Abstract <p>A decrease in the orbital period of the ultracompact binary white dwarf ZTF J0538<InlineEquation ID="IEq3"> <EquationSource Format="TEX">\(+\)</EquationSource>  </InlineEquation>1953, which is one of the Galactic verification binaries in the millihertz frequency range for planned space laser interferometers, has been measured. Based on photometric observations carried out at the 2.5-m telescope of the Caucasian Mountain Observatory of Sternberg Astronomical Institute of Moscow State University (CMO SAI MSU), an <i>O-C</i> diagram is constructed. It can be described by quadratic elements of the brightness variations, which is in agreement to a decrease rate of the orbital period of the system of <InlineEquation ID="IEq4"> <EquationSource Format="TEX">\(dP/dt={-}(1.16\pm 0.22)\times 10^{-11}\)</EquationSource>  </InlineEquation> s/s. The decrease rate of the orbital period in the quadrupole approximation for the emission of gravitational waves by a binary system corresponds to its chirp mass <InlineEquation ID="IEq5"> <EquationSource Format="TEX">\(\mathcal{M}=0.434\pm 0.05\;M_{\odot}\)</EquationSource>  </InlineEquation>, which turned out to be <InlineEquation ID="IEq6"> <EquationSource Format="TEX">\({\sim}30\%\)</EquationSource>  </InlineEquation> higher than the value obtained earlier from spectroscopic mass determination. The chirp mass of ZTF J0538<InlineEquation ID="IEq7"> <EquationSource Format="TEX">\(+\)</EquationSource>  </InlineEquation>1953 inferred from the measured orbital decay rate makes this system the brightest Galactic verification binary for LISA and TianQin space interferometers with a signal-to-noise ratio of <InlineEquation ID="IEq8"> <EquationSource Format="TEX">\({\approx}119\)</EquationSource>  </InlineEquation> and <InlineEquation ID="IEq9"> <EquationSource Format="TEX">\({\approx}30\)</EquationSource>  </InlineEquation> over 5 and 2.5 years of observations, respectively.</p>

Double White Dwarf ZTF J0538\(\boldsymbol{+}\)1953 As the Brightest Verification Binary for Space Laser Interferometers

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2025年7月1日

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S. V. Antipin,
A. A. Belinski,
L. N. Berdinkov,
A. M. Zubareva,
N. A. Maslennikova,
K. A. Postnov,
I. A. Strakhov

摘要

Abstract

A decrease in the orbital period of the ultracompact binary white dwarf ZTF J0538 \(+\) 1953, which is one of the Galactic verification binaries in the millihertz frequency range for planned space laser interferometers, has been measured. Based on photometric observations carried out at the 2.5-m telescope of the Caucasian Mountain Observatory of Sternberg Astronomical Institute of Moscow State University (CMO SAI MSU), an O-C diagram is constructed. It can be described by quadratic elements of the brightness variations, which is in agreement to a decrease rate of the orbital period of the system of \(dP/dt={-}(1.16\pm 0.22)\times 10^{-11}\) s/s. The decrease rate of the orbital period in the quadrupole approximation for the emission of gravitational waves by a binary system corresponds to its chirp mass \(\mathcal{M}=0.434\pm 0.05\;M_{\odot}\) , which turned out to be \({\sim}30\%\) higher than the value obtained earlier from spectroscopic mass determination. The chirp mass of ZTF J0538 \(+\) 1953 inferred from the measured orbital decay rate makes this system the brightest Galactic verification binary for LISA and TianQin space interferometers with a signal-to-noise ratio of \({\approx}119\) and \({\approx}30\) over 5 and 2.5 years of observations, respectively.