ratio.

Young stellar objects (YSOs) may not accumulate their mass steadily, as was previously thought, but in a series of violent events manifesting themselves as sharp brightening events. These events can be caused by fragmentation due to gravitational instabilities in massive gaseous disks surrounding young stars, followed by migration of these dense gaseous clumps onto the star. We report our high angular resolution, coronagraphic near-infrared polarization imaging observations using the High Contrast Instrument for the Subaru Next Generation Adaptive Optics (HiCIAO) of the Subaru 8.2 m Telescope, towards four YSOs which are undergoing luminous accretion outbursts. The obtained infrared images have verified the presence of several hundred AUs scale arms and arcs surrounding these YSOs. In addition, our hydrodynamics simulations and radiative transfer models further demonstrate that these observed structures are indeed explained by strong gravitational instabilities occurring at the beginning of the disk formation phase. The apparently much smoother and older planet-forming disks may be merely the final products of these tempestuous and stochastic processes.

Galaxy clusters provide a large range of environments for the study of how the environment affects galaxy evolution. I will present some recent results on the evolution of galaxies in clusters at z~1 and beyond from two large cluster surveys. SpARCS is an imaging survey designed to search for galaxy clusters up to z~2 using the cluster red-sequence technique based on a combination of Spitzer Space Telescope’s IRAC 3.6um and ground-based z’-band images; GLASS is a multi-object spectroscopic survey of 10 of the richest SpARCS clusters at z~1 using the Gemini 8.2m telescopes. Analysis of GCLASS data show that galaxies in-falling into clusters at z~1 have their star formation suppressed in a relatively short time scale of less than 0.5 Gyr at an average location close to 0.5 r_200 (the cluster-centric radius within which the cluster is largely virialized). From imaging data obtain using the 24um MIPS camera on Spitzer, we also find that lower-mass in-falling galaxies show a possible last-gasp increase in their star formation before become quiescent. Using far-IR/submm data from the Herschel Space telescope, we will take a detailed look at the change in star formation via dust emission in 3 clusters at z~1.2 as galaxies in-fall into the clusters.

I will discuss the process of gas inflow on galaxies and subsequent fueling of star-formation. Using recent ATCA HI observations I will show that galaxies with anomalous local metallicity decrements (gamma-ray burst host galaxies) have substantial atomic gas reservoirs, and are deficient in molecular gas. This suggests that star formation in these galaxies may be fuelled by recent inflow of metal-poor atomic gas. This is controversial, but can happen in low-metallicity gas near the onset of star formation because cooling of gas (necessary for star formation) is faster than the HI-to-H2 conversion.

Evolved stars are the birth places of the chemical elements, and their extensive mass loss provides an important source of gas and dust to the interstellar medium. An understanding of the late stellar evolution and the nature of the mass loss process is important input for studies of the chemical evolution of a galaxy and the formation of next generations of stars. The shaping of the outflows is structured exhibiting arcs, shells, and spirals. Ever since the first discovery of a circumstellar spiral pattern of a heavily mass-losing evolved star, a paradigm whereby such patterns are induced by the orbital motions of the (postulated) central binary stars was emphasized. In addition, many ring-like patterns observed for longer than a few decades can be explained by the same spiral-shell pattern, but viewed at different angles. Recent high-resolution high-sensitivity molecular line maps from the ALMA and other sub-mm/mm interferometers facilitate new detections of circumstellar spiral-like patterns, and therefore the spirals/shells/arcs have led to a resurgence of interests. In this colloquium, I will describe the impact of binaries on the evolution of the late stages of stellar evolution. In particular, I suggest that the coexistence of bipolar (or multipolar) structures and shell-like patterns can both be understood within the framework of unified model.

We are entering a golden age of dust polarimetry with numerous CMB experiments (e.g., SPIDER, BICEP/Keck, LiteBIRD) hunting for primordial gravitational waves through B-mode polarization, and a dozen of big instruments designed to elucidate the roles of magnetic fields in star formation through IR-mm dust polarimetry (e.g., SOFIA, SMA, ALMA, EVLA). The correct determination of B-mode signal, as well as solid understanding of magnetic fields in star formation, are only achieved when we have a quantitative treatment of dust polarization. In this talk, I will present first my results on quantifying the polarization spectrum of a newly discovered emission component, namely anomalous microwave emission. Second, I will review the quantitative, predictive theory of grain alignment based on radiative torques, and discuss ab-initio modeling of dust polarization that incorporates well-tested physics and comparisons with observational data. Third, I will present my plan to develop an accurate, physical model of CMB foreground polarization required for precision Cosmology with CMB-Stage IV experiments. Finally, I will discuss the unique potential of quantitative polarimetry in the next decade to elucidate the roles of magnetic fields in star and planet formation, and to reveal fundamental properties of magnetic turbulence and cosmic dust, through bridging solid theory, numerical simulations with observations.

One of the paramount problems in modern cosmology is to elucidate how the first generation of luminous objects, stars, supernovae, accreting black holes, and galaxies, shaped the early universe at the end of the cosmic dark ages. According to the modern theory of cosmological structure formation, the hierarchical assembly of dark matter halos provided the gravitational potential wells that allowed gas to form stars and galaxies inside them. Modern large telescopes have pushed the detection of galaxies up to a redshift of z ~ 10. However, models of the first luminous objects still require considerable effort to reach the level of sophistication necessary for meaningful predictions, Due to the complexity of involved physical phenomena, this physical understanding may only come by the proper use of numerical simulations. Therefore, I have used state-of-the-art simulations on some of largest supercomputers to study these objects. In my talk, I will discuss the possible physics behind the formation of these first luminous objects by presenting the results from our simulations. I will also give possible observational signatures of the cosmic dawn that will be the prime targets for the future telescopes such as the James Webb Space Telescope (JWST).

