Imaging the Milky Way with Millihertz Gravitational Waves

Abstract

Modern astronomers enjoy access to all-sky images across a wide range of the electromagnetic spectrum from long-wavelength radio to high-energy gamma rays. The most prominent feature in many of these images is our own Galaxy, with different features revealed in each wave band. Gravitational waves (GWs) have recently been added to the astronomers’ toolkit as a nonelectromagnetic messenger. To date, all identified GW sources have been extra-Galactic and transient. However, the Milky Way hosts a population of ultracompact binaries (UCBs), which radiate persistent GWs in the milliHertz band that is not observable with today’s terrestrial gravitational-wave detectors. Space-based detectors such as the Laser Interferometer Space Antenna will measure this population and provide a census of their location, masses, and orbital properties. In this work, we will show how this data can be used to form a false-color image of the Galaxy that represents the intensity and frequency of the gravitational waves produced by the UCB population. Such images can be used to study the morphology of the Galaxy, identify interesting multimessenger sources through cross-matching, and for educational and outreach purposes.

LISA Galactic Binaries with Astrometry from Gaia DR3

“…Figure 5 shows that although the size of the candidate LISA binaries is progressively growing, it is still biased toward the Northern Hemisphere (where the majority of surveys have been conducted so far), and to high latitudes (to avoid the dust extinction and crowding in the Galactic plane). From observations of bright nondegenerate stars, we know that the Galactic stellar population is concentrated in the disk (the region in between the dashed lines) peaking toward the Galactic center (thick black cross in Figure 5), and so we expect LISA detectable binaries to follow the same distribution (e.g., see Szekerczes et al 2023). Figure 6 shows our sample of LISA sources compared to the absolute magnitudes (M G ) and colors (BP − RP) of Gaiaʼs sample of stars with parallax uncertainty below 1% (gray points).…”

Non-Magnetic Negative Coefficient of Thermal Expansion Support Structure between Payloads in the Taiji Space Gravitational Wave Detection Satellite

“…In the field of gravitational wave detection, the ground-based gravitational wave observatory LIGO directly detected a gravitational wave event for the first time in 2016 [4]. However, due to the limitations of the low-frequency Earth vibration and the Earth's curvature, the detection frequency range can only cover 10 Hz~10 4 Hz [5,6]. The sources in this range primarily include black hole mergers with masses ranging from tens to hundreds of times that of our Sun and binary neutron star mergers, holding significant astrophysical and cosmological importance.…”