C. Messenger

Friedrich Schiller University Jena, Jena, Thuringia, Germany

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Publications (180)655.13 Total impact

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    ABSTRACT: The low-mass X-ray binary Scorpius X-1 (Sco X-1) is potentially the most luminous source of continuous gravitational-wave radiation for interferometers such as LIGO and Virgo. For low-mass X-ray binaries this radiation would be sustained by active accretion of matter from its binary companion. With the Advanced Detector Era fast approaching, work is underway to develop an array of robust tools for maximizing the science and detection potential of Sco X-1. We describe the plans and progress of a project designed to compare the numerous independent search algorithms currently available. We employ a mock-data challenge in which the search pipelines are tested for their relative proficiencies in parameter estimation, computational efficiency, robust- ness, and most importantly, search sensitivity. The mock-data challenge data contains an ensemble of 50 Scorpius X-1 (Sco X-1) type signals, simulated within a frequency band of 50-1500 Hz. Simulated detector noise was generated assuming the expected best strain sensitivity of Advanced LIGO and Advanced VIRGO ($4 \times 10^{-24}$ Hz$^{-1/2}$). A distribution of signal amplitudes was then chosen so as to allow a useful comparison of search methodologies. A factor of 2 in strain separates the quietest detected signal, at $6.8 \times 10^{-26}$ strain, from the torque-balance limit at a spin frequency of 300 Hz, although this limit could range from $1.2 \times 10^{-25}$ (25 Hz) to $2.2 \times 10^{-26}$ (750 Hz) depending on the unknown frequency of Sco X-1. With future improvements to the search algorithms and using advanced detector data, our expectations for probing below the theoretical torque-balance strain limit are optimistic.
    Physical Review D 04/2015; 92(2). DOI:10.1103/PhysRevD.92.023006 · 4.86 Impact Factor
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    ABSTRACT: The Advanced LIGO gravitational wave detectors are second-generation instruments designed and built for the two LIGO observatories in Hanford, WA and Livingston, LA, USA. The two instruments are identical in design, and are specialized versions of a Michelson interferometer with 4 km long arms. As in Initial LIGO, Fabry–Perot cavities are used in the arms to increase the interaction time with a gravitational wave, and power recycling is used to increase the effective laser power. Signal recycling has been added in Advanced LIGO to improve the frequency response. In the most sensitive frequency region around 100 Hz, the design strain sensitivity is a factor of 10 better than Initial LIGO. In addition, the low frequency end of the sensitivity band is moved from 40 Hz down to 10 Hz. All interferometer components have been replaced with improved technologies to achieve this sensitivity gain. Much better seismic isolation and test mass suspensions are responsible for the gains at lower frequencies. Higher laser power, larger test masses and improved mirror coatings lead to the improved sensitivity at mid and high frequencies. Data collecting runs with these new instruments are planned to begin in mid-2015.
    Classical and Quantum Gravity 04/2015; 32(7). DOI:10.1088/0264-9381/32/7/074001 · 3.10 Impact Factor
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    ABSTRACT: We describe directed searches for continuous gravitational waves in data from the sixth LIGO science data run. The targets were nine young supernova remnants not associated with pulsars; eight of the remnants are associated with non-pulsing suspected neutron stars. One target's parameters are uncertain enough to warrant two searches, for a total of ten. Each search covered a broad band of frequencies and first and second frequency derivatives for a fixed sky direction. The searches coherently integrated data from the two LIGO interferometers over time spans from 5.3-25.3 days using the matched-filtering F-statistic. We found no credible gravitational-wave signals. We set 95% confidence upper limits as strong (low) as $4\times10^{-25}$ on intrinsic strain, $2\times10^{-7}$ on fiducial ellipticity, and $4\times10^{-5}$ on r-mode amplitude. These beat the indirect limits from energy conservation and are within the range of theoretical predictions for neutron-star ellipticities and r-mode amplitudes.
