iPTF Search for an Optical Counterpart to Gravitational-wave Transient GW150914

June 2016 • 2016ApJ...824L..24K

Authors • Kasliwal, M. M. • Cenko, S. B. • Singer, L. P. • Corsi, A. • Cao, Y. • Barlow, T. • Bhalerao, V. • Bellm, E. • Cook, D. • Duggan, G. E. • Ferretti, R. • Frail, D. A. • Horesh, A. • Kendrick, R. • Kulkarni, S. R. • Lunnan, R. • Palliyaguru, N. • Laher, R. • Masci, F. • Manulis, I. • Miller, A. A. • Nugent, P. E. • Perley, D. • Prince, T. A. • Quimby, R. M. • Rana, J. • Rebbapragada, U. • Sesar, B. • Singhal, A. • Surace, J. • Van Sistine, A.

Abstract • The intermediate Palomar Transient Factory (iPTF) autonomously responded to and promptly tiled the error region of the first gravitational-wave event GW150914 to search for an optical counterpart. Only a small fraction of the total localized region was immediately visible in the northern night sky, due both to Sun-angle and elevation constraints. Here, we report on the transient candidates identified and rapid follow-up undertaken to determine the nature of each candidate. Even in the small area imaged of 126 deg², after extensive filtering, eight candidates were deemed worthy of additional follow-up. Within two hours, all eight were spectroscopically classified by the Keck II telescope. Curiously, even though such events are rare, one of our candidates was a superluminous supernova. We obtained radio data with the Jansky Very Large Array and X-ray follow-up with the Swift satellite for this transient. None of our candidates appear to be associated with the gravitational-wave trigger, which is unsurprising given that GW150914 came from the merger of two stellar-mass black holes. This end-to-end discovery and follow-up campaign bodes well for future searches in this post-detection era of gravitational waves.

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David Cook

Assistant Scientist

Frank Masci

Senior Scientist