Improved Analysis of GW150914 Using a Fully Spin-Precessing Waveform Model

Abstract

This paper presents updated estimates of source parameters for GW150914, a binary black-hole coalescence event detected by the Laser Interferometer Gravitational-wave Observatory (LIGO) in 2015 [Abbott , 061102 (2016).]. Abbott [ , 241102 (2016).] presented parameter estimation of the source using a 13-dimensional, phenomenological precessing-spin model (precessing IMRPhenom) and an 11-dimensional nonprecessing effective-one-body (EOB) model calibrated to numerical-relativity simulations, which forces spin alignment (nonprecessing EOBNR). Here, we present new results that include a 15-dimensional precessing-spin waveform model (precessing EOBNR) developed within the EOB formalism. We find good agreement with the parameters estimated previously [Abbott , 241102 (2016).], and we quote updated component masses of <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"><a:mrow><a:msubsup><a:mrow><a:mn>35</a:mn></a:mrow><a:mrow><a:mo>−</a:mo><a:mn>3</a:mn></a:mrow><a:mrow><a:mo>+</a:mo><a:mn>5</a:mn></a:mrow></a:msubsup></a:mrow></a:math> <c:math xmlns:c="http://www.w3.org/1998/Math/MathML" display="inline"><c:mrow><c:msub><c:mrow><c:mi mathvariant="normal">M</c:mi></c:mrow><c:mrow><c:mo stretchy="false">⊙</c:mo></c:mrow></c:msub></c:mrow></c:math> and <g:math xmlns:g="http://www.w3.org/1998/Math/MathML" display="inline"><g:mn>3</g:mn><g:msubsup><g:mn>0</g:mn><g:mrow><g:mo>−</g:mo><g:mn>4</g:mn></g:mrow><g:mrow><g:mo>+</g:mo><g:mn>3</g:mn></g:mrow></g:msubsup></g:math> <i:math xmlns:i="http://www.w3.org/1998/Math/MathML" display="inline"><i:msub><i:mi mathvariant="normal">M</i:mi><i:mo stretchy="false">⊙</i:mo></i:msub></i:math> (where errors correspond to 90% symmetric credible intervals). We also present slightly tighter constraints on the dimensionless spin magnitudes of the two black holes, with a primary spin estimate <m:math xmlns:m="http://www.w3.org/1998/Math/MathML" display="inline"><m:mo>&lt;</m:mo><m:mn>0.65</m:mn></m:math> and a secondary spin estimate <o:math xmlns:o="http://www.w3.org/1998/Math/MathML" display="inline"><o:mo>&lt;</o:mo><o:mn>0.75</o:mn></o:math> at 90% probability. Abbott [ , 241102 (2016).] estimated the systematic parameter-extraction errors due to waveform-model uncertainty by combining the posterior probability densities of precessing IMRPhenom and nonprecessing EOBNR. Here, we find that the two precessing-spin models are in closer agreement, suggesting that these systematic errors are smaller than previously quoted. Published by the American Physical Society 2016