Actio Nova – August 2024

Cosmic Optometry
In 1917 Einstein published his Theory of General Relativity I states that a mass, the size of our sun, measurably warps space and time. Photographs taken by Sir Arthur Eddington of curved light grazing the sun during a 1919 solar eclipse confirmed this theory.
By the 1930s Einstein proposed that such space time warping would generate two kinds of phenomena: the first was Gravity Waves. These are generated by the merging of massive black holes. Because they were so hard to detect, it wasn’t until 2015 that an instrument called the Laser Interferometer Gravitational-Wave Observatory (LIGO) was able to confirm its existence. Many subsequent studies have buttressed their reality.
Even decades earlier, Einstein’s second of his proposals, Gravitational Lensing, was confirmed. In this situation, massive structures, such as galaxy clusters, curve spacetime so much that the path light takes is visibly bent as it passes by. This bending is comparable to the bending of light in an optical lens.

This process has led to a bounty of information that would have been obscured to us if we depended purely online of sight observations.
A few years ago we had the privilege of having Brian Welch, at Johns Hopkins, demonstrate how gravitational lensing helped him and his team identify the earliest star, Earendel, that existed a mere 900 million years after the Big Bang. The previous record holder was 4 billion years after the Big Bang.

This image obtained from the European Space Agency on March 30, 2022, shows the star Earendel (arrow) captured by the NASA/ESA Hubble Space Telescope- NASA/ESA/AFP
The existence of this star was made possible only because the lensing created by a massive galactic cluster in the foreground magnified its image a thousand-fold. This study and subsequent observations by the James Webb Space Telescope confirm that this is a massive star of thousands of solar masses. Its presence at such an early stage challenges our models of the evolution of the universe.

Example of an Einstein Ring. Credit: ESA/Hubble & NASA; Acknowledgment: Judy Schmidt
This past year, JWST was able to detect a spectacular lensing effect called an Einstein Ring (predicted by the great man 90 years ago) surrounding the galaxy JWST ER1g at z=2, refracts light emanating from the galaxy JWST ERr which is located at the mind-bending distance of 17 billion light years. (While the observable universe is 13.8 billion years old, space has expanded, so our current observable distances are greater than that). This is the furthest lensing observation ever made.
The two galaxies are perfectly aligned so that study of the ring provides new information about dark matter. Careful study of this ring, and the unexpected large value of the refraction of light, has led astronomers to calculate the proportion of dark matter. Because this is a complete ring (they are usually arcs or portions of a ring) astronomers realized that they had underestimated the proportion of dark matter present in this galaxy. This, of course, means revising theories about the role of dark matter in galaxy formation. Despite the perplexities, the beauty of the observation is unmistakable.
Catching Up On Our Zzzs
Astronomers in the JADES program has been sleeping less at night as they gather more data about the evolution of early galaxies. JADES stands for JWST Advanced Deep Extragalactic Survey. Recent observation of the universe at 14 z (some 13.5 billion light years from Earth) has upended our notion that the early universe was simpler than the universe is today. The NIRCam and NIRSpec instruments on the Webb are designed to collect electromagnetic information at Infrared wavelengths. At such wavelengths EM waves can pass through cosmic dust and clouds which are impenetrable to the optically shorter wavelengths. The data gathered from these instruments have forced astronomy to revise its assumptions about our early cosmic evolution. NOTE: this article highlights data from Webb science in progress, which has not yet been through the peer-review process as of May 2024.
A z is an astronomical measure of distance that is tied to the well-established fact that the universe is expanding. The higher the z the further the distance. As the universe expands the wavelength of light emitted by galaxies and stars is lengthened from optical to infrared values: a phenomenon well known as the Doppler Effect. The exact rate of expansion is still a matter of some disagreement. Mindful of this issue, JADES set out to study the early formation of the universe close to the time of the Big Bang. Recent findings from JWST indicate that complex galaxies existed far earlier than was originally estimated.

Stefano Carniani from Scuola Normale Superiore in Pisa, Italy, and Kevin Hainline from the University of Arizona in Tucson, Arizona, principal Investigators of this study, obtained images that confirm the presence of a complex, extremely luminous galaxy existing some 300 million years after the Big Bang.
Spectrographic analysis of the light emanating from this galaxy indicates that this galaxy is a hotbed of new stars. In the graph below, note that the sharp rise in Brightness occurs at about 1.8 microns. This is known as the Lyman Alpha Break. Such a break occurs when multitudes of new stars emit high energy radiation in the ultraviolet region of the spectrum. Estimates of this galaxy’s size and mass support the idea that this is an active star generating galaxy.

This new information challenges many assumptions about how our early galaxy was formed. To begin with, most galaxy formation is thought to take up to a billion years. The existence of such a well-formed galaxy only 300 million years after the Big Bang forces astronomy to consider three possibilities. First, our theory about the rate of galaxy formation may have to be revised. Second, perhaps the time frame of the Big Bang may have to be reset. Finally, the role of dark energy in expanding space is going to have to be better understood.
Only one thing is certain: astronomy textbooks are going to have to be updated.