51863037
Properties of a Gamma-Ray Burst Host Galaxy at z ~ 5
We describe the properties of the host galaxy of the gamma-ray burst GRB 060510B based on a spectrum of the burst afterglow obtained with the Gemini North 8 m telescope. The galaxy lies at a redshift of z = 4.941, making it the fourth highest spectroscopically identified burst host. However, it is the second highest redshift galaxy for which the quality of the spectrum permits a detailed metallicity analysis. The neutral hydrogen column density has a logarithmic value of 21.0-21.2 cm^-2, and the weak metal lines of Ni, S, and Fe show that the metallicity is in excess of a tenth of solar, which is far above the metallicities in damped Lyα absorbers at high redshift. The tightest constraint is from the Fe lines, which place [Fe/H] in excess of -0.8. We argue that the results suggest that metallicity bias could be a serious obstacle to inferring star formation from the GRB population, and we consider how future higher quality measurements could be used to resolve this issue.
118556930
HATS-1b: The First Transiting Planet Discovered by the HATSouth Survey
We report the discovery of HATS-1b, a transiting extrasolar planet orbiting the moderately bright V = 12.05 G dwarf star GSC 6652-00186, and the first planet discovered by HATSouth, a global network of autonomous wide-field telescopes. HATS-1b has a period of P 3.4465 days, mass of Mp 1.86 M J, and radius of Rp 1.30 R J. The host star has a mass of 0.99 M ☉ and radius of 1.04 R ☉. The discovery light curve of HATS-1b has near-continuous coverage over several multi-day timespans, demonstrating the power of using a global network of telescopes to discover transiting planets.
5990408
The Science Case for PILOT I: Summary and Overview
PILOT (the Pathfinder for an International Large Optical Telescope) is a proposed 2.5-m optical/infrared telescope to be located at Dome C on the Antarctic plateau. Conditions at Dome C are known to be exceptional for astronomy. The seeing (above ∼30 m height), coherence time, and isoplanatic angle are all twice as good as at typical mid-latitude sites, while the water-vapour column, and the atmosphere and telescope thermal emission are all an order of magnitude better. These conditions enable a unique scientific capability for PILOT, which is addressed in this series of papers. The current paper presents an overview of the optical and instrumentation suite for PILOT and its expected performance, a summary of the key science goals and observational approach for the facility, a discussion of the synergies between the science goals for PILOT and other telescopes, and a discussion of the future of Antarctic astronomy. Paper II and Paper III present details of the science projects divided, respectively, between the distant Universe (i.e. studies of first light, and the assembly and evolution of structure) and the nearby Universe (i.e. studies of Local Group galaxies, the Milky Way, and the Solar System).
113407190
A THEORETICAL COLOR-VELOCITY CORRELATION FOR SUPERNOVAE ASSOCIATED WITH GAMMA-RAY BURSTS
We carry out the first multi-dimensional radiative transfer calculations to simultaneously compute synthetic spectra and light curves for models of supernovae driven by fast bipolar outflows. These allow us to make self-consistent predictions for the orientation dependence of both color evolution and spectral features. We compare models with different degrees of asphericity and metallicity and find significant observable consequences of both. In aspherical models, we find spectral and light curve features that vary systematically with observer orientation. In particular, we find that the early-phase light curves are brighter and bluer when viewed close to the polar axis but that the peak flux is highest for equatorial (off-axis) inclinations. Spectral line features also depend systematically on observer orientation, including the velocity of the Si II 6355 A line. Consequently, our models predict a correlation between line velocity and color that could assist the identification of supernovae associated with off-axis jet-driven explosions. The amplitude and range of this correlation depends on the degree of asphericity, the metallicity, and the epoch of observation but we find that it is always present and acts in the same direction.
13255925
The Mount Stromlo A bell Cluster Supernova Search
We have initiated a 3 year project to find supernovae in a well-defined sample of high-density southern Abell clusters with redshifts z ≤ 0.08. These observations will provide a volume-limited sample of Type Ia supernovae (SNe Ia) to more than a magnitude below their peak brightness and will enable us to (1) measure the luminosity function of SNe, (2) further explore the correlation of light-curve shape with the absolute luminosity of SNe Ia to better understand SNe Ia as distance indicators, (3) measure SN rates, (4) measure the bulk motion of the Local Group using SNe Ia, and (5) directly compare SN Ia distances with brightest cluster galaxy distances. We use the MACHO wide-field two-color imager on the 1.3 m telescope at Mount Stromlo to routinely monitor ~12 clusters per week. We describe our technique for target selection and scheduling search observations, and for finding and identifying SN candidates. We also describe the results from the first year of our program, including the detection of 19 SNe, several RR Lyrae variables, and hundreds of asteroids.