Molecular gas plays a fundamental role in feeding and regulating star formation and growth of supermassive black holes (SMBH) in galaxy nuclei and is therefore a primary evolutionary parameter in starburst and AGN activity. The Atacama Large Millimeter/submillimeter Array (ALMA) is a powerful instrument for studying galaxy evolution using molecules as observational tools - exploiting their ability to trace dynamical, chemical and physical conditions. These tools are particularly important in studying the "cold Universe" and to probe extremely dust-enshrouded galaxy nuclei which are not accessible by optical or even IR tracers.
I will present recent high resolution ALMA results on vibrationally excited molecules and how they can be used to peek inside the optically thick veil of extremely obscured galaxy nuclei. These lines are efficient probes even when N(H2) exceeds 1e24 cm-2 (A_V > 1000) and trace nuclear disks and bars, enclosed mass inside the dusty core - and are direct measures of the hidden mid-infrared luminosity densities. These nuclei may also drive massive, cold molecular winds that may empty the nuclear regions of gas and dust in a few tens of Myr. With ALMA and the IRAM PdBI telescope we have studied several spectacular outflows - including the peculiar molecular jet of the nearby lenticular NGC1377, the tantalizing twin-outflow of the merger NGC3256 and the powerful molecular wind of the quasar Mrk231. I will briefly discuss the link between the evolutionary phase of the nuclear activity and the onset of cold winds.
Finally, with ALMA the field of extragalactic astrochemistry is undergoing a revolution. If there is time towards the end of the presentation I will show you a few recent beautiful examples of this including the luminous infrarred galaxy NGC4418, the nearby Seyfert galaxy NGC1068 and the iconic ultraluminous infrared galaxy Arp220.

The detailed relation between dark matter halos and galaxies is one of the most critical questions about galaxy formation. Among different models of the galaxy-halo connection, the abundance matching technique provides a simple, heuristic description to populate galaxies in dark matter halos, and has been shown to yield good fits to the clustering of galaxies and other observable spatial statistics. The choice of the halo property that is matched to galaxy luminosity (or stellar mass) further provides insights into the galaxy formation physics. In this talk I will discuss how the choice of the halo property used in the abundance matching technique acts as hidden parameters that control specific behaviors, such as assembly bias, in the resulting mock catalog. Our studies show the degeneracy among these parameters, and demonstrate that these parameters can be constrained by the observable clustering signals.

The effect of gravitational lensing has left traces of cosmological information in the Universe for us to pick up. The full information is encoded in the 3D map of dark matter. As a first step to building up this map, I will describe our recent work using the Dark Energy Survey (DES) Science Verification data to make a weak lensing mass map on a large slice of our Universe. I then discuss a few topics where we combine this map and information from the CMB and galaxies. Looking forward to the completion of DES and several ongoing and future optical surveys, these explorations would allow us to take a new look at the invisible landscape of our Universe.

In order to have a global picture of the cycle of matter in galaxies, we need to understand the interplay of large-scale galactic phenomena with the formation of giant molecular clouds and, ultimately, their subsequent star formation. In this context, we ran a set of SPH numerical simulations of spiral galaxies structurally resembling our own Milky Way, where we can track the formation and evolution of molecular clouds in detail. In this talk, I will present my recent study of such simulations, where I investigate the link between the molecular cloud properties and position with respect to spiral arms, both directly from the simulation (with the 3D densities of H2 and CO) and from an observer’s perspective (with CO emission in PPV space), providing predictions and tests for observations of molecular clouds and star formation in both the Milky Way, and external galaxies.

In order to form stars, matter has to transfer from large and diffuse interstellar clouds, to compact and dense protostellar cores. The physical conditions under which this transformation occurs are still highly debated. One particular sticking point is the timescale over which interstellar clouds contract to form cores: Is it rapid (a couple of free-fall times)? or is it slow (tens of free-fall times)? In this talk, I will present recent observational studies of Galactic plane infrared dark clouds (IRDCs). As a result of their infrared quietness IRDCs are ideal laboratories for the study of the earliest stages of star formation. I will focus on the analysis of the gas dynamics of IRDCs with the objective to evaluate their dynamical states (collapsing/expanding/pressure confined) and timescales. The latter will be then compared to the IRDC free-fall times providing some new elements to the debate on the star formation timescale.

Galaxy clusters with short central cooling times are predicted to host massive inflow of gas and large star formation rates, which are absent observationally – the so-called “cooling-flow problem”. Feedback from the central active galactic nuclei (AGN) is one of the most promising heating mechanisms to counteract radiative cooling. However, it is still uncertain how the feedback energy is transformed into heat and how to distribute heat isotropically. The role of conduction is also not well understood. In particular, it is unexplored whether the AGN-driven turbulence could halt the heat-flux driven buoyancy instability (HBI) that acts to insulate the cluster cores from conductive heating. I will present results from our recent simulations that aim to address the above two questions. Finally, few models to date consider cosmic-ray filled AGN bubbles, which are crucial for bubble evolution. I will discuss how we could use multi-wavelength observations of the Fermi bubbles as a nearby laboratory to understand the processes of AGN feedback.

The realization that large portions of cold, dense protoplanetary disks do not support magnetically-driven turbulence have lead to renewed interest in purely hydrodynamical processes in accretion disks. Such processes may play significant roles in disk evolution, planet formation, as well as explaining observations of transition disks. I will discuss recent theoretical developments in three important examples of hydrodynamic instabilities in protoplanetary disks. I first describe the Rossby Vortex Instability, which has been invoked to form dust-trapping vortices to explain asymmetries observed in several transition disks. I will also present new simulations of vortices in massive 3D disks. I then describe the Vertical Shear Instability and its generic relevance to astrophysical disks. I show that, despite rather stringent thermodynamic requirements, that this instability is indeed viable in realistic, irradiated protoplanetary disks where cooling is regulated by dust opacity. Finally, I present a new analytical treatment of Gravitational Instabilities in rotating disks that includes cooling physics, irradiation and viscosity. I discuss how this generalized linear theory may aid the understanding of disk fragmentation, and show that application of our analyses predict where protoplanetary disks are expected to fragment, in agreement with the current consensus based on direct numerical simulations.

