New observations from JWST

Discussion in 'Astronomy, Exobiology, & Cosmology' started by arfa brane, Mar 9, 2023.

  1. arfa brane call me arf Valued Senior Member

    The new space telescope has provided astronomers and cosmologists with 'exciting' new data.

    What do you think the discovery of old galaxies, which appear to have formed a mere 1 billion years after the big bang, means for the current models? Are the scientists scrambling to explain all the new images?
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  3. Pinball1970 Registered Senior Member

    A paper was published in the RAS,
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  5. Janus58 Valued Senior Member

    From my understanding, the problem they pose are that they appear to be too massive to have had enough time to have formed. This is all predicated on our ability to judge the mass of the galaxies in question.

    So, how do they do this? They start with the brightness of the galaxy. Then they apply something called the Initial Mass Function(IMF) to factor in the ratio of high mass to low mass stars. This is important because the luminosity of a star increases much faster than its mass does. As a result, the total mass of the number of dim stars needed to produce the amount of light equal to that of a much brighter star is greater than the mass of the brighter star. We have a pretty good idea what the IMF is for relatively nearby galaxies and it is consistent from galaxy to galaxy, so it is treated as being universal. So we use this IMF to estimate the mass of much further galaxies.
    But with these very early galaxies, the very real possibility arises that the IMF they are using to calculate their mass isn't correct, and was different during that part of the universe's formation. These galaxies could very well have a much higher proportion of very bright stars, meaning they don't need to be as massive in total to produce the amount of light they do. If the masses of these galaxies are much smaller, then their formation doesn't raise the red flag that massive galaxies do.

    In either case, this is the type of discovery science hopes for; one that teaches us something new about the universe, either that something allowed for massive galaxies to from that early, or that our assumption of a universal IMF is wrong.
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