The first AITN Lite will be a follow-up to last week’s bulletin about the first images coming from the James Webb Space Telescope (JWST). Last week, we discussed the spectacular images from the new facility, but this week we will discuss some of the possible science results that come from these initial images.

The article that I will be discussing is:

https://www.bbc.co.uk/news/science-environment-62311562

and a free, permanent research link to the paper that it refers to can be found here:

https://arxiv.org/abs/2207.12356

I have discussed in the Astronomy in the News bulletins #06 and #26 that the JWST will be detecting the earliest galaxies in the Universe by identifying the light from the first stars that were formed after the Big Bang. Simulations of galaxy formation show that star formation should begin 150-250 million years after the Big Bang, which would correspond to redshifts of z = 15-20.

To identify redshifts of galaxies, two different techniques are used, photometric and spectroscopic. The detections in this article correspond to photometric observations, which I will discuss here. Multiple observations are made of the galaxy at different wavelengths, and a model spectral energy distribution is fit to these measured points. This fit would then reveal the wavelengths at which the Lyman and Balmer breaks occur at (the links should give you more information!).

Using this method, the team here have identified a galaxy at a redshift of 16.7, or just 235 million years after the Big Bang. This detection will be followed up spectroscopically, also using JWST, to determine a more accurate redshift for this galaxy and confirm whether this is a good estimate. The JWST is, however, the perfect facility to make these extremely high redshift detections of galaxies as it operates in the infrared wavelength regime. At the redshifts in question, the Lyman and Balmer breaks would be in the infrared, as the higher the redshift, the redder an optical line will appear!

Curriculum topics to be considered
Electron orbits (Lyman and Balmer series come from this!)
Red shift