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 (FAR) of about 1 in 1.6 × 10 25 years, a distance of 267 ± 52 Mpc, a 90% (50%) localization region of about 23 (5) deg 2 , 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 cut-off 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 GLADE 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 • .

Searching for electromagnetic counterparts to gravitational-wave merger events with the prototype Gravitational-Wave Optical Transient Observer (GOTO-4)

“…Numerous wide-field follow-up missions have tiled GW error boxes searching for transients, including the All-Sky Automated Survery for Supernovae (ASASSN; Shappee et al 2014), the Asteroid Terrestrial impact Last Alert System (ATLAS; Tonry et al 2018), the Deca-Degree Optical Transient Imager (DDOTI; Watson et al 2016), the Dark Energy Survey (DES; Dark Energy Survey Collaboration et al 2016), the Global Rapid Advanced Network Devoted to the Multimessenger Addicts (GRANDMA; Antier et al 2020b), KMT-Net (Kim et al 2016), the Mobile Astronomical System of TElescope Robots (MASTER; Lipunov et al 2010), MeerLICHT (Bloemen et al 2016), PanSTARRS (Kaiser et al 2010), Searches After Gravitational waves Using ARizona Observatories (SAGUARO; Lundquist et al 2019), the Télescope à Action Rapide pour les Objets Transitoires (TAROT; Boër 2001), the Visible and Infrared Survey Telescope for Astronomy (VISTA;Sutherland et al 2015), the VLT Survey Telescope (VST; Capaccioli & Schipani 2011) and the Zwicky Transient Facility (ZTF; Bellm et al 2019). No associated transients were identified (Anand et al 2020;Antier et al 2020b,a;Coughlin et al 2020;Sagués Carracedo et al 2020), but constraining limits were placed on a number of milestone events, including S190814bv, the first NSBH merger candidate identified in GW (Dobie et al 2019;Gomez et al 2019;LIGO Scientific Collaboration & Virgo Collaboration 2019;Ackley et al 2020;Andreoni et al 2020;Vieira et al 2020;Watson et al 2020), and several candidate BNS systems (Goldstein et al 2019;Hosseinzadeh et al 2019;Lundquist et al 2019), including the unusually massive GW190425 (Coughlin et al 2019;Hosseinzadeh et al 2019;Lundquist et al 2019;Abbott et al 2020b).…”

Constraints on the Physical Properties of GW190814 through Simulations Based on DECam Follow-up Observations by the Dark Energy Survey

“…To date, multiple groups have performed and documented optical follow-up observations of GW190814. The Global Relay of Observatories Watching Transients Happen (GROWTH) utilized the public DECam images discussed in this work (Andreoni et al 2020, henceforth G20), Vieira et al (2020) (henceforth V20) collected independent follow-up observations with the MegaCam instrument (Boulade et al 2003) on the Canada-France-Hawaii Telescope, the Electro-magNetic counterparts of GRAvitational wave sources at the VEry Large Telescope (ENGRAVE) Collaboration performed their follow-up observations using the Very Large Telescope (Ackley et al 2020, henceforth E20), Gomez et al (2019) (henceforth M20) carried out follow-up observations with a network of telescopes, and Watson et al (2020) (henceforth W20) utilized the DDOTI wide-field imager. All analyses, in similar fashion to the work presented here, systematically reduce the set of optical counterpart candidates, conclude a nondetection of an EM counterpart to GW190814, and proceed to place constraints on optical and dynamical properties of the candidate NSBH merger.…”

Constraining the Kilonova Rate with Zwicky Transient Facility Searches Independent of Gravitational Wave and Short Gamma-Ray Burst Triggers

“…Searches in optical time-domain survey datasets are complementary to GW follow-up searches. The third Advanced LIGO/Virgo observing run (O3) took place entirely within the time frame in which data used in this work were taken and it was suspended without yielding any optical (or multi-wavelength) counterpart (Ackley et al 2020;Andreoni et al 2019b;Coughlin et al 2019b;Goldstein et al 2019;Gomez et al 2019;Hosseinzadeh et al 2019;Lundquist et al 2019;Andreoni et al 2020a;Antier et al 2020;Gompertz et al 2020;Vieira et al 2020;Watson et al 2020). In addition, it is possible that neutron star mergers occurred in the nearby Universe during O3 and were missed by the GW detectors because of instrument downtime and their unisotropic antenna pattern.…”