General relativistic orbital decay in a seven-minute-orbital-period eclipsing binary system

Area of Science:

• Astrophysics
• Gravitational Waves
• Binary Star Systems

Background:

• General relativity predicts that short-orbital-period binaries emit significant gravitational radiation.
• The Laser Interferometer Space Antenna (LISA) mission is anticipated to detect numerous such systems.
• Few eclipsing double-white-dwarf binaries have been identified, limiting observational studies.

Purpose of the Study:

• To report the discovery of a new eclipsing double-white-dwarf binary system.
• To characterize its orbital period, compactness, and gravitational wave emission.
• To assess its potential for detection by the upcoming LISA mission.

Main Methods:

• Photometric observations to identify eclipses and determine orbital period.
• Spectroscopic analysis to confirm double-lined nature and orbital dynamics.
• Analysis of orbital decay to verify consistency with general relativity predictions.

Main Results:

• Discovery of ZTF J153932.16+502738.8, an eclipsing double-white-dwarf binary with a 6.91-minute orbital period.
• The system exhibits a compact orbit, deep eclipses, and double-lined spectroscopic features.
• Observed rapid orbital decay is consistent with general relativity predictions for gravitational wave emission.

Conclusions:

• ZTF J153932.16+502738.8 is a unique, extremely compact binary system.
• It represents a strong source of gravitational radiation, nearing the peak sensitivity of LISA.
• The system is expected to be readily detectable by LISA shortly after its launch.