[en] Binary black holes with total masses between ∼20 and 200 M_o-dot require numerical relativity to describe the detectable signal in ground-based, gravitational-wave detectors. The time-frequency properties of the signals suggest that both modeled, matched filter searches and unmodeled, burst searches can expect to detect high mass binary signals. This paper presents a comparison of a matched filter pipeline and two unmodeled burst pipelines on the inspiral, merger and ring-down phases of compact binary coalescence by evaluating the sensitivity to binaries with total masses between 25 and 100 M_o-dot at a fixed false alarm rate. All three algorithms provided an average range of ∼250 Mpc for a 50,50 M_o-dot binary at 10^-7 Hz false alarm rate.

[en] The nature of dark matter (DM) remains one of the biggest open questions in physics. One intriguing DM candidate, primordial black holes (PBHs), has faced renewed interest following the Laser Interferometer Gravitational-wave Observatory’s (LIGO) detection of gravitational waves from merging stellar mass black holes. While subsequent work has ruled out the possibility that DM could consist solely of black holes similar to those that LIGO has detected with masses above $10M_{\odot <!--\; ???\; -->}$, LIGO’s connection to DM remains unknown. In this work, we consider a distribution of PBHs that accounts for all of the DM, is consistent with all of LIGO’s observations arising from PBH binaries, and resolves tension in previous surveys of microlensing events in the Milky Way halo. The PBH mass distribution that we consider offers an important prediction—LIGO may detect black holes smaller than have ever been observed with ∼1% of the black holes it detects having a mass less than the mass of our Sun and ∼10% with masses in the mass gap. Approximately one year of operating advanced LIGO at design sensitivity should be adequate to begin to see a hint of a primordial black hole mass distribution. Detecting PBH binaries below a solar mass will be readily distinguishable from other known compact binary systems, thereby providing an unambiguous observational window for advanced LIGO to pin down the nature of DM.

[en] The first detections of gravitational waves from binary neutron star mergers with advanced LIGO and Virgo observatories are anticipated in the next five years. These detections could pave the way for multi-messenger gravitational-wave (GW) and electromagnetic (EM) astronomy if GW triggers are successfully followed up with targeted EM observations. However, GW sky localization is relatively poor, with expected localization areas of ∼10-100 deg²; this presents a challenge for following up GW signals from compact binary mergers. Even for wide-field instruments, tens or hundreds of pointings may be required. Prioritizing pointings based on the relative probability of successful imaging is important since it may not be possible to tile the entire gravitational-wave localization region in a timely fashion. Galaxy catalogs were effective at narrowing down regions of the sky to search in initial attempts at joint GW/EM observations. The relatively limited range of initial GW instruments meant that few galaxies were present per pointing and galaxy catalogs were complete within the search volume. The next generation of GW detectors will have a 10-fold increase in range thereby increasing the expected number of galaxies per unit solid angle by a factor of ∼1000. As an additional complication, catalogs will be highly incomplete. Nevertheless, galaxy catalogs can still play an important role in prioritizing pointings for the next era of GW searches. We show how to quantify the advantages of using galaxy catalogs to prioritize wide-field follow-ups as a function of only two parameters: the three-dimensional volume within the field of view of a telescope after accounting for the GW distance measurement uncertainty, and the fraction of the GW sky localization uncertainty region that can be covered with telescope pointings. We find that the use of galaxy catalogs can improve the probability of successful imaging by ∼10% to ∼300% relative to follow-up strategies that do not utilize such catalogs for the scenarios we considered. We determine that catalogs with a 75% completeness perform comparably to complete catalogs in most cases, while 33%-complete catalogs can lead to lower follow-up success rates than complete catalogs for small fields of view, though still providing an advantage over strategies that do not use a catalog at all.

[en] We investigate the application of the singular value decomposition to compact-binary, gravitational-wave data-analysis. We find that the truncated singular value decomposition reduces the number of filters required to analyze a given region of parameter space of compact-binary coalescence waveforms by an order of magnitude with high reconstruction accuracy. We also compute an analytic expression for the expected signal loss due to the singular value decomposition truncation.

