Bulletin of the American Physical Society
APS April Meeting 2011
Volume 56, Number 4
Saturday–Tuesday, April 30–May 3 2011; Anaheim, California
Session Y11: Gravitational Wave Astronomy |
Hide Abstracts |
Sponsoring Units: DAP GGR Chair: Alan Weinstein, California Institute of Technology Room: Garden 2 |
Tuesday, May 3, 2011 1:30PM - 1:42PM |
Y11.00001: Low-latency Selection of Gravitational-wave Event Candidates for EM Follow-up Observation Amber Stuver Interferometric gravitational wave (GW) detectors have reached the sensitivity and refinement in data analysis to begin to participate in the multi-messenger astronomy community as an event generator. The LIGO and Virgo Collaborations have entered into MOUs with Swift and wide-field optical telescopes and developed an infrastructure to implement low-latency Target-of-Opportunity (ToO) requests in search of optical transients accompanying a candidate GW event. This infrastructure begins with the aggregation of near real-time candidate GW events in a database along with their significance estimation. If sufficiently significant, an automated set of scripts generates a proposed observing plan and vetting experts are notified via email, SMS and control room alerts. These experts then evaluate the observing plan and the performance of the interferometers to decide on the execution of a ToO request. Once a ToO is executed and the images and other post-processing information are collected from the telescopes, image-processing pipelines will seek to reveal candidate optical transients and measure their significance. Presented here is the detailed overview of this infrastructure as refined and executed during a winter 2009-2010 and summer 2010 follow-up run. [Preview Abstract] |
Tuesday, May 3, 2011 1:42PM - 1:54PM |
Y11.00002: The Low-Latency Search for Gravitational Waves from Compact Binary Coalescence Larry Price During the summer of 2010, the first low-latency search for gravitational waves from compact binary coalescences was performed using the LIGO and Virgo instruments. The aim was to provide triggers for follow-up by electromagnetic telescopes. In this presentation we will describe the low-latency pipeline used to produce these triggers, including the time-delay-based procedure used to localize them on the sky. [Preview Abstract] |
Tuesday, May 3, 2011 1:54PM - 2:06PM |
Y11.00003: Gravity Waves Produced by a Fluctuating Stress Tensor during Inflation L.H. Ford, Chun-Hsien Wu, Jen-Tsung Hsiang, Kin-Wang Ng We show that the vacuum fluctuations of the stress tensor of a quantum field can produce tensor perturbations in inflationary models. These are passive fluctuations of gravity driven by the stress tensor, and hence distinct from the mechanism usually considered to produce gravity waves in inflation. Here we analyze the case of a conformally invariant quantum field, such as the electromagnetic field. The perturbations produced during inflation result in a spectrum of fluctuating gravity waves whose magnitude grows with increasing duration of the inflationary period. This primordial spectrum is non-scale invariant, being enhanced at shorter wavelengths, and non-Gaussian in character. The fact that its effects have not yet been observed may be used to place limits upon the duration of the inflationary period. This limit is compatible with adequate inflation to solve the horizon and flatness problems, but raises the possibility that the gravity waves from stress tensor fluctuations during inflation might be observable. [Preview Abstract] |
Tuesday, May 3, 2011 2:06PM - 2:18PM |
Y11.00004: Gravitational Wave Astronomy of Supermassive Black Hole Binaries with Pulsar Timing Arrays Xihao Deng, Lee Samuel Finn Pulsar timing arrays act to detect gravitational waves (GWs) by observing the small, correlated effect the waves have on pulse arrival times at the Earth. We find that pulsar timing observations of GWs are able to determine the sky position and other parameters of supermassive black hole binaries with extreme accuracy, given the high-precision astrometry and timing measurements of a group of millisecond pulsars expected to be provided by the Square Kilometer Array. We also discover that it is possible to use multiple GW sources to refine the distances to nearby pulsars in the array. In particular, one can achieve sub-parsec distance measurements for pulsars within 3 kpc through the observation of several supermassive black hole binaries. [Preview Abstract] |
Tuesday, May 3, 2011 2:18PM - 2:30PM |
