Researchers measure size-luminosity relation of galaxies less than a billion years after Big Bang

A world crew of researchers together with the Kavli Institute for the Physics and Arithmetic of the Universe (Kavli IPMU) has studied the relation between galaxy dimension and luminosity of among the earliest galaxies within the universe taken by the brand-new James Webb Area Telescope (JWST), lower than a billion years after the Massive Bang, studies a brand new examine in The Astrophysical Journal Letters.

The result’s a part of the Grim Lens-Amplified Survey from Area (GLASS) Early-Launch Science Program, led by College of California, Los Angeles, Professor Tommaso Treu. It’s aimed toward learning the early universe when the first stars/galaxies ignited, which ionized the impartial gasoline within the universe on the time and allowed mild to shine by way of. That is known as the epoch of reionization.

Nonetheless, particulars of reionization have remained unknown as a result of telescopes till right this moment haven’t been able to observing galaxies on this interval of the universe’s historical past intimately. Discovering out extra concerning the epoch of reionization would assist researchers perceive how stars and galaxies have advanced to create right this moment’s universe as we see it.

One examine, led by Kavli IPMU JSPS Fellow Lilan Yang, and together with Undertaking Researcher Xuheng Ding, used multiband NIRCAM imaging information from the GLASS-JWST program to measure galaxy dimension and luminosity to determine the morphology and the size-luminosity relation from rest-frame optical to UV.

“It is the primary time that we are able to examine the galaxy’s properties in rest-frame optical at redshift bigger than 7 with JWST, and the size-luminosity is necessary for figuring out the form of luminosity operate which signifies the first sources liable for the cosmic reionization, i.e., quite a few faint galaxies or comparatively much less vibrant galaxies.

“The unique wavelength of sunshine will shift to longer wavelength when it travels from the early universe to us. Thus, the rest-frame wavelength is used to make clear their intrinsic wavelength, fairly than noticed wavelength. Beforehand, with Hubble Area Telescope, we all know the properties of galaxies solely in rest-frame UV band. Now, with JWST, we are able to measure longer wavelength than UV,” mentioned first writer Yang.

The researchers discovered the primary rest-frame optical size-luminosity relation of galaxies at redshift bigger than 7, or roughly 800 million years after the Massive Bang, permitting them to review the scale as operate of wavelength. They discovered the median dimension on the reference luminosity is roughly 450–600 parsecs and decreased barely from rest-frame optical to UV. However was this anticipated?

“The reply is we do not know what’s to anticipate. Earlier simulation research give a spread of predictions,” mentioned Yang.

The crew additionally discovered the slope of the scale–luminosity relationship was considerably steeper within the shortest wavelength band when permitting the slope to differ.

“That will recommend greater floor brightness density at shorter wavelength, therefore much less observational incompleteness correction when estimating luminosity operate, however the outcome is just not conclusive. We do not wish to over-interpret right here,” mentioned Yang.

The crew’s paper was printed on October 18, 2022, in The Astrophysical Journal Letters.