Constraints on Neutrino Natal Kicks from Black-Hole Binary VFTS 243 Article Swipe
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· 2024
· Open Access
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· DOI: https://doi.org/10.1103/physrevlett.132.191403
· OA: W4396767807
The recently reported observation of VFTS 243 is the first example of a massive black-hole binary system with negligible binary interaction following black-hole formation. The black-hole mass (<a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"><a:mo>≈</a:mo><a:mn>10</a:mn><a:msub><a:mi>M</a:mi><a:mo stretchy="false">⊙</a:mo></a:msub></a:math>) and near-circular orbit (<d:math xmlns:d="http://www.w3.org/1998/Math/MathML" display="inline"><d:mi>e</d:mi><d:mo>≈</d:mo><d:mn>0.02</d:mn></d:math>) of VFTS 243 suggest that the progenitor star experienced complete collapse, with energy-momentum being lost predominantly through neutrinos. VFTS 243 enables us to constrain the natal kick and neutrino-emission asymmetry during black-hole formation. At 68% confidence level, the natal kick velocity (mass decrement) is <f:math xmlns:f="http://www.w3.org/1998/Math/MathML" display="inline"><f:mo>≲</f:mo><f:mn>10</f:mn><f:mtext> </f:mtext><f:mtext> </f:mtext><f:mi>km</f:mi><f:mo>/</f:mo><f:mi mathvariant="normal">s</f:mi></f:math> (<i:math xmlns:i="http://www.w3.org/1998/Math/MathML" display="inline"><i:mrow><i:mo>≲</i:mo><i:mn>1.0</i:mn><i:msub><i:mrow><i:mi>M</i:mi></i:mrow><i:mrow><i:mo stretchy="false">⊙</i:mo></i:mrow></i:msub></i:mrow></i:math>), with a full probability distribution that peaks when <l:math xmlns:l="http://www.w3.org/1998/Math/MathML" display="inline"><l:mrow><l:mo>≈</l:mo><l:mn>0.3</l:mn><l:msub><l:mrow><l:mi>M</l:mi></l:mrow><l:mrow><l:mo stretchy="false">⊙</l:mo></l:mrow></l:msub></l:mrow></l:math> were ejected, presumably in neutrinos, and the black hole experienced a natal kick of <o:math xmlns:o="http://www.w3.org/1998/Math/MathML" display="inline"><o:mrow><o:mn>4</o:mn><o:mtext> </o:mtext><o:mtext> </o:mtext><o:mi>km</o:mi><o:mo>/</o:mo><o:mi mathvariant="normal">s</o:mi></o:mrow></o:math>. The neutrino-emission asymmetry is <r:math xmlns:r="http://www.w3.org/1998/Math/MathML" display="inline"><r:mo>≲</r:mo><r:mn>4</r:mn><r:mo>%</r:mo></r:math>, with best fit values of <t:math xmlns:t="http://www.w3.org/1998/Math/MathML" display="inline"><t:mrow><t:mo>∼</t:mo><t:mn>0</t:mn><t:mi>–</t:mi><t:mn>0.2</t:mn><t:mo>%</t:mo></t:mrow></t:math>. Such a small neutrino natal kick accompanying black-hole formation is in agreement with theoretical predictions. Published by the American Physical Society 2024
