10,145 research outputs found
Very Old Isolated Compact Objects as Dark Matter Probes
Very old isolated neutron stars and white dwarfs have been suggested to be
probes of dark matter. To play such a role, two requests should be fulfilled,
i.e., the annihilation luminosity of the captured dark matter particles is
above the thermal emission of the cooling compact objects (request-I) and also
dominate over the energy output due to the accretion of normal matter onto the
compact objects (request-II). Request-I calls for very dense dark matter medium
and the critical density sensitively depends on the residual surface
temperature of the very old compact objects. The accretion of
interstellar/intracluster medium onto the compact objects is governed by the
physical properties of the medium and by the magnetization and rotation of the
stars and may outshine the signal of dark matter annihilation. Only in a few
specific scenarios both requests are satisfied and the compact objects are dark
matter burners. The observational challenges are discussed and a possible way
to identify the dark matter burners is outlined.Comment: 9 pages including 1 Figure, to appear in Phys. Rev.
A possible Macronova in the late afterglow of the `long-short' burst GRB 060614
Long-duration ( s) -ray bursts that are believed to originate
from the death of massive stars are expected to be accompanied by supernovae.
GRB 060614, that lasted 102 s, lacks a supernova-like emission down to very
stringent limits and its physical origin is still debated. Here we report the
discovery of near-infrared bump that is significantly above the regular
decaying afterglow. This red bump is inconsistent with even the weakest known
supernova. However, it can arise from a Li-Paczy\'{n}ski macronova the
radioactive decay of debris following a compact binary merger. If this
interpretation is correct GRB 060614 arose from a compact binary merger rather
than from the death of a massive star and it was a site of a significant
production of heavy r-process elements. The significant ejected mass favors a
black hole-neutron star merger but a double neutron star merger cannot be ruled
out.Comment: Minor revision; The version published in Nature Communication
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