A1 Refereed original research article in a scientific journal
Pan-STARRS and PESSTO search for an optical counterpart to the LIGO gravitational-wave source GW150914
Authors: Smartt SJ, Chambers KC, Smith KW, Huber ME, Young DR, Cappellaro E, Wright DE, Coughlin M, Schultz ASB, Denneau L, Flewelling H, Heinze A, Magnier EA, Primak N, Rest A, Sherstyuk A, Stalder B, Stubbs CW, Tonry J, Waters C, Willman M, Anderson JP, Baltay C, Botticella MT, Campbell H, Dennefeld M, Chen TW, Della Valle M, Elias-Rosa N, Fraser M, Inserra C, Kankare E, Kotak R, Kupfer T, Harmanen J, Galbany L, Gal-Yam A, Le Guillou L, Lyman JD, Maguire K, Mitra A, Nicholl M, Olivares F, Rabinowitz D, Razza A, Sollerman J, Smith M, Terreran G, Valenti S, Gibson B, Goggia T
Publisher: OXFORD UNIV PRESS
Publication year: 2016
Journal: Monthly Notices of the Royal Astronomical Society
Journal name in source: MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
Journal acronym: MON NOT R ASTRON SOC
Volume: 462
Issue: 4
First page : 4094
Last page: 4116
Number of pages: 23
ISSN: 0035-8711
eISSN: 1365-2966
DOI: https://doi.org/10.1093/mnras/stw1893
We searched for an optical counterpart to the first gravitational-wave source discovered by LIGO (GW150914), using a combination of the Pan-STARRS1 wide-field telescope and the Public ESO Spectroscopic Survey of Transient Objects (PESSTO) spectroscopic follow-up programme. As the final LIGO sky maps changed during analysis, the total probability of the source being spatially coincident with our fields was finally only 4.2 per cent. Therefore, we discuss our results primarily as a demonstration of the survey capability of Pan-STARRS and spectroscopic capability of PESSTO. We mapped out 442 deg(2) of the northern sky region of the initial map. We discovered 56 astrophysical transients over a period of 41 d from the discovery of the source. Of these, 19 were spectroscopically classified and a further 13 have host galaxy redshifts. All transients appear to be fairly normal supernovae (SNe) and AGN variability and none is obviously linked with GW150914. We illustrate the sensitivity of our survey by defining parametrized light curves with time-scales of 4, 20 and 40 d and use the sensitivity of the Pan-STARRS1 images to set limits on the luminosities of possible sources. The Pan-STARRS1 images reach limiting magnitudes of iP1 = 19.2, 20.0 and 20.8, respectively, for the three time-scales. For long time-scale parametrized light curves (with full width half-maximum similar or equal to 40 d), we set upper limits of M-i <= -17.2(+1.4)(-0.9) if the distance to GW150914 is D-L = 400 +/- 200 Mpc. The number of Type Ia SN we find in the survey is similar to that expected from the cosmic SN rate, indicating a reasonably complete efficiency in recovering SN like transients out to D-L = 400 +/- 200 Mpc.
