Ultracool dwarfs in deep extragalactic surveys using the virtual observatory: ALHAMBRA and COSMOS

We present sensitive 850 μm imaging of the Cosmological Evolution Survey (COSMOS) field using 640 hr of new and archival observations taken with SCUBA-2 at the East Asian Observatory’s James Clerk Maxwell Telescope. The SCUBA-2 COSMOS survey (S2COSMOS) achieves a median noise level of σ 850μm = 1.2 mJy beam−1 over an area of 1.6 sq. degree (main; Hubble Space Telescope/Advanced Camera for Surveys footprint), and σ 850μm = 1.7 mJy beam−1 over an additional 1 sq. degree of supplementary (supp) coverage. We present a catalog of 1020 and 127 sources detected at a significance level of >4σ and >4.3σ in the main and supp regions, respectively, corresponding to a uniform 2% false-detection rate. We construct the single-dish 850 μm number counts at S 850 > 2 mJy and show that these S2COSMOS counts are in agreement with previous single-dish surveys, demonstrating that degree-scale fields are sufficient to overcome the effects of cosmic variance in the S 850 = 2–10 mJy population. To investigate the properties of the galaxies identified by S2COSMOS sources we measure the surface density of near-infrared-selected galaxies around their positions and identify an average excess of 2.0 ± 0.2 galaxies within a 13″ radius (∼100 kpc at z ∼ 2). The bulk of these galaxies represent near-infrared-selected submillimeter galaxies and/or spatially correlated sources and lie at a median photometric redshift of z = 2.0 ± 0.1. Finally, we perform a stacking analysis at submillimeter and far-infrared wavelengths of stellar-mass-selected galaxies (M ⋆ = 1010–1012 M ⊙) from z = 0–4, obtaining high-significance detections at 850 μm in all subsets (signal-to-noise ratio, S/N = 4–30), and investigate the relation between far-infrared luminosity, stellar mass, and the peak wavelength of the dust spectral energy distribution. The publication of this survey adds a new deep, uniform submillimeter layer to the wavelength coverage of this well-studied COSMOS field.

Dwarf galaxies are important tracers of small-scale cosmological structure, yet much of our knowledge about these systems comes from the limited sample of dwarf galaxies within the Local Group. To make a comprehensive inventory of dwarf populations in the local Universe, we require effective methods for deriving distance estimates for large numbers of faint, low surface brightness objects. Here we test the surface brightness fluctuation (SBF) method, traditionally applied to brighter early-type galaxies, on a sample of 20 nearby dwarf galaxies detected in the Cosmological Evolution Survey (COSMOS) field. These objects are partially resolved in the Hubble Space Telescope (HST) Advanced Camera for Surveys (ACS) images and have confirmed redshift distances in the range 17–130 Mpc. We discuss the many model choices required in applying the SBF method and explore how these affect the final distance estimates. Amongst other variations on the method, when applying the SBF method, we alter the standard equation to include a term accounting for the power spectrum of the background, greatly improving our results. For the most robust modelling choices, we find a roughly Gaussian SBF signal that correlates linearly with distance out to distances of 50–100 Mpc, but with only a fraction of the power expected. At larger distances, there is excess power relative to that predicted, probably from undetected point sources. Overall, obtaining accurate SBF distances to faint, irregular galaxies remains challenging, but may yet prove possible with the inclusion of more information about galaxy properties and point source populations, and the use of more advanced techniques.

