The StoreGate: a Data Model for the Atlas Software Architecture

The Atlas collaboration at CERN has adopted the Gaudi software architecture which belongs to the blackboard family: data objects produced by knowledge sources (e.g. reconstruction modules) are posted to a common in-memory data base from where other modules can access them and produce new data objects. The StoreGate has been designed, based on the Atlas requirements and the experience of other HENP systems such as Babar, CDF, CLEO, D0 and LHCB, to identify in a simple and efficient fashion (collections of) data objects based on their type and/or the modules which posted them to the Transient Data Store (the blackboard). The developer also has the freedom to use her preferred key class to uniquely identify a data object according to any other criterion. Besides this core functionality, the StoreGate provides the developers with a powerful interface to handle in a coherent fashion persistable references, object lifetimes, memory management and access control policy for the data objects in the Store. It also provides a Handle/Proxy mechanism to define and hide the cache fault mechanism: upon request, a missing Data Object can be transparently created and added to the Transient Store presumably retrieving it from a persistent data-base, or even reconstructing it on demand.Comment: Talk from the 2003 Computing in High Energy and Nuclear Physics (CHEP03), La Jolla, Ca, USA, March 2003, 4 pages, LaTeX, MOJT00

Quantum phase transition in Bose-Fermi mixtures

We study a quantum Bose-Fermi mixture near a broad Feshbach resonance at zero temperature. Within a quantum field theoretical model a two-step Gaussian approximation allows to capture the main features of the quantum phase diagram. We show that a repulsive boson-boson interaction is necessary for thermodynamic stability. The quantum phase diagram is mapped in chemical potential and density space, and both first and second order quantum phase transitions are found. We discuss typical characteristics of the first order transition, such as hysteresis or a droplet formation of the condensate which may be searched for experimentally.Comment: 16 pages, 17 figures; typos corrected, one figure adde

Near-Infrared Spectroscopy of the Y0 WISEP J173835.52+273258.9 and the Y1 WISE J035000.32-565830.2: the Importance of Non-Equilibrium Chemistry

We present new near-infrared spectra, obtained at Gemini Observatory, for two Y dwarfs: WISE J035000.32-565830.2 (W0350) and WISEP J173835.52+273258.9 (W1738). A FLAMINGOS-2 R=540 spectrum was obtained for W0350, covering 1.0 < lambda um < 1.7, and a cross-dispersed GNIRS R=2800 spectrum was obtained for W1738, covering 0.993-1.087 um, 1.191-1.305 um, 1.589-1.631 um, and 1.985-2.175 um, in four orders. We also present revised YJH photometry for W1738, using new NIRI Y and J imaging, and a re-analysis of the previously published NIRI H band images. We compare these data, together with previously published data for late-T and Y dwarfs, to cloud-free models of solar metallicity, calculated both in chemical equilibrium and with disequilibrium driven by vertical transport. We find that for the Y dwarfs the non-equilibrium models reproduce the near-infrared data better than the equilibrium models. The remaining discrepancies suggest that fine-tuning the CH_4/CO and NH_3/N_2 balance is needed. Improved trigonometric parallaxes would improve the analysis. Despite the uncertainties and discrepancies, the models reproduce the observed near-infrared spectra well. We find that for the Y0, W1738, T_eff = 425 +/- 25 K and log g = 4.0 +/- 0.25, and for the Y1, W0350, T_eff = 350 +/- 25 K and log g = 4.0 +/- 0.25. W1738 may be metal-rich. Based on evolutionary models, these temperatures and gravities correspond to a mass range for both Y dwarfs of 3-9 Jupiter masses, with W0350 being a cooler, slightly older, version of W1738; the age of W0350 is 0.3-3 Gyr, and the age of W1738 is 0.15-1 Gyr.Comment: Accepted on March 30 2016 for publication in Ap

A Comparison of Near-Infrared Photometry and Spectra for Y Dwarfs with a New Generation of Cool Cloudy Models

