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.
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.
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.
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.
118629327
Supernova 2012ec: Identification of the progenitor and early monitoring with PESSTO
Research by JRM is supported through a Royal Society Research 
Fellowship. SJS is supported by FP7/2007-2013/ERC Grant agreement no. [291222]. GP acknowledges support from the Millennium 
Center for Supernova Science through grant P10-064-F funded by 
‘Programa Bicentenario de Ciencia y Tecnolog´ia de CONICYT’, 
‘Programa Iniciativa Cient´ifica Milenio deMIDEPLAN’ and 
proyecto interno UNAB DI-303-13/R. Research by AGY and his 
group is supported by funding from the FP7/ERC, Minerva and 
GIF grants.
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).
119162725
Observation of CP violation in B+ to DK+ decays
An analysis of B → DK and B → Dπ decays is presented where the D meson is reconstructed in the two-body final states: Kπ, KK, ππ and πK. Using 1.0 fb of LHCb data, measurements of several observables are made including the first observation of the suppressed mode B ± → [πK]DK . CP violation in B → DK decays is observed with 5.8σ significance. Submitted to Physics Letters B
121618250
Diffusion and drift studies of Ar-DME/CO2/CH4 gas mixtures for a radial TPC in the E > B field
Abstract We have performed systematic studies of electron diffusion and drift in three gas mixtures: Ar(50%)-DME(50%), Ar(50%)CO 2 (50%), and Ar(90%)CH 4 (10%) inside the E > B field, with the aim to build a high-resolution radial Time-Projection-Chamber (TPC). Our TPC design is unconventional in that: (1) it drifts electron clusters in a radial electric field perpendicular to a magnetic field; (2) it employs microstrip gas chamber (MSGC) with pads for readout. To achieve the required spatial resolution and two-track resolution, we find that one must use a gas mixture based on a “cool” gas such as CO 2 or DME (dimethylether (CH 3 ) 2 O). Such a gas mixture has low diffusion coefficients and small Lorentz angle in the E > B field. Its transport parameters are less sensitive to the magnetic field. Our measurements are compared with two transport calculations. For the Ar(90%)CH 4 (10%) gas mixture, the calculations based upon the moments method agree well with our measurements, while the calculations using the Magboltz program largely over-predict our measurements for transverse diffusion and Lorentz angle. For the Ar(50%)-DME(50%) and Ar(50%)CO 2 (50%) gas mixtures, which have slow drift and low diffusion, our measurements are consistent with calculations based upon either the moments method or the Magboltz program.
122986581
Experimental determination of ionization cluster size distributions in counting gases
The distribution of the number of electrons contained in the ionization clusters formed along the track of minimum ionizing particles has been determined experimentally. Results are presented for argon, helium, methane, ethane, propane, isobutane and carbon dioxide, i.e., for gases which are commonly used as counting gases in drift chambers. The probabilities w(n) for the formation of a cluster containing n electrons were found to be monotonically decreasing for increasing n. Typical values for w(1) are 0.66 (Ar), 0.77 (He), and 0.79 (CH4). The results are compared with model predictions.
116929324
Search for the lepton-flavor violating decays $B^0_s \rightarrow e^{\pm}\mu^{\mp}$ and $B^0 \rightarrow e^{\pm} \mu^{\mp}$
A search for the lepton-flavour violating decays $B^0_s \to e^{\pm} \mu^{\mp}$ and $B^0 \to e^{\pm} \mu^{\mp}$ is performed with a data sample, corresponding to an integrated luminosity of 1.0 fb$^{-1}$ of $pp$ collisions at $\sqrt{s} = 7$ TeV, collected by the LHCb experiment. The observed number of $B^0_s \to e^{\pm} \mu^{\mp}$ and $B^0 \to e^{\pm} \mu^{\mp}$ candidates is consistent with background expectations. Upper limits on the branching fractions of both decays are determined to be $BR(B^0_s \to e^{\pm} \mu^{\mp}) 107$ TeV/c$^2$ and $M_{\rm LQ} (B^0 \to e^{\pm} \mu^{\mp}) > 126$ TeV/c$^2$ at 95% C.L., and are a factor of two higher than the previous bounds.
119225855
A search for low-mass WIMPs with EDELWEISS-II heat-and-ionization detectors
We report on a search for low-energy (E < 20 keV) WIMP-induced nuclear recoils using data collected in 2009 - 2010 by EDELWEISS from four germanium detectors equipped with thermal sensors and an electrode design (ID) which allows to efficiently reject several sources of background. Using an exposure of 113 kg.d, we find no evidence for an exponential distribution of low-energy nuclear recoils that could be attributed to WIMP elastic scattering. For WIMPs of mass 10 GeV, the observation of one event in the WIMP search region results in a 90% CL limit of 1.0 \times 10^-5 pb on the spin-independent WIMP-nucleon scattering cross-section, which constrains the parameter space associated with the findings reported by the CoGeNT, DAMA and CRESST experiments.