http://www.vallis.org/blogspace My Experimental Blosxom Weblog. en http://www.vallis.org/blogspace/2013/05/17#1305.3881 <p class="story_para"> <b>Authors</b>: Ken D. Olum, Evan Pierce </p> <p class="story_para"> <b>Date</b>: 16 May 2013 </p> <p class="story_para"> <b>Abstract</b>: Core-collapse supernovae emit on the order of 3x10&circ;53 ergs in high-energy neutrinos over a time of order 10 seconds, and so decrease their mass by about 0.2 solar mass. If the explosion is nearly spherically symmetric, there will be little gravitational wave emission. Nevertheless, the sudden decrease of mass of the progenitor may cause a change in the gravitational time delay of signals from a nearby pulsar. We calculate the change in arrival times as successive pulses pass through the neutrino shell at different times, and find that the effect may be detectable in ideal circumstances. </p> <p class="story_para"> <a href="http://www.arxiv.org/abs/1305.3881">abs</a> <a href="http://www.arxiv.org/pdf/1305.3881">pdf</a></p> http://www.vallis.org/blogspace/2013/05/14#1305.2963 <p class="story_para"> <b>Authors</b>: Michalis Agathos, Walter Del Pozzo, Tjonnie G. F. Li, Chris Van Den Broeck, John Veitch, Salvatore Vitale </p> <p class="story_para"> <b>Date</b>: 13 May 2013 </p> <p class="story_para"> <b>Abstract</b>: We present a Bayesian data analysis pipeline for testing GR using gravitational wave signals from coalescing compact binaries, and in particular binary neutron stars. In this study, we investigate its performance when sources with spins are taken into account. </p> <p class="story_para"> <a href="http://www.arxiv.org/abs/1305.2963">abs</a> <a href="http://www.arxiv.org/pdf/1305.2963">pdf</a></p> http://www.vallis.org/blogspace/2013/05/14#1305.2934 <p class="story_para"> <b>Authors</b>: Neil J.Cornish, Joseph D. Romano </p> <p class="story_para"> <b>Date</b>: 13 May 2013 </p> <p class="story_para"> <b>Abstract</b>: We present a unified description of gravitational-wave data analysis that unites the template-based analysis used to detect deterministic signals from well-modeled sources, such as binary-black-hole mergers, with the cross-correlation analysis used to detect stochastic gravitational-wave backgrounds. </p> <p class="story_para"> <a href="http://www.arxiv.org/abs/1305.2934">abs</a> <a href="http://www.arxiv.org/pdf/1305.2934">pdf</a></p> http://www.vallis.org/blogspace/2013/05/09#1305.1789 <p class="story_para"> <b>Authors</b>: Adam Pound </p> <p class="story_para"> <b>Date</b>: 8 May 2013 </p> <p class="story_para"> <b>Abstract</b>: In order to extract physical parameters from the waveform of an extreme-mass-ratio binary, one requires a second-order--accurate description of the motion of the smaller of the two objects in the binary. Using a method of matched asymptotic expansions, I derive the second-order equation of motion of a small, nearly spherical and non-rotating compact object in an arbitrary vacuum spacetime. I find that the motion is geodesic in a certain locally defined effective metric satisfying the vacuum Einstein equation through second order, and I outline a method of numerically calculating this effective metric. </p> <p class="story_para"> <a href="http://www.arxiv.org/abs/1305.1789">abs</a> <a href="http://www.arxiv.org/pdf/1305.1789">pdf</a></p> http://www.vallis.org/blogspace/2013/04/26#1304.6875 <p class="story_para"> <b>Authors</b>: John Antoniadis, Paulo C. C. Freire, Norbert Wex, Thomas M. Tauris, Ryan S. Lynch, Marten H. van Kerkwijk, Michael Kramer, Cees Bassa, Vik S. Dhillon, Thomas Driebe, Jason W. T. Hessels, Victoria M. Kaspi, Vladislav I. Kondratiev, Norbert Langer, Thomas R. Marsh, Maura A. McLaughlin, Timothy T. Pennucci, Scott M. Ransom, Ingrid H. Stairs, Joeri van Leeuwen, Joris P. W. Verbiest, David G. Whelan </p> <p class="story_para"> <b>Date</b>: 25 Apr 2013 </p> <p class="story_para"> <b>Abstract</b>: Many physically motivated extensions to general relativity (GR) predict significant deviations in the properties of spacetime surrounding massive neutron stars. We report the measurement of a 2.01 +/- 0.04 solar