Search for high-energy neutrinos from gravitational wave event GW151226 and candidate LVT151012 with ANTARES and IceCube

The Advanced LIGO observatories detected gravitational waves from two binary black hole mergers during their first observation run (O1). We present a high-energy neutrino follow-up search for the second gravitational wave event, GW151226, as well as for gravitational wave candidate LVT151012. We find two and four neutrino candidates detected by IceCube, and one and zero detected by Antares, within $\pm 500\mathrm{s}$ around the respective gravitational wave signals, consistent with the expected background rate. None of these neutrino candidates are found to be directionally coincident with GW151226 or LVT151012. We use nondetection to constrain isotropic-equivalent high-energy neutrino emission from GW151226, adopting the GW event’s 3D localization, to less than $2\times 10^{51}–2\times 10^{54}\mathrm{erg}$.

Figure 1

GW skymap for GW151226 (top) and LVT151012 (bottom), and the reconstructed directions for high-energy neutrino candidates detected by IceCube (green crosses) and Antares (blue cross) within $\pm 500\mathrm{s}$ around the GW signals. The maps are in equatorial coordinates. The GW skymap shows the reconstructed probability density contours of the GW event 90% C.L. GW shading indicates the reconstructed probability density of the GW event, darker regions corresponding to higher probability. The neutrino directional uncertainties are below 1° for most of the candidates, and in any case too small to be shown. Neutrino event numbers refer to the first column of Table 1.

Figure 2

Upper limit for high-energy neutrino spectral fluence (${\nu }_{\mu }+{\overline{\nu }}_{\mu }$) as a function of source direction corresponding to GW151226, assuming $dN/dE\propto E^{-2}$ (top) and $dN/dE\propto E^{-2}\exp [-(E/100\mathrm{TeV}{)}^{1/2}]$ (bottom) neutrino spectra. The region surrounded by a white line shows the part of the sky in which Antares is more sensitive (lowest declinations), while in the rest of the sky, IceCube is more sensitive. For comparison, the 90% credible-level contour for the GW skymap is also shown.

Figure 3

Same as Fig. 2, but for LVT151012.

Figure 4

Upper limit on the total energy radiated in high-energy neutrinos by the progenitor of GW151226 as a function of source direction, assuming $dN/dE\propto E^{-2}$ (top) and $dN/dE\propto E^{-2}\exp [-(E/100\mathrm{TeV}{)}^{1/2}]$ (bottom) neutrino spectra. The direction-dependent constraint is derived from the direction-dependent neutrino spectral fluence upper limit (see Fig. 2) as well as the reconstructed 3D GW localization.