The density profiles of dark matter halos are an essential input for models of galaxy formation, as well as for the interpretation of numerous observations such as weak and strong lensing signals. These profiles are commonly thought to be universal and modeled using the NFW form, assuming that they depend on only two parameters: mass and concentration. In this talk, I will show that the outer density profiles depend on an additional parameter, the mass accretion rate, and present an accurate new fitting formula that takes this dependence into account. Similarly, I will present a universal model for halo concentrations that is based on a previously unknown dependence of concentration on the local slope of the matter power spectrum. Finally, I will introduce a novel feature in the density profiles, the splashback radius. Contrary to the common belief that halos have no well-defined edge, this radius provides a physically motivated definition of the halo boundary.

Knowledge of the interstellar medium (ISM) is essential to understand the stellar life cycle, beside others. The ISM can be traced by the emission or absorption lines of molecules, atoms and ions. Different molecules/atoms/ions trace different phases of the ISM, and some important molecules/ions/atoms can only be detected at frequencies above 1 THz. On sub-millimeter telescopes, heterodyne receivers are generally used for line observations. During my PhD, I built and characterized a 2.6 THz heterodyne receiver. This operating frequency of 2.6 THz is one of the highest reached by recent heterodyne receivers, and in order to characterize and improve this receiver, 3 important aspects were investigated: 1) The stability of the receiver, which determines the optimal integration time of the receiver before it has to be recalibrated. 2) The design and test of a Martin-Puplett interferometer which allows to superimpose the local oscillator signal and the observed signal with a very good efficiency. 3) The design, simulation and characterization of a new kind of phase grating (The Global phase grating) able to efficiently split the local oscillator beam into several beams, which allows the development of a multi-pixel heterodyne receiver. In conclusion, this work constitutes an important step toward the realization of a stable and highly sensitive 2.6 THz multi-pixel heterodyne receiver using a Martin-Puplett interferometer diplexer, for the next generation of sub-millimeter/farIR space missions.

It is well-established that galaxies and their central supermassive black holes co-evolve. The properties of AGN hosts and their interactions of, i.e. the feeding and feedback of AGNs, are key processes to understand these co-evolutions. In this talk, I will introduce some of our recent and ongoing work on the direct and indirect interactions of AGNs and their host galaxies, particularly using the data from 2D spectroscopy. I will also introduce our own 2D spectrograph, CHILI, and particularly its science implications. In the end, I will briefly mention our work that are not 2D-related, particularly the one that studies AGNs using infrared spectroscopy and explores high-z low-luminosity AGNs with the HETDEX survey.

Pathways leading to the formation of complex organic molecules will be described. Gas phase processes that may build large carbon-chain species in cold molecular clouds will be summarised. Catalytic reactions on grain surfaces can lead to a large variety of organic species, and models of molecule formation by atom additions to multiply-bonded molecules will be presented. The subsequent desorption of these mixed molecular ices can initiate a distinctive organic chemistry in hot molecular cores.

The general ion-molecule pathways leading to even larger organics will be outlined. The predictions of this theory will be compared with observations to show how possible organic formation pathways in the interstellar medium may be constrained. In particular, the success of the theory in explaining trends in the known interstellar organics, in predicting recently-detected interstellar molecules, and, just as importantly, non-detections, will be discussed. The most urgently needed laboratory data required by these and future theoretical models, both for gas-phase and solid-phase reactions, will be emphasized.

Ehrenfreund, P. & Charnley, S.B. (2000), Annu. Rev. Astron. Astrophys., 38, 429

The most prodigious starburst galaxies are absent in massive galaxy clusters today, but their connection with large scale environments is less clear at z>2. I present our search of dusty star-forming galaxies (DSFGs; SFR>100 Msun/yr) within and around a protocluster at z~2.1 in the COSMOS field. Both DSFGs and color-selected SFGs show significant overdensities around the protocluster, and this structure spans across several tens of cMpc, considerably larger than previously observed. The cluster core and the extended DSFG- and SFG-rich structure together demonstrate an active cluster formation phase, in which the cluster is accreting a significant amount of material from large scale structure while the more mature core may begin to virialize. The finding of this DSFG-rich structure, along with a number of other protoclusters with excess DSFGs and AGNs found to date, suggest that the overdensities of these rare galaxies indeed trace significant mass overdensities. However, it remains puzzling how these intense star formers are triggered concurrently. Although an increased probability of galaxy interactions and/or enhanced gas supply can trigger the excess of DSFGs, our stacking analysis based on 850 micron images and morphological analysis based on rest-frame optical imaging do not show such enhancements of merger fraction and gas content in this structure.

Nuclear rings, dust lanes, and nuclear spirals are common structures in the inner region of barred galaxies, with their shapes and properties linked to the physical parameters of the galaxies. We use high-resolution hydrodynamical simulations to study gas inflow patterns in barred galaxies, with special attention on the nuclear rings. The location and thickness of nuclear rings are tightly correlated with galactic properties, such as the bar pattern speed and bulge central density, within certain ranges. We identify the backbone of nuclear rings with a major orbital family of bars. The rings form exactly at the radius where the residual angular momentum of inflowing gas balances the centrifugal force. We propose a new simple method to predict the bar pattern speed for barred galaxies possessing a nuclear ring, without actually doing simulations. We apply this method to some real galaxies and find that our predicted bar pattern speed compare reasonably well with other estimates. Our study may have important implications for using nuclear rings to measure the parameters of real barred galaxies with detailed gas kinematics. I will also discuss the latest results of extending current work to model the gas features in the Milky Way.

Multi-wavelength observations of Active Galactic Nuclei (AGNs) have suggested that their internal structures are consisted of various components, such as an accretion disk, broad line regions, an obscuring dusty torus, and narrow line regions, over an extensive spatial scales. However, their origin and mutual relations have not been understood, andit is also unclear whether these structures are universal among AGNs.

In this seminar, I will review recent progress in theoretical modeling of circumnuclear gas structures in AGNs, mainly based on our radiation-hydrodynamic simulations. In a series of our studies, we found dynamic behavior of the gas around the SMBH due to the effect of the radiation feedback, in contrast to the classic picture. Spectroscopic properties in typical Seyfert galaxies are well reproduced in these models. Some characteristic features suggested by recent infrared and X-ray observations can be also explained.