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    ABSTRACT: We present results of a search for continuously-emitted gravitational radiation, directed at the brightest low-mass X-ray binary, Scorpius X-1. Our semi-coherent analysis covers 10 days of LIGO S5 data ranging from 50-550 Hz, and performs an incoherent sum of coherent $\mathcal{F}$-statistic power distributed amongst frequency-modulated orbital sidebands. All candidates not removed at the veto stage were found to be consistent with noise at a 1% false alarm rate. We present Bayesian 95% confidence upper limits on gravitational-wave strain amplitude using two different prior distributions: a standard one, with no a priori assumptions about the orientation of Scorpius X-1; and an angle-restricted one, using a prior derived from electromagnetic observations. Median strain upper limits of 1.3e-24 and 8e-25 are reported at 150 Hz for the standard and angle-restricted searches respectively. This proof of principle analysis was limited to a short observation time by unknown effects of accretion on the intrinsic spin frequency of the neutron star, but improves upon previous upper limits by factors of ~1.4 for the standard, and 2.3 for the angle-restricted search at the sensitive region of the detector.
    Physical Review D 12/2014; 91(6). DOI:10.1103/PhysRevD.91.062008 · 4.86 Impact Factor
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    ABSTRACT: We report the results of a multimessenger search for coincident signals from the LIGO and Virgo gravitational-wave observatories and the partially completed IceCube high-energy neutrino detector, including periods of joint operation between 2007-2010. These include parts of the 2005-2007 run and the 2009-2010 run for LIGO-Virgo, and IceCube's observation periods with 22, 59 and 79 strings. We find no significant coincident events, and use the search results to derive upper limits on the rate of joint sources for a range of source emission parameters. For the optimistic assumption of gravitational-wave emission energy of $10^{-2}$ M$_\odot$c$^2$ at $\sim 150$ Hz with $\sim 60$ ms duration, and high-energy neutrino emission of $10^{51}$ erg comparable to the isotropic gamma-ray energy of gamma-ray bursts, we limit the source rate below $1.6 \times 10^{-2}$ Mpc$^{-3}$yr$^{-1}$. We also examine how combining information from gravitational waves and neutrinos will aid discovery in the advanced gravitational-wave detector era.
    Physical Review D 11/2014; 90:102002. DOI:10.1103/PhysRevD.90.102002 · 4.86 Impact Factor
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    ABSTRACT: In this paper we present the results of a coherent narrow-band search for continuous gravitational-wave signals from the Crab and Vela pulsars conducted on Virgo VSR4 data. In order to take into account a possible small mismatch between the gravitational wave frequency and two times the star rotation frequency, inferred from measurement of the electromagnetic pulse rate, a range of 0.02 Hz around two times the star rotational frequency has been searched for both the pulsars. No evidence for a signal has been found and 95$\%$ confidence level upper limits have been computed both assuming polarization parameters are completely unknown and that they are known with some uncertainty, as derived from X-ray observations of the pulsar wind torii. For Vela the upper limits are comparable to the spin-down limit, computed assuming that all the observed spin-down is due to the emission of gravitational waves. For Crab the upper limits are about a factor of two below the spin-down limit, and represent a significant improvement with respect to past analysis. This is the first time the spin-down limit is significantly overcome in a narrow-band search.
    Physical Review D 10/2014; 91(2). DOI:10.1103/PhysRevD.91.022004 · 4.86 Impact Factor
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    ABSTRACT: In 2009-2010, the Laser Interferometer Gravitational-wave Observa- tory (LIGO) operated together with international partners Virgo and GEO600 as a network to search for gravitational waves of astrophysical origin. The sensitiv- ity of these detectors was limited by a combination of noise sources inherent to the instrumental design and its environment, often localized in time or frequency, that couple into the gravitational-wave readout. Here we review the performance of the LIGO instruments during this epoch, the work done to characterize the de- tectors and their data, and the effect that transient and continuous noise artefacts have on the sensitivity of LIGO to a variety of astrophysical sources.
