14,389 research outputs found

    Timing Analysis of Targeted Hunter Searches

    Get PDF
    One can determine all primitive number fields of a given degree and discriminant with a finite search of potential defining polynomials. We develop an asymptotic formula for the number of polynomials which need to be inspected which reflects both archimedean and non-archimedean restrictions placed on the coefficients of a defining polynomial

    Multi-Messenger Gravitational Wave Searches with Pulsar Timing Arrays: Application to 3C66B Using the NANOGrav 11-year Data Set

    Get PDF
    When galaxies merge, the supermassive black holes in their centers may form binaries and, during the process of merger, emit low-frequency gravitational radiation in the process. In this paper we consider the galaxy 3C66B, which was used as the target of the first multi-messenger search for gravitational waves. Due to the observed periodicities present in the photometric and astrometric data of the source of the source, it has been theorized to contain a supermassive black hole binary. Its apparent 1.05-year orbital period would place the gravitational wave emission directly in the pulsar timing band. Since the first pulsar timing array study of 3C66B, revised models of the source have been published, and timing array sensitivities and techniques have improved dramatically. With these advances, we further constrain the chirp mass of the potential supermassive black hole binary in 3C66B to less than (1.65±0.02)×109 M⊙(1.65\pm0.02) \times 10^9~{M_\odot} using data from the NANOGrav 11-year data set. This upper limit provides a factor of 1.6 improvement over previous limits, and a factor of 4.3 over the first search done. Nevertheless, the most recent orbital model for the source is still consistent with our limit from pulsar timing array data. In addition, we are able to quantify the improvement made by the inclusion of source properties gleaned from electromagnetic data to `blind' pulsar timing array searches. With these methods, it is apparent that it is not necessary to obtain exact a priori knowledge of the period of a binary to gain meaningful astrophysical inferences.Comment: 14 pages, 6 figures. Accepted by Ap

    Observations on the ecology and conservation status of Haloragis exalata subsp. exalata (Haloragaceae) in southern New South Wales

    Get PDF
    Haloragis exalata F. Muell. subspecies exalata (family Haloragaceae), a perennial forb, is currently listed as Vulnerable, under both national and New South Wales threatened species conservation legislation. Very few herbarium records existed until recently. Recent discoveries of Haloragis exalata subsp. exalata in new sites on the NSW South Coast and Southern Tablelands prompted us to carry out surveys for the two varieties of the taxon, var. exalata and var. laevis. Our surveys in 2004– 2007 aimed to relocate historical collection sites and target areas of potentially suitable habitat in these areas. Our work has substantially increased the number of known localities for Haloragis exalata subsp. exalata var. exalata. It can be locally abundant. Ecologically it appears to function as a gap species whose populations are almost invariably found at sites where disturbance through temporary inundation, physical disturbance, or fire, has exposed bare earth with higher levels of light at ground level than would be present when the local vegetation community is intact. There are morphological differences between populations in disjunct areas. Haloragis exalata subsp. exalata var. laevis is much more restricted. As a result, the conservation status of Haloragis exalata subsp. exalata may need revision, considering that a) var. exalata is more widespread than previously known, but that b) there is only one known extant population of var. laevis, and that c) the population from Geehi area may be a distinct taxon

    Men Are More Likely than Women to Slow in the Marathon

    Get PDF
    Studies on nonelite distance runners suggest that men are more likely than women to slow their pace in a marathon. Purpose: This study determined the reliability of the sex difference in pacing across many marathons and after adjusting women\u27s performances by 12% to address men\u27s greater maximal oxygen uptake and also incorporating information on racing experience. Methods: Data were acquired from 14 US marathons in 2011 and encompassed 91,929 performances. For 2929 runners, we obtained experience data from a race-aggregating Web site. We operationalized pace maintenance as the percentage change in pace observed in the second half of the marathon relative to the first half. Pace maintenance was analyzed as a continuous variable and as two categorical variables, as follows: maintain the pace, defined as slowing=30%. Results: The mean change in pace was 15.6% and 11.7% for men and women, respectively (P \u3c 0.0001). This sex difference was significant for all 14 marathons. The odds for women were 1.46 (95% confidence interval, 1.41–1.50; P \u3c 0.0001) times higher than men to maintain the pace and 0.36 (95% confidence interval, 0.34–0.38; P \u3c 0.0001) times that of men to exhibit marked slowing. Slower finishing times were associated with greater slowing, especially in men (interaction, P \u3c 0.0001). However, the sex difference in pacing occurred across age and finishing time groups. Making the 12% adjustment to women’s performances lessened the magnitude of the sex difference in pacing but not its occurrence. Although greater experience was associated with less slowing, controlling for the experience variables did not eliminate the sex difference in pacing. Conclusions: The sex difference in pacing is robust. It may reflect sex differences in physiology, decision making, or both

    Mixed Degree Number Field Computations

    Get PDF
    We present a method for computing complete lists of number fields in cases where the Galois group, as an abstract group, appears as a Galois group in smaller degree. We apply this method to find the 25 octic fields with Galois group PSL₂(7) and smallest absolute discriminant. We carry out a number of related computations, including determining the octic field with Galois group 2³:GL₃(2) of smallest absolute discriminant

    Septic Number Fields Which are Ramified Only at One Small Prime

    Get PDF
    AbstractWe find all number fields which can be generated from a degree 7 polynomial satisfying the conditions that only one prime, p, ramifies and p< 11

    Gravitational-wave Constraints on the Equatorial Ellipticity of Millisecond Pulsars

    Get PDF
    We present a search for continuous gravitational waves from five radio pulsars, comprising three recycled pulsars (PSR J0437−4715, PSR J0711−6830, and PSR J0737−3039A) and two young pulsars: the Crab pulsar (J0534+2200) and the Vela pulsar (J0835−4510). We use data from the third observing run of Advanced LIGO and Virgo combined with data from their first and second observing runs. For the first time we are able to match (for PSR J0437−4715) or surpass (for PSR J0711−6830) the indirect limits on gravitational-wave emission from recycled pulsars inferred from their observed spin-downs, and constrain their equatorial ellipticities to be less than 10−8 . For each of the five pulsars, we perform targeted searches that assume a tight coupling between the gravitational-wave and electromagnetic signal phase evolution. We also present constraints on PSR J0711−6830, the Crab pulsar and the Vela pulsar from a search that relaxes this assumption, allowing the gravitational-wave signal to vary from the electromagnetic expectation within a narrow band of frequencies and frequency derivatives
    • …
    corecore