We have obtained deep g, r, and i-band Subaru and ultra-deep 3.6 μm IRAC images of parts of the multiply-wrapped stellar stream around the nearby edge-on galaxy NGC 5907. We have fitted the surface brightness measurements of the stream with FSPS stellar population synthesis models to derive the metallicity and age of the brightest parts of the stream. The resulting relatively high metallicity ([Fe/H] = −0.3) is consistent with a major merger scenario but a satellite accretion event cannot be ruled out.

The Chinese Spectral Radioheliograph (CSRH) with two arrays in 400MHz-2GHz/2-15GHz ranges with 64/520 frequency channels have been established in Mingantu Observing Station, Inner Mongolia of China, since 2013 and is in test observations now. CSRH is renamed as Mingantu Ultrawide SpEctral Radioheliograph (MUSER) after its accomplishment. We introduce the progress and current status of MUSER. The first burst imaging results of MUSER is presented.

We present results from the LCOGT Supernova Key Project, a three year program to obtain lightcurves and spectra of 600 supernovae. The Las Cumbres Observatory Global Telescope Network is a network of eleven robotic 1m and 2m telescopes located at 5 sites around the world. With this facility long term monitoring of transient phenomena is possible, as are nearly instantaneous observations. We report on both core-collapse and thermonuclear supernovae observed within days of explosion, allowing insight into their progenitor stars.

We have mapped cold atomic gas in 21cm line H i self-absorption (HISA) at arcminute resolution over more than 90% of the Milky Way's disk. To probe the formation of H2 clouds, we have compared our HISA distribution with CO J = 1-0 line emission. Few HISA features in the outer Galaxy have CO at the same position and velocity, while most inner-Galaxy HISA has overlapping CO. But many apparent inner-Galaxy HISA-CO associations can be explained as chance superpositions, so most inner-Galaxy HISA may also be CO-free. Since standard equilibrium cloud models cannot explain the very cold H i in many HISA features without molecules being present, these clouds may instead have significant CO-dark H2.

We have aggregated together data available in the literature, or analysed by us, to compute the lightcurves of most young supernovae (SNe) that have been detected in X-rays. Currently the database contains about 60 SNe spanning all the various types, but it is expanding rapidly. We use this library of lightcurves and spectra to explore the diversity of SNe, the characteristics of the environment into which they are expanding, and the implications for their progenitors. X-ray spectra can provide insight into the density structure, composition and metallicity of the surrounding medium, and the ionization level, through the spectra themselves as well as the X-ray absorption. Since core-collapse SNe expand mainly in environments created by the progenitor star mass-loss, this can provide crucial information about the nature of the progenitor star, and its mass-loss parameters in the decades or centuries before its death. In a few cases, via detailed modelling, we can distinguish the composition of the SN ejecta from that of the environment. X-ray observations therefore provide an invaluable probe into the stellar environments of core-collapse SNe, complementing data available at other wavelengths. We provide an overview of the X-ray lightcurves of various SN types, the implications for their environment, and clues to their progenitor stars.

The Lyman-α (Lyα) Solar Telescope (LST) is one of the payloads for the proposed Space-Borne Advanced Solar Observatory (ASO-S). LST consists of a Solar Disk Imager (SDI) with a field-of-view (FOV) of 1.2 R⊙ (R⊙ = solar radius), a Solar Corona Imager (SCI) with an FOV of 1.1 - 2.5 R⊙, and a full-disk White-light Solar Telescope (WST) with the same FOV as the SDI, which also serves as the guiding telescope. The SCI is designed to work in the Lyα (121.6 nm) waveband and white-light (for polarization brightness observation), while the SDI will work in the Lyα waveband only. The WST works in both visible (for guide) and ultraviolet (for science) broadband. The LST will observe the Sun from disk-center up to 2.5 R⊙ for both solar flares and coronal mass ejections with high tempo-spatial resolution

