6132403
Millimeter Observations of GRB 030329: Continued Evidence for a Two-Component Jet
We present the results of a dedicated campaign on the afterglow of GRB 030329 with the millimeter interferometers of the Owens Valley Radio Observatory (OVRO) and the Berkeley-Illinois-Maryland Association (BIMA), and with the MAMBO-2 bolometer array on the IRAM 30 m telescope. These observations allow us to trace the full evolution of the afterglow of GRB 030329 at frequencies of 100 and 250 GHz for the first time. The millimeter light curves exhibit two main features: a bright, constant flux density portion and a steep power-law decline. The absence of bright, short-lived millimeter emission is used to show that the GRB central engine was not actively injecting energy well after the burst. The millimeter data support a model, advocated by Berger et al., of a two-component jetlike outflow in which a narrow-angle jet is responsible for the high-energy emission and early optical afterglow, and a wide-angle jet carrying most of the energy is powering the radio and late optical afterglow emission.
28576228
CORE-COLLAPSE SUPERNOVAE FROM THE PALOMAR TRANSIENT FACTORY: INDICATIONS FOR A DIFFERENT POPULATION IN DWARF GALAXIES
We use the first compilation of 72 core-collapse supernovae (SNe) from the Palomar Transient Factory (PTF) to study their observed subtype distribution in dwarf galaxies compared to giant galaxies. Our sample is the largest single-survey, untargeted, spectroscopically classified, homogeneous collection of core-collapse events ever assembled, spanning a wide host-galaxy luminosity range (down to M_r ≈ –14 mag) and including a substantial fraction (>20%) of dwarf (M_r ≥ –18 mag) hosts. We find more core-collapse SNe in dwarf galaxies than expected and several interesting trends emerge. We use detailed subclassifications of stripped-envelope core-collapse SNe and find that all Type I core-collapse events occurring in dwarf galaxies are either SNe Ib or broad-lined SNe Ic (SNe Ic-BL), while "normal" SNe Ic dominate in giant galaxies. We also see a significant excess of SNe IIb in dwarf hosts. We hypothesize that in lower metallicity hosts, metallicity-driven mass loss is reduced, allowing massive stars that would have appeared as "normal" SNe Ic in metal-rich galaxies to retain some He and H, exploding as Ib/IIb events. At the same time, another mechanism allows some stars to undergo extensive stripping and explode as SNe Ic-BL (and presumably also as long-duration gamma-ray bursts). Our results are still limited by small-number statistics, and our measurements of the observed N(Ib/c)/N(II) number ratio in dwarf and giant hosts (0.25^(+0.3)_(–0.15) and 0.23^(+0.11)_(–0.08), respectively; 1σ uncertainties) are consistent with previous studies and theoretical predictions. As additional PTF data accumulate, more robust statistical analyses will be possible, allowing the evolution of massive stars to be probed via the dwarf-galaxy SN population.
15685797
X-Ray Timing of the Enigmatic Neutron Star RX J0720.4–3125
RX J0720.4-3125 is the third brightest neutron star in the soft X-ray sky and has been a source of mystery since its discovery, as its long 8 s period separates it from the population of typical radio pulsars. Three models were proposed for this source: a neutron star accreting from the interstellar medium, an off-beam radio pulsar, or an old, cooling magnetar. Using data from Chandra, ROSAT, and BeppoSAX, we are able to place an upper limit to the period derivative, || < 3.6 × 10-13 s s-1 (3 σ). While our upper limit on allows for the accretion model, this model is increasingly untenable for another similar but better studied neutron star, RX J1856.5-3754, and we therefore consider the accretion model unlikely for RX J0720.4-3125. We constrain the initial magnetic field of RX J0720.4-3125 to be 1014 G based on cooling models, suggesting that it is not and never was a magnetar but is instead a middle-aged neutron star. We propose that it is either a long-period high magnetic field pulsar with ~ 10-13 s s-1, similar to PSR J1814-1744, or a neutron star born with an initial period of ≈8.3 s and ~ 10-15 s s-1. The proximity of RX J0720.4-3125 is strongly suggestive of a large population of such objects; if so, radio pulsar surveys must have missed many of these sources.
