Triage of astrometric binaries – how to find triple systems and dormant black hole secondaries in the Gaia orbits

Shahaf, Sahar; Mazeh, T.; Faigler, S.; Holl, B.

doi:10.1093/mnras/stz1636

Cited by 40 publications

(37 citation statements)

References 35 publications

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“…( 8), we will call the expression with α the observational AMRF or just A and the right-most expression the theoretical AMRF. As Shahaf et al (2019) showed, the AMRF is a useful parameter for separating BH systems from non-degenerate systems, as we also show in Sect. 5.2.…”

Section: Identifying the Ob+bh Systemssupporting

confidence: 63%

“…The next step is to separate the needles -the OB+BH systems -from the haystack -normal binaries with two main-sequence components. For this, we used the method described by Shahaf et al (2019). Their method astrometrically identifies binaries with a compact object, based on the observed astrometric signal of the binaries.…”

Section: Identifying the Ob+bh Systemsmentioning

confidence: 99%

“…The dotted horizontal lines show the maximum of the theoretical AMRF for main-sequence binaries and triple mainsequence systems with a 30M primary. Based on these maxima, Shahaf et al (2019) distinguish between three classes (also indicated on the figure for a 30M primary). Systems with an observational A above the maximum of the triple-AMRF (corresponding to 0.365, 0.313, and 0.257 for the 9, 20, and 30 M pri-Fig.…”

Section: The Theoretical Amrf Curves For Different Massesmentioning

confidence: 99%

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Uncovering astrometric black hole binaries with massive main-sequence companions with Gaia

Janssens,

Shenar,

Sana

et al. 2021

Preprint

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Context. In the era of gravitational wave astrophysics and precise astrometry of billions of stellar sources, the hunt for compact objects is more alive than ever. Rarely seen massive binaries with a compact object are a crucial phase in the evolution towards compact object mergers. With the upcoming Gaia data release (DR3), the first Gaia astrometric orbital solutions for binary sources will become available, potentially revealing many such binaries. Aims. We investigate how many black holes (BH) with massive main-sequence dwarf companions (OB+BH binaries) are expected to be detected as binaries in Gaia DR3 and at the end of the nominal 5-yr mission. We estimate how many of those are identifiable as OB+BH binaries and we discuss the distributions of the masses of both components as well as of their orbital periods. We also explore how different BH-formation scenarios affect these distributions. Methods. We apply observational constraints to tailored models for the massive star population, which assume a direct collapse and no kick upon BH formation, to estimate the fraction of OB+BH systems that will be detected as binaries by Gaia, and consider these the fiducial results. These OB+BH systems follow a distance distribution according to that of the second Alma Luminous Star catalogue (ALS II). We use a method based on astrometric data to identify binaries with a compact object and investigate how many of the systems detected as binaries are identifiable as OB+BH binaries. Different scenarios for BH natal kicks and supernova mechanisms are explored and compared to the fiducial results. Results. In the fiducial case we conservatively estimate that 77% of the OB+BH binaries in the ALS II catalogue will be detected as binaries in DR3, of which 89% will be unambiguously identifiable as OB+BH binaries. At the end of the nominal 5-yr mission, the detected fraction will increase to 85%, of which 82% will be identifiable. The 99% confidence intervals on these fractions are of the order of a few percent. These fractions become smaller for different BH-formation scenarios. Conclusions. Assuming direct collapse and no natal kick, we expect to find around 190 OB+BH binaries with Gaia in DR3 among the sources in ALS II, which increases the known sample of OB+BH binaries by more than a factor of 20, covering an uncharted parameter space of long-period binaries (10 P 1000 d). Our results further show that the size and properties of the OB+BH population that is identifiable using Gaia DR3 will contain crucial observational constraints to improve our understanding of BH formation. An additional ∼5 OB+BH binaries could be identified at the end of the nominal 5-yr mission, which are expected to have either very short (P 10 d) or long periods (P 1000 d).

