The International Pulsar Timing Array: First data release

International audienceThe highly stable spin of neutron stars can be exploited for a variety of (astro)physical investigations. In particular, arrays of pulsars with rotational periods of the order of milliseconds can be used to detect correlated signals such as those caused by gravitational waves. Three such 'pulsar timing arrays' (PTAs) have been set up around the world over the past decades and collectively form the 'International' PTA (IPTA). In this paper, we describe the first joint analysis of the data from the three regional PTAs, i.e. of the first IPTA data set. We describe the available PTA data, the approach presently followed for its combination and suggest improvements for future PTA research. Particular attention is paid to subtle details (such as underestimation of measurement uncertainty and long-period noise) that have often been ignored but which become important in this unprecedentedly large and inhomogeneous data set. We identify and describe in detail several factors that complicate IPTA research and provide recommendations for future pulsar timing efforts. The first IPTA data release presented here (and available on-line) is used to demonstrate the IPTA's potential of improving upon gravitational-wave limit

All-sky search for long-duration gravitational wave transients with initial LIGO

We present the results of a search for long-duration gravitational wave transients in two sets of data collected by the LIGO Hanford and LIGO Livingston detectors between November 5, 2005 and September 30, 2007, and July 7, 2009 and October 20, 2010, with a total observational time of 283.0 days and 132.9 days, respectively. The search targets gravitational wave transients of duration 10-500 s in a frequency band of 40-1000 Hz, with minimal assumptions about the signal waveform, polarization, source direction, or time of occurrence. All candidate triggers were consistent with the expected background; as a result we set 90% confidence upper limits on the rate of long-duration gravitational wave transients for different types of gravitational wave signals. For signals from black hole accretion disk instabilities, we set upper limits on the source rate density between 3.4×10-5 and 9.4×10-4 Mpc-3 yr-1 at 90% confidence. These are the first results from an all-sky search for unmodeled long-duration transient gravitational waves. © 2016 American Physical Society

All-sky search for long-duration gravitational wave transients with initial LIGO

We present the results of a search for long-duration gravitational wave transients in two sets of data collected by the LIGO Hanford and LIGO Livingston detectors between November 5, 2005 and September 30, 2007, and July 7, 2009 and October 20, 2010, with a total observational time of 283.0 days and 132.9 days, respectively. The search targets gravitational wave transients of duration 10-500 s in a frequency band of 40-1000 Hz, with minimal assumptions about the signal waveform, polarization, source direction, or time of occurrence. All candidate triggers were consistent with the expected background; as a result we set 90% confidence upper limits on the rate of long-duration gravitational wave transients for different types of gravitational wave signals. For signals from black hole accretion disk instabilities, we set upper limits on the source rate density between 3.4×10-5 and 9.4×10-4 Mpc-3 yr-1 at 90% confidence. These are the first results from an all-sky search for unmodeled long-duration transient gravitational waves. © 2016 American Physical Society

Constraints on cosmic strings using data from the first Advanced LIGO observing run

Cosmic strings are topological defects which can be formed in grand unified theory scale phase transitions in the early universe. They are also predicted to form in the context of string theory. The main mechanism for a network of Nambu-Goto cosmic strings to lose energy is through the production of loops and the subsequent emission of gravitational waves, thus offering an experimental signature for the existence of cosmic strings. Here we report on the analysis conducted to specifically search for gravitational-wave bursts from cosmic string loops in the data of Advanced LIGO 2015-2016 observing run (O1). No evidence of such signals was found in the data, and as a result we set upper limits on the cosmic string parameters for three recent loop distribution models. In this paper, we initially derive constraints on the string tension Gμ and the intercommutation probability, using not only the burst analysis performed on the O1 data set but also results from the previously published LIGO stochastic O1 analysis, pulsar timing arrays, cosmic microwave background and big-bang nucleosynthesis experiments. We show that these data sets are complementary in that they probe gravitational waves produced by cosmic string loops during very different epochs. Finally, we show that the data sets exclude large parts of the parameter space of the three loop distribution models we consider