Comets are probably the best archives of the nascent solar system, 4.5 Gyr ago, and their compositions reveal crucial clues on the structure and dynamics of the early protoplanetary disk. Anhydrous minerals (olivine and pyroxene) have been identified in cometary dust for a few decades. Surprisingly, samples from comet Wild2 returned by the Stardust mission in 2006 also contain high temperature mineral assemblages like chondrules and refractory inclusions, which are typical components of primitive meteorites (carbonaceous chondrites - CCs). A few Stardust samples have also preserved some organic matter of comet Wild 2 that share some similarities with CCs. Interplanetary dust falling on Earth originate from comets and asteroids in proportions to be further constrained. These cosmic dust particles mostly show similarities with CCs, which in turn only represent a few percent of meteorites recovered on Earth. At least two (rare) families of cosmic dust particles have shown strong evidences for a cometary origin: the chondritic porous interplanetary dust particles (CP-IDPs) collected in the terrestrial stratosphere by NASA, and the ultracarbonaceous Antarctic Micrometeorites (UCAMMs) collected from polar snow and ice by French and Japanese teams. Analyses of dust particles from the Jupiter family comet 67P/Churyumov-Gerasimenko by the dust analyzers on Rosetta orbiter (COSIMA, GIADA, MIDAS) suggest a relationship to interplanetary dust/micrometeorites. A growing number of evidences highlights the existence of a continuum between asteroids and comets, already in the early history of the solar system.

Due to their environment isolated elliptical galaxies (IEs) should not be undergoing extant evolutionary processes yet many IEs have interacting dwarf companions, and where no merger remnants are visible IEs are often dynamically young. Furthermore, some IEs do not require dark matter to explain their dynamics. However, according to Cold Dark Matter (CDM) simulations all elliptical galaxies should be dark matter dominated, even if isolated, and IEs are much rarer in nature than predicted by CDM. Moreover, merging at the ~107 M⊙ level was recently discovered in the M31 system, showing that hierarchical merging may indeed be scale-free, as predicted by CDM. It seems a natural question to ask: what can IEs tell us about CDM? Here we analyse several IEs as probes of CDM. Our results spawn many new questions.

Cosmological hydrodynamical simulations show that the baryonic elements that at z = 0 form the stellar populations of late-type galaxies (LTGs), display, at high z, a gaseous web-like organization, where different singular structures (walls, filaments, nodes) show up. The analysis also shows that the spheroid-to-be elements are the first to be involved in the singular structures, while thick and thin disk-to-be elements chronologically follow them. We discuss how these differences at high z can explain the differences among these three components at z = 0.

How is gas converted into stars across cosmic time? Observations of star-forming galaxies at high redshift indicate that the conditions of the interstellar medium (ISM) were remarkably distinct from typical spirals in the local universe. Nevertheless, these observations are biased towards objects brighter than L*, due to the large luminosity distances involved. Here I present a survey targeting the molecular gas in galaxies at low redshift (z ~ 0.2) with ISM conditions remarkably similar to those observed at earlier epochs, including high star formation rates and lower metallicities. CO observations performed with CARMA indicate that these galaxies follow the same star-formation law as local spirals and other galaxies at the same redshift, albeit at much higher densities. We also present recent results from our ALMA program studying galaxies down to 12 + log(O/H) ~ 8, and discuss the implications of these data to our understanding of the molecular gas reservoir and the conversion factor between CO luminosity and gas mass in environments that are simultaneously low in metal content and extremely dense.

Disk galaxies in cosmological numerical simulations grow by accreting gas from the cosmic web. This gas reaches the external disk, and then spirals in dragged along by tidal forces and/or disk instabilities. The importance of gas infall is as clear from numerical simulations as it is obscure to observations. Extremely metal poor (XMP) galaxies seem to be the best example we have of the gas accretion process at work. They have large off-center starbursts which show significant metallicity drop compared with the host galaxy. This observation is naturally explained as a gas accretion event caught in the act. We present preliminary results of the kinematical properties of the metal poor starbursts in XMPs, which suggest that the starbursts are kinematically decoupled entities within the host galaxy.