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Section: Identifying the Ob+bh Systemssupporting

confidence: 63%

Section: Identifying the Ob+bh Systemsmentioning

confidence: 99%

Section: The Theoretical Amrf Curves For Different Massesmentioning

confidence: 99%

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Uncovering astrometric black hole binaries with massive main-sequence companions with Gaia

Janssens,

Shenar,

Sana

et al. 2021

Preprint

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“…Carmichael et al 2021), radial velocity studies (e.g. Shahaf & Mazeh 2019), and microlensing observations (e.g. Han et al 2016;Poleski et al 2017) of main-sequence stars show that substellar objects exist in orbits of ∼ 1 AU.…”

Section: Introductionmentioning

confidence: 99%

ZTFJ0038+2030: A Long-period Eclipsing White Dwarf and a Substellar Companion

Roestel

Kupfer

Bell

et al. 2021

ApJL

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In a search for eclipsing white dwarfs using the Zwicky Transient Facility lightcurves, we identified a deep eclipsing white dwarf with a dark, substellar companion. The lack of an infrared excess and an orbital period of 10 hours made this a potential exoplanet candidate. We obtained high-speed photometry and radial velocity measurements to characterize the system. The white dwarf has a mass of 0.50 ± 0.02 M and a temperature of 10900 ± 200 K. The companion has a mass of 0.059 ± 0.004 M and a small radius of 0.0783 ± 0.0013 R . It is one of the smallest transiting brown dwarfs known and likely old, 8 Gyr. The ZTF discovery efficiency of substellar objects transiting white dwarfs is limited by the number of epochs and as ZTF continues to collect data we expect to find more of these systems. This will allow us to measure period and mass distributions and allows us to understand the formation channels of white dwarfs with substellar companions.

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“…While there is clearly much to be learned about astrometric binaries in which both stars are luminous, here we are interested in the rarer cases of luminous stars hosting dark companions such as black holes (BH). Several previous studies have focused on the population of unseen BH binaries with orbital periods shorter than Gaia's lifetime (Mashian & Loeb 2017;Breivik et al 2017;Yamaguchi et al 2018;Yalinewich et al 2018;Yi et al 2019;Shahaf et al 2019;Wiktorowicz et al 2020;Shikauchi et al 2020). These studies have been motivated in part by recent claimed detections of such detached BH binaries, both in the field (Thompson et al 2019;Liu et al 2019;Rivinius et al 2020;Jayasinghe et al 2021) and in globular clusters (Giesers et al 2018(Giesers et al , 2019.…”

Section: Introductionmentioning

confidence: 99%

Weighing the Darkness: Astrometric Mass Measurement of Hidden Stellar Companions Using Gaia

Andrews

Breivik

Chatterjee³

2019

ApJ

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In astrometric binaries, the presence of a dark, unseen star can be inferred from the gravitational pull it induces on its luminous binary companion. While the orbit of such binaries can be characterized with precise astrometric measurements, constraints made from astrometry alone are not enough to measure the component masses. In this work, we determine the precision with which Gaia can astrometrically measure the orbits and -with additional observations -the component masses, for luminous stars hosting hidden companions. Using realistic mock Gaia observations, we find that Gaia can precisely measure the orbits of binaries hosting hidden brown-dwarfs out to tens of pc and hidden white dwarf and neutron star companions at distances as far as several hundred pc. Heavier black hole companions may be measured out to 1 kpc or farther. We further determine how orbital period affects this precision, finding that Gaia can characterize orbits with periods as short as 10 days and as long as a few 10 3 days, with the best measured orbits having periods just short of Gaia's mission lifetime. Extending Gaia's nominal five-year mission lifetime by an additional five years not only allows for the measurement of longer period orbits, but those longer period binaries can be seen at even greater distances.

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Triage of astrometric binaries – how to find triple systems and dormant black hole secondaries in the Gaia orbits

Cited by 40 publications

References 35 publications

Uncovering astrometric black hole binaries with massive main-sequence companions with Gaia

Uncovering astrometric black hole binaries with massive main-sequence companions with Gaia

ZTFJ0038+2030: A Long-period Eclipsing White Dwarf and a Substellar Companion

Weighing the Darkness: Astrometric Mass Measurement of Hidden Stellar Companions Using Gaia

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