Galaxies in the Early Universe Preferred their Food Cold

This illustration shows a galaxy forming only a few hundred million years after the big bang, when gas was a mix of transparent and opaque during the Era of Reionization. Data from NASA’s James Webb Space Telescope shows that cold gas is falling onto these galaxies. Credit: NASA/ESA/CSA/Joseph Olmsted (STScI)

One of the main objectives of the James Webb Space Telescope (JWST) is to study the early Universe by using its powerful infrared optics to spot the first galaxies while they were still forming. Using Webb data, a team led by the Cosmic Dawn Center in Denmark pinpointed three galaxies that appear to have been actively forming just 400 to 600 million years after the Big Bang. This places them within the Era of Reionization, when the Universe was permeated by opaque clouds of neutral hydrogen that were slowly heated and ionized by the first stars and galaxies.

This process caused the Universe to become transparent roughly 1 billion years after the Big Bang and (therefore) visible to astronomers today. When the team consulted the data obtained by Webb, they observed that these galaxies were surrounded by an unusual amount of dense gas composed almost entirely of hydrogen and helium, which likely became fuel for further galactic growth. These findings already reveal valuable information about the formation of early galaxies and show how Webb is exceeding its mission objectives.

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Remember Those Impossibly Massive Galaxies? They May Be Even More Massive

The first image taken by the James Webb Space Telescope, featuring the galaxy cluster SMACS 0723. Credit: NASA, ESA, CSA, and STScI

The James Webb Space Telescope (JWST) was designed to probe the mysteries of the Universe, not the least of which is what the first galaxies looked like. These galaxies formed during the Epoch of Reionization (aka. “Cosmic Dawn”), which lasted from about 100 to 500 million years after the Big Bang. By observing these galaxies and comparing them to ones that see closer to our own today, astronomers hope to test the laws of physics on the grandest of scales and what role (if any) Dark Matter and Dark Energy have played.

Unfortunately, early into its campaign, the JWST detected galaxies from this period so massive that they were inconsistent with our understanding of how the Universe formed. The most widely-accepted theory for how this all fits together is known as the Lambda Cold Dark Matter (LCDM) cosmological model, which best describes the structure and evolution of the Universe. According to the latest results from the Cosmic Dawn Center, these galaxies may be even more massive than previously thought, further challenging our understanding of the cosmos.

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Weekly Space Hangout -Sept 13, 2017: Dr. Claudia Lagos from ICRAR

Hosts:
Fraser Cain (universetoday.com / @fcain)
Dr. Paul M. Sutter (pmsutter.com / @PaulMattSutter)
Dr. Kimberly Cartier ( KimberlyCartier.org / @AstroKimCartier )
Dr. Morgan Rehnberg (MorganRehnberg.com / @MorganRehnberg ChartYourWorld.org)

Special Guest:
This week’s guest is Dr. Claudia Lagos (@CDPLagos).
Claudia is the Research Assistant at the International Centre for Radio Astronomy Research, in the University of Western Australia. Dr. Lagos is one of the core researchers for the Cosmic Dawn Centre (DAWN). Her expertise is in modelling of physical processes in galaxies, such as gas accretion onto galaxies, star formation, stellar feedback, gas accretion onto black holes, among other similar mechanisms.

Their stories this week:

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