NO CORRELATION BETWEEN FERMI GBM SIGNAL AND GW150914

Image: Merging black holes. Credit: NASA

Recently it has been suggested that electromagnetic signals detected by Fermi GBM could be associated with the merger of the two black holes detected by LIGO (GW150914).

In a recent paper (Lyutikov 2016) the author assesses that the physical constraints required by the association of the Fermi GBM signal contemporaneous with GW150914 - radiative power of 10⁴⁹ erg s⁻¹, and corresponding magnetic fields on the black hole of the order of 10¹² Gauss - are astrophysically highly implausible.

Combined with the relatively high random probability of coincidence of 0.22 percents, he concludes that the electromagnetic signal is likely unrelated to the BH merger.

Lyutikov 2016 (preprint) - Fermi GBM signal contemporaneous with GW150914 - an unlikely association (arXiv)

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CONSTRAINTS ON THE LOCATION OF A POSSIBLE 9TH PLANET

Image: The six most distant known objects in the solar system with orbits exclusively beyond Neptune (magenta) all mysteriously line up in a single direction. Such an orbital alignment can only be maintained by some outside force, Batygin and Brown say. Their paper argues that a planet with 10 times the mass of the earth in a distant eccentric orbit anti-aligned with the other six objects (orange) is required to maintain this configuration. Credit: Caltech The astronomers have noticed some of the dwarf planets and other small, icy objects tend to follow orbits that cluster together. To explain the unusual distribution of these Kuiper Belt objects, several authors have advocated the existence of a superEarth planet in the outer solar system ( planet Nine or planet X ).

ORBITAL PERIODS OF THE PLANETS

For orbital period generally we refer to the sidereal period, that is the temporal cycle that it takes an object to make a full orbit, relative to the stars. This is the orbital period in an inertial (non-rotating) frame of reference (365,25 days for the earth).

CONTAMINATION BY SUPERNOVAE IN GLOBULAR CLUSTERS

Credit: ALMA (ESO/NAOJ/NRAO)/Alexandra Angelich (NRAO/AUI/NSF) Only a small amount of the supernovae products remains trapped within globular clusters and this "catch" only occurs in the most massive cases (mass cluster ≥ 10^6 solar masses).

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