mass pulsar in a 2.46-hr orbit with a 0.172 +/- 0.003 solar mass white dwarf. The high pulsar mass and the compact orbit make this system a sensitive laboratory of a previously untested strong-field gravity regime. Thus far, the observed orbital decay agrees with GR, supporting its validity even for the extreme conditions present in the system. The resulting constraints on deviations support the use of GR-based templates for ground-based gravitational wave detectors. Additionally, the system strengthens recent constraints on the properties of dense matter and provides insight to binary stellar astrophysics and pulsar recycling. </p> <p class="story_para"> <a href="http://www.arxiv.org/abs/1304.6875">abs</a> <a href="http://www.arxiv.org/pdf/1304.6875">pdf</a></p> http://www.vallis.org/blogspace/2013/04/26#1304.6780v1 <p class="story_para"> <b>Authors</b>: Lior Shamir (1), John F. Wallin (2), Alice Allen (3), Bruce Berriman (4), Peter Teuben (5), Robert J. Nemiroff (6), Jessica Mink (7), Robert J. Hanisch (8), Kimberly DuPrie (3) ((1) Lawrence Technological University, (2) Middle Tennessee State University, (3) Astrophysics Source Code Library, (4) Infrared Processing and Analysis Center, California Institute of Technology, (5) University of Maryland, (6) Michigan Technological University, (7) Harvard-Smithsonian Center for Astrophysics, (8) Space Telescope Science Institute) </p> <p class="story_para"> <b>Date</b>: 25 Apr 2013 </p> <p class="story_para"> <b>Abstract</b>: While software and algorithms have become increasingly important in astronomy, the majority of authors who publish computational astronomy research do not share the source code they develop, making it difficult to replicate and reuse the work. In this paper we discuss the importance of sharing scientific source code with the entire astrophysics community, and propose that journals require authors to make their code publicly available when a paper is published. That is, we suggest that a paper that involves a computer program not be accepted for publication unless the source code becomes publicly available. The adoption of such a policy by editors, editorial boards, and reviewers will improve the ability to replicate scientific results, and will also make the computational astronomy methods more available to other researchers who wish to apply them to their data. </p> <p class="story_para"> <a href="http://www.arxiv.org/abs/1304.6780v1">abs</a> <a href="http://www.arxiv.org/pdf/1304.6780v1">pdf</a></p> http://www.vallis.org/blogspace/2013/04/26#1304.6725 <p class="story_para"> <b>Authors</b>: Richard Brito, Vitor Cardoso, Paolo Pani </p> <p class="story_para"> <b>Date</b>: 24 Apr 2013 </p> <p class="story_para"> <b>Abstract</b>: Massive bosonic fields of arbitrary spin are predicted by general extensions of the Standard Model. It has been recently shown that there exists a family of bimetric theories of gravity - including massive gravity - which are free of Boulware-Deser ghosts at the nonlinear level. This opens up the possibility to describe consistently the dynamics of massive spin-2 particles in a gravitational field. Within this context, we develop the study of massive spin-2 fluctuations - including massive gravitons - around Schwarzschild and slowly-rotating Kerr black holes. Our work has two important outcomes. First, we show that the Schwarzschild geometry is linearly unstable for small tensor masses, against a spherically symmetric mode. Second, we provide solid evidence that the Kerr geometry is also generically unstable, both against the spherical mode and against long-lived superradiant modes. In the absence of nonlinear effects, the observation of spinning black holes bounds the graviton mass to be smaller than 5x10&circ;{-23} eV. </p> <p class="story_para"> <a href="http://www.arxiv.org/abs/1304.6725">abs</a> <a href="http://www.arxiv.org/pdf/1304.6725">pdf</a></p> http://www.vallis.org/blogspace/2013/04/26#1304.6720 <p class="story_para"> <b>Authors</b>: Rodrigo Fern&amp;#xe1;ndez, Brian D. Metzger </p> <p class="story_para"> <b>Date</b>: 24 Apr 2013 </p> <p