scholarly journals Searching for gravitational-wave bursts from cosmic string cusps with the Parkes Pulsar Timing Array

2020 ◽  
Vol 501 (1) ◽  
pp. 701-712
Author(s):  
N Yonemaru ◽  
S Kuroyanagi ◽  
G Hobbs ◽  
K Takahashi ◽  
X-J Zhu ◽  
...  
Keyword(s):  
False Alarm ◽  
Gravitational Wave ◽  
Cosmic String ◽  
Cosmic Strings ◽  
False Alarm Probability ◽  
String Tension ◽  
Detection Algorithm ◽  
Pulsar Timing ◽  
Upper Limits ◽  
Pulsar Timing Array

ABSTRACT Cosmic strings are potential gravitational-wave (GW) sources that can be probed by pulsar timing arrays (PTAs). In this work we develop a detection algorithm for a GW burst from a cusp on a cosmic string, and apply it to Parkes PTA data. We find four events with a false alarm probability less than 1 per cent. However further investigation shows that all of these are likely to be spurious. As there are no convincing detections we place upper limits on the GW amplitude for different event durations. From these bounds we place limits on the cosmic string tension of Gμ ∼ 10−5, and highlight that this bound is independent from those obtained using other techniques. We discuss the physical implications of our results and the prospect of probing cosmic strings in the era of Square Kilometre Array.

scholarly journals Stochastic gravitational-wave background from metastable cosmic strings

2021 ◽  
Vol 2021 (12) ◽  
pp. 006
Author(s):  
Wilfried Buchmüller ◽  
Valerie Domcke ◽  
Kai Schmitz
Keyword(s):  
Gravitational Wave ◽  
Cosmic Strings ◽  
Long Strings ◽  
Wave Spectrum ◽  
Cosmic Time ◽  
String Tension ◽  
Relevant Parameter ◽  
Pulsar Timing ◽  
Near Future ◽  
Gravitational Wave Background

Abstract A metastable cosmic-string network is a generic consequence of many grand unified theories (GUTs) when combined with cosmic inflation. Metastable cosmic strings are not topologically stable, but decay on cosmic time scales due to pair production of GUT monopoles. This leads to a network consisting of metastable long strings on superhorizon scales as well as of string loops and segments on subhorizon scales. We compute for the first time the complete stochastic gravitational-wave background (SGWB) arising from all these network constituents, including several technical improvements to both the derivation of the loop and segment contributions. We find that the gravitational waves emitted by string loops provide the main contribution to the gravitational-wave spectrum in the relevant parameter space. The resulting spectrum is consistent with the tentative signal observed by the NANOGrav and Parkes pulsar timing collaborations for a string tension of G μ ∼ 10-11…-7 and has ample discovery space for ground- and space-based detectors. For GUT-scale string tensions, G μ ∼ 10-8…-7, metastable strings predict a SGWB in the LIGO-Virgo-KAGRA band that could be discovered in the near future.

scholarly journals Implications of the NANOGrav results for inflation

2020 ◽  
Author(s):  
Sunny Vagnozzi
Keyword(s):  
Gravitational Wave ◽  
Spectral Index ◽  
Power Law ◽  
Big Bang ◽  
Big Bang Nucleosynthesis ◽  
Pulsar Timing ◽  
Upper Limits ◽  
Gravitational Wave Background ◽  
Pulsar Timing Array ◽  
O 10

Abstract The NANOGrav pulsar timing array experiment reported evidence for a stochastic common-spectrum process affecting pulsar timing residuals in its 12.5-year dataset, which might be interpreted as the first detection of a stochastic gravitational wave background (SGWB). I examine whether the NANOGrav signal might be explained by an inflationary SGWB, focusing on the implications for the tensor spectral index nT and the tensor-to-scalar ratio r. Explaining NANOGrav while complying with upper limits on r from BICEP2/Keck Array and Planck requires $r \gtrsim {\cal O}(10^{-6})$ in conjunction with an extremely blue tensor spectrum, 0.7 ≲ nT ≲ 1.3. After discussing models which can realize such a blue spectrum, I show that this region of parameter space can be brought in agreement with Big Bang Nucleosynthesis constraints for a sufficiently low reheating scale, Trh ≲ 100 GeV − 1 TeV. With the important caveat of having assumed a power-law parametrization for the primordial tensor spectrum, an inflationary interpretation of the NANOGrav signal is therefore not excluded.

scholarly journals Erratum: Placing limits on the stochastic gravitational-wave background using European Pulsar Timing Array data

2012 ◽  
Vol 425 (2) ◽  
pp. 1597-1597 ◽  
Author(s):  
R. van Haasteren ◽  
Y. Levin ◽  
G. H. Janssen ◽  
K. Lazaridis ◽  
M. Kramer ◽  
...  
Keyword(s):  
Gravitational Wave ◽  
Array Data ◽  
Pulsar Timing ◽  
Gravitational Wave Background ◽  
Pulsar Timing Array

scholarly journals CANNY ALGORITHM, COSMIC STRINGS AND THE COSMIC MICROWAVE BACKGROUND

2010 ◽  
Vol 19 (02) ◽  
pp. 183-217 ◽  
Author(s):  
REBECCA J. DANOS ◽  
ROBERT H. BRANDENBERGER
Keyword(s):  
Cosmic Strings ◽  
Simulated Data ◽  
String Tension ◽  
Detection Algorithm ◽  
Small Scale ◽  
Scale Invariant ◽  
South Pole Telescope ◽  
Scaling Solution ◽  
Order Of Magnitude ◽  
Canny Algorithm

We describe a new code to search for signatures of cosmic strings in cosmic microwave anisotropy maps. The code implements the Canny algorithm, an edge detection algorithm designed to search for the lines of large gradients in maps. Such a gradient signature which is coherent in position-space is produced by cosmic strings via the Kaiser–Stebbins effect. We test the power of our new code to set limits on the tension of the cosmic strings by analyzing simulated data, with and without cosmic strings. We compare maps with a pure Gaussian scale-invariant power spectrum with maps which have a contribution of a distribution of cosmic strings obeying a scaling solution. The maps have angular scale and angular resolution comparable to what current and future ground-based small-scale cosmic microwave anisotropy experiments will achieve. We present tests of the codes, indicate the limits on the string tension which could be set with the current code, and describe various ways to refine the analysis. Our results indicate that when applied to the data of ongoing cosmic microwave experiments such as the South Pole Telescope project, the sensitivity of our method to the presence of cosmic strings will be more than an order of magnitude better than the limits from existing analyses.

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