We present YJHK photometry, or a subset, for the six Y dwarfs discovered in WISE data by Cushing et al.. The data were obtained using NIRI on the Gemini North telescope. We also present a far-red spectrum obtained using GMOS-North for WISEPC J205628.90+145953.3. We compare the data to Morley et al. (2012) models, which include cloud decks of sulfide and chloride condensates. We find that the models with these previously neglected clouds can reproduce the energy distributions of T9 to Y0 dwarfs quite well, other than near 5um where the models are too bright. This is thought to be because the models do not include departures from chemical equilibrium caused by vertical mixing, which would enhance the abundance of CO, decreasing the flux at 5um. Vertical mixing also decreases the abundance of NH_3, which would otherwise have strong absorption features at 1.03um and 1.52um that are not seen in the Y0 WISEPC J205628.90+145953.3. We find that the five Y0 to Y0.5 dwarfs have 300 < T_eff K < 450, 4.0 < log g < 4.5 and f_sed ~ 3. These temperatures and gravities imply a mass range of 5 - 15 M_Jupiter and ages around 5 Gyr. We suggest that WISEP J182831.08+265037.8 is a binary system, as this better explains its luminosity and color. We find that the data can be made consistent with observed trends, and generally consistent with the models, if the system is composed of a T_eff = 325 K and log g ~ 4.0 secondary, corresponding to masses of 10 and 7 M_Jupiter and an age around 2 Gyr. If our deconvolution is correct, then the T_eff = 300 K cloud-free model fluxes at K and W2 are too faint by 0.5 - 1.0 magnitudes. We will address this discrepancy in our next generation of models, which will incorporate water clouds and mixing.Comment: 39 pages, 10 Figures, 8 Tables. Accepted by ApJ. This revision replaces Figures 9 and 10 with B & W versions, corrects figure captions for color online only, corrects references. Text is unchanged. Tables 3, 4 and 8 are available at http://www.gemini.edu/staff/sleggett, other model data are available at http://www.ucolick.org/~cmorley/cmorley/Data.htm

Properties of the T8.5 Dwarf Wolf 940 B

We present 7.5-14.2um low-resolution spectroscopy, obtained with the Spitzer Infrared Spectrograph, of the T8.5 dwarf Wolf 940 B, which is a companion to an M4 dwarf with a projected separation of 400 AU. We combine these data with previously published near-infrared spectroscopy and mid-infrared photometry, to produce the spectral energy distribution for the very low-temperature T dwarf. We use atmospheric models to derive the bolometric correction and obtain a luminosity of log L/Lsun = -6.01 +/- 0.05. Evolutionary models are used with the luminosity to constrain the values of effective temperature (T_eff) and surface gravity, and hence mass and age for the T dwarf. We further restrict the allowed range of T_eff and gravity using age constraints implied by the M dwarf primary, and refine the physical properties of the T dwarf by comparison of the observed and modelled spectroscopy and photometry. This comparison indicates that Wolf 940 B has a metallicity within 0.2 dex of solar, as more extreme values give poor fits to the data - lower metallicity produces a poor fit at lambda > 2um while higher metallicity produces a poor fit at lambda < 2um. This is consistent with the independently derived value of [m/H] = +0.24 +/- 0.09 for the primary star, using the Johnson & Apps (2008) M_K:V-K relationship. We find that the T dwarf atmosphere is undergoing vigorous mixing, with an eddy diffusion coefficient K_zz of 10^4 to 10^6 cm^2 s^-1. We derive an effective temperature of 585 K to 625 K, and surface gravity log g = 4.83 to 5.22 (cm s^-2), for an age range of 3 Gyr to 10 Gyr, as implied by the kinematic and H alpha properties of the M dwarf primary. The lower gravity corresponds to the lower temperature and younger age for the system, and the higher value to the higher temperature and older age. The mass of the T dwarf is 24 M_Jupiter to 45 M_Jupiter for the younger to older age limit.Comment: 24 pages which include 5 Figures and 3 Tables. Accepted for publication in the Astrophysical Journal July 2 201

Resolved Spectroscopy of the T8.5 and Y0-0.5 Binary WISEPC J121756.91+162640.2AB

We present 0.9 - 2.5 um resolved spectra for the ultracool binary WISEPC J121756.91+162640.2AB. The system consists of a pair of brown dwarfs that straddles the currently defined T/Y spectral type boundary. We use synthetic spectra generated by model atmospheres that include chloride and sulfide clouds (Morley et al.), the distance to the system (Dupuy & Kraus), and the radius of each component based on evolutionary models (Saumon & Marley) to determine a probable range of physical properties for the binary. The effective temperature of the T8.5 primary is 550 - 600 K, and that of the Y0 - Y0.5 secondary is 450 K. The atmospheres of both components are either free of clouds or have extremely thin cloud layers. We find that the masses of the primary and secondary are 30 and 22 M_Jup, respectively, and that the age of the system is 4 - 8 Gyr. This age is consistent with astrometric measurements (Dupuy & Kraus) that show that the system has kinematics intermediate between those of the thin and thick disks of the Galaxy. An older age is also consistent with an indication by the H - K colors that the system is slightly metal-poor.Comment: 21 pages which include 6 Figures and 3 Tables. Accepted on November 8 2013 for publication in Ap