What are the spectroscopic binaries with high mass functions near the Gaia DR3 main sequence?

Abstract

The 3rd data release of the Gaia mission includes orbital solutions for $>10^5$ single-lined spectroscopic binaries, representing more than an order of magnitude increase in sample size over all previous studies. This dataset is a treasure trove for searches for quiescent black hole + normal star binaries. We investigate one population of black hole candidate binaries highlighted in the data release: sources near the main sequence in the color-magnitude diagram (CMD) with dynamically-inferred companion masses $M_2$ larger than the CMD-inferred mass of the luminous star. We model light curves, spectral energy distributions, and archival spectra of the 14 such objects in DR3 with high-significance orbital solutions and inferred $M_2>3M_{\odot }$. We find that 100\% of these sources are mass-transfer binaries containing a highly stripped lower giant donor ($0.2\lesssim M/M_{\odot }\lesssim 0.4$) and much more massive ($2\lesssim M/M_{\odot }\lesssim 2.5$) main-sequence accretor. The Gaia orbital solutions are for the donors, which contribute about half the light in the Gaia RVS bandpass but only $\lesssim 20\%$ in the $g-$band. The accretors' broad spectral features likely prevented the sources from being classified as double-lined. The donors are all close to Roche lobe-filling ($R/R_{\mathrm{Roche}\mathrm{lobe}}>0.8$), but modeling suggests that a majority are detached ($R/R_{\mathrm{Roche}\mathrm{lobe}}<1$). Binary evolution models predict that these systems will soon become detached helium white dwarf + main sequence "EL CVn" binaries. Our investigation highlights both the power of Gaia data for selecting interesting sub-populations of binaries and the ways in which binary evolution can bamboozle standard CMD-based stellar mass estimates.

10 pages, 7 figures. Accepted to MNRAS

References in corpus (9)

• Modules for Experiments in Stellar Astrophysics (MESA)
• Gaia Data Release 3: Summary of the content and survey properties
• Modules for Experiments in Stellar Astrophysics (MESA): Pulsating Variable Stars, Rotation, Convective Boundaries, and Energy Conservation
• The All-Sky Automated Survey for Supernovae (ASAS-SN) Light Curve Server v1.0
• Initial Performance of the NEOWISE Reactivation Mission
• Gaia-2MASS 3D maps of Galactic interstellar dust within 3 kpc
• The Gaia-ESO Survey: double, triple and quadruple-line spectroscopic binary candidates
• Unicorns and Giraffes in the binary zoo: stripped giants with subgiant companions
• Properties and nature of Be stars 30. Reliable physical properties of a semi-detached B9.5e+G8III binary BR CMi = HD 61273 compared to those of other well studied semi-detached emission-line binaries

Cited by in corpus (18)

• A Sun-like star orbiting a black hole
• A red giant orbiting a black hole
• A non-interacting Galactic black hole candidate in a binary system with a main-sequence star
• Triage of the Gaia DR3 astrometric orbits. I. A sample of binaries with probable compact companions
• Search for a Black Hole Binary in Gaia DR3 Astrometric Binary Stars with Spectroscopic Data
• Probable Dormant Neutron Star in a Short-Period Binary System
• The White Dwarf Binary Pathways Survey -- IX. Three long period white dwarf plus subgiant binaries
• Spectroscopic follow-up of black hole and neutron star candidates in ellipsoidal variables from Gaia DR3
• Blue Stragglers and Friends: Initial Evolutionary Pathways in Close Low-Mass Binaries: Literature Review
• Searching for compact objects in binaries with Gaia DR3
• Population demographics of white dwarf binaries with intermediate separations: Gaia constraints on post-AGB mass transfer
• Spatial and Binary Parameter Distributions of Black Hole Binaries in the Milky Way Detectable with Gaia
• Detection of single-degenerate massive binaries with Gaia: The impact of blue supergiants, triples, mass precision, and high-precision parallax requirements
• High mass function ellipsoidal variables in the Gaia Focused Product Release: searching for black hole candidates in the binary zoo
• An upper limit on the frequency of short-period black hole companions to Sun-like stars
• Everything that glitters is not gold: V1315 Cas is not a dormant black hole
• A comprehensive Gaia view of ellipsoidal and rotational red giant binaries
• Two unseen massive white dwarf candidates in close binaries