Lens Flare: Magnified X-Ray Binaries as Passive Beacons in SETI. (arXiv:2002.00128v1 [astro-ph.HE])
<a href="http://arxiv.org/find/astro-ph/1/au:+Lacki_B/0/1/0/all/0/1">Brian C. Lacki</a>
Low mass X-ray binaries (LMXBs) containing neutron stars are both extremely
luminous and compact, emitting up to ~10^6 L_sun within a kilometer-scale
boundary layer. This combination allows for easy modulation, motivating X-ray
SETI. When X-ray lenses smaller than planets (100 – 1,000 km) magnify the LMXB
boundary layer, it brightens by a factor of several thousand for about a
second. In addition, there should be occultation events where the neutron star
is blocked out. Passive X-ray lenses could require little maintenance and the
LMXB light source itself shines for millions of years, serving as an effective
beacon for interstellar communication. A very large number of lenses would be
needed to ensure detection from all directions, however, and gathering material
to construct them could be very difficult. Avoiding collisions between lenses
and aiming them pose additional challenges. Both “lens flares” and eclipses of
LMXBs are easily detectable in the Galaxy, although they would be rare events,
occurring once per decade. Our X-ray instruments could detect the flares to
several Mpc, but it is unlikely they would be observing the LMXB during a
flare.
Low mass X-ray binaries (LMXBs) containing neutron stars are both extremely
luminous and compact, emitting up to ~10^6 L_sun within a kilometer-scale
boundary layer. This combination allows for easy modulation, motivating X-ray
SETI. When X-ray lenses smaller than planets (100 – 1,000 km) magnify the LMXB
boundary layer, it brightens by a factor of several thousand for about a
second. In addition, there should be occultation events where the neutron star
is blocked out. Passive X-ray lenses could require little maintenance and the
LMXB light source itself shines for millions of years, serving as an effective
beacon for interstellar communication. A very large number of lenses would be
needed to ensure detection from all directions, however, and gathering material
to construct them could be very difficult. Avoiding collisions between lenses
and aiming them pose additional challenges. Both “lens flares” and eclipses of
LMXBs are easily detectable in the Galaxy, although they would be rare events,
occurring once per decade. Our X-ray instruments could detect the flares to
several Mpc, but it is unlikely they would be observing the LMXB during a
flare.
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