[en] Recent advances in the description of compact binary systems have produced gravitational waveforms that include inspiral, merger and ring-down phases. Comparing results from numerical simulations with those of post-Newtonian, and related, expansions has provided motivation for employing post-Newtonian waveforms in near merger epochs when searching for gravitational waves and has encouraged the development of analytic fits to full numerical waveforms. Until searches employ full waveforms as templates, data analysts can still conduct separate inspiral, merger and ring-down searches. Improved knowledge about the end of the inspiral phase, the beginning of the merger and the ring-down frequencies will increase the efficiency of searches over each phase separately without needing the exact waveform. We will show that knowledge of the final spin, of which there are many theoretical models and analytic fits to simulations, may give an insight into the time-frequency properties of the merger. We also present implications on the ability to probe the tidal disruption of neutron stars through gravitational waves.

[en] Low-latency event triggers to signify the presence of gravitational waves from coalescing binaries will be required to make prompt electromagnetic follow-up observations of electromagnetic counterparts. We present the recent progress made on implementing the time-domain low-latency detection algorithm known as summed parallel infinite impulse response (SPIIR) filtering into a real gravitational wave search pipeline.

[en] Gravitational-wave searches for the merger of compact binaries use matched filtering as the method of detecting signals and estimating parameters. Such searches construct a fine mesh of filters covering a signal parameter space at high density. Previously it has been shown that singular-value decomposition can reduce the effective number of filters required to search the data. Here we study how the basis provided by the singular-value decomposition changes dimension as a function of template-bank density. We will demonstrate that it is sufficient to use the basis provided by the singular-value decomposition of a low-density bank to accurately reconstruct arbitrary points within the boundaries of the template bank. Since this technique is purely numerical, it may have applications to interpolating the space of numerical relativity waveforms.

[en] The detection of gravitational waves from compact binaries relies on a computationally burdensome processing of gravitational-wave detector data. The parameter space of compact-binary-coalescence gravitational waves is large and optimal detection strategies often require nearly redundant calculations. Previously, it has been shown that singular value decomposition of search filters removes redundancy. Here we will demonstrate the use of singular value decomposition for a composite detection statistic. This can greatly improve the prospects for a computationally feasible rapid detection scheme across a large compact binary parameter space.

[en] Rapid detection of compact binary coalescence (CBC) with a network of advanced gravitational-wave detectors will offer a unique opportunity for multi-messenger astronomy. Prompt detection alerts for the astronomical community might make it possible to observe the onset of electromagnetic emission from CBC. We demonstrate a computationally practical filtering strategy that could produce early-warning triggers before gravitational radiation from the final merger has arrived at the detectors.

[en] Advanced ground-based gravitational-wave (GW) detectors begin operation imminently. Their intended goal is not only to make the first direct detection of GWs, but also to make inferences about the source systems. Binary neutron-star mergers are among the most promising sources. We investigate the performance of the parameter-estimation (PE) pipeline that will be used during the first observing run of the Advanced Laser Interferometer Gravitational-wave Observatory (aLIGO) in 2015: we concentrate on the ability to reconstruct the source location on the sky, but also consider the ability to measure masses and the distance. Accurate, rapid sky localization is necessary to alert electromagnetic (EM) observatories so that they can perform follow-up searches for counterpart transient events. We consider PE accuracy in the presence of non-stationary, non-Gaussian noise. We find that the character of the noise makes negligible difference to the PE performance at a given signal-to-noise ratio. The source luminosity distance can only be poorly constrained, since the median 90% (50%) credible interval scaled with respect to the true distance is 0.85 (0.38). However, the chirp mass is well measured. Our chirp-mass estimates are subject to systematic error because we used gravitational-waveform templates without component spin to carry out inference on signals with moderate spins, but the total error is typically less than ${10}^{-<!--\; ???\; -->3}{M}_{\odot <!--\; ???\; -->}$. The median 90% (50%) credible region for sky localization is $\sim <!--\; ???\; -->600{\mathrm{d}\mathrm{e}\mathrm{g}}^2$ ($\sim <!--\; ???\; -->150{\mathrm{d}\mathrm{e}\mathrm{g}}^2$), with 3% (30%) of detected events localized within $100{\mathrm{d}\mathrm{e}\mathrm{g}}^2.$ Early aLIGO, with only two detectors, will have a sky-localization accuracy for binary neutron stars of hundreds of square degrees; this makes EM follow-up challenging, but not impossible.