I will also show preliminary results of modeling the multi-phase ISM affected by an AGN and nuclear starburst for a nearby AGN. These numerical approach with radiative transfer calculations could be a powerful tool for understanding observations of molecular/atomic gases by ALMA.

Almost 20 years ago, the discovery of submillimeter galaxies (SMGs) had opened up a whole new window for observational astronomy, which subsequently lead to a paradigm shift in our understanding of galaxy formation and evolution. Panchromatic follow-up studies and dedicated missions such as Herschel have improved our knowledge of SMGs immensely. However, many fundamental questions are still under debate; How many are they? How are they formed? How massive they are? Are they the long sought-after predecessors of present day massive ellipticals? In this talk, I will present our latest results from SCUBA-2, ALMA, and HST, and explain how some of these questions are starting to converge. In the meantime, I will also show new evidence that further challenges the current galaxy formation models. Finally, with new surveys such as S2COSMOS and STUDIES, I will explain how are we going to make a major step forward and push the observational constraints of SMGs to a new level.

The New Horizons (NH) mission was selected by NASA in November 2001 to conduct the first in situ reconnaissance of Pluto and the Kuiper belt. The NH spacecraft was launched on 2006 January 19, received a gravity assist from Jupiter during closest approach on 2007 February 28, and flew 12,500 km above Pluto's surface on 2015 July 14. NH carried a sophisticated suite of seven scientific instruments, altogether weighing less than 30 kg and drawing less than 30 W of power, that includes panchromatic and color imagers, ultraviolet and infrared spectral imagers, a radio science package, plasma and charged particle sensors, and a dust counting experiment. The NH flyby of the Pluto system executed flawlessly, providing unprecedented detail on the Pluto-Charon binary and Pluto's four small moons (Styx, Nix, Kerberos, and Hydra, in order of their orbital distance from Pluto). Pluto's surface displays diverse landforms, terrain ages, albedos, colors, and composition gradients. Evidence is found for a water-ice crust, geologically young surface units, surface ice convection, volatile transport, and glacial flow. NH discovered trace hydrocarbons in Pluto's atmosphere, multiple global haze layers, and a surface pressure near 10 microbars. Pluto's diverse surface geology and long term activity raise fundamental questions about how small planets remain active many billions of years (Gyr) after formation. Charon displays tectonics, evidence for a heterogeneous crustal composition, and a puzzling giant hood of dark material covering its North Pole. Crater density statistics for Charon's surface give a crater retention age of 4-4.5 Ga, indicating that Charon's geological evolution largely ceased early in its history. Nix and Hydra have high albedos suggestive of H2O-ice covered surfaces. Crater densities on Nix and Hydra indicate surface ages > 4 Ga. All the small satellites have highly elongated shapes and are rotating much faster then synchronous with their orbital periods, with rotational poles clustered near the Pluto-Charon orbital plane. The NH spacecraft remains healthy and was targeted toward the flyby of a small (~30-40 km) KBO in late-2015, enabling the study of an object (2014 MU69) in a completely different dynamical class (cold classical) than Pluto, if NASA approves an Extended Mission phase. In addition to the flyby 2014 MU69, the proposed Extended Mission would also include observations of more than 20 other KBOs at resolutions and geometries not feasible from Earth, and studies of the heliospheric plasma, neutral H and He, and the dust environment out to 50 AU from the Sun.

Revealing the acceleration of the cosmic expansion is one of the most important issues not only in cosmology but in fundamental physics. The mysterious dark energy could be driving the acceleration, or gravity law predicted from Einstein’s theory of general relativity could be breaking down at cosmological scales. To investigate the origin of the acceleration, one needs to probe both geometry (expansion history of the Universe) and gravity (structure growth history of the Universe). Thus, observations of large-scale structure of the Universe traced by galaxy surveys are considered as the best probe for this purpose, because the expansion history is probed by a measurement of baryon acoustic oscillations (BAO) and the growth history is probed using redshift-space distortions and weak lensing. In this talk, I will present the constraints on dark energy and gravity theory I obtained using current galaxy surveys. Then I will demonstrate that the accuracy of the current theoretical models for extracting the dark energy or gravity properties is not high enough for the future precision surveys such as the Subaru SuMIRe project (Hyper Suprime Cam / Prime Focus Spectrograph). Particularly, incorrect modeling of redshift-space distortions easily leads to a wrong constraint on gravity theories. In the latter part of my talk, I will present a new theoretical model of redshift-space distortions I have been developing, which achieves a percent level accuracy for galaxy power spectrum up to very small scales. Finally, I will mention how theoretical study of large-scale structure is related to other fields, such as galaxy formation, physics of galaxy clusters, etc.

Black holes are among the most fascinating astrophysical objects and have long entranced the public. I will describe recent progress in discovering black holes beyond one billion solar masses lurking at the centers of massive elliptical galaxies in the local universe. These massive black holes are plausible descendants of luminous quasars in the young universe and inform us of how cosmic structures evolved over the past 10 billion years. Merging black hole binaries in this mass range are also the primary sources of gravity waves in the nano-Hertz range targeted by ongoing pulsar timing array experiments.

The outskirts of massive galaxies are host to a rich variety of enigmatic phenomena, including diffuse stellar halos, tidal streams, dwarf satellites and globular clusters. The huge spatial extent and intrinsic faintness of such systems has so far limited our observational knowledge to the mere tip of this proverbial iceberg. Pioneering techniques with existing instruments are rapidly revising the status quo, and an even more dramatic revolution is due in the next decade as a deluge of data arrives from ultra-deep photometric surveys with HSC and LSST, Gaia’s survey of the Milky Way, and massively-multiplexed spectroscopy in the nearby Universe with DESI, 4MOST, WEAVE and PFS. These new surveys present exciting challenges in the synthesis of information from a wide range of methods, sources and scales, from the most massive galaxy clusters to the Milky Way and the earliest epoch of galaxy formation. In this talk, I will describe my work with cosmological simulations aimed at addressing those challenges and understanding what we can learn from such observations. In particular, I will discuss pressing issues in the ‘big picture’ of Lambda-CDM galaxy formation that could be tackled by testing predictions of a surprisingly intimate relationship between the properties of stellar halos, satellites and dark matter halos.