The Deep Extragalactic VIsible Legacy Survey (DEVILS) is a deep, high-completeness multiwavelength survey based around spectroscopic observations using the Anglo-Australian Telescope’s AAOmega spectrograph. The survey covers $\sim 4.5$ deg$^{2}$ over three extragalactic fields to Y$_{\mathrm{ AB}}< 21.2$ mag and probes sources at $0< z< 1.2$, with a median redshift of $z=0.53$. Here, we describe the DEVILS spectroscopic observations, data reduction, and redshift analysis. We then describe and release to the community all DEVILS data in the 10h [D10, COSMOS (Cosmological Evolution Survey)] region including: (i) catalogues of redshifts, photometry, spectral energy distribution fitting for physical properties, visual morphologies, structural decompositions, and group environments/halo masses, (ii) matched imaging in 28 bands from X-rays to radio continuum, and (iii) reduced 1D spectra. All data are made publicly available through Data Central (datacentral.org.au). Within D10, we obtain 5442 new high-quality spectroscopic redshifts. When combined with existing, lower quality, redshift information ($\mathrm{ {\mathrm i.e.}}$ photometric redshifts), this is increased to 7946. Of these, 3122 have a spectroscopic redshift from another source (many that was not available at the time of the DEVILS observations). As such, DEVILS provides new unique high-quality spectroscopic redshifts for 4824 faint sources in COSMOS. This increases the spectroscopic completeness at Y-mag $\sim$ 21 from $\sim$50 per cent in other samples to $\sim$90 per cent in DEVILS. Finally, we show the power of this data set by exploring the suppression of star formation in overdense environments, split by morphology and stellar mass, and highlighting the ubiquitous nature of environmental quenching.

We show the advantages of a wedding cake design for Sunyaev-Zel'dovich\ncluster surveys. We show that by dividing up a cluster survey into a wide and a\ndeep survey, one can essentially recover the cosmological information that\nwould be diluted in a single survey of the same duration due to the\nuncertainties in our understanding of cluster physics. The parameter degeneracy\ndirections of the deep and wide surveys are slightly different, and combining\nthem breaks these degeneracies effectively. A variable depth survey with a few\nthousand clusters is as effective at constraining cosmological parameters as a\nsingle depth survey with a much larger cluster sample.\n

(abridged) We want to provide further evidence of the origin of the proposed stellar members of Chamaeleon and to identify interlopers from the foreground \epsilon Cha and \eta Cha associations. To this aim, we compile lists of spectroscopically confirmed members of Chamaeleon I and II, \epsilon Cha and \eta Cha, and of background objects in the same line of sight. Using Virtual Observatory tools, we cross-match these lists with the UCAC3 catalogue to get the proper motions of the objects. In the vector point diagram, we identify the different moving groups, and use this information to study the membership of proposed candidate members of the associations from the literature. For those objects with available radial velocities, we compute their Galactic space velocities. We look for correlations between the known properties of the objects and their proper motions. The members of the dark clouds exhibit clearly different proper motions from those of the foreground associations and of the background stars. The data suggest that Chamaeleon II could have different dynamical properties from Chamaeleon I. Although the two foreground clusters \epsilon and \eta Chamaeleontis constitute two different proper motion groups, they have similar spatial motions, which are different from the spatial motion of Chamaeleon I. On the other hand, the space motions of the Chamaeleon II stars look more similar to those of the foreground clusters than to the Chamaeleon I stars, but the numbers are low. Hence, with the available data it is unclear to what extent the stellar populations in both clouds are physically connected to each other. We find no correlations between the proper motions and the properties of the objects in either of the clouds.

The Cosmological Evolution Survey (COSMOS) is a unique tool for studying low level AGN activity and the co-evolution of galaxies and supermassive black holes. COSMOS involves the largest contiguous region of the sky ever imaged by HST; it includes very complete multiwavelength coverage, and the largest joint samples of galaxy and AGN redshifts in any deep survey. The result is a search for AGN with low black hole mass, low accretion rates, and levels of obscuration that can remove them from optical surveys. A complete census of intermediate mass black holes at redshifts of 1 to 3 is required to tell the story of the co-evolution of galaxies and their embedded, and episodically active, black holes.

