In the Dark

I know it’s the Bank Holiday weekend but I could resist a quick post about a new paper that hit the arXiv yesterday (where all new astrophysics papers worth reading can be found). It is led by Joe McCaffrey who is a PhD student in the Department of Theoretical Physics at Maynooth University. The paper has been submitted to the Open Journal of Astrophysics, but obviously I am conflicted so have assigned it to another editor.

UPDATE: the paper is now published here.

As many of you will be aware, there’s been a considerable to-do not to mention a hoo-hah about the detections by JWST of some galaxies at high redshift. Some of these have been shown not to be galaxies at high redshift after all, but some around z=10 seem to be genuine.

Anyway, the abstract of Joe’s paper is this:

Recent observations by JWST have uncovered galaxies in the very early universe via the JADES and CEERS surveys. These galaxies have been measured to have very high stellar masses with substantial star formation rates. There are concerns that these observations are in tension with the ΛCDM model of the universe, as the stellar masses of the galaxies are relatively high for their respective redshifts. Recent studies have compared the JWST observations with large-scale cosmological simulations. While they were successful in reproducing the galaxies seen in JADES and CEERS, the mass and spatial resolution of these simulations were insufficient to fully capture the early assembly history of the simulated galaxies. In this study, we use results from the Renaissance simulations, which are a suite of high resolution simulations designed to model galaxy formation in the early universe. We find that the most massive galaxies in Renaissance have stellar masses and star formation rates that are entirely consistent with the observations from the JADES and CEERS surveys. The exquisite resolution afforded by Renaissance allows us to model the build-up of early galaxies from stellar masses as low as 10⁴ M⊙ up to a maximum stellar mass of a few times 10⁷ M⊙. Within this galaxy formation paradigm, we find excellent agreement with JADES and CEERS. We find no tension between the ΛCDM model and current JWST measurements. As JWST continues to explore the high redshift universe, high resolution simulations, such as Renaissance, will continue to be crucial in understanding the formation history of early embryonic galaxies.

arXiv:2304.13755

The key figure is this one:

The solid curves show the number of galaxies of a given mass one would expect to see as a function of redshift in fields comparable to those observed with estimated values from observations (star-shaped symbols). As you can see the observed points are consistent with the predictions. There’s no tension, so you can all relax.

This entry was posted on April 29, 2023 at 2:58 pm and is filed under Maynooth, The Universe and Stuff with tags arXiv:2304.13755, Department of Theoretical Physics, High redshift galaxies, Joe McCaffrey, John Regan, Maynooth University. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.