Low‐energy electrons (5–50 keV) in the inner magnetosphere

Transport and acceleration of the 5–50 keV electrons from the plasma sheet to geostationary orbit were investigated. These electrons constitute the low‐energy part of the seed population for the high‐energy MeV particles in the radiation belts and are responsible for surface charging. We modeled one nonstorm event on 24–30 November 2011, when the presence of isolated substorms was seen in the AE index. We used the Inner Magnetosphere Particle Transport and Acceleration Model (IMPTAM) with the boundary at 10 R E with moment values for the electrons in the plasma sheet. The output of the IMPTAM modeling was compared to the observed electron fluxes in 10 energy channels (from 5 to 50 keV) measured on board the AMC 12 geostationary spacecraft by the Compact Environmental Anomaly Sensor II with electrostatic analyzer instrument. The behavior of the fluxes depends on the electron energy. The IMPTAM model, driven by the observed parameters such as Interplanetary Magnetic Field (IMF) B y and B z , solar wind velocity, number density, dynamic pressure, and the Dst index, was not able to reproduce the observed peaks in the electron fluxes when no significant variations are present in those parameters. We launched several substorm‐associated electromagnetic pulses at the substorm onsets during the modeled period. The observed increases in the fluxes can be captured by IMPTAM when substorm‐associated electromagnetic fields are taken into account. Modifications of the pulse front velocity and arrival time are needed to exactly match the observed enhancements. Key Points Electron flux peaks due to substorm activity Solar wind driven inner magnetosphere model does not work for quiet times Substorm‐associated fields to explain electron flux peaksPeer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/106068/1/jgra50735.pd

Nowcast model for low‐energy electrons in the inner magnetosphere

We present the nowcast model for low‐energy (<200 keV) electrons in the inner magnetosphere, which is the version of the Inner Magnetosphere Particle Transport and Acceleration Model (IMPTAM) for electrons. Low‐energy electron fluxes are very important to specify when hazardous satellite surface‐charging phenomena are considered. The presented model provides the low‐energy electron flux at all L shells and at all satellite orbits, when necessary. The model is driven by the real‐time solar wind and interplanetary magnetic field (IMF) parameters with 1 h time shift for propagation to the Earth's magnetopause and by the real time Dst index. Real‐time geostationary GOES 13 or GOES 15 (whenever each is available) data on electron fluxes in three energies, such as 40 keV, 75 keV, and 150 keV, are used for comparison and validation of IMPTAM running online. On average, the model provides quite reasonable agreement with the data; the basic level of the observed fluxes is reproduced. The best agreement between the modeled and the observed fluxes are found for <100 keV electrons. At the same time, not all the peaks and dropouts in the observed electron fluxes are reproduced. For 150 keV electrons, the modeled fluxes are often smaller than the observed ones by an order of magnitude. The normalized root‐mean‐square deviation is found to range from 0.015 to 0.0324. Though these metrics are buoyed by large standard deviations, owing to the dynamic nature of the fluxes, they demonstrate that IMPTAM, on average, predicts the observed fluxes satisfactorily. The computed binary event tables for predicting high flux values within each 1 h window reveal reasonable hit rates being 0.660–0.318 for flux thresholds of 5 ·104–2 ·105 cm−2 s−1 sr−1 keV−1 for 40 keV electrons, 0.739–0.367 for flux thresholds of 3 ·104–1 ·105 cm−2 s−1 sr−1 keV−1 for 75 keV electrons, and 0.485–0.438 for flux thresholds of 3 ·103–3.5 ·103 cm−2 s−1 sr−1 keV−1 for 150 keV electrons but rather small Heidke Skill Scores (0.17 and below). This is the first attempt to model low‐energy electrons in real time at 10 min resolution. The output of this model can serve as an input of electron seed population for real‐time higher‐energy radiation belt modeling.Key PointsNowcast model for low‐energy electronsOnline near‐real‐time comparison to GOES MAGED dataFirst successful model for low‐energy electrons in real timePeer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/110719/1/swe20196.pd

