Erken evrende bu kadar çok sayıda galaksinin keşfi, galaksi oluşumuna ilişkin önceki bilgilerin potansiyel bir revizyonunu önermektedir.
NASA’nın yeni uzay teleskopu ile evrenin en eski galaksilerini keşfetmek.
Missouri Üniversitesi’nden Haojing Yan liderliğindeki bir gökbilimciler ekibi,[{” attribute=””>NASA’s James Webb Space Telescope (JWST) Early Release Observations and discovered 87 galaxies that could be the earliest known galaxies in the universe.
The discovery brings the astronomers closer to determining the appearance of galaxies in the universe, estimated to be 200-400 million years after the Big Bang, according to Yan, lead author and associate professor of physics and astronomy at MU.
“Finding such a large number of galaxies in the early parts of the universe suggests that we might need to revise our previous understanding of galaxy formation,” Yan said. “Our finding gives us the first indication that a lot of galaxies could have been formed in the universe much earlier than previously thought.”
A pair of color composite images from the galaxy cluster SMACS 0723-27 and its surrounding area taken by NASA’s James Webb Space Telescope through its Early Release Observations (ERO). A team of astronomers led by Haojing Yan at the University of Missouri used the data from these images to identify the objects of interest for their study. These include galaxies that could be the earliest known galaxies in the universe — about 200-400 million years after the Big Bang. The location of each object of interest is indicated by one of three different colored circles — blue, green, or red — on the color images. These colors correspond with the range of redshifts where they were found — high (blue), very high (green), or extremely high (red). Graphic by Haojing Yan and Bangzheng Sun. Credit: NASA, European Space Agency, Canadian Space Agency, and the Space Telescope Science Institute.
In the study, the astronomers searched for potential galaxies at “very high redshifts.” Yan said the concept of redshifts in astronomy allows astronomers to measure how far away distant objects are in the universe — like galaxies — by looking at how the colors change in the waves of light that they emit.
Haojing Yan. Credit: University of Missouri
“If a light-emitting source is moving toward us, the light is being ‘squeezed,’ and that shorter wavelength is represented by blue light, or blueshift,” Yan said. “But if that source [of light] bizden uzaklaşıyor, ürettiği ışık ‘geriliyor’ ve kırmızı ışık veya kırmızıya kayma ile temsil edilen daha uzun bir dalga boyuna değişiyor.”
Yan, Edwin Hubble’ın 1920’lerin sonlarında evrenimizin sürekli genişlediğine dair keşfinin, astronomide kırmızıya kaymaların nasıl kullanıldığını anlamanın anahtarı olduğunu söyledi.
“Hubble, bizim dışımızdaki galaksilerin[{” attribute=””>Milky Way galaxy are moving away from us, and the more distant they are, the faster they are moving away,” Yan said. “This relates to redshifts through the notion of distances — the higher the redshift an object is at, such as a galaxy, the further away it is from us.”
Therefore, Yan said the search for galaxies at very high redshifts gives astronomers a way to construct the early history of the universe.
“The speed of light is finite, so it takes time for light to travel over a distance to reach us,” Yan said. “For example, when we look at the sun, we aren’t looking at it as what it looks like in the present, but rather what it looked like some eight minutes ago. That’s because that’s how long it takes for the sun’s radiation to reach us. So, when we are looking at galaxies which are very far away, we are looking at their images from a long time ago.”
Using this concept, Yan’s team analyzed the infrared light captured by the JWST to identify the galaxies.
“The higher the redshift a galaxy is at, the longer it takes for the light to reach us, so a higher redshift corresponds to an earlier view of the universe,” Yan said. “Therefore, by looking at galaxies at higher redshifts, we are getting earlier snapshots of what the universe looked like a long time ago.”
The JWST was critical to this discovery because objects in space like galaxies that are located at high redshifts — 11 and above — can only be detected by infrared light, according to Yan. This is beyond what NASA’s Hubble Space Telescope can detect because the Hubble telescope only sees from ultraviolet to near-infrared light.
“JWST, the most powerful infrared telescope, has the sensitivity and resolution for the job,” Yan said. “Up until these first JWST data sets were released [in mid-July 2022], gökbilimcilerin çoğu, evrende kırmızıya kayma 11’in ötesinde çok az sayıda gökada olması gerektiğine inanıyordu. En azından, sonuçlarımız bu görüşe meydan okuyor. Bu keşfin buzdağının sadece görünen kısmı olduğuna inanıyorum çünkü kullandığımız veriler evrenin çok küçük bir alanına odaklanmıştı. Bundan sonra, JWST bize evrenimizin en derin kısımlarına dair yeni bir görüş sağlamaya devam ederken, diğer astronom ekiplerinin uzayın uçsuz bucaksız başka yerlerinde de benzer sonuçlar bulacağını tahmin ediyorum.”
Referans: Haojing Yan, Zhiyuan Ma, Chenxiaoji Ling, Cheng Cheng ve Jia-Sheng Huang, “First Batch of z ≈ 11–20 Aday Objects by James Webb Space Telescope Early Release Observations on SMACS 0723-73” tarafından ortaya çıkarıldı, 28 Aralık 2022 , bu Astrofizik Dergi Mektupları.
DOI: 10.3847/2041-8213/aca80c