We determine the color excesses, photometric distances, ages, astrometric parallaxes and proper motions for 94 open clusters in the northern part of the Milky Way. We estimate the color excesses and photometric distances based on the data from IPHAS photometric survey of the northern Galactic plane using individual total-to-selective extinction ratios R_r=A_r/E_(r-i) for each cluster computed via the color-difference method based on IPHAS r, i, and H_alpha-band, 2MASS J, H, and K_s-band, WISE W1-band, and Pan-STARRS i, z, and y-band data. The inferred R_r values vary significantly from cluster to cluster spanning the R_r=3.1--5.2 interval with a mean and standard deviation equal to <R_r>=3.99 and sigma R_r=0.34, respectively. We identified cluster members using (1) absolute proper motions determined from individual-epoch positions of stars retrieved from IPHAS, 2MASS, URAT1, ALLWISE, UCAC5, and Gaia DR1 catalogs and positions of stars on individual Palomar Sky Survey plates reconstructed based on the data provided in USNO-B1.0 catalog and (2) absolute proper motions provided in Gaia DR2 catalog, and computed the average Gaia DR2 trigonometric parallaxes and proper motions of the clusters. The mean formal error of the inferred astrometric parallaxes of clusters is of about 7microarcseconds, however, a comparison of astrometric and photometric parallaxes of our cluster sample implies that Gaia DR2 parallaxes are, on the average, systematically underestimated by 45 +/-9 microarcseconds. This result agrees with estimates obtained by other authors using other objects. At the same time, we find our photometric distance scale to be correct within the quoted errors (the inferred correction factor is equal to unity to within a standard error of 0.025).

We present a hierarchical Bayesian pipeline, BP3M, that measures positions, parallaxes, and proper motions (PMs) for cross-matched sources between Hubble Space Telescope (HST) images and Gaia—even for sparse fields (N * < 10 per image)—expanding from the recent GaiaHub tool. This technique uses Gaia-measured astrometry as priors to predict the locations of sources in HST images, and is therefore able to put the HST images onto a global reference frame without the use of background galaxies/QSOs. Testing our publicly available code in the Fornax and Draco dwarf spheroidal galaxies, we measure PMs that are a median of 8–13 times more precise than Gaia DR3 alone for 20.5 < G < 21 mag. We are able to explore the effect of observation strategies on BP3M astrometry using synthetic data, finding an optimal strategy to improve parallax and position precision at no cost to the PM uncertainty. Using 1619 HST images in the sparse COSMOS field (median nine Gaia sources per HST image), we measure BP3M PMs for 2640 unique sources in the 16 < G < 21.5 mag range, 25% of which have no Gaia PMs; the median BP3M PM uncertainty for 20.25 < G < 20.75 mag sources is 0.44 mas yr−1 compared to 1.03 mas yr−1 from Gaia, while the median BP3M PM uncertainty for sources without Gaia-measured PMs (20.75 < G < 21.5 mag) is 1.16 mas yr−1. The statistics that underpin the BP3M pipeline are a generalized way of combining position measurements from different images, epochs, and telescopes, which allows information to be shared between surveys and archives to achieve higher astrometric precision than that from each catalog alone.

