Cosmic string bursts in LISA

Author(s)

Auclair, Pierre, Babak, Stanislav, Quelquejay Leclere, Hippolyte, Steer, Danièle A.

Abstract

Cosmic string cusps are sources of short-lived, linearly polarized gravitational wave bursts which can be searched for in gravitational wave detectors. We assess the capability of LISA to detect these bursts using the latest LISA configuration and operational assumptions. For such short bursts, we verify that LISA can be considered as “frozen”, namely that one can neglect LISA’s orbital motion. We consider two models for the network of cosmic string loops, and estimate that LISA should be able to detect 4–30 bursts per year assuming a string tension <math display="inline"><mrow><mi>G</mi><mi>μ</mi><mo>≈</mo><msup><mrow><mn>10</mn></mrow><mrow><mo>-</mo><mn>10.6</mn></mrow></msup><mi>–</mi><msup><mrow><mn>10</mn></mrow><mrow><mo>-</mo><mn>10.1</mn></mrow></msup></mrow></math> and detection threshold <math display="inline"><mi>SNR</mi><mo>≥</mo><mn>20</mn></math>. Nondetection of these bursts would constrain the string tension to <math display="inline"><mi>G</mi><mi>μ</mi><mo>≲</mo><msup><mn>10</mn><mrow><mo>-</mo><mn>11</mn></mrow></msup></math> for both models.

Figures

Caption

Schematic view of a cosmic string burst, with the beaming angle $\beam$ in red and the misalignement angle $\beta$.

Caption

Cusp strain in time domain computed using \cref{eq:cusp-time}, and fixing (see Section \ref{sec:snr}) $\flow=f_1 = 0.1$mHz, $\fhigh=f_2=50$mHz, characteristic of LISA.

Caption

Left panel: Detection efficiency of LISA for a burst of amplitude $A=10^{-21} \mathrm{s}^{-1/3}$ marginalized over the sky-localization of the source and polarization angle. Right panel: Probability that a burst with amplitude $A$ has SNR larger than $\snrcut = 20$.

Caption

Left panel: Detection efficiency of LISA for a burst of amplitude $A=10^{-21} \mathrm{s}^{-1/3}$ marginalized over the sky-localization of the source and polarization angle. Right panel: Probability that a burst with amplitude $A$ has SNR larger than $\snrcut = 20$.

Caption

Expected rate of detected bursts in LISA as a function of the string tension for models BOS and LRS. In case LISA does not detect bursts from cosmic string cusps, the orange hatched region is excluded after $\Tobs = 82 \% \times 4.5$ years and the blue hatched region is excluded after $\Tobs=82 \% \times 10$ years.