class="story_para"> <b>Abstract</b>: Expulsion of neutron-rich matter following the merger of neutron star (NS) binaries is crucial to the radioactively-powered electromagnetic counterparts of these events and to their relevance as sources of r-process nucleosynthesis. Numerical simulations of NS-NS coalescence find, however, a wide range in the quantity of prompt dynamically-ejected mass. Here we explore the long-term (viscous) evolution of remnant black hole accretion disks formed in such mergers by means of two-dimensional, time-dependent hydrodynamical simulations. The evolution of the electron fraction due to charged-current weak interactions is included, and neutrino self-irradiation is modeled as a lightbulb that accounts for the disk geometry and moderate optical depth effects. Over several viscous times (~1s), a fraction ~10% of the initial disk mass is ejected as a moderately neutron-rich wind (Y_e ~ 0.2) powered by viscous heating and nuclear recombination, with neutrino self-irradiation playing a sub-dominant role. Although the properties of the outflow vary in time and direction, their mean values in the heavy-element production region are relatively robust to variations in the initial conditions of the disk and the magnitude of its viscosity. The outflow is sufficiently neutron-rich that most of the ejecta forms heavy r-process elements with mass number A &gt;130, thus representing a new astrophysical source of r-process nucleosynthesis, distinct from that produced in the dynamical ejecta. Due to its moderately high entropy, disk outflows contain a small residual fraction ~1% of helium, which could produce a unique spectroscopic signature. </p> <p class="story_para"> <a href="http://www.arxiv.org/abs/1304.6720">abs</a> <a href="http://www.arxiv.org/pdf/1304.6720">pdf</a></p> http://www.vallis.org/blogspace/2013/04/15#1304.3705 <p class="story_para"> <b>Authors</b>: Jordan Camp, Scott D. Barthelmy, Lindy Blackburn, Kenneth Carpenter, Neil Gehrels, Jonah Kanner, Frank E. Marshall, Judith L. Racusin, Takanori Sakamoto </p> <p class="story_para"> <b>Date</b>: 12 Apr 2013 </p> <p class="story_para"> <b>Abstract</b>: The International Space Station offers a unique platform for rapid and inexpensive deployment of space telescopes. A scientific opportunity of great potential later this decade is the use of telescopes for the electromagnetic follow-up of ground-based gravitational wave detections of neutron star and black hole mergers. We describe this possibility for OpTIIX, an ISS technology demonstration of a 1.5 m diffraction limited optical telescope assembled in space, and ISS-Lobster, a wide-field imaging X-ray telescope now under study as a potential NASA mission. Both telescopes will be mounted on pointing platforms, allowing rapid positioning to the source of a gravitational wave event. Electromagnetic follow-up rates of several per year appear likely, offering a wealth of complementary science on the mergers of black holes and neutron stars. </p> <p class="story_para"> <a href="http://www.arxiv.org/abs/1304.3705">abs</a> <a href="http://www.arxiv.org/pdf/1304.3705">pdf</a></p> http://www.vallis.org/blogspace/2013/04/15#1304.3473 <p class="story_para"> <b>Authors</b>: Nicolas Yunes, Xavier Siemens </p> <p class="story_para"> <b>Date</b>: 11 Apr 2013 </p> <p class="story_para"> <b>Abstract</b>: This review is focused on tests of Einstein's theory of General Relativity with gravitational waves that are detectable by ground-based interferometers and pulsar timing experiments. Einstein's theory has been greatly constrained in the quasi-linear, quasi-stationary regime, where gravity is weak and velocities are small. Gravitational waves will allow us to probe a complimentary, yet previously unexplored regime: the non-linear and dynamical strong-field regime. Such a regime is, for example, applicable to compact binaries coalescing, where characteristic velocities can reach fifty percent the speed of light and compactnesses can reach a half. This review begins with the theoretical basis and the predicted gravitational wave observables of modified