Sometime between the years 2006 and 2012, the broad Hbeta emission line of Mrk 590, once classified as a Seyfert 1 galaxy, completely disappeared! The optical-UV continuum emission has faded to the point where it can be fully accounted for by the host galaxy starlight. As such, Mrk 590 would now be classified as a Seyfert 1.9 or 2 galaxy, which goes against the prevailing scheme of AGN unification where the presence of broad emission lines depends only on source orientation. Similar decreases in the radio and X-ray continuum fluxes suggest that the central engine of Mrk 590 may be turning off or transitioning into a radiatively inefficient mode of accretion. I will talk about the origin of the compact, unresolved radio emission in Mrk 590 and the physical nature of its variability in relation to the variability observed at other wavelengths. I will also present recent CO line observations with ALMA, which provide the strongest limits to date on the molecular gas mass in the central regions, to determine if this AGN is indeed running out of gas to fuel it.

Accreting black holes are observed in a large variety of systems in astronomy: active galactic nuclei, X-ray binaries, tidal disruption events, gamma-ray bursts. While analytical one-dimensional models are very useful, some aspects of accretion physics such as the formation of jets and winds are beyond the scope of such models. Numerical general relativistic MHD simulations are able to include more physics than analytical models and are proving increasingly useful for studying the multidimensional gas dynamics and radiative properties of accretion flows. The talk will review some current progress.

The majority of young low-mass stars are surrounded by disks, consisted of large reservoirs of gas and dust out of which planetary systems eventually form. In the recent years, high spatial resolution observations of such disks have revealed many details that are providing interesting constraints on the disk physics as well as dust dynamics, both of which are essential for understanding planet formation. In particular, large-scale features (e.g, gaps) and asymmetries (e.g., vortices?) are detected, including sources like HL Tau. In this talk we will give an introduction to the disk instabilities, in particular the Rossby wave/vortex instability and a new type of “heavy core” instability related to dust, that might be responsible for explaining asymmetries. We will discuss how gas+dust two-fluid modeling can be coupled with radiative transfer calculations to help interpret the observations and constrain the parameters in such systems. Implications for future observations will be explored as well.

For nearly a century some of the most important astrophysical systems have been described in terms of every-day models or paradigms. For example, stellar interiors are likened to furnaces and the Big Bang is likened to an explosion. In the case of active galaxies and quasars, early observers, who studied the emission lines and ultraviolet continuum of these objects, often referred to the “central engine” that powered their energy output (often as great as 10^40 Watts or higher). We now are reasonably certain that, in each such active galaxy, the central object that is responsible for the “engine” is a supermassive black hole (as large as 20 billion solar masses), which is accreting gas and stars from the galaxy in which it resides. In fact, as more is learned about how an accreting black hole can produce the different types of behavior seen in active galaxies, the more accurate the Engine Paradigm appears to be. A black hole engine has most of the major subsystems that are in a standard automobile internal combustion engine and can be throttled from a quiet idle to an explosive roar. This includes an engine block (the black hole), a fuel supply (actually two types of fuel), a carburetion/fuel-injection system that converts gaseous fuel into a fine mist, a combustion chamber where the internal (gravitational) energy of the fuel is released, and five different exhaust systems to carry the spent fuel away from the combustion chamber. Black hole engines also produce enormous amounts of mechanical energy, which can be used to assist in the explosion of some stars, help trigger star formation in certain cases, and even shut off star formation in an entire galaxy. In this talk I will discuss the inner workings of black hole engines of different sizes and the important roles black holes play in the evolution of stars and galaxies.

Throughout the history of the universe, shocks and large-scale gas flows have moulded the arms of spiral galaxies, formed the bulges of the most massive galaxies in the universe, fed supermassive black holes in the centers of galaxies, fueled generation upon generation of new stars, and enriched the intergalactic medium with metals. For local galaxies, we use multi-object integral field spectroscopy to build the largest sample of galaxies with wide 3-dimensional imaging spectroscopy. We combine these results with insights into the early universe probed through gravitational lensing and near-infrared integral field spectroscopy. I will present the latest results from our large local and high-z 3D surveys to understand the relationship between gas inflows, galactic-scale outflows, star-formation, and active galactic nuclei in galaxies as a function of environment and redshift. I will finish by discussing how this field will be transformed with JWST and in the GMT/TMT era.

Barred-spiral galaxies contain star-forming nuclear rings at their centers. Star formation rates (SFRs) in the rings vary widely in the range of 0.1-10 M⊙ yr−1. Ring star formation appears long lived, lasting over a few Gyrs. Some rings show a well-defined azimuthal age gradient of star clusters along a ring, while others do not. To study what controls star formation in the rings, we use numerical simulations by including a prescription for star formation and feedback effects. In models without spiral arms, SFR in a ring exhibits a strong burst at early time and declines to small values at late time. On the other hand, models with spiral arms outside the bar region show multiple starburst activities at late time caused by arm-induced gas inflows. In all models, young star clusters in rings show an azimuthal age gradient only when the SFR is small. A linear stability analysis shows that rings with no age gradient appear gravitationally unstable, consistent with observations. I will also report our recent efforts on star formation in three-dimensional rings and their impact on hot halo gas.

Molecular clouds form stars in regions of high density gas. That is not a mystery; it is a requirement. What drives the formation of the dense gas in specific places? What is the geometry of the regions of dense gas as they evolve toward star formation? What is the evolving relationship of the dense gas to forming stars as they grow? CARMA Large Area Star Formation Survey (CLASSy) imaged the dense gas structure and kinematics in five, roughly 1 pc scale, regions in the Serpens and Perseus clouds with 7" angular resolution. The spatial distribution and Class of the young stellar population (YSOs) is available for these regions from the Spitzer c2d and Gould Belt surveys. Together, these datasets allow us to compare, at similar spatial resolutions, the distributions of the dense gas and YSOs over regions containing up to 90 identified YSOs. This enable a detailed look at the relationship between the YSO and dense gas distributions, and some interesting answers for our picture of star formation.