    Classical and Quantum Gravity 10/2014; 32(11). DOI:10.1088/0264-9381/32/11/115012 · 3.10 Impact Factor
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    ABSTRACT: Searches for a stochastic gravitational-wave background (SGWB) using terrestrial detectors typically involve cross-correlating data from pairs of detectors. The sensitivity of such cross-correlation analyses depends, among other things, on the separation between the two detectors: the smaller the separation, the better the sensitivity. Hence, a co-located detector pair is more sensitive to a gravitational-wave background than a non-co-located detector pair. However, co-located detectors are also expected to suffer from correlated noise from instrumental and environmental effects that could contaminate the measurement of the background. Hence, methods to identify and mitigate the effects of correlated noise are necessary to achieve the potential increase in sensitivity of co-located detectors. Here we report on the first SGWB analysis using the two LIGO Hanford detectors and address the complications arising from correlated environmental noise. We apply correlated noise identification and mitigation techniques to data taken by the two LIGO Hanford detectors, H1 and H2, during LIGO's fifth science run. At low frequencies, 40 - 460 Hz, we are unable to sufficiently mitigate the correlated noise to a level where we may confidently measure or bound the stochastic gravitational-wave signal. However, at high frequencies, 460-1000 Hz, these techniques are sufficient to set a $95\%$ confidence level (C.L.) upper limit on the gravitational-wave energy density of \Omega(f)<7.7 x 10^{-4} (f/ 900 Hz)^3, which improves on the previous upper limit by a factor of $\sim 180$. In doing so, we demonstrate techniques that will be useful for future searches using advanced detectors, where correlated noise (e.g., from global magnetic fields) may affect even widely separated detectors.
    Physical Review D 10/2014; 91(2). DOI:10.1103/PhysRevD.91.022003 · 4.86 Impact Factor
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    ABSTRACT: Waveguide mirrors possess nano-structured surfaces which can potentially provide a significant reduction in thermal noise over conventional dielectric mirrors. To avoid introducing additional phase noise from motion of the mirror transverse to the reflected light, however, they must possess a mechanism to suppress the phase effects associated with the incident light translating across the nano-structured surface. It has been shown that with carefully chosen parameters this additional phase noise can be suppressed. We present an experimental measurement of the coupling of transverse to longitudinal displacements in such a waveguide mirror designed for 1064 nm light. We bound the level of measured transverse to longitudinal motion between one part in fifty two thousand five hundred and one part in eight thousand seven hundred with 95% confidence, representing a significant improvement over a previously measured grating mirror.
    Classical and Quantum Gravity 10/2014; 32(17). DOI:10.1088/0264-9381/32/17/175005 · 3.10 Impact Factor
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    ABSTRACT: We summarise the parallel session C7 Multi-Messenger Astronomy of GW Sources in the GR20 Amaldi 10 Conference. The talks in this session covered a wide range of topics in multi-messenger astronomy.
    General Relativity and Gravitation 09/2014; 46(9). DOI:10.1007/s10714-014-1771-6 · 1.73 Impact Factor
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    ABSTRACT: We present the results of a search for gravitational waves associated with 223 gamma-ray bursts (GRBs) detected by the InterPlanetary Network (IPN) in 2005-2010 during LIGO's fifth and sixth science runs and Virgo's first, second and third science runs. The IPN satellites provide accurate times of the bursts and sky localizations that vary significantly from degree scale to hundreds of square degrees. We search for both a well-modeled binary coalescence signal, the favored progenitor model for short GRBs, and for generic, unmodeled gravitational wave bursts. Both searches use the event time and sky localization to improve the gravitational-wave search sensitivity as compared to corresponding all-time, all-sky searches. We find no evidence of a gravitational-wave signal associated with any of the IPN GRBs in the sample, nor do we find evidence for a population of weak gravitational-wave signals associated with the GRBs. For all IPN-detected GRBs, for which a sufficient duration of quality gravitational-wave data is available, we place lower bounds on the distance to the source in accordance with an optimistic assumption of gravitational-wave emission energy of $10^{-2}M_{\odot}c^2$ at 150 Hz, and find a median of 13 Mpc. For the 27 short-hard GRBs we place 90% confidence exclusion distances to two source models: a binary neutron star coalescence, with a median distance of 12Mpc, or the coalescence of a neutron star and black hole, with a median distance of 22 Mpc. Finally, we combine this search with previously published results to provide a population statement for GRB searches in first-generation LIGO and Virgo gravitational-wave detectors, and a resulting examination of prospects for the advanced gravitational-wave detectors.
