10828298
SENSITIVE SEARCH FOR RADIO VARIABLES AND TRANSIENTS IN THE EXTENDED CHANDRA DEEP FIELD SOUTH
We report on an analysis of the Extended Chandra Deep Field South (E-CDFS) region using archival data from the Very Large Array, with the goal of studying radio variability and transients at the sub-milliJansky level. The 49 epochs of E-CDFS observations at 1.4 GHz sample timescales from 1 day to 3 months. We find that only a fraction (1%) of unresolved radio sources above 40 μJy are variable at the 4σ level. There is no evidence that the fractional variability changes along with the known transition of radio-source populations below 1 mJy. Optical identifications of the sources show that the variable radio emission is associated with the central regions of an active galactic nucleus or a star-forming galaxy. After a detailed comparison of the efficacy of various source-finding algorithms, we use the best to carry out a transient search. No transients were found. This implies that the areal density of transients with peak flux density greater than 0.21 mJy is less than 0.37 deg^(–2) (at a confidence level of 95%). This result is approximately an order of magnitude below the transient rate measured at 5 GHz by Bower et al. but it is consistent with more recent upper limits from Frail et al. Our findings suggest that the radio sky at 1.4 GHz is relatively quiet. For multi-wavelength transient searches, such as the electromagnetic counterparts to gravitational waves, this frequency may be optimal for reducing the high background of false positives.
206535504
Transformation of a Star into a Planet in a Millisecond Pulsar Binary
Timing observations of a millisecond pulsar reveal a planet that is far denser than any known planet. Millisecond pulsars are thought to be neutron stars that have been spun-up by accretion of matter from a binary companion. Although most are in binary systems, some 30% are solitary, and their origin is therefore mysterious. PSR J1719−1438, a 5.7-millisecond pulsar, was detected in a recent survey with the Parkes 64-meter radio telescope. We show that this pulsar is in a binary system with an orbital period of 2.2 hours. The mass of its companion is near that of Jupiter, but its minimum density of 23 grams per cubic centimeter suggests that it may be an ultralow-mass carbon white dwarf. This system may thus have once been an ultracompact low-mass x-ray binary, where the companion narrowly avoided complete destruction.
51836738
Optical Spectropolarimetry of the GRB 020813 Afterglow
The optical afterglow of gamma-ray burst GRB 020813 was observed for 3 hr with the LRIS spectropolarimeter at the Keck I telescope, beginning 4.7 hr after the burst was detected by the HETE-2. The spectrum reveals numerous metal absorption lines that we identify with two systems at z = 1.223 and z = 1.255. We also detect an [O II] λ3727 emission line at z = 1.255, and we identify this galaxy as the likely host of the GRB. After a correction for Galactic interstellar polarization, the optical afterglow has a linear polarization of 1.8%-2.4% during 4.7-7.9 hr after the burst. A measurement of p = 0.80% ± 0.16% on the following night by Covino et al. demonstrates significant polarization variability over the next 14 hr. The lack of strong variability in the position angle of linear polarization indicates that the magnetic field in the jet is likely to be globally ordered rather than composed of a number of randomly oriented cells. Within the framework of afterglow models with collimated flows, the relatively low observed polarization suggests that the magnetic field components perpendicular and parallel to the shock front are only different by about 20%.
28287780
DISCOVERY OF A NEW PHOTOMETRIC SUB-CLASS OF FAINT AND FAST CLASSICAL NOVAE
We present photometric and spectroscopic follow-up of a sample of extragalactic novae discovered by the Palomar 60 inch telescope during a search for "Fast Transients In Nearest Galaxies" (P60-FasTING). Designed as a fast cadence (1 day) and deep (g < 21 mag) survey, P60-FasTING was particularly sensitive to short-lived and faint optical transients. The P60-FasTING nova sample includes 10 novae in M 31, 6 in M 81, 3 in M 82, 1 in NGC 2403, and 1 in NGC 891. This significantly expands the known sample of extragalactic novae beyond the Local Group, including the first discoveries in a starburst environment. Surprisingly, our photometry shows that this sample is quite inconsistent with the canonical maximum-magnitude-rate-of-decline (MMRD) relation for classical novae. Furthermore, the spectra of the P60-FasTING sample are indistinguishable from classical novae. We suggest that we have uncovered a sub-class of faint and fast classical novae in a new phase space in luminosity-timescale of optical transients. Thus, novae span two orders of magnitude in both luminosity and time. Perhaps the MMRD, which is characterized only by the white dwarf mass, was an oversimplification. Nova physics appears to be characterized by a relatively rich four-dimensional parameter space in white dwarf mass, temperature, composition, and accretion rate.
119466873
The Radio and X-Ray-Luminous Type Ibc Supernova 2003L
We present extensive radio observations of SN 2003L, the most luminous and energetic Type Ibc radio supernova with the exception of SN 1998bw (associated with GRB 980425). Observations from the Very Large Array are well described by fitting a synchrotron self-absorption model to the emission spectrum. This model implies a subrelativistic ejecta velocity, ≈ 0.2c, and a size of r ≈ 4.3 × 1015 cm at t ≈ 10 days. The circumstellar density is suitably fitted with a stellar wind profile, ne ∝ r-2 cm-3 and a constant mass-loss rate of ≈ 7.5 × 10-6 M☉ yr-1. Moreover, the magnetic field follows B ∝ r-1 and the kinetic energy of the radio-bright ejecta is roughly E ≈ 1048 ergs assuming equipartition of energy between relativistic electrons and magnetic fields. Furthermore, we show that free-free absorption does not contribute significantly to the radio spectrum, since it implies ejecta velocities that are inconsistent with size constraints derived from Very Long Baseline Array observations. In conclusion, we find that although SN 2003L has a radio luminosity comparable to that seen in SN 1998bw, it shows no evidence for a significant amount of energy coupled to relativistic ejecta. Using SN 2003L as an example, we comment briefly on the coupling of ejecta velocity and energy in Type Ibc supernovae.
