The Galah survey and symbiotic stars. II. Discovery, validation, and intensive follow-up of 44 new systems accreting at the lowest detectable levels

@misc{munari2026galah,
  title = {{The Galah survey and symbiotic stars. II. Discovery, validation, and intensive follow-up of 44 new systems accreting at the lowest detectable levels}},
  author = {U. Munari and P. Valisa and N. Masetti and M. Fiorucci and M. Perko and B. Jamnik and G. Traven and A. Frigo and J. Bland-Hawthorn and S. Buder and A. R. Casey and G. M. De Silva and P. B. Das and K. C. Freeman and M. R. Hayden and J. Kos and G. F. Lewis and J. Lin and S. L. Martell and K. J. Schlesinger and S. Sharma and J. D. Simpson and D. Stello and D. B. Zucker and T. Zwitter},
  howpublished = {arXiv},
  year = {2026},
  month = nov,
  doi = {10.48550/arxiv.2611.05200},
  eprint = {2611.05200},
  archivePrefix = {arXiv},
  url = {https://arxiv.org/abs/2611.05200},
  note = {CC BY 4.0},
}

TY  - UNPB
TI  - The Galah survey and symbiotic stars. II. Discovery, validation, and intensive follow-up of 44 new systems accreting at the lowest detectable levels
AU  - U. Munari
AU  - P. Valisa
AU  - N. Masetti
AU  - M. Fiorucci
AU  - M. Perko
AU  - B. Jamnik
AU  - G. Traven
AU  - A. Frigo
AU  - J. Bland-Hawthorn
AU  - S. Buder
AU  - A. R. Casey
AU  - G. M. De Silva
AU  - P. B. Das
AU  - K. C. Freeman
AU  - M. R. Hayden
AU  - J. Kos
AU  - G. F. Lewis
AU  - J. Lin
AU  - S. L. Martell
AU  - K. J. Schlesinger
AU  - S. Sharma
AU  - J. D. Simpson
AU  - D. Stello
AU  - D. B. Zucker
AU  - T. Zwitter
PY  - 2026
DA  - 2026/11/03
PB  - arXiv
DO  - 10.48550/arxiv.2611.05200
UR  - https://arxiv.org/abs/2611.05200
AB  - We report the discovery, validation, and characterization of 44 new symbiotic stars (SySts) accreting at the lowest detectable levels (Lacc =< 3 Lsun). Candidates were initially selected from the Galah survey among non-pulsating M-type red giants exhibiting Halpha excess. Between 2021 and 2025, these targets were subjected to intensive multi-wavelength campaigns, including ground-based, high-resolution Echelle spectroscopy over 544 nights, multi-epoch flickering searches down to 1 mmag, and UV/X-ray observations with the Swift satellite. Our high-resolution spectra allowed for a detailed investigation of Halpha flux and line-profile variability. Crucially, the radial velocities measured for the M-giant components yielded reliable spectroscopic orbits for 22 objects and preliminary orbits for an additional eight, corroborated by binary-induced modulations in ASAS-SN photometry. Measured accretion levels vary by factors of up to 20X, emphasizing the need for high-sensitivity, long-term monitoring. Swift X-ray data exclude neutron star companions in all targets, consistent with predominance of white-dwarf degenerates in known SySts. Combined with the 33 objects from Paper I, this sample of 77 new SySts significantly exceeds the number of previously known, accreting-only Galactic symbiotic stars, constituting the bulk of the low-accretion (LowAcc) variety discovered to date and representing >10 percent of all known SySts in the Galaxy. As SySts likely spend most of their lifetimes in LowAcc faint states, characterizing this population is essential for estimating the total Galactic SySt population and evaluating the role of SySts as Type Ia supernova progenitors or sources of UV excess in elliptical galaxies.
ER  -