J/A+A/664/A159 Radial velocities of Galactic SB1s (Mahy+, 2022)
Identifying quiescent compact objects in massive Galactic single-lined
spectroscopic binaries.
Mahy L., Sana H., Shenar T., Sen K., Langer N., Marchant P.,
Abdul-Masih M., Banyard G., Bodensteiner J., Bowman D.M., Dsilva K.,
Fabry M., Hawcroft C., Janssens S., Van Reeth T., Eldridge C.
<Astron. Astrophys. 664, A159 (2022)>
=2022A&A...664A.159M 2022A&A...664A.159M (SIMBAD/NED BibCode)
ADC_Keywords: Stars, variable ; Binaries, spectroscopic ; Spectroscopy ;
Radial velocities ; Optical
Keywords: binaries: general - binaries: spectroscopic - stars: early-type -
stars: evolution - stars: black holes
Abstract:
The quest to detect dormant stellar-mass black holes (BHs) in massive
binaries (i.e., OB+BH systems) is challenging, and only a few
candidates have been claimed to date but must still be confirmed as
such.
To search for these rare objects, we study 32 Galactic O-type stars
that were reported as single-lined spectroscopic binaries (SB1s) in
the literature. In our sample we include Cyg X-1, which is known to
host an accreting stellar-mass BH, and, HD 74194, a supergiant fast
X-ray transient, in order to validate our methodology. The final goal
is to characterise the nature of the unseen companions to determine if
they are main-sequence (MS) stars, stripped helium stars, triples or
compact objects such as neutron stars (NSs) or stellar-mass BHs.
After measuring radial velocities and deriving orbital solutions for
all the systems in our sample, we performed spectral disentangling to
extract putative signatures of faint secondary companions from the
composite spectra. We derived stellar parameters for the visible stars
and estimated the mass ranges of the secondary stars using the binary
mass function. Variability observed in the photometric TESS light
curves was also searched for indications of the presence of putative
companions, degenerate or not.
In 17 of the 32 systems reported as SB1s, we extract secondary
signatures, down to mass ratios of 0.15. For the 17 newly detected
double-lined spectroscopic binaries (SB2s), we derive physical
properties of the individual components and discuss why they have not
been detected as such before. Among the remaining systems, we identify
nine systems with possible NS or low-mass MS companions. For Cyg X-1
and HD 130298, we are not able to extract any signatures for the
companions, while the minimum masses of their companions are estimated
to be about 7 Msun. Our simulations show that secondaries with such a
mass should be detectable from our data set, no matter their nature:
MS star, stripped helium stars or even triples. While this is expected
for Cyg X-1, confirming at the same time our methodology, this also
strongly suggests that HD 130298 could be another candidates to host a
stellar-mass BH.
The quest to detect dormant stellar-mass BHs in massive binaries is
far from over, and many more systems need to be scrutinised. Our
analysis allows us to detect a good candidate, but confirming the BH
nature of their companions will require further dedicated monitorings,
sophisticated analysis techniques, and multi-wavelength observations.
Description:
Search for quiescent stellar-mass BHs in Galactic SB1s.
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
stars.dat 62 32 List of studied stars
rv.dat 33 812 Radial velocities derived for all the stars
in the paper
--------------------------------------------------------------------------------
Byte-by-byte Description of file: stars.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 9 A9 --- Star Star name
14- 15 I2 h RAh Right ascension (J2000)
17- 18 I2 min RAm Right ascension (J2000)
20- 24 F5.2 s RAs Right ascension (J2000)
26 A1 --- DE- Declination sign (J2000)
27- 28 I2 deg DEd Declination (J2000)
30- 31 I2 arcmin DEm Declination (J2000)
33- 36 F4.1 arcsec DEs Declination (J2000)
38- 48 F11.7 d Per Period (from tables 1 and 2 of the paper)
50- 58 F9.7 d e_Per Period error (from tables 1 and 2 of the paper)
60- 62 A3 --- Type [SB1 SB2] SB1 or SB2
(from tables 1 and 2 of the paper)
--------------------------------------------------------------------------------
Byte-by-byte Description of file: rv.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 9 A9 --- Star Star name
11- 19 F9.4 d HJD Heliocentric Julian date (HJD-2450000)
21- 27 F7.2 km/s RV Radial velocity of the star
29- 33 F5.2 km/s e_RV 1 sigma error on the radial velocity measurement
--------------------------------------------------------------------------------
Acknowledgements:
Laurent Mahy, laurent.mahy(at)oma.be
(End) Patricia Vannier [CDS] 27-May-2022