We present the results of the optical follow-up conducted by the TOROS collaboration of the first gravitational-wave event GW150914. We conducted unfiltered CCD observations (0.35-1 Î¼m) with the 1.5 m telescope at Bosque Alegre starting âˆ¼2.5 days after the alarm. Given our limited field of view (âˆ¼100 arcmin2), we targeted 14 nearby galaxies that were observable from the site and were located within the area of higher localization probability. We analyzed the observations using two independent implementations of difference-imaging algorithms, followed by a Random-Forest-based algorithm to discriminate between real and bogus transients. We did not find any bona fide transient event in the surveyed area down to a 5Ïƒ limiting magnitude of r = 21.7 mag (AB). Our result is consistent with the LIGO detection of a binary black hole merger, for which no electromagnetic counterparts are expected, and with the expected rates of other astrophysical transients.
Mario C. Díaz, et. al., (2016) GW150914: FIRST SEARCH for the ELECTROMAGNETIC COUNTERPART of A GRAVITATIONAL-WAVE EVENT by the TOROS COLLABORATION.Astrophysical Journal Letters828:2. DOI: http://doi.org/10.3847/2041-8205/828/2/L16
Astrophysical Journal Letters