488 research outputs found

    Fast response electromagnetic follow-ups from low latency GW triggers

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    © Published under licence by IOP Publishing Ltd. We investigate joint low-latency gravitational wave (GW) detection and prompt electromagnetic (EM) follow-up observations of coalescing binary neutron stars (BNSs). Assuming that BNS mergers are associated with short duration gamma ray bursts (SGRBs), we evaluate if rapid EM follow-ups can capture the prompt emission, early engine activity or reveal any potential by-products such as magnetars or fast radio bursts. To examine the expected performance of extreme low-latency search pipelines, we simulate a population of coalescing BNSs and use these to estimate the detectability and localisation efficiency at different times before merger. Using observational SGRB flux data corrected to the range of the advanced GW interferometric detectors, we determine what EM observations could be achieved from low-frequency radio up to high energy ?-ray. We show that while challenging, breakthrough multi-messenger science is possible through low latency pipelines

    Older women, breast cancer, and social support

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    One in ten women over the age of 65 will develop breast cancer. Despite this high incidence of breast cancer among older women, social support for them is often inadequate. This paper describes a qualitative study of the impact of a breast cancer diagnosis on older women from racially/ethnically diverse populations and their subsequent need for social support. Forty-seven older African American, Asian American, Caucasian and Latina women between the ages of 65 to 83 participated in a larger study examining the impact of breast cancer on women from racially/ethnically diverse populations and the meaning and nature of social support. The women completed an in-depth qualitative interview on the psychosocial impact of breast cancer and the meaning and nature of social support. The results indicate that there are variations in reactions to a breast cancer diagnosis among older women, and that these reactions impact their experiences with seeking social support at diagnosis and during treatment. Respondents were concerned about their aging bodies, potential dependency on others, and loss of autonomy. At the same time, the severity of cancer treatment and existing co-morbidities often meant they needed to learn to receive support, and to reach out if they had no support. The implications of these findings underscore the older cancer patient’s need to strengthen her supportive networks at the time of diagnosis, during treatment, and post-treatment

    Al Qaeda at the bar: coordinating ideologues and mercenaries in terrorist organizations

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    Most terrorist groups have limited lifespans. A number of scholars and casual observers have noted that terrorist organizations often are comprised of two types of participants: ideologues or "true believers" dedicated to the group's cause, and mercenaries, who are adept at raising money through illegal means. The latter are interested primarily in their personal gains and have relatively little ideological commitment. Terrorist groups need both participants in order to function effectively. The purpose of the study is to understand the impact of communication on the compositions of terrorist groups. Three experimental treatments consider a coordination problem, and focus on the behavior of the mercenaries. Participants choose whether or not to participate in a terrorist attack. Payoffs are U-shaped in the number of participants, and increase with the number of successful attacks. The treatments allow communication between a leader and frontline fighters ("leader" treatment) or among the frontline fighters themselves ("communication" treatment). In the first treatment, a group leader can post messages to the members, which has a 19 % coordination success rate. For the communication treatment, all participants can post messages anonymously to each other, which yields a 27 % coordination success rate. By contrast, the baseline ("no communication" treatment) shows a success rate of 11 %. We conclude from our experimental evidence that disrupting communications among the frontline fighters is more effective in terminating terrorist organizations

    Fermi Gamma-ray Imaging of a Radio Galaxy

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    The Fermi Gamma-ray Space Telescope has detected the gamma-ray glow emanating from the giant radio lobes of the radio galaxy Centaurus A. The resolved gamma-ray image shows the lobes clearly separated from the central active source. In contrast to all other active galaxies detected so far in high-energy gamma-rays, the lobe flux constitutes a considerable portion (>1/2) of the total source emission. The gamma-ray emission from the lobes is interpreted as inverse Compton scattered relic radiation from the cosmic microwave background (CMB), with additional contribution at higher energies from the infrared-to-optical extragalactic background light (EBL). These measurements provide gamma-ray constraints on the magnetic field and particle energy content in radio galaxy lobes, and a promising method to probe the cosmic relic photon fields.Comment: 27 pages, includes Supplementary Online Material; corresponding authors: C.C. Cheung, Y. Fukazawa, J. Knodlseder, L. Stawar

    Detection of Gamma-Ray Emission from the Starburst Galaxies M82 and NGC 253 with the Large Area Telescope on Fermi

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    We report the detection of high-energy gamma-ray emission from two starburst galaxies using data obtained with the Large Area Telescope on board the Fermi Gamma-ray Space Telescope. Steady point-like emission above 200 MeV has been detected at significance levels of 6.8 sigma and 4.8 sigma respectively, from sources positionally coincident with locations of the starburst galaxies M82 and NGC 253. The total fluxes of the sources are consistent with gamma-ray emission originating from the interaction of cosmic rays with local interstellar gas and radiation fields and constitute evidence for a link between massive star formation and gamma-ray emission in star-forming galaxies.Comment: Submitted to ApJ Letter

