119108801
HUNTING FOR THE PROGENITOR OF SN 1006: HIGH-RESOLUTION SPECTROSCOPIC SEARCH WITH THE FLAMES INSTRUMENT*
Type Ia supernovae play a significant role in the evolution of the universe and have a wide range of applications. It is widely believed that these events are the thermonuclear explosions of carbon-oxygen white dwarfs close to the Chandrasekhar mass (1.38 M ☉). However, CO white dwarfs are born with masses much below the Chandrasekhar limit and thus require mass accretion to become Type Ia supernovae. There are two main scenarios for accretion: first, the merger of two white dwarfs and, second, a stable mass accretion from a companion star. According to predictions, this companion star (also referred to as donor star) survives the explosion and thus should be visible in the center of Type Ia remnants. In this paper, we scrutinize the central stars (79 in total) of the SN 1006 remnant to search for the surviving donor star as predicted by this scenario. We find no star consistent with the traditional accretion scenario in SN 1006.
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.
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).
118744981
Measurement of mixing and CP violation parameters in two-body charm decays
A bstractA study of mixing and indirect CP violation in D0 mesons through the determination of the parameters yCP and AΓ is presented. The parameter yCP is the deviation from unity of the ratio of effective lifetimes measured in D0 decays to the CP eigenstate K+K− with respect to decays to the Cabibbo favoured mode K−π+. The result measured using data collected by LHCb in 2010, corresponding to an integrated luminosity of 29 pb−1, is yCP = (5.5 ± 6.3stat ± 4.1syst) × 10−3. The parameter AΓ is the asymmetry of effective lifetimes measured in decays of D0 and $ {\overline D^0} $ mesons to K+K−. The result is AΓ = (−5.9 ± 5.9stat ± 2.1syst) × 10−3. A data-driven technique is used to correct for lifetime-biasing effects.
208248288
Search for the doubly charmed baryon $$\Xi_{cc}^+$$
A search for the doubly charmed baryon \(\Xi_{cc}^+\) is performed through its decay to the \(\Lambda_c^ + {K^ -}{\pi ^ +}\) final state, using proton-proton collision data collected with the LHCb detector at centre-of-mass energies of 7, 8 and 13 TeV. The data correspond to a total integrated luminosity of 9 fb−1. No significant signal is observed in the mass range from 3.4 to 3.8 GeV/c2. Upper limits are set at 95% credibility level on the ratio of the \(\Xi_{cc}^+\) production cross-section times the branching fraction to that of \(\Lambda_c^ + \) and \(\Xi_{cc}^{+ +}\) baryons. The limits are determined as functions of the \(\Xi_{cc}^+\) mass for different lifetime hypotheses, in the rapidity range from 2.0 to 4.5 and the transverse momentum range from 4 to 15 GeV/c.
16811603
Kinematic distributions and nuclear effects of J/ψ production in 920 GeV fixed-target proton-nucleus collisions
AbstractMeasurements of the kinematic distributions of J/ψ mesons produced in p–C, p–Ti and p–W collisions at 
$\sqrt{s}=41.6~\mathrm{GeV}$ 
in the Feynman-x region −0.34<xF<0.14 and for transverse momentum up to pT=5.4 GeV/c are presented. The xF and pT dependencies of the nuclear suppression parameter, α, are also given. The results are based on 2.4×105J/ψ mesons reconstructed in both the e+e− and μ+μ− decay channels. The data have been collected by the HERA-B experiment at the HERA proton ring of the DESY laboratory. The measurement explores the negative region of xF for the first time. The average value of α in the measured xF region is 0.981±0.015. The data suggest that the strong nuclear suppression of J/ψ production previously observed at high xF turns into an enhancement at negative xF.
118631869
Limits on neutral Higgs boson production in the forward region in pp collisions at $ \sqrt{s}=7 $ TeV
A bstractLimits on the cross-section times branching fraction for neutral Higgs bosons, produced in pp collisions at $ \sqrt{s}=7 $ TeV, and decaying to two tau leptons with pseudorapidities between 2.0 and 4.5, are presented. The result is based on a dataset, corresponding to an integrated luminosity of 1.0 fb−1, collected with the LHCb detector. Candidates are identified by reconstructing final states with two muons, a muon and an electron, a muon and a hadron, or an electron and a hadron. A model independent upper limit at the 95% confidence level is set on a neutral Higgs boson cross-section times branching fraction. It varies from 8.6 pb for a Higgs boson mass of 90 GeV to 0.7 pb for a Higgs boson mass of 250 GeV, and is compared to the Standard Model expectation. An upper limit on tan β in the Minimal Supersymmetric Model is set in the $ m_{{{h^0}}}^{\max } $ scenario. It ranges from 34 for a CP -odd Higgs boson mass of 90 GeV to 70 for a pseudo-scalar Higgs boson mass of 140 GeV.

126202310
MEASURING THE CHEMICAL COMPOSITION OF COSMIC RAYS AT approximately 10**13-eV - 10**15-eV BY UTILIZING THE SOLAR AND GEOMAGNETIC FIELDS