We describe a large sample of 598 galaxy clusters and rich groups discovered in the data of the Faint Sky Variability Survey (FSVS). The clusters have been identified using a fully automated, semiparametric technique based on a maximum likelihood approach applied to Voronoi tessellation, and enhanced by colour discrimination. The sample covers a wide range of richness, has a density of ~28 clusters/deg^2^, and spans a range of estimated redshifts of 0.05<z<0.9 with mean <z>=0.345. Assuming the presence of a cluster red sequence, the uncertainty of the estimated cluster redshifts is assessed to be {sigma}~0.03. Containing over 100 clusters with z>0.6, the catalogue contributes substantially to the current total of optically selected, intermediate-redshift clusters, and complements the existing, usually X-ray selected, samples. The FSVS fields are accessible for observation throughout the whole year, making them particularly suited for large follow-up programmes. The construction of this FSVS Cluster Catalogue completes a fundamental component of our continuing programmes to investigate the environments of quasars and the chemical evolution of galaxies. We publish here the list of all clusters with their basic parameters, and discuss some illustrative examples in more detail. The full FSVS Cluster Catalogue, together with images and lists of member galaxies etc., will be issued as part of the 'NOAO (National Optical Astronomy Observatories) data products', and accessible at http://www.noao.edu/dpp/ . We describe the format of these data and access to them.
The spectrum of CoIII has been recorded in the region 1562-2564{AA} (64000cm^-1^-39000cm^-1^) by Fourier transform (FT) spectroscopy, and in the region 1317-2500{AA} (164000cm^-1^-40000cm^-1^) using a 10.7m grating spectrograph with phosphor image plate detectors. The spectrum was excited in a cobalt-neon Penning discharge lamp. We classified 514 CoIII lines measured using FT spectroscopy, the strongest having wavenumber uncertainties approaching 0.004cm^-1^ (approximately 0.2m{AA} at 2000{AA}, or 1 part in 10^7^), and 240 lines measured with grating spectroscopy with uncertainties between 5 and 10m{AA}. The wavelength calibration of 790 lines of Raassen & Orti Ortin (1984PhyBC.123..353R) and 87 lines from Shenstone (1960CaJPh..38..677S) has been revised and combined with our measurements to optimize the values of all but one of the 288 previously reported energy levels. Order of magnitude reductions in uncertainty for almost two-thirds of the 3d^6^4s and almost half of the 3d^6^4p revised energy levels are obtained. Ritz wavelengths have been calculated for an additional 100 forbidden lines. Eigenvector percentage compositions for the energy levels and predicted oscillator strengths have been calculated using the Cowan code.
We report CrIII ultraviolet (UV) transition wavelengths measured using a high-resolution Fourier transform spectrometer (FTS), for the first time, available for use as wavelength standards. The doubly ionized iron group element spectra dominate the observed opacity of hot B stars in the UV, and improved, accurate, wavelengths are required for the analysis of astronomical spectra. The spectrum was excited using a chromium-neon Penning discharge lamp and measured with the Imperial College vacuum ultraviolet FTS. 140 classified 3d^3^4s-3d^3^4p CrIII transition lines, in the spectral range 38000 to 49000cm^-1^ (2632 to 2041{AA}), the strongest having wavelength uncertainties less than one part in 10^7^, are presented.
We analyze molecular-gas formation in neutral atomic hydrogen (HI) clouds using the latest CO data, obtained from the FOREST (four-beam receiver system on the 45m telescope) unbiased Galactic plane imaging survey with the Nobeyama 45m telescope, and using HI data taken from the Very Large Array Galactic plane survey. We applied a dendrogram algorithm to the HI data cube to identify HI clouds, and we calculated the HI mass and molecular-gas mass by summing the CO line intensity within each HI cloud. On the basis of the results, we created a catalog of 5737 identified HI clouds with local standard of rest (LSR) velocity of VLSR<=-20km/s in galactic longitude and latitude ranges of 20{deg}<=l<=50{deg} and -1{deg}<=b<=1{deg}, respectively. We found that most of the HI clouds are distributed within a Galactocentric distance of 16kpc, and most of them are in the cold neutral medium phase. In addition, we determined that the high-mass end of the HI mass function is fitted well with a power-law function with an index of 2.3. Although two sequences of self-gravitating and diffuse clouds are expected to appear in the M_tot_-M_H2_ diagram according to previous works based on a plane-parallel model, the observational data show only a single sequence with large scattering within these two sequences. This implies that most of the clouds are mixtures of these two types of clouds. Moreover, we suggest the following scenario of molecular-gas formation: an HI-dominant cloud evolved with increasing H2 mass along a path of M_H2_{prop.to}M^2^_tot_ by collecting diffuse gas before reaching and moving along the curves of the two sequences.
We present UV luminosity functions of dropout galaxies at z~6-10 with the complete Hubble Frontier Fields data. We obtain a catalog of ~450 dropout-galaxy candidates (350, 66, and 40 at z~6-7, 8, and 9, respectively), with UV absolute magnitudes that reach ~-14mag, ~2 mag deeper than the Hubble Ultra Deep Field detection limits. We carefully evaluate number densities of the dropout galaxies by Monte Carlo simulations, including all lensing effects such as magnification, distortion, and multiplication of images as well as detection completeness and contamination effects in a self-consistent manner. We find that UV luminosity functions at z~6-8 have steep faint-end slopes, {alpha}~-2, and likely steeper slopes, {alpha}<~-2 at z~9-10. We also find that the evolution of UV luminosity densities shows a non-accelerated decline beyond z~8 in the case of M_trunc_=-15, but an accelerated one in the case of M_trunc_=-17. We examine whether our results are consistent with the Thomson scattering optical depth from the Planck satellite and the ionized hydrogen fraction Q_HII_ at z<~7 based on the standard analytic reionization model. We find that reionization scenarios exist that consistently explain all of the observational measurements with the allowed parameters of f_esc_=0.17_-0.03_^+0.07^ and M_trunc_>-14.0 for log{xi}_ion_/[erg^-1^Hz]=25.34, where f_esc_ is the escape fraction, Mtrunc is the faint limit of the UV luminosity function, and {xi}_ion_ is the conversion factor of the UV luminosity to the ionizing photon emission rate. The length of the reionization period is estimated to be {Delta}z=3.9_-1.6_^+2.0^ (for 0.1<Q_HII_<0.99), consistent with the recent estimate from Planck.