Implications For The Origin Of GRB 051103 From LIGO Observations

We present the results of a LIGO search for gravitational waves (GWs) associated with GRB 051103, a short-duration hard-spectrum gamma-ray burst (GRB) whose electromagnetically determined sky position is coincident with the spiral galaxy M81, which is 3.6 Mpc from Earth. Possible progenitors for short-hard GRBs include compact object mergers and soft gamma repeater (SGR) giant flares. A merger progenitor would produce a characteristic GW signal that should be detectable at the distance of M81, while GW emission from an SGR is not expected to be detectable at that distance. We found no evidence of a GW signal associated with GRB 051103. Assuming weakly beamed gamma-ray emission with a jet semi-angle of 30 deg we exclude a binary neutron star merger in M81 as the progenitor with a confidence of 98%. Neutron star-black hole mergers are excluded with > 99% confidence. If the event occurred in M81 our findings support the the hypothesis that GRB 051103 was due to an SGR giant flare, making it the most distant extragalactic magnetar observed to date.Comment: 8 pages, 3 figures. For a repository of data used in the publication, go to: https://dcc.ligo.org/cgi-bin/DocDB/ShowDocument?docid=15166 . Also see the announcement for this paper on ligo.org at: http://www.ligo.org/science/Publication-GRB051103/index.ph

Apolipoprotein B gene polymorphisms in patients from Serbia with ischemic cerebrovascular disease

The plasma concentration of apoB has recently been reported to be the best lipid predictor of coronary heart disease. The possible associations of genetic markers in the apolipoprotein B gene (XbaI, EcoRI, MspI, Ins/Del, and 4311 A/G polymorphisms) were evaluated in patients with ischemic cerebrovascular disease (ICVD) and controls of equivalent BMI. The odds ratio for ICVD in the X+X+ genotype was 2.22, 95% CI 1.24-3.96 (P&lt;0.05), while that for ICVD in the Ins/Ins genotype was 2.82, 95% CI 1.57-5.06 (P&lt;0.05). The patients had significantly higher frequency of the 4311A allele compared to the controls (P&lt;0.01). Our results support the assumption that apoB gene polymorphisms may contribute to the extent of cerebrovascular disease risk

Search for gravitational waves associated with the InterPlanetary Network short gamma ray bursts

We outline the scientific motivation behind a search for gravitational waves associated with short gamma ray bursts detected by the InterPlanetary Network (IPN) during LIGO's fifth science run and Virgo's first science run. The IPN localisation of short gamma ray bursts is limited to extended error boxes of different shapes and sizes and a search on these error boxes poses a series of challenges for data analysis. We will discuss these challenges and outline the methods to optimise the search over these error boxes.Comment: Methods paper; Proceedings for Eduardo Amaldi 9 Conference on Gravitational Waves, July 2011, Cardiff, U

Implementation and testing of the first prompt search for gravitational wave transients with electromagnetic counterparts

Aims. A transient astrophysical event observed in both gravitational wave (GW) and electromagnetic (EM) channels would yield rich scientific rewards. A first program initiating EM follow-ups to possible transient GW events has been developed and exercised by the LIGO and Virgo community in association with several partners. In this paper, we describe and evaluate the methods used to promptly identify and localize GW event candidates and to request images of targeted sky locations. Methods. During two observing periods (Dec 17 2009 to Jan 8 2010 and Sep 2 to Oct 20 2010), a low-latency analysis pipeline was used to identify GW event candidates and to reconstruct maps of possible sky locations. A catalog of nearby galaxies and Milky Way globular clusters was used to select the most promising sky positions to be imaged, and this directional information was delivered to EM observatories with time lags of about thirty minutes. A Monte Carlo simulation has been used to evaluate the low-latency GW pipeline's ability to reconstruct source positions correctly. Results. For signals near the detection threshold, our low-latency algorithms often localized simulated GW burst signals to tens of square degrees, while neutron star/neutron star inspirals and neutron star/black hole inspirals were localized to a few hundred square degrees. Localization precision improves for moderately stronger signals. The correct sky location of signals well above threshold and originating from nearby galaxies may be observed with ~50% or better probability with a few pointings of wide-field telescopes.Comment: 17 pages. This version (v2) includes two tables and 1 section not included in v1. Accepted for publication in Astronomy & Astrophysic

All-Sky Search for Periodic Gravitational Waves in the Full S5 LIGO Data

We report on an all-sky search for periodic gravitational waves in the frequency band 50-800 Hz and with the frequency time derivative in the range of 0 through -6 x 10(exp -9) Hz/s. Such a signal could be produced by a nearby spinning and slightly non-axisymmetric isolated neutron star in our galaxy. After recent improvements in the search program that yielded a 10x increase in computational efficiency, we have searched in two years of data. collected during LIGO's fifth science run and have obtained the most sensitive all-sky upper limits on gravitational wave strain to date. Near 150 Hz our upper limit on worst-case linearly polarized strain amplitude h(sub 0) is 1 x 10(exp -24), while at the high end of our frequency ra.nge we achieve a worst-case upper limit of 3.8 x 10(exp -24) for all polarizations and sky locations. These results constitute a factor of two improvement upop. previously published data. A new detection pipeline utilizing a Loosely Coherent algorithm was able to follow up weaker outliers, increasing the volume of space where signals can be detected by a factor of 10, but has not revealed any gravitational wave signals. The pipeline has been tested for robustness with respect to deviations from the model of an isolated neutron star, such as caused by a low-mass or long.period binary companion