Over the recent years, the studies of the chemical evolution of the Milky Way have seen a major leap forward, in part due to large-scale spectroscopic surveys of stars, like APOGEE, Gaia-ESO, LAMOST and GALAH to name a few.

While these surveys have provided significant insight into the overall behavior of a large number of elements in different stellar populations, many details are still not understood. For instance, the mechanism behind the multiple population phenomenon in globular clusters, as well as the onset of AGB star contributions to the Milky Way halo chemistry is not yet well explained.

Nucleosynthesis models typically predict not only the bulk abundances of the elements, but also their isotopic composition. While elemental abundances in stars provide a wealth of information, in cases where the isotopic abundances can be measured even more can be learned, as this gives a detailed look into the preceding nucleosynthesis.

In this talk I will present how the measurement of Mg isotopes from high resolution stellar spectra can provide new insights into the Milky Way chemical evolution. Both in the context of globular clusters as well as other stellar populations. While earlier investigations have used standard 1D stellar atmospheric models, we have for the first time applied state-of-the-art 3D hydrodynamical models to this problem. This has resulted in significantly different isotopic distributions, and will help pave the way to answer some of the outstanding questions in our Galaxy's chemical evolution.

Dust Obscured Galaxies (DOGs) are optically-faint, but infrared (IR)-bright objects at z~2. Their mid-IR (MIR) flux densities are three orders of magnitude larger than those at optical wavelengths, which implies dust heating by significant star formation (SF), an active galactic nucleus (AGN), or both, and the bulk of the optical and ultraviolet (UV) emission from them is absorbed by dust.

Recently, some works have reported that the brighter MIR DOGs are more AGN-dominated, and indicated that black holes in the IR-bright DOGs are expected to show the highest accretion rate during a major merger event. In addition, IR-bright DOGs could tend to reside in richer environments than fainter ones, and the most luminous DOGs may evolve into brightest cluster galaxies. Therefore, particularly IR-bright DOGs are expected to be a crucial population in terms not only of the co-evolution of galaxies and supermassive black holes (SMBHs) but also of structure formation. However, efficient searches for luminous DOGs have been difficult in previous surveys due to their faintness in the optical and low surface densities. Therefore, high-sensitivity and wide-area surveys in both optical and MIR are required to search for the most IR-bright DOGs.

In this talk, I will present our recent studies on IR-bright DOGs based on the Subaru Hyper Suprime-Cam (HSC) and Wide-Field Infrared Survey Explore (WISE). In particular, I will focus on their statistical properties such as IR luminosity function, IR luminosity density, and clustering properties (Toba et al. 2015; 2016b in prep.).

Since the arrival of high resolution data from the Cassini mission we have learned that Saturn’s ring are far from understood, which many principle question open like the age of the rings and their origin. One of the crucial processes that is being studied by our group is the way the mainly water ice particles are clumping together and under what conditions those clumps can survive longer, potentially creating small moons, or would be destroyed again by the shearing forces of differential rotation. When these clumps grow in size they should become visible in imaging data and my work consists of image analysis techniques to quantify small scale structures visible in Cassini Imaging Science subsystem data. Our group also recently discovered via ultra-violet occultation measurements a traveling resonance feature caused by the Janus/Epimetheus moon swap that seems to travel approximately with constant speed radially outwards through Saturn’s rings. Using fitted velocity fits I am tasked to identify further ISS images that can identify the proposed solitary waves — caused by non-linear interactions with the linear standard density waves in the rings — in future ISS data. The Martian south-pole shows a high amount of visual surface activity caused by CO2 gas jets that break though the temporary CO2 ice layer that develops every winter at both poles of Mars. Interestingly, these activities are restricted to certain areas at the poles and it is currently not understood what precisely controls these restrictions in location. I will discuss the relevance of these CO2 gas jets for geomorphology and uncertainties of global and local atmosphere simulations and how the outcomes of the Planet Four project will improve our insights into both these fields.

Understanding the structure formation is one of the most important issues in modern cosmology. In particular, in the era of big astronomical data, connecting observation and theory is crucial to improve precision cosmology, and possibly probe new physics. The observables of the large-scale structure such as galaxy number density generally depends on the density environment. The dependence can traditionally be studied by performing gigantic cosmological N-body simulations and measuring the observables in different density environments. Alternatively, we can perform the so-called ``separate universe simulations,'' in which the effect of the environment is absorbed into the change of the cosmological parameters. In other words, an overdense universe is equivalent to a positively curved universe, and so the structure formation would change accordingly. In this talk, I will introduce the separate universe mapping, and present how the power spectrum and halo mass function changes in different density environments, which are related to the squeezed-limit bispectrum and the halo bias, respectively. I will also discuss our recent progress on extending this approach to multiple fluids such as dynamic dark energy and massive neutrinos.

Recently, the BOSS collaboration submitted a set of papers (arxiv:1607.03143 ~​ 03155) analysing the final data release of the BOSS galaxy sample ​​ within redshift 0.2 < z < 0.75​ (~1.2 million galaxies)​. We obtained two independent 1% distance measurements at ​two ​ redshifts​ (z=0.38 and 0.61)​ which can be used to derive the evolution of our universe and understand better dark energy. I would like to explain the methodologies and the cosmological results. In the second part of this talk, I would like to present our studies of measuring BAO from void clustering (arxiv:1511.04405,1511.04391,1511.04299). It was not possible to measure BAO from voids because of the low statistical power. ​However, ​we have developed a methodology to extract the information from the large scale structure of void clustering observed from BOSS data. In addition, we investigate and model the redshift distortion effect of void clustering​ (arXiv:1605.05352)​ and found that it would be a challenge to measure growth history ​of our universe ​ from voids.