Y11.00005: Search for Gravitational Wave Bursts from Six Magnetars Peter Kalmus Soft gamma repeaters (SGRs) and anomalous X-ray pulsars (AXPs) are thought to be magnetars: neutron stars powered by extreme magnetic fields. These rare objects sporadically produce gamma-ray bursts which could be accompanied by gravitational waves (GWs). We present the results of a search for GW bursts from six galactic magnetars that is sensitive to neutron star $f$-modes, thought to be the most efficient GW emitting oscillatory modes in compact stars. One of them, SGR 0501+4516, is likely $\sim1$\,kpc from Earth, an order of magnitude closer than magnetars targeted in previous GW searches. A second, AXP 1E 1547.0$-$5408, gave a burst with an estimated isotropic energy $>10^{44}$ \,erg which is comparable to the giant flares. We find no evidence of GWs associated with a sample of 1279 electromagnetic triggers from six magnetars occurring between November 2006 and June 2009, in GW data from the LIGO, Virgo, and GEO600 detectors. Our lowest model-dependent GW emission energy upper limits for band- and time-limited white noise bursts in the detector sensitive band, and for $f $-mode ringdowns (at 1090\,Hz), are $3.0\times10^{44} d_{1}^2 $\,erg and $1.4\times10^{47} d_{1}^2 $\,erg respectively, where $d_{1} = \frac{d_{\mathrm{0501}}}{1 \mathrm{kpc}}$ and $d_{\mathrm{0501}}$ is the distance to SGR 0501+4516. These limits are an order of magnitude lower than any previous, and approach the range of electromagnetic energies seen in SGR giant flares for the first time. [Preview Abstract] |
Tuesday, May 3, 2011 2:30PM - 2:42PM |
Y11.00006: Electromagnetic emissions from black hole spacetimes Luis Lehner, Travis Garrett, Eric Hirschmann, Steven Liebling, David Neilsen, Patrick Motl, Carlos Palenzuela Many of the expected astrophysical sources of gravitational waves may also be bright in the electromagnetic spectrum. Concurrent detection in both electromagnetic and gravitational bands promises significant gains in our ability to understand such systems. We discuss how black holes inmersed on the external magnetic field from a circumbinary disk produces a collimated e mission in the form of electromagnetic jets. In particular we illustrate the behavior of single and binary black holes and the depedence of jet with spin and black hole motion. [Preview Abstract] |
Tuesday, May 3, 2011 2:42PM - 2:54PM |
Y11.00007: Gamma-ray burst standard sirens: Precision cosmology from gravitational waves Daniel Holz, Samaya Nissanke, Scott Hughes, Neal Dalal, Jonathan Sievers It has long been hypothesized that at least some gamma-ray bursts are associated with the merger of binary neutron stars, or with the merger of a neutron star with a black hole. Recent observations have accumulated compelling evidence supporting this hypothesis, at least for short-hard gamma-ray bursts. These bursts should then be accompanied by a gravitational-wave signal corresponding to the ?nal inspiral of the compact binary. Simultaneous observation of the gravitational and electromagnetic waves from these bursts would allow us to directly and independently determine both luminosity distance and redshift to the binary, thereby providing an absolutely calibrated, high accuracy standard siren (the gravitational wave analog of a standard candle). We examine the cosmological measurements to be expected from observations of gamma-ray burst standard sirens with a ground-based gravitational wave detector network (including LIGO and Virgo, and possible extensions with AIGO and LCGT). We find that these measurements should be able to map the low-redshift Hubble ?ow with excellent accuracy. [Preview Abstract] |
Tuesday, May 3, 2011 2:54PM - 3:06PM |
Y11.00008: Study of AM CVn Population Density using the Palomar Transient Factory David Levitan, Shri Kulkarni, Tom Prince, Samaya Nissanke, Michele Vallisneri Our understanding of compact stellar binaries - especially detached white dwarf binaries (DWDs) and AM CVns - has increased substantially in recent years, in part due to significantly more detections. These systems are sources of gravitational waves and may also be SN Ia progenitors. Several will serve as verification sources for the Laser Interferometer Space Antenna (LISA). However, the population densities of these systems is poorly understood and simulations do not agree with observations. The last few years have also seen the beginning of several synoptic surveys. While not its primary use, synoptic data is a powerful tool for the detection of outbursting stars (such as AM CVns) as well as eclipsing binaries. Our work specifically uses PTF - the Palomar Transient Factory. We report on our recent observations of PTF-discovered AM CVn systems. We consider the implications of these new detections on our understanding of AM CVns and their population density, and the effects these have on LISA detection of ultra-compact binaries. [Preview Abstract] |
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