The Tarantula Massive Binary Monitoring VI. Characterisation of hidden companions in 51 single-lined O-type binaries: A flat mass-ratio distribution and black-hole binary candidates

被引：37

作者：

Shenar, T. ^{[1
,2
]}

Sana, H. ^{[2
]}

Mahy, L. ^{[2
,3
]}

Maiz Apellaniz, J. ^{[9
]}

Crowther, Paul A. ^{[4
]}

Gromadzki, M. ^{[12
]}

Herrero, A. ^{[5
,6
]}

Langer, N. ^{[7
,8
]}

Marchant, P. ^{[2
]}

Schneider, F. R. N. ^{[10
,11
]}

Sen, K. ^{[7
,8
]}

Soszynski, I ^{[12
]}

Toonen, S. ^{[1
]}

机构：

[1] Anton Pannekoek Inst Astron, Sci Pk 904, NL-1098 XH Amsterdam, Netherlands

[2] Katholieke Univ Leuven, Inst Astron, Celestijnenlaan 200D, B-3001 Leuven, Belgium

[3] Royal Observ Belgium, Ave Circulaire Ringlaan 3, B-1180 Brussels, Belgium

[4] Univ Sheffield, Dept Phys & Astron, Hounsfield Rd, Sheffield S3 7RH, S Yorkshire, England

[5] Inst Astrofis Canarias, Tenerife 38200, Spain

[6] Univ La Laguna, Dept Astrofis, Tenerife 38205, Spain

[7] Univ Bonn, Argelander Inst Astron, Hugel 71, D-53121 Bonn, Germany

[8] Max Planck Inst Radioastron, Hugel 69, D-53121 Bonn, Germany

[9] CSIC INTA, Ctr Astrobiol CAB, Campus ESAC, Madrid 28692, Spain

[10] Heidelberger Inst Theoret Studien, Schloss Wolfsbrunnenweg 35, D-69118 Heidelberg, Germany

[11] Heidelberg Univ, Zentrum Astron, Astron Rech Inst, Monchhofstr 12-14, D-69120 Heidelberg, Germany

[12] Univ Warsaw, Astron Observ, Al Ujazdowskie 4, PL-00478 Warsaw, Poland

来源：

ASTRONOMY & ASTROPHYSICS | 2022年 / 665卷

基金：

英国科学技术设施理事会; 欧盟地平线“2020”; 欧洲研究理事会;

关键词：

binaries: spectroscopic; stars: black holes; Magellanic Clouds; stars: massive; stars: evolution; BLANKETED MODEL ATMOSPHERES; GRAVITATIONAL LENSING EXPERIMENT; WOLF-RAYET BINARY; SPECTRAL CLASSIFICATION; MULTIPLICITY PROPERTIES; COMPOSITE SPECTRA; ORBITAL ANALYSIS; STAR; EVOLUTION; SYSTEM;

D O I：

10.1051/0004-6361/202244245

中图分类号：

P1 [天文学];

学科分类号：

0704 ;

摘要：

Context. Massive binaries hosting a black hole (OB+BH) represent a critical phase in the production of BH mergers in the context of binary evolution. In spite of this, such systems have so far largely avoided detection. Single-lined spectroscopic (SB1) O-type binaries are ideal objects to search for elusive BH companions. Moreover, SB1 binaries hosting two main sequence stars probe a regime of more extreme mass ratios and longer periods compared to double-lined binaries (SB2), and they are thus valuable for establishing the natal mass ratio distribution of massive stars. Aims. We characterise the hidden companions in 51 SB1 O-type and evolved B-type binaries identified in the Large Magellanic Cloud (LMC) in the framework of the VLT-FLAMES Tarantula Survey (VFTS) and its follow-up, the Tarantula Massive Binary Monitoring (TMBM). The binaries cover periods between a few days to years (0 < log P < 3 [d]). Our goals are to hunt for BHs and sample the low-mass end of the mass-ratio distribution. Methods. To uncover the hidden companions, we implemented the shift-and-add grid disentangling algorithm using 32 epochs of spectroscopy acquired in the framework of TMBM with the FLAMES spectrograph, allowing us to detect companions contributing as little as approximate to 1-2% to the visual flux. We further analysed OGLE photometric data for the presence of eclipses or ellipsoidal variations. Results. Out of the 51 SB1 systems, 43 (84%) are found to have non-degenerate stellar companions, of which 28 are confident detections and 15 are less certain (SB1: or SB2:). Of these 43 targets, one is found to be a triple (VFTS 64), and two are found to be quadruples (VFTS 120, 702). Our sample includes a total of eight eclipsing binaries. The remaining eight targets (16%) retain an SB1 classification. We modelled the mass-ratio distribution as f (q) proportional to q(kappa), and derived k through a Bayesian approach. We used massratio constraints from previously known SB2 binaries, newly uncovered SB2 binaries, and SB1 binaries, while accounting for binary detection bias. We found kappa = 0.2 +/- 0.2 for the entire sample and kappa = -0.2 +/- 0.2 when excluding binaries with periods shorter than 10 d. In contrast, kappa = 1.2 +/- 0.5 was retrieved for tight binaries (P < 10 d), and it is proposed here to be a consequence of binary interactions. Aside from the unambiguous O+BH binary VFTS 243, which was analysed in detail in a separate paper, we identified two additional OB+BH candidates: VFTS 514 and 779. Conclusions. Our study firmly establishes a virtually flat natal mass-ratio distribution (kappa = 0) for O-type stars at LMC metallicity, covering the entire mass-ratio range (0.05 < q < 1) and periods in the range 0 < log P < 3 [d]. The nature of the OB+BH candidates should be verified through future monitoring, but the frequency of OB+BH candidates is generally in line with recent predictions at LMC metallicity.

引用

页数：42