41612695
Binary and Millisecond Pulsars
Most of the ~600 known pulsars are single and located in the disk of our 
Galaxy. There is circumstantial evidence that the pulsars in this majority are 
created in supernova (SN) explosions, by the collapse of the cores of massive 
stars (initial mass M_i ≳ M_(cr) ≃ 8 M_⊙). One is created roughly every 100 y in 
the Galaxy.
14167939
Detecting Outer Planets in Edge-on Orbits: Combining Radial Velocity and Astrometric Techniques
The astrometric and radial velocity techniques of extrasolar planet detection attempt to detect the periodic reflex motion of the parent star by extracting this periodic signal from a time-sampled set of observations. The extraction is generally accomplished using periodogram analysis or the functionally equivalent technique of least-squares fitting of sinusoids. In this paper, we use a frequentist approach to examine the sensitivity of the least-squares technique when applied to a combination of radial velocity and astrometric observations. We derive an analytical expression for the sensitivity and show that the combined approach yields significantly better sensitivity than either technique on its own. We discuss the ramifications of this result to upcoming astrometric surveys with the Full-Sky Astrometric Mapping Explorer, the Keck Interferometer, and the Space Interferometry Mission.
11026035
The Incidence of Dwarf Novae in Large Area Transient Searches
Understanding and quantifying the contribution of known classes of transient and variable sources is an important lesson to be learned from the manifold of precursor programs of the near-future large synoptic sky survey programs such as SkyMapper, Pan-STARRS, and LSST. With this goal in mind, we undertook photometric and spectroscopic follow-up observations of four recently reported unidentified transients. For two sources, WFI J132813.7-214237 and WFI J161953.3+031909, we show that unfortunate coincidences led to their previous designation as transients. While the former is now interpreted as the spatial coincidence of a solar system object with a faint background star, the latter is merely a cataclysmic variable unfortunately caught in and out of eclipse. The third candidate, ROTSE3 J160213.1-021311.7, is identified as an SU UMa type dwarf nova with quiescent brightness of R ~ 22.7 and an outburst amplitude of ~5 mag. The fourth event, SDSS-SN 15207, similarly shows evidence for a dwarf nova origin. Our main conclusion is that cataclysmic variables in their various avatars will contribute moderately to the population of transient objects.
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.
8913778
Spitzer Observations of the New Luminous Red Nova M85 OT2006-1
M85 OT2006-1 is the latest and most brilliant addition to the small group of known luminous red novae (LRNe). An identifying characteristic of the previously detected events (M31 RV, V4332 Sgr, and V838 Mon) was a spectral redward evolution connected with an emerging infrared component following the optical decay. Here we report on the discovery of a similar feature in Keck NIRC and Spitzer photometry of M85 OT2006-1 6 months posteruption. We find that its 2.1-22 μm spectral energy distribution is best described by a blackbody with effective temperature T_(eff) = 950 ± 150 K and bolometric luminosity L = 2.9^(+0.4)_(-0.5) × 10^5 L_⊙. Assuming spherical geometry, the blackbody effective radius, R = 2.0^(+0.6)_(-0.4) × 10^4 R_⊙, and corresponding expansion velocity, v = 870^(+260)_(-180) km s^(-1), are remarkably similar to the properties of M31 RV 70 days after its eruption. Furthermore, we propose a search strategy for LRNe in the local universe making use of the longevity of their infrared excess emission and discuss the expected number of events in the Spitzer Infrared Nearby Galaxies Survey.
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.
118517610
Effective couplings approach to neutralino dark matter relic density
In this work, we analyze the electroweak loop corrections to the Neutralino dark matter relic density in the framework of effective coupling. In the first part, we comment on the generic features of the corrections and quantitative changes to the predicted relic density. We analyze the correlation between the characteristics of effective couplings to the nature of neutralino. Effective couplings, however, absorb only the most dominant one loop corrections and are not an exact calculation. In the second part, we assess the validity of effective couplings by comparing them to the full one loop calculations in various regions of parameter space.
91177292
SModelS: a tool for interpreting simplified-model results from the LHC and its application to supersymmetry
We present a general procedure to decompose Beyond the Standard Model (BSM) collider signatures presenting a $$\mathbb {Z}_2$$Z2 symmetry into Simplified Model Spectrum (SMS) topologies. Our method provides a way to cast BSM predictions for the LHC in a model independent framework, which can be directly confronted with the relevant experimental constraints. Our concrete implementation currently focusses on supersymmetry searches with missing energy, for which a large variety of SMS results from ATLAS and CMS are available. As show-case examples we apply our procedure to two scans of the minimal supersymmetric standard model. We discuss how the SMS limits constrain various particle masses and which regions of parameter space remain unchallenged by the current SMS interpretations of the LHC results.
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.
119219379
On the On-Shell Renormalization of the Chargino and Neutralino Masses in the MSSM
We discuss the choice of input parameters for the renormalization of the chargino and neutralino sector in the minimal supersymmetric standard model (MSSM) in the on-shell scheme. We show that one should chose the masses of a bino-like, a wino-like and a higgsino-like state as inputs in order to avoid large corrections to the masses of the other eigenstates in this sector. We also show that schemes where the higgsino-like input state is a neutralino are more stable than those where the mass of the higgsino-like chargino is used as input. The most stable scheme uses the masses of the wino-like chargino as well as the masses of the bino- and higgsino-like neutralinos as inputs.
13913623
Hawking fluxes, back reaction and covariant anomalies
Starting from the chiral covariant effective action approach of Banerjee and Kulkarni (2008 Phys. Lett. B 659 827), we provide a derivation of the Hawking radiation from a charged black hole in the presence of gravitational back reaction. The modified expressions for charge and energy flux, due to the effect of one-loop back reaction are obtained.