gravity theories. The review continues with a brief description of the detectors, including both gravitational wave interferometers and pulsar timing arrays, leading to a discussion of the data analysis formalism that is applicable for such tests. The review ends with a discussion of gravitational wave tests for compact binary systems. </p> <p class="story_para"> <a href="http://www.arxiv.org/abs/1304.3473">abs</a> <a href="http://www.arxiv.org/pdf/1304.3473">pdf</a></p> http://www.vallis.org/blogspace/2013/04/12#1303.2174 <p class="story_para"> <b>Authors</b>: Lindy Blackburn, Michael S. Briggs, Jordan Camp, Nelson Christensen, Valerie Connaughton, Peter Jenke, John Veitch </p> <p class="story_para"> <b>Date</b>: 9 Mar 2013 </p> <p class="story_para"> <b>Abstract</b>: The Advanced LIGO and Advanced Virgo ground-based gravitational-wave detectors are projected to come online 2015-2016, reaching a final sensitivity sufficient to observe dozens of binary neutron star mergers per year by 2018. We present a fully-automated, targeted search strategy for prompt gamma-ray counterparts in offline Fermi-GBM data. The multi-detector method makes use of a detailed model response of the instrument, and benefits from time and sky location information derived from the gravitational-wave signal. </p> <p class="story_para"> <a href="http://www.arxiv.org/abs/1303.2174">abs</a> <a href="http://www.arxiv.org/pdf/1303.2174">pdf</a></p> http://www.vallis.org/blogspace/2013/04/12#1303.2471 <p class="story_para"> <b>Authors</b>: Miroslav Shaltev, Reinhard Prix </p> <p class="story_para"> <b>Date</b>: 11 Mar 2013 </p> <p class="story_para"> <b>Abstract</b>: The search for continuous gravitational waves from unknown isolated sources is computationally limited due to the enormous parameter space that needs to be covered and the weakness of the expected signals. Therefore semi-coherent search strategies have been developed and applied in distributed computing environments such as Einstein@Home, in order to narrow down the parameter space and identify interesting candidates. However, in order to optimally confirm or dismiss a candidate as a possible gravitational-wave signal, a fully-coherent follow-up using all the available data is required. <br />We present a general method and implementation of a direct (2-stage) transition to a fully-coherent follow-up on semi-coherent candidates. This method is based on a grid-less Mesh Adaptive Direct Search (MADS) algorithm using the F-statistic. We demonstrate the detection power and computing cost of this follow-up procedure using extensive Monte-Carlo simulations on (simulated) semi-coherent candidates from a directed as well as from an all-sky search setup. </p> <p class="story_para"> <a href="http://www.arxiv.org/abs/1303.2471">abs</a> <a href="http://www.arxiv.org/pdf/1303.2471">pdf</a></p> http://www.vallis.org/blogspace/2013/04/12#1304.3176 <p class="story_para"> <b>Authors</b>: (1)Larne Pekowsky, (2)Richard O&amp;#x27;Shaughnessy, (1)Jim Healy, (1)Deirdre Shoemaker ((1) Center for Relativistic Astrophysics, Georgia Tech, (2) Center for Gravitation and Cosmology, University of Wisconsin-Milwaukee) </p> <p class="story_para"> <b>Date</b>: 11 Apr 2013 </p> <p class="story_para"> <b>Abstract</b>: Previous analytic and numerical calculations suggest that, at each instant, the emission from a precessing black hole binary closely resembles the emission from a nonprecessing analog. In this paper we quantitatively explore the validity and limitations of that correspondence, extracting the radiation from a large collection of roughly two hundred generic black hole binary merger simulations both in the simulation frame and in a corotating frame that tracks precession. To a first approximation, the corotating-frame waveforms resemble nonprecessing analogs, based on similarity over a band-limited frequency interval defined using a fiducial detector (here, advanced LIGO) and the source's total mass $M$. By restricting attention to masses $M\in 200, 2500 M_\odot$, we insure our comparisons are sensitive only to our simulated late-time