On the properties of the massive binary black hole merger GW170729
Creators: name: Chatziioannou, Katerina
name: Cotesta, Roberto
name: Ghonge, Sudarshan
name: Lange, Jacob
name: Ng, Ken K. -Y.
name: Bustillo, Juan Calderon
name: Clark, James
name: Haster, Carl-Johan
name: Khan, Sebastian
name: Puerrer, Michael
name: Raymond, Vivien
name: Vitale, Salvatore
name: Afshari, Nousha
name: Babak, Stanislav
name: Barkett, Kevin
name: Blackman, Jonathan
name: Bohe, Alejandro
name: Boyle, Michael
name: Buonanno, Alessandra
name: Campanelli, Manuela
name: Carullo, Gregorio
name: Chu, Tony
name: Flynn, Eric
name: Fong, Heather
name: Garcia, Alyssa
name: Giesler, Matthew
name: Haney, Maria
name: Hannam, Mark
name: Harry, Ian
name: Healy, James
name: Hemberger, Daniel
name: Hinder, Ian
name: Jani, Karan
name: Khamersa, Bhavesh
name: Kidder, Lawrence E.
name: Kumar, Prayush
name: Laguna, Pablo
name: Lousto, Carlos O.
name: Lovelace, Geoffrey
name: Littenberg, Tyson B.
name: London, Lionel
name: Millhouse, Margaret
name: Nuttall, Laura K.
name: Ohme, Frank
name: O'Shaughnessy, Richard
name: Ossokine, Serguei
name: Pannarale, Francesco
name: Schmidt, Patricia
name: Pfeiffer, Harald P.
name: Scheel, Mark A.
name: Shao, Lijing
name: Shoemaker, Deirdre
name: Szilagyi, Bela
name: Taracchini, Andrea
name: Teukolsky, Saul A.
name: Zlochower, Yosef
Publisher: name: arXiv
Year: 2019
Subjects: subject: General Relativity and Quantum Cosmology (gr-qc)
subject: High Energy Astrophysical Phenomena (astro-ph.HE)
subject: FOS: Physical sciences
subject: FOS: Physical sciences

description: We present a detailed investigation into the properties of GW170729, the gravitational wave with the most massive and distant source confirmed to date. We employ an extensive set of waveform models, including new improved models that incorporate the effect of higher-order waveform modes which are particularly important for massive systems. We find no indication of spin-precession, but the inclusion of higher-order modes in the models results in an improved estimate for the mass ratio of $(0.3-0.8)$ at the 90\% credible level. Our updated measurement excludes equal masses at that level. We also find that models with higher-order modes lead to the data being more consistent with a smaller effective spin, with the probability that the effective spin is greater than zero being reduced from $99\%$ to $94\%$. The 90\% credible interval for the effective spin parameter is now $(-0.01-0.50)$. Additionally, the recovered signal-to-noise ratio increases by $\sim0.3$ units compared to analyses without higher-order modes. We study the effect of common spin priors on the derived spin and mass measurements, and observe small shifts in the spins, while the masses remain unaffected. We argue that our conclusions are robust against systematic errors in the waveform models. We also compare the above waveform-based analysis which employs compact-binary waveform models to a more flexible wavelet- and chirplet-based analysis. We find consistency between the two, with overlaps of $\sim 0.9$, typical of what is expected from simulations of signals similar to GW170729, confirming that the data are well-described by the existing waveform models. Finally, we study the possibility that the primary component of GW170729 was the remnant of a past merger of two black holes and find this scenario to be indistinguishable from the standard formation scenario.
description: 14 pages, 8 figures, final published version, samples available at https://git.ligo.org/katerina.chatziioannou/gw170729hm_datarelease