We explore the evolution of hydrogen-rich and hydrogen-deficient white dwarf stars with masses between 1.012 and 1.307M_{sun}, and initial metallicity of Z=0.02. These sequences are the result of main-sequence stars with masses between 8.8 and 11.8M_{sun}. The simulations were performed with MESA (Modules for Experiments in Stellar Astrophysics), starting at the zero-age main sequence, through thermally pulsing and mass-loss phases, ending at the white dwarf cooling sequence. We present reliable chemical profiles for the whole mass range considered, covering the different expected central compositions (i.e. C/O, O/Ne and Ne/O/Mg) and its dependence on the stellar mass. In addition, we present detailed chemical profiles of hybrid C/O-O/Ne core white dwarfs, found in the mass range between 1.024 and 1.15M_{sun}. We present the initial-to-final mass relation, the mass-radius relation and cooling times considering the effects of atmosphere and core composition.
The high spectral resolution R~45000 provided by IGRINS (Immersion Grating INfrared Spectrometer) at MacDonald Observatory and R~100000 achieved by CRIRES (CRyogenic high-resolution InfraRed) Echelle Spectrograph) at VLT challenges the present knowledge of infrared spectra. We aim to predict the full infrared spectrum of molecular hydrogen at a comparable accuracy. We take advantage of the recent theoretical ab-initio studies on molecular hydrogen to compute both the electric quadrupole and magnetic dipole transitions taking place within the ground electronic molecular state of Hydrogen. We compute the full infrared spectrum of molecular hydrogen at an unprecedented accuracy and derive for the first time the emission probabilities including both electric quadrupole ({Delta}J=0, +/-2) and magnetic dipole transitions ({Delta}J=0) as well as the total radiative lifetime of each rovibrational state. Inclusion of magnetic dipole transitions increases the emission probabilities by factors of a few for highly excited rotational levels, which occur in the 3-20{mu} range.
We present full-polarization VLBA maps of the ground-state, main-line, ^2^{Pi}_3/2_, J=3/2 OH masers in 18 Galactic massive star-forming regions. This is the first large polarization survey of interstellar hydroxyl masers at VLBI resolution. A total of 184 Zeeman pairs are identified, and the corresponding magnetic field strengths are indicated. We also present spectra of the NH_3_ emission or absorption in these star-forming regions.
We present the results of SPT-GMOS, a spectroscopic survey with the Gemini Multi-Object Spectrograph (GMOS) on Gemini South. The targets of SPT-GMOS are galaxy clusters identified in the SPT-SZ survey, a millimeter-wave survey of 2500deg^2^ of the southern sky using the South Pole Telescope (SPT). Multi-object spectroscopic observations of 62 SPT-selected galaxy clusters were performed between 2011 January and 2015 December, yielding spectra with radial velocity measurements for 2595 sources. We identify 2243 of these sources as galaxies, and 352 as stars. Of the galaxies, we identify 1579 as members of SPT-SZ galaxy clusters. The primary goal of these observations was to obtain spectra of cluster member galaxies to estimate cluster redshifts and velocity dispersions. We describe the full spectroscopic data set and resulting data products, including galaxy redshifts, cluster redshifts, and velocity dispersions, and measurements of several well-known spectral indices for each galaxy: the equivalent width, W, of [OII]{lambda}{lambda}3727, 3729 and H-{delta}, and the 4000{AA} break strength, D4000. We use the spectral indices to classify galaxies by spectral type (i.e., passive, post-starburst, star-forming), and we match the spectra against photometric catalogs to characterize spectroscopically observed cluster members as a function of brightness (relative to m*). Finally, we report several new measurements of redshifts for ten bright, strongly lensed background galaxies in the cores of eight galaxy clusters. Combining the SPT-GMOS data set with previous spectroscopic follow-up of SPT-SZ galaxy clusters results in spectroscopic measurements for >100 clusters, or ~20% of the full SPT-SZ sample.
In this second paper of a series on the accuracy and precision of the determination of age and metallicity of simple stellar populations (SSPs) by means of the full spectrum fitting technique, we study the influence of star cluster mass through stochastic fluctuations of the number of stars near the top of the stellar mass function, which dominate the flux in certain wavelength regimes depending on the age.We consider SSP models based on the Padova isochrones, spanning the age range 7.0<=log(age/yr)<=10.1. Simulated spectra of star clusters in the mass range 10^4^<=M/M_{sun}_<10^6^ are compared with SSP model spectra to determine best-fit ages and metallicities using a full-spectrum fitting routine in four wavelength regimes: the blue optical (0.35-0.70um), the red optical (0.6-1.0um), the near-IR (1.0-2.5um), and the mid-IR (2.5-5.0um). We compare the power of each wavelength regime in terms of both the overall precision of age and metallicity determination, and of its dependence on cluster mass. We also study the relevance of spectral resolution in this context by utilizing two different spectral libraries (BaSeL and BT-Settl). We highlight the power of the mid-IR regime in terms of identifying young massive clusters in dusty star forming regions in distant galaxies. The spectra of the simulated star clusters and SSPs are made available online to enable follow-up studies by the community.