Two galaxies seen in the distant sky might in fact be the same galaxy. The reason why could be huge.
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If cosmic strings exist, they could distort our view of the
universe. Image credit: Allexxandar |
A team of astrophysicists says they may have found evidence
for "cosmic strings", long-hypothesized defects in the universe left
over from its early in its expansion.
Cosmic strings were first suggested in the 1970s by
theoretical physicist Tom W. B. Kibble, and later revived in the context of
string theory. The one-dimensional strings, far narrower even than a proton,
are thought to have sprung into existence in the very first second of the
universe and could potentially stretch right across it.
The strings, sometimes referred to as cracks in the
universe, had not been detected since they were conceived, though there were a
few ideas on how we might. When strings cross, for instance, it could provide
us an opportunity to find them.
"Once formed, a loop is doomed," the LIGO
Scientific Collaboration explains. "It oscillates, radiates
gravitationally, shrinks and eventually evaporates. Strong gravitational
emission occurs at the pinch-off points of the loop, the cusps, which move with
a velocity close to the speed of light. Powerful bursts of gravitational waves
are expected to be produced by cosmic string cusps."
Cosmic strings should also be detectable in the Cosmic
Microwave Background (CMB) – the leftover radiation from the Big Bang that is
faintly detectable and permeates all of the known universe. Here, described in
a new pre-print paper, a team found several potential candidates for cosmic
strings, focusing on an area called CSc-1.
Cosmic strings – if they do exist – would be extremely
dense, and a potential source of potentially detectable gravitational waves.
They could also cause gravitational lensing, where space-time is warped by
immensely heavy objects, sometimes magnifying objects far into the distance to
astronomers.
Looking at two galaxies in the region they identified as the
best candidate, the team suspects they may have found evidence of gravitational
lensing. Two galaxies near each other and captured by the Himalayan Chandra
Telescope could in fact be one galaxy, according to the team. Analyzing it,
they found similar spectra between the two (or one) galaxy/ies.
"Our modeling of observational data in CSc-1 shows that
a large number of pairs can be explained by the complex geometry of the
string," the researchers wrote in their paper. "Considering a model
of a cosmic string with the bend in the image plane can improve the search for
GL event candidates. In particular, modeling of the SDSSJ110429-A,B galaxy pair
has shown that the observed angle between the components of the pair can be
explained if the string is strongly inclined to the line of sight and,
possibly, bent in the image plane."
The team is of course cautious, given that cosmic strings
have so far not been detected, and would like to observe further potential
evidence using more powerful telescopes.
The study is published on pre-print server arXiv and has
been accepted for publication in Bulletin de la Société Royale des Sciences de
Liège.