Stellar populations are fossil records of several physical processes which occur in galaxies and their distribution within these objects may provide important clues on how they form and evolve. By using parameters from image processing we have been developing a new approach to understand the spatial distribution of stellar populations and how this is correlated with the form and evolution of galaxies. In this work we present some results obtained with data from the CALIFA survey.

We study the role of environment in the evolution of galaxies up to z = 0.7 using the final zCOSMOS-bright data set. We use the colour as a proxy for the quenched population, and measure the dependence of the red fraction of galaxies on stellar mass and two environmental indicators: the local overdensity of galaxies δ and a demarcation of galaxies to centrals and satellites. The analysis is carried out by quantifying the role of different quenching processes. We find that the measured dependence of the red fraction of galaxies on stellar mass and environment can be well described by two quenching processes: one related only to stellar mass (mass quenching) and the other related to the local environment (environment quenching). Within the errors, these processes are independent of each other, and consistent with the z ~ 0 measurement. Moreover, the red fraction of centrals fr,cen (both singleton centrals and centrals in the groups) does not show any trend with δ and more than 95% of fr,cen is consistent with being produced through the mass quenching alone. The satellite galaxies are redder than the centrals at the same stellar mass and δ, requiring additional environment quenching. Given the observed fractional distribution of satellites at different overdensities, the normalized excess in the red fraction of satellites with respect to the red fraction of centrals is consistent with a scenario in which the satellites account for most of the δ-dependences observed in the overall population of galaxies covering 0.1 < z < 0.7.

Spectrometer/Telescope for Imaging X-rays (STIX) is a part of Solar Orbiter (SO) science payload. SO will be launched in October 2018, and after three years of cruise phase, it will reach orbit with perihelion distance of 0.3 a.u. STIX is a Fourier imager equipped with pairs of grids that comprise the flare hard X-ray tomograph. Similar imager types were already used in the past (eq. RHESSI, Yohkoh/HXT), but STIX will incorporate Moiré modulation and a new type of pixelized detectors with CdTe sensor. We developed a method of modeling these detectors' response matrix (DRM) using the Geant4 simulations of X-ray photons interactions with CdTe crystals. Taking into account known detector effects (Fano noise, hole tailing etc.) we modeled the resulting spectra with high accuracy. Comparison of Caliste-SO laboratory measurements of 241Am decay spectrum with our results shows a very good agreement. The modeling based on the Geant4 simulations significantly improves our understanding of detector response to X-ray photons. Developed methodology gives opportunity for detailed simulation of whole instrument response with complicated geometry and secondary radiation from cosmic ray particles taken into account. Moreover, we are developing the Geant4 simulations of aging effects which decrease detector's performance.

Theory and observation strongly favor the notion that asymmetric explosions drive core-collapse supernovae, but where and how this asymmetry becomes introduced is uncertain. The most likely places of origin are in the explosion mechanism itself or the interior structure of the star into which the explosion proceeds. Investigating the recently uncovered bubble-like interiors of young, nearby supernova remnants may provide a way to unravel which of these competing processes dominate.

Comets, asteroids, meteorites, micrometeorites, interplanetary dust particles (IDPs), and ultra-carbonaceous Antarctic micrometeorites (UCAMMs) may contain carbonaceous material, which was exogenously delivered to the early Earth. Carbonaceous chondrites have an enormous variety of extra-terrestrial compounds, including all the key compounds important in terrestrial biochemistry. Comets contain several carbon-rich species and, in addition, the hypervelocity impact-shock of a comet can produce several α-amino acids. The analysis of the carbonaceous content of extra-terrestrial matter provides a window into the resources delivered to the early Earth, which may have been used by the first living organisms.

