GROWTH on S190814bv: Deep Synoptic Limits on the Optical/Near-Infrared Counterpart to a Neutron Star-Black Hole Merger
Creators: name: Andreoni, Igor
name: Goldstein, Daniel A.
name: Kasliwal, Mansi M.
name: Nugent, Peter E.
name: Zhou, Rongpu
name: Newman, Jeffrey A.
name: Bulla, Mattia
name: Foucart, Francois
name: Hotokezaka, Kenta
name: Nakar, Ehud
name: Nissanke, Samaya
name: Raaijmakers, Geert
name: Bloom, Joshua S.
name: De, Kishalay
name: Jencson, Jacob E.
name: Ward, Charlotte
name: Ahumada, Tomás
name: Anand, Shreya
name: Buckley, David A. H.
name: Caballero-García, Maria D.
name: Castro-Tirado, Alberto J.
name: Copperwheat, Christopher M.
name: Coughlin, Michael W.
name: Cenko, S. Bradley
name: Gromadzki, Mariusz
name: Hu, Youdong D.
name: Karambelkar, Viraj R.
name: Perley, Daniel A.
name: Sharma, Yashvi
name: Valeev, Azamat F.
name: Cook, David O.
name: Fremling, U. Christoffer
name: Kumar, Harsh
name: Taggart, Kirsty
name: Bagdasaryan, Ashot
name: Cooke, Jeff
name: Dahiwale, Aishwarya
name: Dhawan, Suhail
name: Dobie, Dougal
name: Gatkine, Pradip
name: Golkhou, V. Zach
name: Goobar, Ariel
name: Chaves, Andreas Guerra
name: Hankins, Matthew
name: Kaplan, David L.
name: Kong, Albert K. H.
name: Kool, Erik C.
name: Mohite, Siddharth
name: Sollerman, Jesper
name: Tzanidakis, Anastasios
name: Webb, Sara
name: Zhang, Keming
Publisher: name: arXiv
Year: 2019
Subjects: subject: High Energy Astrophysical Phenomena (astro-ph.HE)
subject: FOS: Physical sciences
subject: FOS: Physical sciences

description: On 2019 August 14, the Advanced LIGO and Virgo interferometers detected the high-significance gravitational wave (GW) signal S190814bv. The GW data indicated that the event resulted from a neutron star--black hole (NSBH) merger, or potentially a low-mass binary black hole merger. Due to the low false alarm rate and the precise localization (23 deg$^2$ at 90\%), S190814bv presented the community with the best opportunity yet to directly observe an optical/near-infrared counterpart to a NSBH merger. To search for potential counterparts, the GROWTH collaboration performed real-time image subtraction on 6 nights of public Dark Energy Camera (DECam) images acquired in the three weeks following the merger, covering $&gt;$98\% of the localization probability. Using a worldwide network of follow-up facilities, we systematically undertook spectroscopy and imaging of optical counterpart candidates. Combining these data with a photometric redshift catalog, we ruled out each candidate as the counterpart to S190814bv and we placed deep, uniform limits on the optical emission associated with S190814bv. For the nearest consistent GW distance, radiative transfer simulations of NSBH mergers constrain the ejecta mass of S190814bv to be $M_\mathrm{ej} &lt; 0.04$~$M_{\odot}$ at polar viewing angles, or $M_\mathrm{ej} &lt; 0.03$~$M_{\odot}$ if the opacity is $κ&lt; 2$~cm$^2$g$^{-1}$. Assuming a tidal deformability for the neutron star at the high end of the range compatible with GW170817 results, our limits would constrain the BH spin component aligned with the orbital momentum to be $ χ&lt; 0.7$ for mass ratios $Q &lt; 6$, with weaker constraints for more compact neutron stars. We publicly release the photometry from this campaign at http://www.astro.caltech.edu/~danny/static/s190814bv.
description: Accepted to ApJ with no major changes