Placing limits on the stochastic gravitational-wave background using European Pulsar Timing Array data

Haasteren, Rutger van; Levin, Y.; Janssen, G. H.; Lazaridis, K.; Krämer, M.; Stappers, B. W.; Desvignes, G.; Purver, M. B.; Lyne, A. G.; Ferdman, R. D.; Jessner, A.; Cognard, I.; Theureau, G.; D’Amico, N.; Possenti, A.; Burgay, M.; Corongiu, A.; Hessels, J. W. T.; Smits, R.; Verbiest, J. P. W.

doi:10.1111/j.1365-2966.2011.18613.x

Cited by 241 publications

(249 citation statements)

References 27 publications

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“…It is widely considered that a stochastic GW background due to the combined emission from a large number of individual SMBBHs over cosmological volume (e.g., Sesana 2013b; Ravi et al 2014, for recent work) provides the most promising target; indeed, some studies suggested that a detection of this type could occur as early as 2016 (Siemens et al 2013). Analyses of actual PTA data have previously focused on a search for such a GW background, leading to more and more stringent constraints on the fractional energy density of the background (Jenet et al 2006;Yardley et al 2011;van Haasteren et al 2011;Demorest et al 2013;Shannon et al 2013). Over the past few years interest has grown substantially regarding the prospects of detecting single-source GWs using PTAs, for example, for individual SMBBHs (Sesana et al 2009;Lee et al 2011;Mingarelli et al 2012;Ravi et al 2015), for GW memory effects associated with SMBBH mergers (Seto 2009;Cordes & Jenet 2012;Madison et al 2014), for GW bursts (Pitkin 2012) and for unanticipated sources (Cutler et al 2014).…”

Section: Introductionmentioning

confidence: 99%

Detection and localization of single-source gravitational waves with pulsar timing arrays

Zhu¹,

Wen²,

Hobbs³

et al. 2015

Monthly Notices of the Royal Astronomical Society

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Pulsar timing arrays (PTAs) can be used to search for very low frequency (10 −9 -10 −7 Hz) gravitational waves (GWs). In this paper we present a general method for the detection and localization of single-source GWs using PTAs. We demonstrate the effectiveness of this new method for three types of signals: monochromatic waves as expected from individual supermassive binary black holes in circular orbits, GWs from eccentric binaries and GW bursts. We also test its implementation in realistic data sets that include effects such as uneven sampling and heterogeneous data spans and measurement precision. It is shown that our method, which works in the frequency domain, performs as well as published time-domain methods. In particular, we find it equivalent to the F e -statistic for monochromatic waves. We also discuss the construction of null streams -data streams that have null response to GWs, and the prospect of using null streams as a consistency check in the case of detected GW signals. Finally, we present sensitivities to individual supermassive binary black holes in eccentric orbits. We find that a monochromatic search that is designed for circular binaries can efficiently detect eccentric binaries with both high and low eccentricities, while a harmonic summing technique provides greater sensitivities only for binaries with moderate eccentricities.

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Section: Introductionmentioning

confidence: 99%

Detection and localization of single-source gravitational waves with pulsar timing arrays

Zhu¹,

Wen²,

Hobbs³

et al. 2015

Monthly Notices of the Royal Astronomical Society

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“…However, these constraints are strongly dependent on uncertain string physics, most notably the network loop production scale and the nature of string radiation from cusps, i.e., points on the strings approaching the speed of light c. The most optimistic constraint based on the European Pulsar Timing Array is Gµ/c 2 < 4.0 × 10 −9 (van Haasteren et al 2011), but a much more conservative estimate of Gµ/c 2 < 5.3 × 10 −7 can be found in Sanidas et al (2012), together with a string parameter constraint survey and an extensive discussion of these uncertainties. Such gravitational wave limits do not apply to global strings or to strings for which other radiative channels are available.…”

Section: Introductionmentioning

confidence: 99%

Planck2013 results. XXV. Searches for cosmic strings and other topological defects

