Precise Parameters for Two LISA Sources

Abstract

We present precise parameters for two compact double white dwarf binaries, SDSS J232230.20+050942.0 (J2322+0509) and SDSS J063449.92+380352.2 (J0634+3803), with orbital periods of 20 and 26.5 minutes, respectively. These systems will serve as verification sources for the Laser Interferometer Space Antenna (LISA). To significantly improve the electromagnetic (EM) constraints on these two systems and the LISA detectability predictions, we conducted spectroscopic follow-up observations using HST/STIS, Keck I/LRIS, and Keck II/ESI. Our analysis significantly improves the temperature, surface gravity, and mass constraints for both primary and secondary components in J2322+0509, as well as dynamical properties such as radial velocities and orbital periods in both systems. For J2322+0509, we derive an updated inclination of $i$ = 25${}_{-3.0}^{+4.5}$ deg, while for J0634+3803, we obtain $i$ = 43${}_{-5.6}^{+7.0}$ deg. We assess the detectability of these sources using LDASOFT. Incorporating EM priors on inclination significantly enhances the gravitational wave signal recovery, reducing uncertainties in amplitude by a factor of 2-4 and shortening the detection time by up to a few months. Our results underscore the importance of multi-messenger observations in characterizing double white dwarf binaries and maximizing LISA's early scientific capabilities.

12 pages, 5 figures. Accepted for publication in ApJ. In press

References in corpus (21)

• Gaia Data Release 3: Summary of the content and survey properties
• The Transiting Exoplanet Survey Satellite
• The UKIRT Infrared Deep Sky Survey (UKIDSS)
• The Zwicky Transient Facility: System Overview, Performance, and First Results
• Estimating distances from parallaxes. V: Geometric and photogeometric distances to 1.47 billion stars in Gaia Early Data Release 3
• The ELM Survey. I. A Complete Sample of Extremely Low Mass White Dwarfs
• Updated Gaia-2MASS 3D maps of Galactic interstellar dust
• One Relation for All Wavelengths: The Far-Ultraviolet to Mid-Infrared Milky Way Spectroscopic R(V) Dependent Dust Extinction Relationship
• Global Analysis of the Gravitational Wave Signal from Galactic Binaries
• Measurements of Physical Parameters of White Dwarfs: A Test of the Mass-Radius Relation
• An 8.8 minute orbital period eclipsing detached double white dwarf binary
• A New Gravitational Wave Verification Source
• Identifying LISA verification binaries among the Galactic population of double white dwarfs
• The ELM Survey. IX. A Complete Sample of Low Mass White Dwarf Binaries in the SDSS Footprint
• Gravitational Wave Radiation of Double Degenerates with Extremely low-mass WD companions
• The ELM Survey South. II. Two dozen new low mass white dwarf binaries
• A 1201 s Orbital Period Detached Binary: the First Double Helium Core White Dwarf LISA Verification Binary
• Measuring tides and binary parameters from gravitational wave data and eclipsing timings of detached white dwarf binaries
• Two new Double-lined Spectroscopic Binary White Dwarfs
• Orbital decay in an accreting and eclipsing 13.7 minute orbital period binary with a luminous donor
• The Discovery of Two LISA Sources within 0.5 kpc