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Australia: The Land Where Time Began |
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Fast Radio Burst Host Galaxy
In recent years, radio signals of millisecond duration that originate in
distant galaxies have apparently been discovered in the so-called fast
radio bursts (Lorimer et al.,
2007; Keane et al., 2012;
Thornton et al., 2013;
Spitler et al., 2014;
Burke-Spolaor & Bannister, 2014; Ravi, Shannon & Jameson, 2015; Petroff
et al., 2015; Masui et
al., 2015; Champion et
al., 2015). These signals are
dispersed according to a precise physical law and this is a key
observable quantity, which, in tandem with a measurement of redshift can
be used for fundamental physical investigations (McQuinn, 2014; Zhou et
al., 2014). Every fast radio
burst has a dispersion measurement, but this is the first to have a
redshift measurement, as a result of the difficulty involved in
pinpointing their celestial coordinates. In this paper Keane et
al. report the discovery of a
fast radio burst and the identification of a fading radio transient that
lasted about 6 days following the event, which Keane et
al. used to identify the host
galaxy; they measured the redshift of the galaxy to be z = 0.492 ±
0.008. In combination, the dispersion measure and the redshift provide a
direct measurement of the cosmic density of ionised baryons in the
intergalactic medium of ΩIGM = 4.9 ± 1.3 %, which agrees with
the expectation from the Wilkinson Microwave Anisotropy Probe (Hinshaw
et al., 2013), and including
all the so-called ‘missing baryons’. According to Keane et
al., the about 6 day radio
transient is largely consistent with the radio afterglow of a short
γ-ray burst (Hinshaw et al.,
2013), and progenitor models such as giant pulses from pulsars and
supernovae are not supported by its existence and timescale. This is in
contrast with the interpretation (Masui et
al., 2015) of another fast
radio burst that was recently discovered, which suggests there are at
least 2 classes of bursts.
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Author: M.H.Monroe Email: admin@austhrutime.com Sources & Further reading |