inspiral, merger, and ringdown signals. In this mass region, every one of our precessing simulations can be fit by some physically similar member of the \texttt{IMRPhenomB} phenomenological waveform family to better than 95%; most fit significantly better. The best-fit parameters at low and high mass correspond to natural physical limits: the pre-merger orbit and post-merger perturbed black hole. Our results suggest that physically-motivated synthetic signals can be derived by viewing radiation from suitable nonprecessing binaries in a suitable nonintertial reference frame. While a good first approximation, precessing systems have degrees of freedom (i.e., the transverse spins) which a nonprecessing simulation cannot reproduce. We quantify the extent to which these missing degrees of freedom limit the utility of synthetic precessing signals for detection and parameter estimation. </p> <p class="story_para"> <a href="http://www.arxiv.org/abs/1304.3176">abs</a> <a href="http://www.arxiv.org/pdf/1304.3176">pdf</a></p> http://www.vallis.org/blogspace/2013/04/12#1304.3332 <p class="story_para"> <b>Authors</b>: (1)A. Lundgren, (2)R. O&amp;#x27;Shaughnessy ((1) AEI-Hannover, (2) Center for Gravitation and Cosmology, University of Wisconsin-Milwaukee) </p> <p class="story_para"> <b>Date</b>: 11 Apr 2013 </p> <p class="story_para"> <b>Abstract</b>: Current searches for gravitational waves from compact binaries use templates where the binary does not precess. By contrast, generic black hole-neutron star binaries will significantly precess, inducing modulations that nonprecessing searches are particularly ill-suited to recover. In this paper we provide a closed-form representation of the single-spin precessing waveform in the frequency domain by reorganizing the signal as a sum over harmonics, each of which resembles a nonprecessing waveform. This form enables simple analytic calculations (e.g., a Fisher matrix) and computationally fast frequency-domain templates. We have verified that our \texttt{SpinTaylorF2SingleSpin} model is faithful to the time-domain \texttt{SpinTaylorT2} model: for the majority of generic BH-NS binaries, the corresponding signals generated from each model agree to better than 1%. Our waveform model is now available as part of the publicly-available \texttt{lalsimulation} waveform-generation code. </p> <p class="story_para"> <a href="http://www.arxiv.org/abs/1304.3332">abs</a> <a href="http://www.arxiv.org/pdf/1304.3332">pdf</a></p> http://www.vallis.org/blogspace/2013/03/21#1301.5730 <p class="story_para"> <b>Authors</b>: Bhal Chandra Joshi </p> <p class="story_para"> <b>Date</b>: 24 Jan 2013 </p> <p class="story_para"> <b>Abstract</b>: In the last decade, the use of an ensemble of radio pulsars to constrain the characteristic strain caused by a stochastic gravitational wave background has advanced the cause of detection of very low frequency gravitational waves significantly. This electromagnetic means of gravitational wave detection, called Pulsar Timing Array(PTA), is reviewed in this article. The principle of operation of PTA, the current operating PTAs and their status is presented along-with a discussion of the main challenges in the detection of gravitational waves using PTA. </p> <p class="story_para"> <a href="http://www.arxiv.org/abs/1301.5730">abs</a> <a href="http://www.arxiv.org/pdf/1301.5730">pdf</a></p> http://www.vallis.org/blogspace/2013/03/21#1301.5616 <p class="story_para"> <b>Authors</b>: Mark Hannam, Duncan A. Brown, Stephen Fairhurst, Chris L. Fryer, Ian W. Harry </p> <p class="story_para"> <b>Date</b>: 23 Jan 2013 </p> <p class="story_para"> <b>Abstract</b>: Gravitational-wave observations of compact binaries have the potential to uncover the distribution of masses and angular momenta of black holes and neutron stars in the universe. The binary components' physical parameters can be inferred from their effect on the phasing of the gravitational-wave signal, but a partial degeneracy between the components' mass ratio and their angular momenta limits our ability to measure the individual component masses. At the typical