number_of_galaxies_in_universe_with_JWST_SMACS0723.ipynb by Pr Hervé Dole, IAS, Université Paris-Saclay updated: 20241215
The notebook computes the number of atoms in the Observable Universe, based on the extrapolation of deep JWST images of SMACS0723.
You need to have a fits image of : JWST f356 of SMACS0723 to compute the number of galaxies. Otherwise, read the comments to get the number.
The notebook organisation is the following:
- compute the number of galaxies in SMACS0723
- compute the sky area covered by SMACS0723 and the factor needed to cover the whole sky
- compute the mass of the sun, and the number of atoms in the sun
- compute the number of stars in a galaxy
We multiply the number of atoms in a star * numbers of stars in a galaxy * number of galaxies in the observable universe (as extrapolated from JWST SMACS0723) and get ~1.e79 atoms.
If we correct for the missing baryons we reach about 1.e80 atoms.
References:
- https://youtu.be/74EGTJElxGQ by Physics Explained, pen and pencil version.
- Fukugita & Peebles 2004 ApJ : https://arxiv.org/abs/astro-ph/0406095
- Nicastro et al., 2018, Nat : https://arxiv.org/abs/1806.08395
- Ettori, 2003, MNRAS : https://arxiv.org/abs/astro-ph/0305296
- JWST data download : https://mast.stsci.edu/search/ui/#/jwst/results?resolve=true&target=SMACS0723&data_types=image,measurements&instruments=NIRCAM&optical_element=F356W&custom_col_sel_0=productLevel&custom_col_val_0=3&radius=3&radius_units=arcminutes&useStore=false