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In Budai et al. (2020) we argued that angular non-stationarities of gamma-rayburst (GRB) jets can result in a statistical connection between the anglevalues deduced from jet break times and the variabilities of prompt lightcurves. The connection should be an anti-correlation if luminosity densities ofjets follow a power-law or a uniform profile, and a correlation if they have aGaussian profile. In this follow-up paper, we search for the connection bymeasuring Spearman's rank correlation coefficient in a sample of 19 long GRBsobserved by the Swift satellite. Using 16 of the GRBs with well-defined anglemeasurements, we find $\rho = -0.20_{-0.09}^{+0.09}$ and $p =0.46_{-0.19}^{+0.23}$. Adding three more GRBs to the sample, each with a pairof equally possible angle values, can strengthen the anti-correlation to$\rho=-0.31_{-0.08}^{+0.07}$ and $p=0.19_{-0.09}^{+0.14}$. We show that theseresults are incompatible with non-stationary jets having Gaussian profiles, andthat $\gtrsim\!100$ GRBs with observed afterglows would be needed to confirmthe potential existence of the angle-variability anti-correlation with$3\sigma$ significance. If the connection is real, GRB jet angles would beconstrainable from prompt gamma light curves, without the need of afterglowobservations.

Statistical search for angular non-stationarities of long gamma-ray burst jets using Swift data