signal amplitudes expected by the Advanced Laser Interferometer Gravitational-wave Observatory (signal-to-noise ratios between 10 and 20), we show that it will in many cases be difficult to distinguish whether the components are neutron stars or black holes. We identify when the masses of the binary components could be unambiguously measured outside the range of current observations: a system with a chirp mass $\mathcal{M} \le 0.871 $ M$_\odot$ would unambiguously contain the smallest-mass neutron star observed, and a system with $\mathcal{M} \ge 2.786 \Msun$ must contain a black hole. However, additional information would be needed to distinguish between a binary containing two 1.35 M$_\odot$ neutron stars and an exotic neutron-star--black-hole binary. We also identify those configurations that could be unambiguously identified as black-hole binaries, and show how the observation of an electromagnetic counterpart to a neutron-star--black-hole binary could be used to constrain the black-hole spin. </p> <p class="story_para"> <a href="http://www.arxiv.org/abs/1301.5616">abs</a> <a href="http://www.arxiv.org/pdf/1301.5616">pdf</a></p> http://www.vallis.org/blogspace/2013/03/21#1302.3885 <p class="story_para"> <b>Authors</b>: Daniel J. D&amp;#x27;Orazio, Janna Levin </p> <p class="story_para"> <b>Date</b>: 15 Feb 2013 </p> <p class="story_para"> <b>Abstract</b>: As a black hole and neutron star approach during inspiral, the field lines of a magnetized neutron star eventually thread the black hole event horizon and a short-lived electromagnetic circuit is established. The black hole acts as a battery that provides power to the circuit, thereby lighting up the pair just before merger. Although originally suggested as a promising electromagnetic counterpart to gravitational-wave detection, the luminous signals are promising more generally as potentially detectable phenomena, such as short gamma-ray bursts. To aid in the theoretical understanding, we present analytic solutions for the electromagnetic fields of a magnetic dipole in the presence of an event horizon. In the limit that the neutron star is very close to a Schwarzschild horizon, the Rindler limit, we can solve Maxwell's equations exactly for a magnetic dipole on an arbitrary worldline. We present these solutions here and investigate a proxy for a small segment of the neutron star orbit around a big black hole. We find that the voltage the black hole battery can provide is in the range ~10&circ;16 statvolts with a projected luminosity of 10&circ;42 ergs/s for an M=10M_sun black hole, a neutron star with a B-field of 10&circ;12 G, and an orbital velocity ~0.5c at a distance of 3M from the horizon. Larger black holes provide less power for binary separations at a fixed number of gravitational radii. The black hole/neutron star system therefore has a significant power supply to light up various elements in the circuit possibly powering jets, beamed radiation, or even a hot spot on the neutron star crust. </p> <p class="story_para"> <a href="http://www.arxiv.org/abs/1302.3885">abs</a> <a href="http://www.arxiv.org/pdf/1302.3885">pdf</a></p> http://www.vallis.org/blogspace/2013/03/21#1302.4499 <p class="story_para"> <b>Authors</b>: Kent Yagi, Nicolas Yunes </p> <p class="story_para"> <b>Date</b>: 19 Feb 2013 </p> <p class="story_para"> <b>Abstract</b>: Neutron stars are not only described by their mass and radius, but also by how fast they spin (moment of inertia) and how much they can be deformed (Love number and quadrupole moment). These depend sensitively on the star's internal structure. We find universal relations between the moment of inertia, the Love number and the quadrupole moment that are independent of the equation of state. These relations can be used to learn observationally about neutron star deformations, break degeneracies in gravitational wave observations, and test General Relativity independently of nuclear-structure. </p> <p class="story_para"> <a href="http://www.arxiv.org/abs/1302.4499">abs</a> <a href="http://www.arxiv.org/pdf/1302.4499">pdf</a></p> http://www.vallis.org/blogspace/2013/03/21#1302.6297 <p class="story_para"> <b>Authors</b>: Geoffrey Lovelace, Matthew D. Duez, Francois Foucart, Lawrence E. Kidder, Harald P. Pfeiffer, Mark A. Scheel, Bela Szilagyi </p> <p class="story_para"> <b>Date</b>: 26 Feb 2013 </p> <p class="story_para"> <b>Abstract</b>: Black hole-neutron star (BHNS) binaries are important sources of gravitational waves for second-generation interferometers, and BHNS mergers are also a proposed engine for short, hard gamma-ray bursts. The behavior of both the spacetime (and thus the emitted gravitational waves) and the neutron star matter in a BHNS merger depend strongly and nonlinearly on the black hole's spin. While there is a significant possibility that astrophysical black holes could have spins that are nearly extremal (i.e. near the theoretical maximum), to date fully relativistic simulations of BHNS binaries have included black-hole spins only up to $S/M&circ;2$=0.9, which corresponds to the black hole having approximately half as much rotational energy as possible, given the black hole's mass. In this paper, we present a new simulation of a BHNS binary with a mass ratio $q=3$ and black-hole spin $S/M&circ;2$=0.97, the highest simulated to date. We find that the black hole's large spin leads to the most massive accretion disk and the largest tidal tail outflow of any fully relativistic BHNS simulations to date, even exceeding the results implied by extrapolating results from simulations with lower black-hole spin. The disk appears to be remarkably stable. We also find that the high black-hole spin persists until shortly before the time of merger; afterwards, both merger and accretion spin down the black hole. </p> <p class="story_para"> <a href="http://www.arxiv.org/abs/1302.6297">abs</a> <a href="http://www.arxiv.org/pdf/1302.6297">pdf</a></p> http://www.vallis.org/blogspace/2013/03/21#1302.6049 <p class="story_para"> <b>Authors</b>: R. J. E. Smith, I. Mandel, A. Vecchio </p> <p class="story_para"> <b>Date</b>: 25 Feb 2013 </p> <p class="story_para"> <b>Abstract</b>: The coalescence of a stellar-mass compact object into an intermediate-mass black hole (intermediate mass-ratio coalescence; IMRAC) is an important astrophysical source for ground-based gravitational-wave interferometers in the so-called advanced configuration. However, the ability to carry out effective matched-filter based searches for these systems is limited by the lack of reliable waveforms. Here we consider binaries in which the intermediate-mass black hole has mass in the range 24 - 200 solar masses with a stellar-mass companion having masses in the range 1.4 - 18.5 solar masses. In addition, we constrain the mass ratios, q, of the binaries to be in the range 1/140 &lt; q &lt; 1/10 and we restrict our study to the case of circular binaries with non-spinning components. We investigate the relative contribution to the signal-to-noise ratio (SNR) of the three different phases of the coalescence: inspiral, merger and ringdown. We show that merger and ringdown contribute to a substantial fraction of the total SNR over a large portion of the mass parameter space, although in a limited portion the SNR is dominated by the inspiral phase. We further identify three regions in the IMRAC mass-space in which: (i) inspiral-only searches could be performed with losses in detection rates L in the range 10% &lt; L &lt; 27%, (ii) searches based on inspiral-only templates lead to a loss in detection rates in the range 27% &lt; L &lt; 50%$, and (iii) templates that include merger and ringdown are essential to prevent losses in detection rates greater than 50%. We investigate the effectiveness with which the inspiral-only portion of the IMRAC waveform space is covered by comparing several existing waveform families in this regime. Our results reinforce the importance of extensive numerical relativity simulations of IMRACs and the need for further studies of suitable approximation schemes in this mass range. </p> <p class="story_para"> <a href="http://www.arxiv.org/abs/1302.6049">abs</a> <a href="http://www.arxiv.org/pdf/1302.6049">pdf</a></p>