    Physical Review Letters 06/2014; 113(1):011102. DOI:10.1103/PhysRevLett.113.011102 · 7.51 Impact Factor
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    ABSTRACT: Gravitational waves from a variety of sources are predicted to superpose to create a stochastic background. This background is expected to contain unique information from throughout the history of the universe that is unavailable through standard electromagnetic observations, making its study of fundamental importance to understanding the evolution of the universe. We carry out a search for the stochastic background with the latest data from LIGO and Virgo. Consistent with predictions from most stochastic gravitational-wave background models, the data display no evidence of a stochastic gravitational-wave signal. Assuming a gravitational-wave spectrum of Omega_GW(f)=Omega_alpha*(f/f_ref)^alpha, we place 95% confidence level upper limits on the energy density of the background in each of four frequency bands spanning 41.5-1726 Hz. In the frequency band of 41.5-169.25 Hz for a spectral index of alpha=0, we constrain the energy density of the stochastic background to be Omega_GW(f)<5.6x10^-6. For the 600-1000 Hz band, Omega_GW(f)<0.14*(f/900 Hz)^3, a factor of 2.5 lower than the best previously reported upper limits. We find Omega_GW(f)<1.8x10^-4 using a spectral index of zero for 170-600 Hz and Omega_GW(f)<1.0*(f/1300 Hz)^3 for 1000-1726 Hz, bands in which no previous direct limits have been placed. The limits in these four bands are the lowest direct measurements to date on the stochastic background. We discuss the implications of these results in light of the recent claim by the BICEP2 experiment of the detection of inflationary gravitational waves.
    Physical Review Letters 06/2014; 113(23). DOI:10.1103/PhysRevLett.113.231101 · 7.51 Impact Factor
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    Xilong Fan · Christopher Messenger · Ik Siong Heng
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    ABSTRACT: Joint gravitational wave (GW) and electromagnetic (EM) observations, as a key research direction in multi-messenger astronomy, will provide deep insight into the astrophysics of a vast range of astronomical phenomena. Uncertainties in the source sky location estimate from gravitational wave observations mean follow-up observatories must scan large portions of the sky for a potential companion signal. A general frame of joint GW-EM observations is presented by a multi-messenger observational triangle. Using a Bayesian approach to multi-messenger astronomy, we investigate the use of galaxy catalogue and host galaxy information to reduce the sky region over which follow-up observatories must scan, as well as study its use for improving the inclination angle estimates for coalescing binary compact objects. We demonstrate our method using a simulated neutron stars inspiral signal injected into simulated Advanced detectors noise and estimate the injected signal sky location and inclination angle using the Gravitational Wave Galaxy Catalogue. In this case study, the top three candidates in rank have $72\%$, $15\%$ and $8\%$ posterior probability of being the host galaxy, receptively. The standard deviation of cosine inclination angle (0.001) of the neutron stars binary using gravitational wave-galaxy information is much smaller than that (0.02) using only gravitational wave posterior samples.