Context. We present the third data release of the European Space Agency’s Gaia mission, Gaia DR3. This release includes a large variety of new data products, notably a much expanded radial velocity survey and a very extensive astrophysical characterisation of Gaia sources. Aims. We outline the content and the properties of Gaia DR3, providing an overview of the main improvements in the data processing in comparison with previous data releases (where applicable) and a brief discussion of the limitations of the data in this release. Methods. The Gaia DR3 catalogue is the outcome of the processing of raw data collected with the Gaia instruments during the first 34 months of the mission by the Gaia Data Processing and Analysis Consortium. Results. The Gaia DR3 catalogue contains the same source list, celestial positions, proper motions, parallaxes, and broad band photometry in the G, GBP, and GRP pass-bands already present in the Early Third Data Release, Gaia EDR3. Gaia DR3 introduces an impressive wealth of new data products. More than 33 million objects in the ranges GRVS &lt; 14 and 3100 &lt; Teff &lt; 14 500, have new determinations of their mean radial velocities based on data collected by Gaia. We provide GRVS magnitudes for most sources with radial velocities, and a line broadening parameter is listed for a subset of these. Mean Gaia spectra are made available to the community. The Gaia DR3 catalogue includes about 1 million mean spectra from the radial velocity spectrometer, and about 220 million low-resolution blue and red prism photometer BP/RP mean spectra. The results of the analysis of epoch photometry are provided for some 10 million sources across 24 variability types. Gaia DR3 includes astrophysical parameters and source class probabilities for about 470 million and 1500 million sources, respectively, including stars, galaxies, and quasars. Orbital elements and trend parameters are provided for some 800 000 astrometric, spectroscopic and eclipsing binaries. More than 150 000 Solar System objects, including new discoveries, with preliminary orbital solutions and individual epoch observations are part of this release. Reflectance spectra derived from the epoch BP/RP spectral data are published for about 60 000 asteroids. Finally, an additional data set is provided, namely the Gaia Andromeda Photometric Survey, consisting of the photometric time series for all sources located in a 5.5 degree radius field centred on the Andromeda galaxy. Conclusions. This data release represents a major advance with respect to Gaia DR2 and Gaia EDR3 because of the unprecedented quantity, quality, and variety of source astrophysical data. To date this is the largest collection of all-sky spectrophotometry, radial velocities, variables, and astrophysical parameters derived from both low- and high-resolution spectra and includes a spectrophotometric and dynamical survey of SSOs of the highest accuracy. The non-single star content surpasses the existing data by orders of magnitude. The quasar host and galaxy light profile collection is the first such survey that is all sky and space based. The astrophysical information provided in Gaia DR3 will unleash the full potential of Gaia’s exquisite astrometric, photometric, and radial velocity surveys.

ABSTRACTThis work presents the first comprehensive study of structure formation at the peak epoch of cosmic star formation over 1.4 ≤ z ≤ 3.6 in the Cosmic Evolution Survey (COSMOS) field, including the most massive high-redshift galaxy proto-clusters at that era. We apply the extended COSMIC BIRTH algorithm to account for a multitracer and multisurvey Bayesian analysis at Lagrangian initial cosmic times. Combining the data of five different spectroscopic redshift surveys (zCOSMOS-deep, VUDS, MOSDEF, ZFIRE, and FMOS–COSMOS), we show that the corresponding unbiased primordial density fields can be inferred, if a proper survey completeness computation from the parent photometric catalogues, and a precise treatment of the non-linear and non-local evolution on the light-cone is taken into account, including (i) gravitational matter displacements, (ii) peculiar velocities, and (iii) galaxy bias. The reconstructions reveal a holistic view on the known proto-clusters in the COSMOS field and the growth of the cosmic web towards lower redshifts. The inferred distant dark matter density fields concurrently with other probes like tomographic reconstructions of the intergalactic medium will explore the interplay of gas and dark matter and are ideally suited to study structure formation at high redshifts in the light of upcoming deep surveys.

With the recent advent of new-generation observational instruments, astronomy enters the 'data flood' era. The growing scale and complication of astronomical activities forces scientists to look for new technologies and tools. A workflow environment seems to be a good solution for many new requirements, but before scientists can use it commonly, it has to be suitably adapted and simplified. We have created ai¾źuniversal environment based on the Kepler workflow system that empowers scientists with such capabilities. It offers three access levels depending on the needs and skills of the user: 1 Kepler desktop application extended by our library of domain specific modules and workflows, 2 web application used to share workflows, 3 cloud service with on-demand Virtual Research Environment consisting of a set of tools and applications useful for astronomers. Our environment includes also interoperability mechanisms with the Virtual Observatory and other domain-specific tools and services.

We present the conceptual framework of the Astronomical Hub (AstroHub), a unified platform combining various optical instruments at a single observatory. Its major approach lies in arranging conditions for research groups to install telescopes and equipment and participate in joint projects. AstroHub is planned to integrate Virtual Observatory (VO) tools, FAIR data principles, and a telescope network to create a powerful and attractive ecosystem for both robust near-Earth object (NEO) monitoring and diverse deep space research. We provide an overview of the AstroHub development directions in the case study of the Assy-Turgen Observatory.