THE RATE OF BINARY BLACK HOLE MERGERS INFERRED FROM ADVANCED LIGO OBSERVATIONS SURROUNDING GW150914

A transient gravitational-wave signal, GW150914, was identi fi ed in the twin Advanced LIGO detectors on 2015 September 2015 at 09:50:45 UTC. To asse ss the implications of this discovery, the detectors remained in operation with unchanged con fi gurations over a period of 39 days around the time of t he signal. At the detection statistic threshold corresponding to that observed for GW150914, our search of the 16 days of simultaneous two-detector observational data is estimated to have a false-alarm rate ( FAR ) of < ́ -- 4.9 10 yr 61 , yielding a p -value for GW150914 of < ́ - 210 7 . Parameter estimation follo w-up on this trigger identi fi es its source as a binary black hole ( BBH ) merger with component masses ( )( ) = - + - + mm M ,36,29 12 4 5 4 4 at redshift = - + z 0.09 0.04 0.03 ( median and 90% credible range ) . Here, we report on the constraints these observations place on the rate of BBH coalescences. Considering only GW150914, assuming that all BBHs in the universe have the same masses and spins as this event, imposing a search FAR threshold of 1 per 100 years, and assuming that the BBH merger rate is constant in the comoving frame, we infer a 90% credible range of merger rates between – -- 2 53 Gpc yr 31 ( comoving frame ) . Incorporating all search triggers that pass a much lower threshold while accounting for the uncerta inty in the astrophysical origin of each trigger, we estimate a higher rate, ranging from – -- 13 600 Gpc yr 31 depending on assumptions about the BBH mass distribution. All together, our various rate estimat es fall in the conservative range – -- 2 600 Gpc yr 31

Research on stable, high-efficiency, large-area amorphous silicon based modules -- Task B

This report documents progress in developing a stable, high- efficiency, four-terminal hybrid tandem module. The module consists of a semi-transparent, thin-film silicon:hydrogen alloy (TFS) top circuit and a copper indium diselenide (CuInSe{sub 2}) bottom circuit. Film deposition and patterning processes were successfully extended to 0.4-m{sup 2} substrates. A 33.2-W (8.4% efficient) module with a 3970-cm{sup 2} aperture area and a white back reflector was demonstrated; without the back reflector, the module produced 30.2 W (7.6% efficient). Placing a laminated, 31.6-W, 8.1%-efficient CuInSe{sub 2} module underneath this TFS module, with an air gap between the two, produces 11.2 W (2.9% efficient) over a 3883-cm{sup 2} aperture area. Therefore, the four-terminal tandem power output is 41.4 W, translating to a 10.5% aperture-area efficiency. Subsequently, a 37.8-W (9.7% aperture-area efficiency) CuInSe{sub 2} module was demonstrated with a 3905-cm{sup 2} aperture area. Future performances of single-junction and tandem modules of this size were modeled, and predicted power outputs exceed 50 W (13% efficient) for CuInSe{sub 2} and 65 W (17% efficient) for TFS/CuInSe{sub 2} tandem modules

Progression from high-grade prostatic intraepithelial neoplasia to cancer: a randomized trial of combination vitamin-E, soy, and selenium

Item does not contain fulltextPURPOSE: High-grade prostatic intraepithelial neoplasia (HGPIN) is a putative precursor of invasive prostate cancer (PCa). Preclinical evidence suggests vitamin E, selenium, and soy protein may prevent progression of HGPIN to PCa. This hypothesis was tested in a randomized phase III double-blind study of daily soy (40 g), vitamin E (800 U), and selenium (200 mug) versus placebo. PATIENTS AND METHODS: Three hundred three men in 12 Canadian centers were analyzed. The main eligibility criterion was confirmed HGPIN in at least one of two biopsies within 18 months of random assignment. Treatment was administered daily for 3 years. Follow-up prostate biopsies occurred at 6, 12, 24, and 36 months postrandomization. The primary end point was time to development of invasive PCa. Kaplan-Meier plots and log-rank tests were used to compare two treatment groups for this end point. RESULTS: For all patients, the median age was 62.8 years. The median baseline prostate-specific antigen (PSA; n = 302) was 5.41 ug/L; total testosterone (n = 291) was 13.4 nmol/L. Invasive PCa developed among 26.4% of patients. The hazard ratio for the nutritional supplement to prevent PCa was 1.03 (95% CI, 0.67 to 1.60; P = .88). Gleason score distribution was similar in both groups with 83.5% of cancers graded Gleason sum of 6. Baseline age, weight, PSA, and testosterone did not predict for development of PCa. The supplement was well tolerated with flatulence reported more frequently (27% v 17%) among men receiving micronutrients. CONCLUSION: This trial does not support the hypothesis that combination vitamin E, selenium, and soy prevents progression from HGPIN to PCa