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    XiLong Fan · Christopher Messenger · Ik Siong Heng
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    ABSTRACT: We present a general framework for incorporating astrophysical information into Bayesian parameter estimation techniques used by gravitational wave data analysis to facilitate multi-messenger astronomy. Since the progenitors of transient gravitational wave events, such as compact binary coalescences, are likely to be associated with a host galaxy, improvements to the source sky location estimates through the use of host galaxy information are explored. To demonstrate how additional host galaxy properties can be included, we show that more than 90% of 1000 simulations based on the Gravitational Wave Galaxy Catalogue, the top 10 most likely galaxies account for a 50% total probability of hosting a gravitational wave source, and the true gravitational wave source host galaxy is in the top one (ten) galaxy candidates 50% (70%) of the time. Furthermore, we show that by including host galaxy information, a better estimate of the inclination angle of a compact binary gravitational wave source can be obtained. Similar statistical results highlighting the effects of using either blue or K band galaxy luminosity information on galaxy rank and posterior probability are also reported.
    The Astrophysical Journal 06/2014; 795(1). DOI:10.1088/0004-637X/795/1/43 · 6.28 Impact Factor
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    ABSTRACT: We present the first results of an all-sky search for continuous gravitational waves from unknown spinning neutron stars in binary systems using LIGO and Virgo data. Using a specially developed analysis program, the TwoSpect algorithm, the search was carried out on data from the sixth LIGO Science Run and the second and third Virgo Science Runs. The search covers a range of frequencies from 20 Hz to 520 Hz, a range of orbital periods from 2 to ~2,254 h and a frequency- and period-dependent range of frequency modulation depths from 0.277 to 100 mHz. This corresponds to a range of projected semi-major axes of the orbit from ~0.6e-3 ls to ~6,500 ls assuming the orbit of the binary is circular. While no plausible candidate gravitational wave events survive the pipeline, upper limits are set on the analyzed data. The most sensitive 95% confidence upper limit obtained on gravitational wave strain is 2.3e-24 at 217 Hz, assuming the source waves are circularly polarized. Although this search has been optimized for circular binary orbits, the upper limits obtained remain valid for orbital eccentricities as large as 0.9. In addition, upper limits are placed on continuous gravitational wave emission from the low-mass x-ray binary Scorpius X-1 between 20 Hz and 57.25 Hz.
    Physical Review D 05/2014; 90(6). DOI:10.1103/PhysRevD.90.062010 · 4.86 Impact Factor
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    ABSTRACT: In this paper we report on a search for short-duration gravitational wave bursts in the frequency range 64 Hz-1792 Hz associated with gamma-ray bursts (GRBs), using data from GEO600 and one of the LIGO or Virgo detectors. We introduce the method of a linear search grid to analyse GRB events with large sky localisation uncertainties such as the localisations provided by the Fermi Gamma-ray Burst Monitor (GBM). Coherent searches for gravitational waves (GWs) can be computationally intensive when the GRB sky position is not well-localised, due to the corrections required for the difference in arrival time between detectors. Using a linear search grid we are able to reduce the computational cost of the analysis by a factor of O(10) for GBM events. Furthermore, we demonstrate that our analysis pipeline can improve upon the sky localisation of GRBs detected by the GBM, if a high-frequency GW signal is observed in coincidence. We use the linear search grid method in a search for GWs associated with 129 GRBs observed satellite-based gamma-ray experiments between 2006 and 2011. The GRBs in our sample had not been previously analysed for GW counterparts. A fraction of our GRB events are analysed using data from GEO600 while the detector was using squeezed-light states to improve its sensitivity; this is the first search for GWs using data from a squeezed-light interferometric observatory. We find no evidence for GW signals, either with any individual GRB in this sample or with the population as a whole. For each GRB we place lower bounds on the distance to the progenitor, assuming a fixed GW emission energy of $10^{-2} M_{\odot}c^{2}$, with a median exclusion distance of 0.8 Mpc for emission at 500 Hz and 0.3 Mpc at 1 kHz. The reduced computational cost associated with a linear search grid will enable rapid searches for GWs associated with Fermi GBM events in the Advanced detector era.