We have made a deep and wide imaging survey with all nine AKARI/IRC bands from 2 to 24$\mu$m within a half degree of the North Ecliptic Pole. The survey covered a circular area of 0.38deg$^2$ centered at RA $=$ 17h56m, Dec $=$ 66°37' where a deep optical multi-band survey has been conducted by Subaru/Suprime-Cam. The 5$\sigma$ sensitivity of the survey for point sources is 11.0, 48, 117, and 275$\mu$Jy at wavelengths 3, 7, 15, and 24$\mu$m, respectively. The survey is limited by sky noise at wavelengths from 7 to 24$\mu$m, and limited by source confusion from 2 to 4$\mu$m. We have also made a point source catalog at each band, consisting of more than 5000 sources with a 50% completeness limit of 93$\mu$Jy at 15$\mu$m. Our results are consistent with the pilot survey at faint fluxes and has better statistical significance at the bright fluxes. This is the first near- and mid-infrared sub-mJy extragalactic survey with contiguous wavelength coverage from 2 to 24$\mu$m and a large band-merged catalogue. It will provide powerful and unique diagnostics of obscured star-formation and AGN activities in the galaxies up to $z=2$.

We study the spatial structure and sub‐structure of regions rich in Hipparcos stars with blue BT – VT colours. These regions, which comprise large stellar complexes, OB associations, and young open clusters, are tracers of on‐going star formation in the Galaxy. The DBSCAN (Density‐Based Spatial Clustering of Applications with Noise) data clustering algorithm is used to look for spatial overdensities of early‐type stars. Once an overdensity, “agglomerate”, is identified, we carry out a data and bibliographic compilation of their star member candidates. The actual membership in agglomerate of each early‐type star is studied based on its heliocentric distance, proper motion, and previous spectro‐photometric information. We identify 35 agglomerates of early‐type Hipparcos stars. Most of them are associated to previously known clusters and OB associations. The previously unknown P Puppis agglomerate is subject of a dedicated study with Virtual Observatory tools. It is actually a new, nearby, young open cluster (d ∼ 470 pc, age ∼ 20 Ma) with a clear radial density gradient.We list P Puppis and other six agglomerates (including NGC 2451 A, vdBH 23, and Trumpler 10) as new sites for substellar searches because of their youth, closeness, and spatial density. We investigate in detail the sub‐structure in the Orion, CMa‐Pup and Pup‐Vel OB complexes (“super‐agglomerates”). We confirm or discover some stellar overdensities in the Orion complex, like the 25 Ori group, the Horsehead region (including the σ Orionis cluster), and the η Orionis agglomerate. Finally, we derive accurate parallactic distances to the Pleiades, NGC 2451 A, and IC 2391, describe several field early‐type stars at d &lt; 200 pc, and discuss the incompleteness of our search. (© 2008 WILEY‐VCH Verlag GmbH &amp; Co. KGaA, Weinheim)

We revisit the subject of Be candidate stars towards the Magellanic Clouds, previously studied by the authors using SPM4 proper motions. We obtain Gaia DR2 parallaxes and proper motions for 2357 and 994 LMC and SMC Be candidates, respectively. Parallaxes and proper motions versus colour V − I easily reveal the presence of the redder galactic contaminant foreground, as concluded in our previous work, but this time we do find a few red Be candidates consistent with being true Magellanic objects. A membership assessment to each Magellanic Cloud is done for each Be candidate, based on the distribution of their parallaxes and proper motions. From a compilation of published catalogues of spectroscopically confirmed emission line stars,we find that 41 (LMC) and 56 (SMC) of the Be candidates have shown the Hα line in emission. Near-infrared IRSF JHKs magnitudes are obtained for about 70 per cent of the Be candidates with Gaia DR2 astrometric data. Mid-infrared SAGE IRAC 3.6, 4.5, 5.8, and 8.0 $\mu$m magnitudes are obtained for about 85 per cent as well. After discarding possible Herbig Ae/Be stars, one LMC and three SMC B emission line confirmed stars show significantly redder optical, near- and mid-infrared colours than what has been typically measured for Classical Be stars – they are called red Be stars. Taking into account that classical Be stars do not show these red colours, further studies about these four stars are needed in order to establish their true nature and explain the observed red excess.