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The uncertainty of science: A new study has found that the accepted consensus for the formation of large elliptical galaxies does not work, and that, rather than forming from the merger of smaller spiral galaxies, ellipticals formed in place from the material at hand.
From the press release [pdf].
“We started from the data, available in complete form only for the closer galaxies and in incomplete form for the more distant ones, and we filled the ‘gaps’ by interpreting and extending the data based on a scenario we devised” comments Mancuso. The analysis also took into account the phenomenon of gravitational lensing, which allows us to observe very distant galaxies belonging to ancient cosmic epochs.
In this “direct” manner (i.e., model-independent) the SISSA group obtained an image of the evolution of galaxies even in very ancient epochs (close, in a cosmic timescale, to the epoch of reionization). This reconstruction demonstrates that elliptical galaxies cannot have formed through the merging of other galaxies, “simply because there wasn’t enough time to accumulate the large quantity of stars seen in these galaxies through these processes”, comments Mancuso. “This means that the formation of elliptical galaxies occurs through internal, in situ processes of star formation.
The important take-away of this result is that it shows that the present theory of galaxy formation, where smaller spiral galaxies merge to form larger elliptical galaxies, does not fit the data. And if a theory does not fit the data, it must be abandoned.