Gravitational Waves From Known Pulsars: Results From The Initial Detector Era

We present the results of searches for gravitational waves from a large selection of pulsars using data from the most recent science runs (S6, VSR2 and VSR4) of the initial generation of interferometric gravitational wave detectors LIGO (Laser Interferometric Gravitational-wave Observatory) and Virgo. We do not see evidence for gravitational wave emission from any of the targeted sources but produce upper limits on the emission amplitude. We highlight the results from seven young pulsars with large spin-down luminosities. We reach within a factor of five of the canonical spin-down limit for all seven of these, whilst for the Crab and Vela pulsars we further surpass their spin-down limits. We present new or updated limits for 172 other pulsars (including both young and millisecond pulsars). Now that the detectors are undergoing major upgrades, and, for completeness, we bring together all of the most up-to-date results from all pulsars searched for during the operations of the first-generation LIGO, Virgo and GEO600 detectors. This gives a total of 195 pulsars including the most recent results described in this paper.United States National Science FoundationScience and Technology Facilities Council of the United KingdomMax-Planck-SocietyState of Niedersachsen/GermanyAustralian Research CouncilInternational Science Linkages program of the Commonwealth of AustraliaCouncil of Scientific and Industrial Research of IndiaIstituto Nazionale di Fisica Nucleare of ItalySpanish Ministerio de Economia y CompetitividadConselleria d'Economia Hisenda i Innovacio of the Govern de les Illes BalearsNetherlands Organisation for Scientific ResearchPolish Ministry of Science and Higher EducationFOCUS Programme of Foundation for Polish ScienceRoyal SocietyScottish Funding CouncilScottish Universities Physics AllianceNational Aeronautics and Space AdministrationOTKA of HungaryLyon Institute of Origins (LIO)National Research Foundation of KoreaIndustry CanadaProvince of Ontario through the Ministry of Economic Development and InnovationNational Science and Engineering Research Council CanadaCarnegie TrustLeverhulme TrustDavid and Lucile Packard FoundationResearch CorporationAlfred P. Sloan FoundationAstronom

Application of a Hough Search for Continuous Gravitational Waves on Data from the Fifth LIGO Science Run

We report on an all-sky search for periodic gravitational waves in the frequency range 50-1000 Hertz with the first derivative of frequency in the range 8.9 10(exp 10) Hertz per second to zero in two years of data collected during LIGO's fifth science run. Our results employ a Hough transform technique, introducing a chi(sup 2) test and analysis of coincidences between the signal levels in years 1 and 2 of observations that offers a significant improvement in the product of strain sensitivity with compute cycles per data sample compared to previously published searches. Since our search yields no surviving candidates, we present results taking the form of frequency dependent, 95% confidence upper limits on the strain amplitude h(sub 0). The most stringent upper limit from year 1 is 1.0 10(exp 24) in the 158.00-158.25 Hertz band. In year 2, the most stringent upper limit is 8.9 10(exp 25) in the 146.50-146.75 Hertz band. This improved detection pipeline, which is computationally efficient by at least two orders of magnitude better than our flagship Einstein@Home search, will be important for 'quicklook' searches in the Advanced LIGO and Virgo detector era

A First Search for coincident Gravitational Waves and High Energy Neutrinos using LIGO, Virgo and ANTARES data from 2007

We present the results of the first search for gravitational wave bursts associated with high energy neutrinos. Together, these messengers could reveal new, hidden sources that are not observed by conventional photon astronomy, particularly at high energy. Our search uses neutrinos detected by the underwater neutrino telescope ANTARES in its 5 line configuration during the period January - September 2007, which coincided with the fifth and first science runs of LIGO and Virgo, respectively. The LIGO-Virgo data were analysed for candidate gravitational-wave signals coincident in time and direction with the neutrino events. No significant coincident events were observed. We place limits on the density of joint high energy neutrino - gravitational wave emission events in the local universe, and compare them with densities of merger and core-collapse events.Comment: 19 pages, 8 figures, science summary page at http://www.ligo.org/science/Publication-S5LV_ANTARES/index.php. Public access area to figures, tables at https://dcc.ligo.org/cgi-bin/DocDB/ShowDocument?docid=p120000