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.
20207808
DISCOVERY OF A COSMOLOGICAL, RELATIVISTIC OUTBURST VIA ITS RAPIDLY FADING OPTICAL EMISSION
We report the discovery by the Palomar Transient Factory (PTF) of the transient source PTF11agg, which is distinguished by three primary characteristics: (1) bright (Rpeak = 18.3mag), rapidly fading (ΔR = 4mag in Δt = 2 days) optical transient emission; (2) a faint (R = 26.2 ± 0.2mag), blue (g � − R = 0.17 ± 0.29mag) quiescent optical counterpart; and (3) an associated year-long, scintillating radio transient. We argue that these observed properties are inconsistent with any known class of Galactic transients (flare stars, X-ray binaries, dwarf novae), and instead suggest a cosmological origin. The detection of incoherent radio emission at such distances implies a large emitting region, from which we infer the presence of relativistic ejecta. The observed properties are allconsistentwiththepopulationoflong-durationgamma-raybursts(GRBs),markingthefirsttimesuchanoutburst has been discovered in the distant universe independent of a high-energy trigger. We searched for possible highenergy counterparts to PTF11agg, but found no evidence for associated prompt emission. We therefore consider three possible scenarios to account for a GRB-like afterglow without a high-energy counterpart: an “untriggered” GRB (lack of satellite coverage), an “orphan” afterglow (viewing-angle effects), and a “dirty fireball” (suppressed high-energy emission). The observed optical and radio light curves appear inconsistent with even the most basic predictions for off-axis afterglow models. The simplest explanation, then, is that PTF11agg is a normal, on-axis long-durationGRBforwhichtheassociatedhigh-energyemissionwassimplymissed.However,wehavecalculated the likelihood of such a serendipitous discovery by PTF and find that it is quite small (≈2.6%). While not definitive, we nonetheless speculate that PTF11agg may represent a new, more common (>4 times the on-axis GRB rate at 90% confidence) class of relativistic outbursts lacking associated high-energy emission. If so, such sources will be uncovered in large numbers by future wide-field optical and radio transient surveys.
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.
15128408
Hawking radiation, covariant boundary conditions, and vacuum states
The basic characteristics of the covariant chiral current and the covariant chiral energy-momentum tensor are obtained from a chiral effective action. These results are used to justify the covariant boundary condition used in recent approaches of computing the Hawking flux from chiral gauge and gravitational anomalies. We also discuss a connection of our results with the conventional calculation of nonchiral currents and stress tensors in different (Unruh, Hartle-Hawking and Boulware) states.
119246679
Modified dispersion relations and the response of the rotating Unruh-DeWitt detector
We study the response of a rotating monopole detector that is coupled to a massless scalar field which is described by a nonlinear dispersion relation in flat spacetime. Since it does not seem to be possible to evaluate the response of the rotating detector analytically, we resort to numerical computations. Interestingly, unlike the case of the uniformly accelerated detector that has been considered recently, we find that defining the transition probability rate of the rotating detector poses no difficulties. Further, we show that the response of the rotating detector can be computed exactly (albeit, numerically) even when it is coupled to a field that is governed by a nonlinear dispersion relation. We also discuss the response of the rotating detector in the presence of a cylindrical boundary on which the scalar field is constrained to vanish. While superluminal dispersion relations hardly affect the standard results, we find that subluminal dispersion relations can lead to relatively large modifications.
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.
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.
119248722
Testing theCP-violating MSSM in stau decays at the LHC and ILC
We study CP violation in the two-body decay of a scalar tau into a neutralino and a tau, which should be probed at the LHC and ILC. From the normal tau polarization, a CP asymmetry is defined which is sensitive to the CP phases of the trilinear scalar coupling parameter A{sub {tau}}, the gaugino mass parameter M{sub 1}, and the Higgsino mass parameter {mu}, in the stau-neutralino sector of the minimal supersymmetric standard model. Asymmetries of more than 70% are obtained in scenarios with strong stau mixing. As a result, detectable CP asymmetries in stau decays at the LHC are found, motivating further detailed experimental studies for probing the supersymmetry CP phases.