Accurate knowledge of the fundamental properties of stars--mass, temperature, and luminosity--are key to our understanding of stellar evolution. In particular, empirical measurements of stellar mass are difficult to make and are generally limited to stars that dynamically interact with a companion (e.g., eclipsing or astrometric binaries), a precious but ultimately small sample. First, I will discuss my development of a recent technique that uses the rotation of the protoplanetary disk--a consequence of the star formation process and still present around many pre-main sequence stars--to measure the stellar mass. To vet the absolute accuracy of this technique, I led the analysis of an ALMA Cycle 1/2 program to observe the few circumbinary disks around double-lined spectroscopic binary stars, enabling an independent confirmation of the total stellar mass. Our comparison with radial-velocity results demonstrates that the disk-based dynamical mass technique can reliably achieve precise measurements of stellar mass on the order of 2-5%, clearing the way for widespread application of this technique to measure the masses of *single* stars. Second, I will discuss our development of novel statistical techniques for spectroscopic inference. Young stars exhibit rich and variable spectra; although interesting phenomena in their own right, accretion veiling and star spots complicate the retrieval of accurate photospheric properties. Moreover, the uncertain spectral type--effective temperature scale for low mass pre-main sequence stars introduces a systematic error when placing a star on the Hertzsprung Russell diagram. The Gaussian process techniques we have developed to address these problems are also generally applicable to a wide range of spectroscopic problems. Lastly, I will discuss recent progress in measuring the masses of a large sample of single pre-main sequence stars observed with the Submillimeter Array, which will double the number of disk-based dynamical mass estimates of pre-main sequence stars. With ALMA, the disk-based technique holds enormous promise to become the primary means of stellar mass for statistically large samples of pre-main sequence stars, ushering in a new era of high precision in star and planet formation studies.

The depth/diameter (d/D) ratio of simple lunar craters (D<15km) is known to be ~0.2 at the time of formation; larger complex craters (D>15km) have smaller d/D ratios. We examine the spatial distribution of high d/D ratio (>0.18) craters using LU60645GT catalogue (Salamunićcar et al. 2012). We select craters larger than 8km for which the census is known to be almost complete over the whole lunar surface. We find that the number density of steep craters in maria is significantly lower than in highlands, which may be explained by the age differences of the background surfaces. We also find that the spatial density of steep craters in the equatorial region is lower than in the polar region. On the contrary, higher cratering flux on the lunar equator has been claimed: from the numerical calculations with the orbital distribution of observed Earth Crossing Objects (ECOs) larger than 1km (Le Feuvre & Wieczorek 2008; Ito & Malhotra 2010) and from the distribution of steepest slopes at a 25m baseline (Kreslavsky & Head, 2016). In order to reconcile our findings with previous observations, we hypothesize that the cratering rate at low latitudes has been higher for meter to decameter size ECOs than for kilometer size objects since the Late Imbrian epoch; smaller objects have triggered more frequent mass wasting on the pre-existing large steep craters (D>8km, d/D>0.18) at low latitudes, thereby reducing the surviving number of steep craters. Our hypothesis is supported by the finding that the power-law slope in the H magnitude distribution for the low inclination ECOs (i<15 deg) is steeper than for the high inclination objects.

(1) Chemical abundances of planetary nebulae (PNe) provide a powerful tool for constraining stellar and galactic evolutionary models. Both fields still have unanswered questions that can be addressed with higher-precision abundances. We are collecting a large sample of high-quality optical spectra of compact PNe to combine with already-acquired Spitzer mid-infrared spectra to determine the most accurate and uniform set of Galactic PN chemical abundances. In this talk, I will discuss the current status of the project and present the preliminary results. (2) Star formation requires cold, dense, gravitationally bound clouds, which must themselves form somehow from warmer ambient material. How does this process occur, and where? The cold, diffuse interstellar clouds making this transition are hard to detect in standard HI and CO emission line surveys, but they can be observed in HI self-absorption or narrow-line HI emission. I will describe how such "dark neutral medium" clouds can be mapped over large areas of the Galaxy, what we have learned so far, and the challenges involved in their analysis.

A long-standing question about star formation is whether it is sensitive to large-scale galaxy structures. Observations show that strong bars (high ellipticity and long length) typically contain less or no star formation, while weak bars (low ellipticity and short) have more. This suggests that large-scale structure can indeed influence star formation. Yet galactic bar is a poorly-explored region, its actual effect on star formation is not yet clear. If star formation does care about galaxy structures, this should be reflected in the properties of giant molecular clouds (GMCs), because their conditions determine whether a star can form. In this research, we study the impact of bar on the properties of simulated GMCs formed in a set of galaxies for which their bar strength differs in a quantitatively controlled way. We also discuss the possibility to observe the environmental dependence of GMCs by considering the observational bias.

Many observations have tested the standard cosmological model called LCDM which assumes dark matter and dark energy. Those observations revealed that phenomena predicted from LCDM model are almost consistent with observational results. However, the nature of dark energy is still unknown and this energy cannot be explained by known physics. Accordingly, another solution is also proposed which is called as f(R) gravity. In this theory, the cosmic acceleration is explained by modifying the gravitational theory. Since the effects from f(R) gravity are imprinted in matter distribution of the Universe, weak lensing which traces matter distribution on light path would be a powerful tool to give a constrain on the theory. In order to investigate the possibilities to constrain f(R) gravity with weak lensing analysis in Subaru/Hyper Suprime-Cam (HSC) survey, we carried out weak lensing simulations. Through the analysis of the weak lensing simulations, we found that weak lensing analysis with HSC could provide ten times stronger constraint on f(R) gravity model.

Pulsars are some of physics and astrophysics' most exotic objects, and they have already earned two Nobel Prizes. We currently know of about 2500 of them in our Galaxy, but a small subset, the millisecond pulsars (MSPs), are truly remarkable. These systems are notoriously hard to detect, yet their numbers have more than doubled in the past 5 years via surveys using the world's most sensitive telescopes, new instrumentation, and huge amounts of computing. Specialized "timing" observations of these systems, accounting for each and every one of the billions of rotations of the stars, are providing fantastic results in basic physics. In this talk I'll focus on the efforts to directly detect gravitational waves from super-massive black hole binaries, make strong-field tests of general relativity, and determine the nature of the densest form of matter known in the universe.