3943345
First Searches for Optical Counterparts to Gravitational-wave Candidate Events
During the Laser Interferometer Gravitational-wave Observatory and Virgo joint science runs in 2009-2010, gravitational wave (GW) data from three interferometer detectors were analyzed within minutes to select GW candidate events and infer their apparent sky positions. Target coordinates were transmitted to several telescopes for follow-up observations aimed at the detection of an associated optical transient. Images were obtained for eight such GW candidates. We present the methods used to analyze the image data as well as the transient search results. No optical transient was identified with a convincing association with any of these candidates, and none of the GW triggers showed strong evidence for being astrophysical in nature. We compare the sensitivities of these observations to several model light curves from possible sources of interest, and discuss prospects for future joint GW-optical observations of this type.
96462303
INORGANIC SCINTILLATORS FOR PARTICLE BEAM PROFILE DIAGNOSTICS OF HIGHLY BRILLIANT AND HIGHLY ENERGETIC ELECTRON BEAMS
Scintillating screens are widely used for particle beam diagnostics, especially in transverse profile measurements at hadron machines and low energy electron machines where the intensity of optical transition radiation (OTR) is rather low. Their usage may serve as an alternative way to overcome limitations in OTR based beam diagnostics imposed by the influence of coherent emission. However, there is only little information about scintillator properties for applications with highly energetic electrons. Therefore, test experiments have been performed at the Mainz Microtron MAMI in order to study the screen applicability. The status of these experiments is presented and the results are discussed in view of scintillator material properties and observation geometry.
31218324
First results of an aging test of a full scale MWPC prototype for the LHCb muon system
Abstract Aging studies for a multi-wire proportional chamber of the LHCb muon system have been performed using the CERN Gamma Irradiation Facility. The irradiated four-gap chamber corresponds to a full-size prototype with 1500 cm 2 sensitive area and has been operated with an Ar/CO 2 /CF 4 (40:50:10) gas mixture. A linear charge of ∼0.25 C/cm for 100 m anode wire length has been accumulated over a period of 6 months, which corresponds to the charge collected in 5 LHCb years. The observed aging effects do not prohibit the use of these chambers in the LHCb experiment.
116943240
Measurement of the semileptonic $CP$ asymmetry in $B^0-\overline{B}{}^0$ mixing
The semileptonic $CP$ asymmetry in $B^0-\overline{B}{}^0$ mixing, $a_{\rm sl}^d$, is measured in proton-proton collision data, corresponding to an integrated luminosity of 3.0 fb$^{-1}$, recorded by the LHCb experiment. Semileptonic $B^0$ decays are reconstructed in the inclusive final states $D^-\mu^+$ and $D^{*-}\mu^+$, where the $D^-$ meson decays into the $K^+\pi^-\pi^-$ final state, and the $D^{*-}$ meson into the $\overline{D}{}^0(\rightarrow K^+\pi^-)\pi^-$ final state. The asymmetry between the numbers of $D^{(*)-}\mu^+$ and $D^{(*)+}\mu^-$ decays is measured as a function of the decay time of the $B^0$ mesons. The $CP$ asymmetry is measured to be $a_{\rm sl}^d = (-0.02 \pm 0.19 \pm 0.30)\%$, where the first uncertainty is statistical and the second systematic. This is the most precise measurement of $a_{\rm sl}^d$ to date and is consistent with the prediction from the Standard Model.
55602552
SINGLE-SHOT LONGITUDINAL DIAGNOSTICS WITH THZ RADIATION AT THE FREE-ELECTRON LASER FLASH
The longitudinal charge distribution in the electron bunches has a strong impact on the lasing process in a Free-Electron Laser based on the principle of Self Amplified Spontaneous Emission of radiation. For the ultraviolet and soft X ray FEL FLASH at DESY, structures in the range of ten to hundred micrometers play a crucial role. The investigation of the longitudinal charge distribution in the electron bunches on a bunch-by-bunch basis is an important issue for optimizing the bunch compression and improving the performance of the machine. This paper introduces a new tool for longitudinal diagnostics based on THz spectroscopy of coherent radiation. A novel spectrometer has been designed which permits to analyze the radiation of single electron bunches in a broad spectral range and with high resolution. Preliminary measurements with this spectrometer are presented.
112598195
Diagnostics of the Muon System Front-end Electronics during the LHCb Experiment
This document describes a method to diagnose the Muon on-detector Front-End Electronics (FEE) during the LHCb experiment by means of threshold scan and noise rate analysis. The method does not make use of charge injection and it shows correct operation even with high voltage applied to chambers. The proposed technique can be used by the LHCb Muon Control System to provide alarm signals when parameters are out of specifications. Results and statistics obtained at CERN and INFN laboratories will be presented later on.