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

Abstract

General relativity 1 predicts that short orbital period binaries emit significant gravitational radiation, and the upcoming Laser Interferometer Space Antenna (LISA) 2 is expected to 1

A 1201 s Orbital Period Detached Binary: The First Double Helium Core White Dwarf LISA Verification Binary

“…Our mass estimates imply that the cool WD may be less massive than the hot WD. The same result is seen in ZTF J1539+5027 (Burdge et al 2019a). This would be surprising because one expects the cool WD to have evolved first, and thus be more massive than the hot WD.…”

“…Here, we report the discovery of the 1201 s orbital period binary SDSS J232230.20+050942.06 (hereafter J2322+0509). This is the third shortest-period detached binary after J0651+2844 (Brown et al 2011) and ZTF J1539+5027 (Burdge et al 2019a). While similar in period to J0935+4411 (Kilic et al 2014) and PTF J0533+0209 (Burdge et al 2019b), J2322+0509 has a face-on orientation i = 27 • .…”

ZTF J1901+5309: a 40.6-min orbital period eclipsing double white dwarf system

“…Then, by manual inspection, we selected systems to follow up (in particular, those which appeared to have a string of significant negative outliers phasing up into an eclipse-like feature). ZTF J1901+5309 was the second such object we identified after ZTF J1539+5027 (Burdge et al 2019). This was possible due to its location in the ZTF high declination survey, which has a sampling cadence of 6 times per night (3 in ZTF g-band, 3 in ZTF r-band); this is the same survey in which ZTF J1539+5027 was discovered.…”

“…We now use the phase-resolved spectroscopy from LRIS to measure the orbital velocities of the white dwarfs in the binary (see Burdge et al (2019) for a full discussion). The spectra exhibit broad and shallow hydrogen absorption lines, which are characteristic of a hot DA white dwarf, in Figure 4.…”

“…We discovered ZTF J1901+5309 by running the conditional entropy period-finding algorithm (Graham et al 2013) over the ZTF observations of a sample of all Pan-STARRS objects satisfying the color cut g − r < 0.0 and r − i < 0.0, in the same manner as described in Burdge et al (2019).…”