Diffuse interstellar bands (DIBs) are absorption features, observed ubiquitously in the interstellar medium (ISM). Understanding their nature is one of the longest unsolved problems in astronomy since their discovery in 1920s. I will present new results of their properties derived from an analysis of about half of a million of SDSS quasar, galaxy, and stellar spectra. Utilizing the SDSS spectroscopic dataset, we measure DIB absorption strengths at 0.1% level and create a map of the DIB distribution across the sky. With this new map, we are able to study how DIBs correlate with other ISM tracers such as dust, atomic hydrogen, and molecular hydrogen. Our results show that each DIB has a different correlation with atomic and molecular hydrogen which can be parametrized by a simple manner. Finally, I will show that our new DIB parametrization is sufficient to reproduce a large collection of observational results reported in the literature.

Finding ultraviolet photodestruction rates for the many atoms and molecules present in space is an interesting subject for fundamental study in laboratory and theoretical chemical physics. I will discuss the photodestruction process and its application to the molecules observed in interstellar clouds, protoplanetary disks, and planetary atmospheres. I will also discuss some detailed studies of N2 and CO photodissociation and their effect on the isotope-dependent fractionation of N, C and O atoms between different molecular forms, as observed in interstellar space and within the Solar system.

Stars are formed in clustered environments out of dense molecular cloud cores. The initial spatial distribution of massive versus low-mass member stars is dictated by the conditions in the molecular cloud. Yet, there seems to be a universal origin of stellar masses, the "initial mass function" among stellar systems including star clusters. With time, via mutual gravitational interaction among member stars, the cluster is virialized and tends to become spherical. The low-mass members, however, are vulnerable and prone to escaping from the system. Furthermore, external Galactic perturbation act to disrupt the originally bound system, manifest by tidal tails and moving stellar groups. Eventually all the members are dispersed and supply the disk population. I will review the theories and our recent observational diagnosis regarding the formation and dynamical processes of a star cluster, using photometric and kinematic data taken from sky survey projects supplied by our own imaging and spectroscopic observations.

I will describe a method that can be used to reconstruct the initial conditions of the local universe accurately. The method is applied to the SDSS volume. High-resolution simulations of the reconstructed initial conditions have been carried to recover of the formation histories and structures observed in the local universe. I will also describe how the results can be used to study the formation and structure of the local cosmic web and of galaxies that are embedded in it.

Gas flows are one of the fundamental yet poorly understood processes driving galaxy evolution. This talk focuses on exploring gas flows in local galaxies by studying metallicity gradients and galactic-scale outflows in normal star-forming galaxies. This is made possible by new integral field spectroscopy data that provide simultaneously spatial and spectral information of galaxies. With the new 3D data, I study metallicity gradients and galactic winds to understand inflows and outflows in star-forming galaxies. I show that metallicity gradients in isolated disk galaxies are remarkably simple and universal. Simple chemical evolution models reveal that these simple metallicity gradients are a direct result of the coevolution of gas and stellar disk while galactic disks build up their masses from inside-out. Tight constraints on their mass outflow rates and inflow rates can be placed. I also investigate galactic winds in normal star-forming galaxies using data from the SAMI Galaxy Survey. I show that galactic winds are found to be very common even in normal star-forming galaxies that were not expected to host winds. By comparing galaxies with and without hosting winds, I show that galaxies with high star formation rate surface densities and bursty star formation histories are more likely to develop large-scale galactic winds.

While ultraluminous supersoft X-ray sources (ULSs) bear features for intermediate mass black holes or very massive white dwarfs possibly close to Chandrasekhar mass limit, our recent discovery of processing relativistic baryonic jets from a prototype ULS in M81 demonstrate that they are not IMBHs or WDs, but black holes accreting at super-Eddington rates. This discovery strengthens the recent ideas that ULXs are stellar black holes with supercritical accretion,as demonstrated in the case of M101 ULX-1, and provides a vivid manifestation of what happens when a black hole devours too much, that is, it will generate thick disk winds and fire out sub-relativistic baryonic jets along the funnel as predicted by recent numerical simulations.

Heavy modulated mass-loss takes place during the Asymptotic Giant Branch evolution of low-and intermediate-mass stars. In the process several processes play their role: metallicity, stellar mass, rotation, magnetic fields, the presence of companions and a possible interaction with the ISM. I will describe how our new stellar evolution models with rotation can rule out single main sequence stars to achieve the needed physical conditions to cause asymmetrical mass-loss. We have quantified under which circumstances the presence of companions can induce sufficient tidal spin-up to form bipolar Planetary Nebulae. Finally, by computing models of star-planet interactions we have explored the role that substellar companions have in the overall stellar evolution and thus how they might influence PNe properties.

We investigate the stellar population properties of a sample of 24 massive quenched galaxies at 1.25< zspec< 2.09 identified in the COSMOS field with our Subaru/Multi-object Infrared Camera and Spectrograph near-IR spectroscopic observations. Tracing the stellar population properties as close to their major formation epoch as possible, we try to put constraints on the star formation history, post-quenching evolution, and possible progenitor star-forming populations for such massive quenched galaxies. By using a set of Lick absorption line indices on a rest-frame optical composite spectrum, the average age, metallicity [Z/H], and α-to-iron element abundance ratio [α/Fe] are derived as log(age/Gyr)=0.04-0.08+0.10, [Z/H]=0.24-0.14+0.20, and [α /Fe]=0.31-0.12+0.12, respectively. If our sample of quenched galaxies at < z≥1.6 is evolved passively to z = 0, their stellar population properties will align in excellent agreement with local counterparts at similar stellar velocity dispersions, which qualifies them as progenitors of local massive early-type galaxies. Redshift evolution of stellar population ages in quenched galaxies combined with low redshift measurements from the literature suggests a formation redshift of zf∼ 2.3, around which the bulk of stars in these galaxies have been formed. The measured [α/Fe] value indicates a star formation timescale of ≲ 1 Gyr, which can be translated into a specific star formation rate of ≃ 1 Gyr-1 prior to quenching. Based on these findings, we discuss identifying possible progenitor star-forming galaxies at z≃ 2.3. We identify normal star-forming galaxies, i.e., those on the star-forming main sequence, followed by a rapid quenching event, as likely precursors of the quenched galaxies at

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