Ade¹,

Aghanim²,

Armitage-Caplan³

et al. 2014

A&A

278

191

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Planck data have been used to provide stringent new constraints on cosmic strings and other defects. We describe forecasts of the CMB power spectrum induced by cosmic strings, calculating these from network models and simulations using line-of-sight Boltzmann solvers. We have studied Nambu-Goto cosmic strings, as well as field theory strings for which radiative effects are important, thus spanning the range of theoretical uncertainty in the underlying strings models. We have added the angular power spectrum from strings to that for a simple adiabatic model, with the extra fraction defined as f 10 at multipole = 10. This parameter has been added to the standard six parameter fit using COSMOMC with flat priors. For the Nambu-Goto string model, we have obtained a constraint on the string tension of Gµ/c 2 < 1.5 × 10 −7 and f 10 < 0.015 at 95% confidence that can be improved to Gµ/c 2 < 1.3 × 10 −7 and f 10 < 0.010 on inclusion of high-CMB data. For the Abelian-Higgs field theory model we find, Gµ AH /c 2 < 3.2 × 10 −7 and f 10 < 0.028. The marginalised likelihoods for f 10 and in the f 10 -Ω b h 2 plane are also presented. We have additionally obtained comparable constraints on f 10 for models with semilocal strings and global textures. In terms of the effective defect energy scale these are somewhat weaker at Gµ/c 2 < 1.1 × 10 −6 . We have made complementarity searches for the specific non-Gaussian signatures of cosmic strings, calibrating with all-sky Planck resolution CMB maps generated from networks of post-recombination strings. We have validated our non-Gaussian searches using these simulated maps in a Planck-realistic context, estimating sensitivities of up to ∆Gµ/c 2 ≈ 4 × 10 −7 . We have obtained upper limits on the string tension at 95% confidence of Gµ/c 2 < 9.0 × 10 −7 with modal bispectrum estimation and Gµ/c 2 < 7.8 × 10 −7 for real space searches with Minkowski functionals. These are conservative upper bounds because only post-recombination string contributions have been included in the non-Gaussian analysis.

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“…In addition, some of the binaries may be sufficiently luminous to stand out above the diffuse background level and could be individually observed [24,30]. The search for GWs from a SMBHB background [25][26][27][28] and from individual resolvable sources [29][30][31][32][33][34] has recently catalysed the PTA GW search effort, and it is plausible that in the next 5 to 10 years GWs could indeed be detected. If not, stringent constraints can be placed on aspects of the assembly history of SMBHBs [17][18][19][20].…”

Section: Introductionmentioning

confidence: 99%

Characterizing gravitational wave stochastic background anisotropy with pulsar timing arrays

et al. 2013

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Detecting a stochastic gravitational wave background, particularly radiation from individually unresolvable supermassive black hole binary systems, is one of the primary targets for Pulsar Timing Arrays. Increasingly more stringent upper limits are being set on these signals under the assumption that the background radiation is isotropic. However, some level of anisotropy may be present and the characterisation of the gravitational wave energy density at different angular scales carries important information. We show that the standard analysis for isotropic backgrounds can be generalised in a conceptually straightforward way to the case of generic anisotropic background radiation by decomposing the angular distribution of the gravitational wave energy density on the sky into multipole moments. We introduce the concept of generalised overlap reduction functions which characterise the effect of the anisotropy multipoles on the correlation of the timing residuals from the pulsars timed by a Pulsar Timing Array. In a search for a signal characterised by a generic anisotropy, the generalised overlap reduction functions play the role of the so-called Hellings and Downs curve used for isotropic radiation. We compute the generalised overlap reduction functions for a generic level of anisotropy and Pulsar Timing Array configuration. We also provide an order of magnitude estimate of the level of anisotropy that can be expected in the background generated by super-massive black hole binary systems.

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Placing limits on the stochastic gravitational-wave background using European Pulsar Timing Array data

Cited by 241 publications

References 27 publications

Detection and localization of single-source gravitational waves with pulsar timing arrays

Detection and localization of single-source gravitational waves with pulsar timing arrays

Planck2013 results. XXV. Searches for cosmic strings and other topological defects

Characterizing gravitational wave stochastic background anisotropy with pulsar timing arrays

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