    Physical Review D 05/2014; 89(12). DOI:10.1103/PhysRevD.89.122004 · 4.86 Impact Factor
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    ABSTRACT: We report on an all-sky search for periodic gravitational waves in the frequency range 50–1000 Hz with the first derivative of frequency in the range −8.9 × 10−10 Hz s−1 to zero in two years of data collected during LIGO's fifth science run. Our results employ a Hough transform technique, introducing a χ2 test and analysis of coincidences between the signal levels in years 1 and 2 of observations that offers a significant improvement in the product of strain sensitivity with compute cycles per data sample compared to previously published searches. Since our search yields no surviving candidates, we present results taking the form of frequency dependent, 95% confidence upper limits on the strain amplitude h0. The most stringent upper limit from year 1 is 1.0 × 10−24 in the 158.00–158.25 Hz band. In year 2, the most stringent upper limit is 8.9 × 10−25 in the 146.50–146.75 Hz band. This improved detection pipeline, which is computationally efficient by at least two orders of magnitude better than our flagship Einstein@Home search, will be important for 'quick-look' searches in the Advanced LIGO and Virgo detector era.
    Classical and Quantum Gravity 04/2014; 31(8):085014. DOI:10.1088/0264-9381/31/8/085014 · 3.10 Impact Factor
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    ABSTRACT: This paper reports on an unmodeled, all-sky search for gravitational waves from merging intermediate mass black hole binaries (IMBHB). The search was performed on data from the second joint science run of the LIGO and Virgo detectors (July 2009 - October 2010) and was sensitive to IMBHBs with a range up to $\sim 200$ Mpc, averaged over the possible sky positions and inclinations of the binaries with respect to the line of sight. No significant candidate was found. Upper limits on the coalescence-rate density of non-spinning IMBHBs with total masses between 100 and $450 \ \mbox{M}_{\odot}$ and mass ratios between $0.25$ and $1\,$ were placed by combining this analysis with an analogous search performed on data from the first LIGO-Virgo joint science run (November 2005 - October 2007). The most stringent limit was set for systems consisting of two $88 \ \mbox{M}_{\odot}$ black holes and is equal to $0.12 \ \mbox{Mpc}^{-3} \ \mbox{Myr}^{-1}$ at the $90\%$ confidence level. This paper also presents the first estimate, for the case of an unmodeled analysis, of the impact on the search range of IMBHB spin configurations: the visible volume for IMBHBs with non-spinning components is roughly doubled for a population of IMBHBs with spins aligned with the binary's orbital angular momentum and uniformly distributed in the dimensionless spin parameter up to 0.8, whereas an analogous population with anti-aligned spins decreases the visible volume by $\sim 20\%\,$.
    Physical Review D 04/2014; 89(12). DOI:10.1103/PhysRevD.89.122003 · 4.86 Impact Factor

Publication Stats

3k Citations
655.13 Total Impact Points

Institutions

  • 2014
    • Friedrich Schiller University Jena
      • Abbe Center of Photonics (ACP)
      Jena, Thuringia, Germany
  • 2007–2014
    • University of Glasgow
      • School of Physics and Astronomy
      Glasgow, Scotland, United Kingdom
  • 2013
    • University of South Wales
      Понтиприте, Wales, United Kingdom
  • 2011–2013
    • Leibniz Universität Hannover
      • Institute of Gravitation Physics
      Hanover, Lower Saxony, Germany
  • 2009–2013
    • Max Planck Institute for Physics
      München, Bavaria, Germany
  • 2005–2013
    • Cardiff University
      • School of Physics and Astronomy
      Cardiff, Wales, United Kingdom
    • California Institute of Technology
      • Department of Physics
      Pasadena, California, United States
  • 2003–2009
    • Max Planck Institute for Gravitational Physics (Albert-Einstein-Institute)
      Potsdam, Brandenburg, Germany
  • 2004–2005
    • University of Birmingham
      • School of Physics and Astronomy
      Birmingham, England, United Kingdom
  • 2003–2004
    • Carleton College
      نورثفیلد، مینه‌سوتا, Minnesota, United States