noise curve is determined by fundamental noise sources only. The purple line is the median total , combining BBH and BNS, using the model described in [@gw170817_stoch] with updated mass distributions and rates from [@gwtc-1; @RatesAndPop_O2], and the gray box is the Poisson error region. The dotted gray line is the sum of the upper limit for the BBH+BNS backgrounds with the upper limit on the NSBH background.[]{data-label="fig:cbc"}](OGW_CBC.pdf){width="49.00000%"}

*Implications for cosmic string models* — Cosmic strings [@Kibble:1976sj; @Vilenkin:2000jqa] are linear topological defects which are expected to be generically produced within the context of Grand Unified Theories [@Jeannerot:2003qv]. The dynamics of a cosmic string network is driven by the formation of loops and the emission of gravitational waves [@Vachaspati:1984gt; @Sakellariadou:1990ne]. One may therefore use the  in order to constrain the parameters of a cosmic string network.

We will focus on Nambu-Goto strings [@NG_Nambu; @NG_Goto], for which the string thickness is zero and the intercommutation probability equals unity. Gravitational waves will allow us to constrain the string tension $G\mu/c^2$, where $\mu$ denotes the mass per unit length. This dimensionless parameter is the single quantity that characterizes a Nambu-Goto string network.

We will consider two analytic models of cosmic string loop distributions [@Blanco-Pillado:2013qja; 