2020/02/29 by Brian C. Lacki
Physics and Astronomy · #Astronomy #Astrophysical Phenomena and Observations #Astrophysics #Astrophysics and Cosmic Phenomena #Flare #Galaxy #Gamma-ray bursts and supernovae #Gravitational microlensing #Low Mass #Neutron star #Occultation #Physics #Stars #astro-ph.HE #physics.pop-ph
paper · pdf · doi:10.3847/1538-4357/abc1e3
published as ApJ 905 (2020), 18 · Published, 23 pages, 4 figures, 1 table. An animated version of Figure 3 is available at http://seti.berkeley.edu/lens_flare/ChromaticSpectrumEvolution.mp4
openalex publication_date 2020/12/01 · arxiv created 2021/01/28 · arxiv updated 2021/01/29 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
Abstract Low-mass X-ray binaries (LMXBs) containing neutron stars are both extremely luminous and compact, emitting up to ∼10 6 within a kilometer-scale boundary layer. This combination allows for easy modulation, motivating an X-ray Search for Extraterrestrial Intelligence. When X-ray lenses with radii magnify the LMXB boundary layer, it brightens by a factor of several thousand for a fraction of a second. In addition, there should be occultation events where the neutron star is blocked out. Passive X-ray lenses could require little internal power, and the LMXB light source itself shines for millions of years, with potential for an effective beacon for interstellar communication. A very large number of lenses would be needed to ensure frequent signals in all directions, however, and gathering material to construct them could be very difficult. Avoiding collisions between lenses, aiming them, and building and maintaining their precise shapes pose additional challenges. “Lens flares” of bright LMXBs are easily detectable in the Galaxy, although they would be rare events, occurring perhaps once per decade. Our more sensitive X-ray instruments could detect the eclipses of Galactic LMXBs and possibly intergalactic flares, but it is unlikely they would be observing the LMXB at the right time.