15848181
The Spectrum of the Brown Dwarf Gliese 229B
We present a spectrum of the cool K) brown dwarf Gliese 229B. This spectrum, with a (T eff \ 900 relatively high signal-to-noise ratio per spectral resolution element spans the wavelength range (Z30), from 0.837 k mt o 5.0 km. We identify a total of four di†erent major methane absorption features, includ- ing the fundamental band at 3.3 km, at least four steam bands, and two neutral cesium features. We con-rm the recent detection of carbon monoxide (CO) in excess of what is predicted by thermochemical equilibrium calculations. Carbon is primarily involved in a chemical balance between methane and CO at the temperatures and pressures present in the outer parts of a brown dwarf. At lower temperatures, the balance favors methane, while in the deeper, hotter regions, the reaction reverses to convert methane into CO. The presence of CO in the observable part of the atmosphere is therefore a sensitive indicator of vertical Nows. The high signal-to-noise ratio in the 1 k mt o 2.5 km region permits us to place con- straints on the quantity of dust in the atmosphere of the brown dwarf. We are unable to reconcile the observed spectrum with synthetic spectra that include the presences of dust. The presence of CO but lack of dust may be a clue to the location of the boundaries of the outer convective region of the atmo- sphere: The lack of dust may mean that it is not being conveyed into the photosphere by convection, or that it exists in patchy clouds. If the dust is not in clouds, but rather sits below the outer convective region, we estimate that the boundary between outer convective and inner radiative layers is between 1250 K and 1600 K, in agreement with recent models. Subject headings: circumstellar matter E line: identi-cation E stars: individual (Gliese 229B) E stars: low-mass, brown dwarfs
119250843
Top Polarization in Sbottom Decays at the LHC
We perform a comprehensive analysis of the polarization of the top quarks originating from sbottom-pair production at the LHC, followed by sbottom decays to top+chargino. We study moreover the expected net polarization of top quarks produced in sbottom-to-chargino and stop-to-neutralino decays in scenarios with small chargino - neutralino mass difference, where these decays may be hard to distinguish. We show that, in contrast to top quarks produced via the Standard Model processes, the average polarization of top quarks originating from these SUSY decays can obtain any value between +1 and -1. We further study the effect of this polarization on the top quark decay kinematics. On the one hand this may be used to construct measures of this polarization, on the other hand it may be used to enhance the search reach in certain scenarios. Exploiting top polarization may also prove useful for searches for "natural" SUSY with light higgsinos, which is typically very difficult to detect at the LHC.
118387184
Higher order WKB corrections to black hole entropy in brick wall formalism
We calculate the statistical entropy of a quantum field with an arbitrary spin propagating on the spherical symmetric black hole background by using the brick wall formalism at higher orders in the WKB approximation. For general spins, we find that the correction to the standard Bekenstein–Hawking entropy depends logarithmically on the area of the horizon. Furthermore, we apply this analysis to the Schwarzschild and Schwarzschild–AdS(dS) black holes and discuss our results.
116599063
Hawking fluxes and covariant anomalies
A non-destructive, direct method and apparatus for producing stretch blow molded articles having at least one physical dimension within a preselected range. The apparatus includes an injection mold defining an injection mold interior surface having a first differentially dimensioned portion disposed at a preselected location thereon and capable of producing a parison having a parison exterior surface including a first marker formed by contact with the first differentially dimensioned portion, and a stretch blow mold defining a stretch blow mold interior surface having a second differentially dimensioned portion disposed at a predetermined location thereon and capable of producing the article from the parison including a second marker formed by contact with the second differentially dimensioned portion. Relative position of the first marker with respect to the second marker indicates whether a dimension is within a preselected range. The method includes injection molding a parison so that a parison exterior surface includes a first marker disposed at a preselected position thereon and formed by contact with a first differentially dimensioned portion disposed at a preselected location on an injection mold interior surface, and stretch blow molding an article from the parison so that an article exterior surface includes a second marker disposed at a predetermined position thereon and formed by contact with a second differentially dimensioned portion disposed at a predetermined location on a stretch blow mold interior surface.
119245317
Toward a public analysis database for LHC new physics searches using MADANALYSIS 5
We present the implementation, in the MadAnalysis 5 framework, of several ATLAS and CMS searches for supersymmetry in data recorded during the first run of the LHC. We provide extensive details on the validation of our implementations and propose to create a public analysis database within this framework.
119114244
Transport in non-conformal holographic fluids
A bstractWe have considered non-conformal fluid dynamics whose gravity dual is a certain Einstein dilaton system with Liouville type dilaton potential, characterized by an intrinsic parameter η. We have discussed the Hawking-Page transition in this framework using hard-wall model and it turns out that the critical temperature of the Hawking-Page transition encapsulates a non-trivial dependence on η. We also obtained transport coefficients such as AC conductivity, shear viscosity and diffusion constant in the hydrodynamic limit, which show non-trivial η dependent deviations from those in conformal fluids, although the ratio of the shear viscosity to entropy density is found to saturate the universal bound. Some of the retarded correlators are also computed in the high frequency limit for case study.