    X-ray emission from the Sombrero galaxy: discrete sources

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    We present a study of discrete X-ray sources in and around the bulge-dominated, massive Sa galaxy, Sombrero (M104), based on new and archival Chandra observations with a total exposure of ~200 ks. With a detection limit of L_X = 1E37 erg/s and a field of view covering a galactocentric radius of ~30 kpc (11.5 arcminute), 383 sources are detected. Cross-correlation with Spitler et al.'s catalogue of Sombrero globular clusters (GCs) identified from HST/ACS observations reveals 41 X-rays sources in GCs, presumably low-mass X-ray binaries (LMXBs). We quantify the differential luminosity functions (LFs) for both the detected GC and field LMXBs, whose power-low indices (~1.1 for the GC-LF and ~1.6 for field-LF) are consistent with previous studies for elliptical galaxies. With precise sky positions of the GCs without a detected X-ray source, we further quantify, through a fluctuation analysis, the GC LF at fainter luminosities down to 1E35 erg/s. The derived index rules out a faint-end slope flatter than 1.1 at a 2 sigma significance, contrary to recent findings in several elliptical galaxies and the bulge of M31. On the other hand, the 2-6 keV unresolved emission places a tight constraint on the field LF, implying a flattened index of ~1.0 below 1E37 erg/s. We also detect 101 sources in the halo of Sombrero. The presence of these sources cannot be interpreted as galactic LMXBs whose spatial distribution empirically follows the starlight. Their number is also higher than the expected number of cosmic AGNs (52+/-11 [1 sigma]) whose surface density is constrained by deep X-ray surveys. We suggest that either the cosmic X-ray background is unusually high in the direction of Sombrero, or a distinct population of X-ray sources is present in the halo of Sombrero.Comment: 11 figures, 5 tables, ApJ in pres

    Fermi Large Area Telescope observations of PSR J1836+5925

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    The discovery of the gamma-ray pulsar PSR J1836+5925, powering the formerly unidentified EGRET source 3EG J1835+5918, was one of the early accomplishments of the Fermi Large Area Telescope (LAT). Sitting 25 degrees off the Galactic plane, PSR J1836+5925 is a 173 ms pulsar with a characteristic age of 1.8 million years, a spindown luminosity of 1.1×1034\times10^{34} erg s1^{-1}, and a large off-peak emission component, making it quite unusual among the known gamma-ray pulsar population. We present an analysis of one year of LAT data, including an updated timing solution, detailed spectral results and a long-term light curve showing no indication of variability. No evidence for a surrounding pulsar wind nebula is seen and the spectral characteristics of the off-peak emission indicate it is likely magnetospheric. Analysis of recent XMM observations of the X-ray counterpart yields a detailed characterization of its spectrum, which, like Geminga, is consistent with that of a neutron star showing evidence for both magnetospheric and thermal emission.Comment: Accepted to Astrophysical Journa

    Measurement of D-s(+) and D-s(*+) production in B meson decays and from continuum e(+)e(-) annihilation at √s=10.6 GeV

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    This is the pre-print version of the Article. The official published version can be accessed from the links below. Copyright @ 2002 APSNew measurements of Ds+ and Ds*+ meson production rates from B decays and from qq̅ continuum events near the Υ(4S) resonance are presented. Using 20.8 fb-1 of data on the Υ(4S) resonance and 2.6 fb-1 off-resonance, we find the inclusive branching fractions B(B⃗Ds+X)=(10.93±0.19±0.58±2.73)% and B(B⃗Ds*+X)=(7.9±0.8±0.7±2.0)%, where the first error is statistical, the second is systematic, and the third is due to the Ds+→φπ+ branching fraction uncertainty. The production cross sections σ(e+e-→Ds+X)×B(Ds+→φπ+)=7.55±0.20±0.34pb and σ(e+e-→Ds*±X)×B(Ds+→φπ+)=5.8±0.7±0.5pb are measured at center-of-mass energies about 40 MeV below the Υ(4S) mass. The branching fractions ΣB(B⃗Ds(*)+D(*))=(5.07±0.14±0.30±1.27)% and ΣB(B⃗Ds*+D(*))=(4.1±0.2±0.4±1.0)% are determined from the Ds(*)+ momentum spectra. The mass difference m(Ds+)-m(D+)=98.4±0.1±0.3MeV/c2 is also measured.This work was supported by DOE and NSF (USA), NSERC (Canada), IHEP (China), CEA and CNRS-IN2P3 (France), BMBF (Germany), INFN (Italy), NFR (Norway), MIST (Russia), and PPARC (United Kingdom). Individuals have received support from the Swiss NSF, A. P. Sloan Foundation, Research Corporation, and Alexander von Humboldt Foundation

    Measurement of the branching fraction and CP content for the decay B(0) -> D(*+)D(*-)