"Shouldn't find a galaxy like this": The next puzzle about the young universe
In the early days of the universe, galaxies had to make the cosmos transparent; not all their light was meant to reach us. GS-z13-1 therefore raises questions.
The small red dot in the section is JADES-GS-z13-1,
(Image: NASA, ESA, CSA, JADES Collaboration, J. Witstok (University of Cambridge/University of Copenhagen), P. Jakobsen (University of Copenhagen), A. Pagan (STScI), M. Zamani (ESA/Webb))
Signals received by the James Webb space telescope from one of the galaxies furthest away from us should not reach us at all and pose a mystery for researchers. NASA has made this public. The light of the galaxy with the designation GS-z13-1 has a redshift of z = 13.0, meaning that it can be seen as it appeared around 330 million years after the Big Bang. However, the so-called Lyman-α line of the spectrum, which can be traced back to hydrogen atoms, is unexpectedly strong. At that time, the universe should not have been transparent enough to let them through. The discovery could have major consequences for our understanding of the early history of the universe.
(Image:Â NASA, ESA, CSA, J. Witstok (University of Cambridge, University of Copenhagen), J. Olmsted (STScI))
By way of explanation, Roberto Maiolino, a member of the research team, recalls that the cosmos was opaque for hundreds of millions of years after the Big Bang in the so-called Dark Ages: "The early universe was shrouded in a dense fog of neutral hydrogen." It was only during the so-called reionization that the translucent universe we know today emerged. It is actually assumed that this epoch was only completed around a billion years after the Big Bang. But the surprisingly clear Lyman-α line of GS-z13-1 seems to contradict this, as the signal would then have to have been largely swallowed up.
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"We really shouldn't have found a galaxy like this, given what we know about the formation of the early universe," NASA quotes Kevin Hainline, another astronomer involved. One could imagine the early universe as being shrouded in a dense fog in which not even the strongest lighthouses were visible. And now there is this clear signal. The source of the Lyman-α line itself is therefore still unclear, but it is conceivable that it originates from stars of the very first population. Population III refers to the first generation of stars that consisted almost exclusively of hydrogen and helium and have not yet been detected.
Constant surprises for cosmology
The analysis of GS-z13-1 was presented last week in the scientific journal Nature. The work proves once again how powerful the James Webb space telescope is and what an enormous help it is in researching the early universe. The instrument repeatedly discovers details that cannot be reconciled with our theories and computer models of the early universe. The reionization epoch has also been researched with the instrument. This has revealed, for example, that comparatively small dwarf galaxies in particular have cleared the early universe and made it transparent. The process itself has also been observed directly.
(mho)