We present the first results from SWAN: “Survey of Water and Ammonia in Nearby galaxies”. Nearby galaxies are conveniently located to probe molecular gas properties on scales of 10 to 200 pc, which are appropriate for the study of Giant Molecular Clouds (GMCs). The resolution of the Very Large Array in D and C configurations corresponds to a few 10s of parsecs in these galaxies. To advance studies of galaxy evolution it is paramount to understand how processes in the molecular Interstellar Medium(ISM) and star formation are linked on these scales. We have observed the metastable transitions of ammonia and the 22GHz water maser line in four nearby galaxies: NGC 253, IC 342, NGC 2146, and NGC 6946 using the VLA. These galaxies were chosen to span an order of magnitude in star formation rate, and a range of galactic ecosystems. We use the ammonia transitions to derive kinetic temperatures, which exposes the heating and cooling balance of the ISM. We then aim to relate these conditions to energetic feedback from star formation as indicated by water masers.

Currently, our analysis is focused on NGC 253. NGC 253 is a barred spiral starburst galaxy with a nucleated star formation rate (SFR) of ≈ 3M⊙ per year. We use a distance of 3.9Mpc for analysis. We have observed ammonia transitions (1,1) to (5,5) and the 22GHz water maser line with a resolution of ≈63pc. We have identified nine regions across the nucleated starburst for study. The ammonia (3,3) line appears to be masing in the centermost 200pc. We have identified two regions of water maser emission. The first region is a minor axis extension, about the center of the galaxy, and is very close to the outflow. By means of these measurements, we gain an understanding of the molecular ISM associated with the nucleated starburst environment in NGC 253.

We show that redshift-space distortions of galaxy correlations have a strong effect on correlation functions with the signature of the Baryon Acoustic Oscillations (BAO). Near the line of sight, the features become sharper as a result of redshift-space distortions. We analyze the SDSS DR7 main-galaxy sample (MGS), splitting the sample into slices 2.5 deg on the sky in various rotations. Measuring 2D correlation functions in each slice, we do see a sharp bump along the line of sight. Using Mexican-hat wavelets, we localize it to (110 ± 10) h − 1 Mpc and estimate its significance at about 4σ.

We present two pilot studies for the search and characterization of accretion events in star-forming dwarf galaxies. Our strategy consists of two complementary approaches: i) the direct search for stellar substructures around dwarf galaxies through deep wide-field imaging, and ii) the characterization of the chemical properties in these systems up to large galacto-centric distances. We show our results for two star-forming dwarf galaxies, the starburst irregular NGC 4449, and the extremely metal-poor dwarf DDO 68.

In this study we tested the prospects of using 2D chemical abundance ratio distributions (CARDs) found in stars of the stellar halo to determine its formation history. First, we used simulated data from eleven “MW-like” halos to generate satellite template sets of 2D CARDs of accreted dwarf satellites which are comprised of accreted dwarfs from various mass regimes and epochs of accretion. Next, we randomly drew samples of ~ 103–4 mock observations of stellar chemical abundance ratios ([α/Fe], [Fe/H]) from those eleven halos to generate samples of the underlying densities for our CARDs to be compared to our templates in our analysis. Finally, we used the expectation-maximization algorithm to derive accretion histories in relation to the satellite template set (STS) used and the sample size. For certain STS used we typically can identify the relative mass contributions of all accreted satellites to within a factor of 2. We also find that this method is particularly sensitive to older accretion events involving low-luminous dwarfs e.g. ultra-faint dwarfs — precisely those events that are too ancient to be seen by phase-space studies of stars and too faint to be seen by high-z studies of the early Universe. Since our results only exploit two chemical dimensions and near-future surveys promise to provide ~ 6–9 dimensions, we conclude that these new high-resolution spectroscopic surveys of the stellar halo will allow us (given the development of new CARD–generating dwarf models) to recover the luminosity function of infalling dwarf galaxies — and the detailed accretion history of the halo — across cosmic time.