A Galaxy-targeted Search for the Optical Counterpart of the Candidate NS-BH Merger S190814bv with Magellan
Abstract
On 2019 August 14 the Laser Interferometer Gravitational Wave Observatory (LIGO) and the Virgo gravitational wave interferometer announced the detection of a binary merger, S190814bv, with a low false alarm rate of about 1 in 1.6 × 1025 yr, a distance of 267 ± 52 Mpc, a 90% (50%) localization region of about 23 (5) deg2, and a probability of being a neutron star-black hole (NS-BH) merger of >99%. The LIGO/Virgo Collaboration (LVC) defines NS-BH such that the lighter binary member has a mass of <3 M ☉ and the more massive one has >5 M ☉, and this classification is in principle consistent with a BH-BH merger depending on the actual upper mass cutoff for neutron stars. Additionally, the LVC designated a probability that the merger led to matter outside the final BH remnant of <1%, suggesting that an electromagnetic (EM) counterpart is unlikely. Here we report our optical follow-up observations of S190814bv using the Magellan Baade 6.5 m telescope to target all 96 galaxies in the Galaxy List for the Advanced Detector Era catalog within the 50% localization volume (representing about 70% of the integrated luminosity within this region). No counterpart was identified to a median 3σ limiting magnitude of i = 22.2 (M i ≈ -14.9 mag), comparable to the brightness of the optical counterpart of the binary neutron star merger GW170817 at the distance of S190814bv; similarly, we can rule out an on-axis jet typical of short GRBs. However, we cannot rule out other realistic models, such as a kilonova with only ∼0.01 M ☉ of lanthanide-rich material, or an off-axis jet with a viewing angle of θ obs ≳ 15°.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- October 2019
- DOI:
- arXiv:
- arXiv:1908.08913
- Bibcode:
- 2019ApJ...884L..55G
- Keywords:
-
- Gravitational waves;
- Neutron stars;
- Astrophysical black holes;
- Observational astronomy;
- 678;
- 1108;
- 98;
- 1145;
- Astrophysics - High Energy Astrophysical Phenomena
- E-Print:
- 10 pages, 1 table, 4 figures, accepted to ApJL
