000006555 001__ 6555
000006555 005__ 20240110142547.0
000006555 0247_ $$2DOI$$a10.1051/0004-6361/202244742
000006555 037__ $$aSCART-2024-0012
000006555 100__ $$aBanyard, G
000006555 245__ $$aSearching for compact objects in the single-lined spectroscopic binaries of the young Galactic cluster NGC 6231
000006555 260__ $$c2023
000006555 520__ $$aContext. Recent evolutionary computations predict that a few percent of massive O or early-B stars in binary systems should have a dormant stellar-mass black hole (BH) as a companion. However, despite several reported candidate X-ray quiet OB+BH systems over the last couple of years, finding them with certainty remains challenging. Yet these have great importance as they can be gravitational wave (GW) source progenitors, and they are landmark systems in constraining supernova kick physics.  Aims: This work aims to characterise the hidden companions to the single-lined spectroscopic binaries (SB1s) identified in the B star population of the young open Galactic cluster NGC 6231 to find candidate systems for harbouring compact object companions.  Methods: With the orbital solutions for each SB1 constrained in a previous study, we applied Fourier spectral disentangling to multi-epoch optical VLT/FLAMES spectra of each target to extract a potential signature of a faint companion, and to identify newly disentangled double-lined spectroscopic binaries (SB2s). For targets where the disentangling does not reveal any spectral signature of a stellar companion, we performed atmospheric and evolutionary modelling on the primary (visible) star to obtain constraints on the mass and nature of the unseen companion.  Results: For seven of the 15 apparent SB1 systems, we extracted the spectral signature of a faint companion, resulting in seven newly classified SB2 systems with mass ratios down to near 0.1. From the remaining targets, for which no faint companion could be extracted from the spectra, four are found to have companion masses that lie in the predicted mass ranges of neutron stars (NSs) and BHs. Two of these targets have companion masses between 1 and 3.5 M⊙, making them potential hosts of NSs (or lower mass main sequence stars). The other two have mass ranges between 2.5 to 8 M⊙ and 1.6 and 26 M⊙, respectively, and so are identified as candidates for harbouring BH companions.  Conclusions: We present four SB1 systems in NGC 6231 that are candidates for harbouring compact objects, among which CD−41 11038 and CXOU J165421.3-415536 are the most convincing cases. We propose further observational tests involving photometric and interferometric follow-up observations of these objects.
000006555 594__ $$aNO
000006555 6531_ $$astars: early-type
000006555 6531_ $$astars: massive
000006555 6531_ $$astars: evolution
000006555 6531_ $$astars: black holes
000006555 6531_ $$abinaries: spectroscopic
000006555 6531_ $$aopen clusters and associations: individual: NGC 6231
000006555 6531_ $$aAstrophysics - Solar and Stellar Astrophysics
000006555 6531_ $$aAstrophysics - Astrophysics of Galaxies 
000006555 6531_ $$aAstrophysics - High Energy Astrophysical Phenomena
000006555 700__ $$aMahy, L
000006555 700__ $$aSana, H
000006555 700__ $$aBodensteiner, J
000006555 700__ $$aVillaseñor, J I
000006555 700__ $$aSen, K
000006555 700__ $$aLanger, N
000006555 700__ $$ade Mink, S
000006555 700__ $$aPicco, A
000006555 700__ $$aShenar, T
000006555 773__ $$c19$$nA60$$pAstronomy & Astrophysics$$v674$$y2023
000006555 8560_ $$flaurent.mahy@ksb-orb.be
000006555 8564_ $$s3591122$$uhttp://publi2-as.oma.be/record/6555/files/Banyard_2023.pdf
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000006555 905__ $$apublished in
000006555 980__ $$aREFERD